[1]

Chapter 1

Introduction

1.1 Introduction

To protect our natural eco-systems from further damage is critical, especially for the survival

of some endangered species. The oceans, streams and lakes that are the lifeblood of many

local eco-systems are used as dumping grounds, hurting everything that relies on these water

sources. The great pacific garbage patch is a great example of the worst side of our wasteful

practices [1]

. Demands are increasing every year for water while resources are becoming more

and more limited. Since many individuals are unaware (or, sadly, just don’t care) that this

issue needs attention, it is up to more informed and proactive individuals and companies to

take up the slack. The increase in water demand is a contribution of various factors including

growing population, increased agricultural needs, industrial use of water and water needed for

electricity production. The problem of water waste is severe in countries where people are

using the same inefficient methods for irrigation of agricultural land [2]

.

1.1.1 Industrialization & Environment

Industrialization (or Industrialisation) is a process that happens in countries when they start to

use machines to do work that was once done by people. Industrialization changes the society

as it happens. During the industrialisation of a country people leave farming work to take

higher paid jobs in factories in towns. Industrialization is part of a process where people

adopt easier and cheaper ways to make things. Using better technology, it becomes possible

to produce more goods in a shorter span of time. A single person can produce more things.

After industrialization people also do more specialized jobs. For example before

industrialization, a shoemaker produced the whole shoe. He worked on one pair of shoes,

finished that, and then did the next pair of shoes. With industrialization, there are many

people involved in making shoes. An individual shoemaker has a smaller task, however.

There is one person that cuts the sole of the shoe. Another person stitches it on. In short there

is division of labour. The machines to make the shoes cost a lot of money so the factory will

be owned by a rich person who can afford the machines [3]

.

[2]

Industrialization in the name of growth has loaded tremendous pressure on environment.

Industrialization & environment in the developing countries tries to run hand to hand. But

knowingly or unknowingly, industrialization ran faster without caring for environment to win

the race. The pace of industrialization has increased several folds in last decade [4]

.

Probably most of the major environmental problems of the next century will result from the

continuation and sharpening of existing problems that currently do not receive enough

political attention. The problems are not necessarily noticed in many countries or then

nothing is done even the situation has been detected. The most emerging issues are climate

changes, freshwater scarcity, deforestation, and fresh water pollution and population growth.

These problems are very complex and their interactions are hard to define. It is very

important to examine problems through the social-economic-cultural system. Even the

interconnections between environmental problems are now better known, we still lack exact

information on how the issues are linked, on what degree they interact and what are the most

effective measures. One problem is to integrate land- and water use planning to provide food

and water security [5]

.

Rapid industrialization to meet the public need has deteriorated the environment to its fullest

extent during last two decade. Industrial effluents, polluted air, noise pollution, Green House

gas effect, etc not only a concern for human habitat but also a concern for the forthcoming

disasters. In order to lead a healthy life we are deteriorating the environment in shadow [4]

.

As described above, World over, the industries are becoming increasingly concerned about

achieving and demonstrating their environmental performance because of the growing

compulsions from tough legislations and mounting public pressures [4]

.

Environmental disasters such as Bhopal tragedy, Rhine river pollution, Chernobyl disaster,

Acid rain damage ,Ozone layer depletion has led to growing public pressures on governments

all over the world Which started imposing stringent legislation with severe penalties in

environmental issues related to environmental & safety system. These standards do not lay

down specific environmental performance criteria; these are system standards which describe

the management of environment based on company’s environmental policy, objectives and

targets defined on the basis of their significant environmental effects [4]

.

[3]

Industry is becoming increasingly concerned about achieving and demonstrating sound

environmental performance because of growing compulsions from stringent legislation and

Mounting public pressure. There was a time, not long ago, when the harm caused in

environment due to human and industrial activities was no body’s concern [4]

.

Pollutants affect not only living environment but also social, cultural, political and aesthetic

values. In the recent years there is a growing alertness against this environmental pollution [4]

.

On the one hand the advancements of Science & Technology have added to the human

comforts by giving us automobiles, electrical appliances better medicines, better chemical to

control harmful insects and pest but on the Approach for Assessing Environment other hand

they gave us a very serious problem to face pollution [4]

.

The continued increase in the pollution coupled with the industrial revolution has had the

vital impact on natural resources. The resultant deterioration of environment and fast

depletion of natural resources threaten the sustainability of economic development [4]

.

One of the most pressing and complex challenges facing by our generation are to search out a

workable synthesis between economic development and environmental behavior [4]

.

1.1.2 Industrial Water Pollution

Industry is a huge source of water pollution, it produces pollutants that are extremely harmful

to people and the environment. Many industrial facilities use freshwater to carry away waste

from the plant and into rivers, lakes and oceans.

Water pollution is caused due to the discharge of harmful chemicals and compounds in water,

which leaves the water unsuitable for drinking and other purposes. This renders the water

useless for humans, and also endangers aquatic life.

Pollution refers to contamination of the environment by harmful and waste materials, which

brings about a significant change in the quality of the surrounding atmosphere, hydrosphere,

biosphere, lithosphere & today even in the space. Water pollution signifies contamination of

water bodies, which make them unfit for drinking and other uses. Although, 70% of the Earth

is covered by water, the water of the seas and the oceans is saline and hence, cannot be used

for drinking, agriculture and industrial uses. Only the water bodies like lakes, ponds, rivers,

reservoirs and streams provide us with fresh water [6]

.

[4]

Agricultural and Industrial work has the use of many chemicals that can run-off into water

and pollute it. Metals and solvents from industrial work pollute rivers and lakes. Aquatic life

is endangered by these and made infertile. Pesticides are used to control weeds, insects and

fungi. Run-offs of these pesticides poison the aquatic life. If birds, humans and other animals

eat infected fish they may be poisoned. Petroleum is a different type of chemical pollutant

that pollutes water by oil spills in case a ship ruptures. Oil spills have a localized effect on

wildlife, but can spread for miles. This oil can cause the death of many fish and stick to the

feathers of seabirds. This loses their ability to fly.

Pollution happens when silt and other suspended solids like soil, construction, wash off

ploughed fields enters river banks. Eutrophication occurs under natural conditions, in lakes,

rivers and other water bodies. This is an aging process that fills in the water body with

sediment and organic matter. In case these sediments enter various water bodies, fish

respiration is affected; plant productivity and water depth is decreased [7]

.

Industrial Effluents in the Water

Water pollution is caused by emission of domestic or urban sewage, agricultural waste,

pollutants and industrial effluents into water bodies. Nowadays, its main source is the waste

material discharged by industrial units. Waste materials like acids, alkalies, toxic metals, oil,

grease, dyes, pesticides and even radioactive materials are poured into the water bodies by

many industrial units. Some other important pollutants include polychlorinated biphenyl

(PCB) compounds, lubricants and hot water discharged by power plants. The pollutants

unloaded into the water bodies usually dissolve or remain suspended in water. Sometimes,

they also accumulate on the bottom of the water bodies.

Another important pollutant, that can endanger marine life, is the oil spilled by oil tanks. As

per the estimates of the United Nations, 1.3 million barrels of oils are spilled annually into the

Persian Gulf, and about 285 million gallons are spilled into the oceans every year.

The industrial effluents contain pollutants like asbestos, phosphates, phenolic compounds,

pesticides, toxic dyes, mercury, lead, nitrates, sulfur, sulfuric acid, oil and many other

poisonous materials. In many countries, industrial water is not treated adequately before

discharging it into rivers or lakes. This is particularly true in the case of small-scale industries

that do not have sufficient capital to invest in pollution control equipment [6]

.

[5]

1.1.3 Organic Pollution Due to Industrialization

Here in the present study emphasis has been put on water pollution caused by organic

pollutants & removal of such organic pollutants from water bodies. Organic pollutants

include Oil, gasoline, plastics, pesticides, cleaning solvents, detergents. They enter into the

environment from various sources like industrial effluents, household cleansers, surface

runoff from farms & yards. Organic pollutants can (1) threaten human health by causing

nervous system damage (some pesticides), reproductive disorders (some solvents) and some

cancers (gas, oil, solvents). (2) Harm fish and wildlife [8]

.

Organic pollution originates from domestic sewage, urban run-off, industrial effluents and

agriculture wastewater, sewage treatment plants and industry including food processing, pulp

and paper making, agriculture and aquaculture. During the decomposition process of organic

pollutants the dissolved oxygen in the receiving water may be consumed at a greater rate than

it can be replenished, causing oxygen depletion and having severe consequences for the

stream biota. Wastewater with organic pollutants contains large quantities of suspended

solids which reduce the light available to photosynthetic organisms and, on settling out, alter

the characteristics of the river bed, rendering it an unsuitable habitat for many invertebrates.

Organic pollutants include pesticides, fertilizers, hydrocarbons, phenols, plasticizers,

biphenyls, detergents, oils, greases, pharmaceuticals, proteins and carbohydrates [9, 10, 11]

.

Organic Pollutants:

Persistent organic pollutants (POPs) are toxic chemicals that adversely affect human health

and the environment around the world. Because they can be transported by wind and water,

most POPs generated in one country can and do affect people and wildlife far from where

they are used and released. They persist for long periods of time in the environment and can

accumulate and pass from one species to the next through the food chain [12]

.

Persistent Organic Pollutants (POPs) are chemical substances that persist in the environment,

bio-accumulate through the food web, and pose a risk of causing adverse effects to human

health and the environment. With the evidence of long-range transport of these substances to

regions where they have never been used or produced and the consequent threats they pose to

the environment of the whole globe, the international community has now, at several

[6]

occasions, called for urgent global actions to reduce and eliminate releases of these

chemicals.

Highly toxic to humans and the environment

Persistent in the environment, resisting bio-degradation

Taken up and bio-accumulated in terrestrial and aquatic ecosystems

Capable of long-range, transboundary atmospheric transport and deposition

In nature these substances affect plant and animal development and growth. They can cause

reduced reproductive success, birth defects, behavioral changes and death. They are

suspected human carcinogens and disrupt the immune and endocrine systems [13]

.

Surfactants have large applications in textiles, fibers, food, paints, polymers, cosmetics,

pharmaceuticals, mining, oil recovery, pulp-paper industries etc. & in laundry, soaps,

dishwashing liquids & shampoo. Other important uses are in the many industrial applications

for surfactants in lubricants, emulsion polymerisation, textile processing, mining flocculates,

petroleum recovery, wastewater treatment and many other products and processes.

Surfactants are also used as dispersants after oil spills. There are hundreds of compounds that

can be used as surfactants and are usually classified by their ionic behaviour in solutions:

anionic, cationic, non-ionic or amphoteric (zwiterionic). Each surfactant class has its own

specific properties. There are many sources of surfactants that are discharged into natural

waters. Industrial sources include textile, surfactant and detergent formulation. Surfactants

are also used in laundries and households and are therefore found in discharges from sewage

treatment works. They also have agricultural applications in pesticides, dilutants and

dispersants [14]

.

Surfactants are compounds composed of both hydrophilic and hydrophobic or lipophobic

groups. In view of their dual hydrophilic and hydrophobic nature, surfactants tend to

concentrate at the interfaces of aqueous mixtures; the hydrophilic part of the surfactant

orients itself towards the aqueous phase and the hydrophobic parts orient itself away from the

aqueous phase into the second phase.

[7]

The hydrophobic part of a surfactant molecule is generally derived from a hydrocarbon

containing 8 to 20 carbon atoms (e.g. fatty acids, paraffins, olefins, alkylbenzenes). The

hydrophilic portion may either ionise in aqueous solutions (cationic, anionic) or remain un-

ionise (non-ionic). Surfactants and surfactant mixtures may also be amphoteric or

zwitterionic [14]

.

Surfactants are responsible for causing foams in rivers and effluent treatment plants and they

reduce the quality of water. Surfactants cause changes in ecosystem. Prolonged exposure of

skin to surfactants can disrupt the lipid coating that protects skin (and other) cells. Surfactant

presence into surface water, such as rivers or lakes, may lead to a harmful situation for

aquatic flora and fauna, due to the fact that may interact with oxygen transfer by modifying

surface tension. Binding ability of these products with other dangerous substances (such as

pharmaceuticals) is another hazardous property that may damage environmental equilibrium

[14].

Dyes are the one of the major constituents of the wastewater generated from many industries

related to textile, paint and varnishes, ink, plastics, pulp and paper, cosmetics, tannery etc.

and also of the industries that produce dyes. Water pollution due to effluents from textile

dyeing industry is a cause of serious concern. Color is an important aspect of human world.

We like to wear clothes of all kinds of colors and hues, eat food decorated with colors, even

our medicines are colorful. No wonder then, that a lot of research has gone into the

production of color. Today there are more than ten thousand dyes available commercially and

seven lakh tons of dyes are produced annually [15]

. Dyes can be of many different structural

varieties like acidic, basic, disperse, azo, anthraquinone based and metal complex dyes

among others. The textile industry is the largest consumer of dye stuffs. During the coloration

process a large percentage of the synthetic dye does not bind to the textile yarn and is lost to

the waste stream. Approximately 10-15% dyes are released into the environment during

dyeing process making the effluent highly colored and aesthetically unpleasant. The residual

dyes from different sources (e.g., textile industries, paper and pulp industries, dye and dye

intermediates industries, pharmaceutical industries, tannery, and Kraft bleaching industries,

etc.) are considered a wide variety of organic pollutants introduced into the natural water

resources or wastewater treatment systems [15]

.

[8]

The environmental issues associated with residual dye content or residual colour in treated

textile effluents are always a concern for each textile operator that directly discharges, both

sewage treatment works and commercial textile operations, in terms of respecting the colour

and residual dye requirements placed on treated effluent discharge. High concentrations of

textile dyes in water bodies stop the reoxygenation capacity of the receiving water and cut off

sunlight, thereby upsetting biological activity in aquatic life and also the photosynthesis

process of aquatic plants or algae [15]

.

The main environmental concern with dyes is their absorption and reflection of sunlight

entering the water and thus causes reduction in photosynthesis and DO level in river water. In

addition, some dyes degrade into compounds that have toxic, mutagenic and carcinogenic

effect on living organism. The effluent from textile industries thus carries a large number of

dyes and other additives which are added during the colouring process. These are difficult to

remove in conventional water treatment procedures and can be transported easily through

sewers and rivers especially because they are designed to have high water solubility. Thus

dyes are a potential hazard to living organisms. It is hence important to safeguard the

environment from such contaminants [16]

.

Phenolic resins, which are used as a binding material in insulation materials, chipboard,

paints, and casting sand foundries, are the major source of phenol emissions. Phenol is also

found in medicinal preparations including throat lozenges, mouthwashes, gargles, and

antiseptic lotions. Presence of phenolic compounds even at low concentration in the industrial

waste water adversely affects aquatic as well as human life directly or indirectly when

disposed off to public sewage, river or surface water. Sometimes these form complex

compounds with metal ions, discharged from other industries, which are more carcinogenic in

nature than the Phenolic compounds. The toxicity imparted by phenolic compounds is

responsible for health hazards and dangerous to aquatic life [17]

.

Phenol, also known as carbolic acid, is an important organic synthetic raw materials, white

needle-like crystals at room temperature, has a special smell, soluble in water, exposed to the

air can be oxidized into pink colour. Phenol is widely used, mainly as a raw materials and

intermediates for the manufacture of phenolic resin, the production of herbicides, wood

preservatives, fertilizers, explosives, rubber, paper, pharmaceutical synthesis industry. Phenol

can coagulate protein, has a bactericidal effect, Lysol children disinfectant phenol and cresol

[9]

soap, used as disinfectants, pesticides, etc. In the production process, if not pay attention to

the protection or due to various accidents, phenol can cause acute poisoning of the human

body; the most common is skin lesions. Phenol is a highly toxic substance can be absorbed

through the skin, gastrointestinal, respiratory and systemic symptoms of poisoning, a large

number of short-term exposure to phenol can cause acute damage of the central nervous

system, liver and kidney, cardiac muscle, blood and other multi-organ systems. Due to the

inhalation of high concentrations of phenol vapor or dust cause acute poisoning (it is very

rare), common skin contact is not timely processing of the damage caused. Phenol has a

strong corrosive effect on skin and mucous membrane, skin contact cause severe burns of the

local skin, swelling of the skin, black necrosis, can also be absorbed through the skin into the

body cause toxic effects to heart, liver, kidney, nervous system. Mild cases are dizziness,

headache, fatigue, nausea, irritability and other symptoms of severe cases quickly to

unconscious [18]

.

Pesticides are an area of concern for maintaining water quality because of their widespread

use. These chemicals are used in both urban areas and agricultural settings. Pesticides are

used by a wide spectrum of users, from individuals, to companies, to municipalities [19]

. The

large-scale application of pesticides and herbicides in agricultural field and forestry, fast

growing of agrochemical industries worldwide and the domestic activity of controlling pest

cause various pesticides and herbicides entering into the surface and groundwater resources.

The leaching runoff and industrial discharges are responsible for this contamination in

surface water. Some pesticides are "lipophilic", meaning that they are soluble in, and

accumulate in, fatty tissue such as edible fish tissue and human fatty tissue [20]

.

Phosphate is often used by agriculture in forms of pesticides/insecticides are water soluble. In

a period of a few weeks or months, phosphate added to the soil converts to less soluble forms

if it has not been taken up by plants. Unused phosphate often precipitates with calcium, iron,

and aluminum, or is incorporated into organic matter and is essentially insoluble. At this

point, phosphate poses little danger to the water system. The exception to this situation occurs

in very sandy soils, where some leaching may take place. A more serious problem connected

with phosphate is when it enters surface waters by way of runoff. Phosphate is often

responsible for eutrophication of freshwater, as nitrogen is in marine waters. The result of

large amounts of phosphate reaching surface waters is often a great increase in growth of

[10]

algae and the reduction of other life forms in these waters. The water solubility of an

insecticide is a measure of how easily it goes into solution with water. When these

compounds go into solution they are capable of leaching or running off into bodies of water.

Many systemic pesticides are water soluble to allow them to be taken up into plants. Other

pesticides are formulated in water soluble forms to facilitate their application in water

mixtures or reduce their potential for damage to plant foliage. These water soluble pesticides

can be readily dissolved in water and carried through the soil from one location to another

[19].

1.1.4 Effluent Characteristics of Textile, Pharmaceutical & Pesticide Industries

In many arid and semi-arid countries water is becoming an increasingly scarce resource and

planners are forced to consider any sources of water which might be used economically and

effectively to promote further development. Many countries have included wastewater reuse

as an important dimension of water resources planning.

1.1.4.1 Characteristics of Effluent Water in Textile Industries

Textile sector is putting enormous impact on country’s economy out of various activities in

textile industry, chemical processing contributes about 70% of pollution. Waste stream

generated in this industry is essentially based on water-based effluent generated in the various

activities of wet processing of textiles. It is well known that wet processing mills consume

large volume of water for various processes such as sizing, desizing, and scouring, bleaching,

mercerization, dyeing, printing, finishing and ultimately washing. In fact, in a practical

estimate, it has been found that 45% material in preparatory processing, 33% in dyeing and

22% are re-processed in finishing. The fact is that the effluent in textile generated in different

steps is well beyond the standard and thus it is highly polluted and dangerous [21]

.

[11]

Table 1.1:Characteristics of Waste Water from Textile Chemical Processing

Properties Unit Standards Cotton Synthetic Wool

pH -- 5.5 – 9.0 8 - 12 7 - 9 3 - 10

BOD,5 days mg/L 30 - 350 150 - 750 150 - 200 5000 – 8000

COD mg/L 250 200 - 2400 400 - 650 10,000 – 20,000

TDS mg/L 2100 2100 - 7700 1060 - 1080 10,000 – 13,000

Classification of Textile Waste Which are Generated in Textile Industry

Textile waste is broadly classified into four categories, each of having characteristics that

demand different pollution prevention and treatment approaches. Such categories are

discussed as follow;

1. Hard to Treat Wastes

This category of waste includes those that are persistent, resist treatment, or interfere with the

operation of waste treatment facilities. Non-biodegradable organic or inorganic materials are

the chief sources of wastes, which contain colour, metals, phenols, certain surfactants, toxic

organic compounds, pesticides and phosphates [21]

.

The chief sources are:

Color & metal → dyeing operation

Phosphates → preparatory processes and dyeing

Non-biodegradable organic materials → surfactants

Since these types of textile wastes are difficult to treat, the identification and elimination of

their sources are the best possible ways to tackle the problem. Some of the methods of

prevention are chemical or process substitution, process control and optimization,

recycle/reuse and better work practices [21]

.

[12]

B. Hazardous or Toxic Wastes:

These wastes are a subgroup of hard to treat wastes. But, owing to their substantial impact on

the environment, they are treated as a separate class. In textiles, hazardous or toxic wastes

include metals, chlorinated solvents, non-biodegradable or volatile organic materials. Some

of these materials often are used for non-process applications such as machine cleaning.

C. High Volume Wastes:

Large volume of wastes is sometimes a problem for the textile processing units. Most

common large volume wastes include:

High volume of waste water

Wash water from preparation and continuous dyeing processes and alkaline wastes

from preparatory processes

Batch dye waste containing large amounts of salt, acid or alkali

These wastes sometimes can be reduced by recycle or reuse as well as by process and

equipment modification.

D. Dispersible Wastes:

The following operations in textile industry generate highly dispersible waste:

Waste stream from continuous operation (e.g. preparatory, dyeing, printing and

finishing)

Print paste (printing screen, squeeze and drum cleaning)

Lint (preparatory, dyeing and washing operations)

Foam from coating operations

Solvents from machine cleaning

Still bottoms from solvent recovery (dry cleaning operation)

Batch dumps of unused processing (finishing mixes) [21]

[13]

1.1.4.2 Characteristics of Effluent Water in Pharmaceutical Industries

Waste waters from pharmaceutical industries are complex, with a variable nature. The

wastewater generated from pharmaceutical industry generally liquid - based wastewater

generated in the various processes as mentioned below. Wastewater consists of high organic

content thereby making the wastewater as high COD wastewater [22]

.

Water is used and wastewater is generated in pharmaceutical manufacturing processes as

follows:

Water of reaction: Water formed during the chemical reaction.

Process solvent: Water used to transport or support the chemicals involved in the

reaction process; this water is usually removed from the process through a separation

stage, such as centrifugation, decantation, drying, or stripping.

Process stream washes: water added to the carrier, spent acid, or spent base which has

been separated from the reaction mixture, in order to purify the stream by washing away

the impurities.

Product washes: water added to the reaction medium to purify an intermediate or final

product by washing away the impurities (this water is subsequently removed through a

separation stage); or water used to wash the crude product after it has been removed from

the reaction medium.

Spent Acid/Caustic: spent acid and caustic streams, which may be primarily water,

discharged from the process during the separation steps which follow the reaction step in

which acid and basic reagents are used to facilitate, catalyze, or participate.

Condensed steam: steam used as a sterilizing medium and in steam strippers for solvent

recovery and wastewater treatment [23]

.

Table 1.2 shows general characteristics of Effluent Generated from Pharmaceutical

Industry [22]

.

[14]

Table 1.2: General Characteristic of Effluent Generated from Pharmaceutical Industry

Sr. No. Parameters Unit Concentration

1 pH -- 1.5 – 6.0

2 BOD (5days, 20ºC) mg/L 900 – 4000

3 COD mg/L 2000 – 6000

4 Total Dissolved Solid (TDS) mg/L 1350 – 7250

5 Total Suspended Solids (TSS) mg/L 500 – 2000

6 Total Kjeldahl Nitrogen (TKN) mg/L 800 – 1000

7 Oil & Grease mg/L 35 – 2000

8 Phenol mg/L 18 – 25

1.1.4.3 Characteristics of Effluent Water in Pesticide/Insecticide Manufacturing

Industries

Agrochemical/Pesticide wastewater has great pollution problems due to its high Chemical

Oxygen Demand, Biochemical Oxygen Demand, high Total Dissolved Solids and highly

alkaline pH [24]

.

Moreover the wastewater depicts wide variation in the wastewater characteristics depending on

the type of agrochemicals manufactured and on the use of raw materials utilized. Additionally

the high pH and TDS also add to the environmental problems [24]

.

Because of the nature of pesticides and their components, wastewaters generated from

manufacturing plants usually contain toxins. The pollutants or groups of pollutants likely to be

present in raw wastewater include halomethanes, cyanides, haloethers, phenols, polynuclear

aromatics, heavy metals, chlorinated ethane and ethylenes ,pesticides, dienes [25]

.

[15]

Water consumption & waste generation:

Washing and cleaning operations provide the principal sources of wastewater in formulating

and packaging operations. Because these primary sources are associated with cleanup of spills,

leaks, area wash downs, and storm water runoff.

Wastewaters from formulation and packaging operations typically have low levels of BOD,

COD and TSS, and pH is generally neutral [25]

.

Table 1.3 shows general characteristics of effluent generated from pesticide industry [24]

.

Table 1.3: General Characteristic of Effluent Generated from Pesticide Industry

Sr.

No. Parameters Unit Concentration

1 pH -- 12 - 14

2 BOD (5days, 20ºC) mg/L 2000 - 3000

3 COD mg/L 6000 - 7000

4 Total Dissolved Solid (TDS) mg/L 12000 - 13000

5 Total Suspended Solids (TSS) mg/L 2000 - 2500

1.1.5 Recycle & Reuse

Fresh water is a scarce commodity; People at all levels from general public to, governmental

bodies, and industry understand the implications of good quality water availability in terms of

quantity, cost and wastage. As a consequence, there is an emerging consensus on wastewater

recycle/reuse [26]

.

Recycling is a process, to prevent waste, to change (waste) materials into new products

which are of potentially useful. It reduces the consumption of fresh raw materials, reduces

energy usage, reduces air pollution (from incineration) & water pollution (from landfilling)

[16]

by reducing the need for ―conventional‖ waste disposal, & lower greenhouse gas emissions

[27, 28].

Recycling is a key component of modern waste reduction & is the third component of

―Reduce, Reuse & Recycle‖ waste hierarchy. The hierarchy has taken many forms over the

past decade, but the basic concept has remained the cornerstone of most waste minimization

strategies. The aim of the waste hierarchy is to extract the maximum practical benefits from

products & to generate the minimum amount of waste.

In the recycling process; discards are separated into materials that may be incorporated into

new products. This is different from reuse in that energy is used to change the physical

properties of the material. Initiatives include Composting, Beverage Container Deposits &

buying products with a high content of post-consumer material. Within recycling there is

distinction between two types:

Upcycle – Converting low-value materials into high-value products. (more desirable)

Downcycle – Converting valuable products into low-value raw materials. (less

desirable)

To reuse is to use an item again after it has been used. This includes conventional reuse

where the item is used again for the same function, & new-life reuse where it is used for a

different function. In contrast, recycling is the breaking down of the used item into raw

materials which are used to make new items [29]

.

Reusing and recycling alternative water supplies is a key part of reducing the pressure on our

water resources and the environment. Helping us adapt to climate change and population

growth. When considering alternative water supplies, you should choose the most appropriate

water source, taking into account end use, risk, resource and energy requirements.

One should look into reusing low-risk water sources, such as rainwater or storm water, before

recycling higher risk source water, such as grey water and sewage.

Using rainwater is an easy and effective way to conserve our water supplies and

reduce the amount of mains water you use.

[17]

Grey water (all non-toilet household wastewater) can be a good water resource during

times of drought and water restrictions, but its reuse can carry health and

environmental risks.

Recycling wastewater can ease the pressure on our water resources and avoid the need

to discharge wastewater to the environment. Recycling wastewater can provide water

that, with some management controls, is suitable for a wide range of uses including

irrigation and toilet flushing.

Reusing and recycling industrial water can ease the pressure on our water resources

and avoid the need to discharge to the sewer and/or environment. With appropriate

management, which may include treatment, industrial water can be used for a wide

range of purposes including industrial uses (e.g. cooling or material washing) or non-

industrial uses (e.g. irrigation or toilet flushing). To reuse industrial water in a safe

and sustainable way you should identify, assess and appropriately manage the risks

[30].

Public awareness and government application of effluent standards has already forced

many industries to implement appropriate treatment technologies. Initially, industries

adopted simple physico-chemical treatment systems, but rapid degradation of the

environment has forced governments to implement more stringent regulations for

wastewater effluent and these standards have led to more advanced biological and

membrane technologies. As water for industrial applications becomes less easily

accessible, industry is looking for ways to recycle and reuse treated water [31]

.

Reusing wastewater is an attractive economic alternative and helps conserve an essential

commodity for future generations. Economic use also reduces the quantity of waste diverted

to treatment facilities and further lowers treatment costs. Companies invest in wastewater

treatment and reuse not just to comply with effluent standards but because product recycling

and raw material recovery benefit a company’s image as well as the bottom line. In contrast

to agriculture, only a small fraction of industrial water is actually consumed. Most is

discharged as wastewater [31]

.

[18]

1.1.5.1 Reuse of Treated Industrial or Municipal Wastewater

Treatment of industrial wastewater using appropriate technology and recycling treated water

back to the same or a different process is one solution. Reclaimed wastewater, for example,

has been used for years to replace cooling and boiler feed water. Municipal wastewater can

be used in industrial applications only after some tertiary treatment depending on the

application.

In Italy, effluent for industry and agriculture started in the early 1980s. Because there can be

problems with reclaimed municipal wastewater such as scaling, corrosion, bacterial slime or

fouling and foaming, proper care has to be taken during treatment in the form of disinfection,

regular monitoring, and avoiding physical contact with reclaimed water. Scaling reduces heat

transfer in cooling towers due to deposits of impurities such as calcium, magnesium, sodium

chloride and silica. Effluent from municipal wastewater treatment plants can be used for

boiler feed water after advanced treatment with membrane technology [31]

.

1.1.6 Pollutant Removal Techniques

However, years of increased industrial, agricultural & domestic activities have resulted in the

generation of large amount of wastewater containing a number of toxic pollutants, which are

polluting the available fresh water continuously. With the realization that pollutants present

in water adversely affect human & animal life, domestic activities, pollution control &

management is now a high priority area. The availability of clean water for various activities

is becoming the most challenging task for researchers & practitioners worldwide.

Toxic organic pollutants cause several environmental problems to our environment. The most

common organic pollutants named persistent organic pollutants (POPs). POPs are compounds

of great concern due to their toxicity, persistence, long-range transport ability [32]

, travel long

distances and persist in living organisms. POPs are carbon-based chemical compounds and

mixtures. Many of these compounds have been or continue to be used in large quantities and

due to their environmental persistence, have the ability to bioaccumulate and biomagnify [33]

.

Efficient techniques for the removal of highly toxic organic compounds from water have

drawn significant interest. A number of methods such as coagulation, filtration with

coagulation, precipitation, ozonation, adsorption, ion exchange, reverse osmosis and

[19]

advanced oxidation processes have been used for the removal of organic pollutants from

polluted water and wastewater [34]

. Advancements in water treatment technology have

affected all areas of industrial water treatment. Although mechanical filtration, such as

reverse osmosis, is widely employed to filter contaminants, other technologies including the

use of ozone generators, wastewater evaporation and bioremediation are also able to address

the challenges of industrial water treatment [35]

. Ozone treatment is a process in which ozone

gas is injected into waste streams as a means to reduce or eliminate the need for water

treatment chemicals or sanitizers that may be hazardous, including chlorine [36]

. Most

wastewater treatment plants generate ozone by imposing a high voltage alternating current (6

to 20 kilovolts) across a dielectric discharge gap that contains an oxygen-bearing gas. Ozone

is generated onsite because it is unstable and decomposes to elemental oxygen in a short

amount of time after generation. Ozone is a very strong oxidant and virucide. The

mechanisms of disinfection using ozone include: (1) Direct oxidation/destruction of the cell

wall with leakage of cellular constituents outside of the cell. (2) Reactions with radical by-

products of ozone decomposition. (3) Damage to the constituents of the nucleic acids (purines

and pyrimidines). When ozone decomposes in water, the free radicals hydrogen peroxy

(HO2) and hydroxyl (OH) that are formed have great oxidizing capacity and play an active

role in the disinfection process. It is generally believed that the bacteria are destroyed because

of protoplasmic oxidation resulting in cell wall disintegration (cell lysis) [37]

. Coagulation

consists of the addition of a chemical that, through a chemical reaction, forms an insoluble

end product that serves to remove substances from the wastewater. Polyvalent metals are

commonly used as coagulating chemicals in wastewater treatment and typical coagulants

would include lime (that can also be used in neutralization), certain iron containing

compounds (such as ferric chloride or ferric sulfate) and alum (aluminum sulfate) [38]

. Ion

exchange involves the exchange or replacement of dissolved constituents by attachment to an

electrostatically ion exchange material, which often consists of a synthetic resin. Ion

exchange is a reversible chemical reaction wherein positively or negatively charged ions

present in the water are replaced by similarly charged ions present within the resin. When the

replacement ions on the resin are exhausted, the resin is recharged with more replacement

Ions. The process relies on the fact that water solutions must be electrically neutral.

Therefore, ions in the resin bed are exchanged with ions of similar charge in the water and as

result of the exchange process; no reduction in ions is obtained. But its applicability is limited

since the technology is not capable of removing TDS levels above approximately 5000 mg/L.

[20]

In the reverse osmosis process cellophane-like membranes separate purified water from

contaminated water [39]

. RO is when a pressure is applied to the concentrated side of the

membrane forcing purified water into the dilute side, the rejected impurities from the

concentrated side being washed away in the reject water [40]

. Advanced oxidation processes

(abbreviation: AOPs), in a broad sense, refers to a set of chemical treatment procedures

designed to remove organic (and sometimes inorganic) materials in water and waste water by

oxidation through reactions with hydroxyl radicals (·OH) [41]

.

Among all these above mentioned methods have been found to be limited, since they often

involve high capital and operational costs. On the other hand ion exchange and reverse

osmosis are more attractive processes because the pollutant values can be recovered along

with their removal from the effluents. Reverse osmosis, ion exchange and advanced oxidation

processes do not seem to be economically feasible because of their relatively high investment

and operational cost [34]

.

Among the possible techniques for water treatments, the adsorption process by solid

adsorbents shows potential as one of the most efficient methods for the treatment and

removal of organic contaminants in wastewater treatment. Adsorption has advantages over

the other methods because of simple design and can involve low investment in term of both

initial cost and land required. The adsorption process is widely used for treatment of

industrial wastewater from organic and inorganic pollutants and meet the great attention from

the researchers. In recent years, the search for low-cost adsorbents that have pollutant –

binding capacities has intensified. Materials locally available such as natural materials,

agricultural wastes and industrial wastes can be utilized as low-cost adsorbents. Activated

carbon produced from these materials can be used as adsorbent for water and wastewater

treatment RO can also act as an ultra-filter removing particles such as some micro-organisms

that may be too large to pass through the pores of the membrane [42]

.

1.1.7 Adsorption Phenomena

Adsorption is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid

to a surface [43]

. This process creates a film of the adsorbate on the surface of the adsorbent.

This process differs from absorption, in which a fluid (the absorbate) permeates or is

dissolved by a liquid or solid (the absorbent) [44]

. Adsorption is a surface-based process while

[21]

absorption involves the whole volume of the material. The term sorption encompasses both

processes, while desorption is the reverse of it. Adsorption is a surface phenomenon [45]

.

Similar to surface tension, adsorption is a consequence of surface energy. In a bulk material,

all the bonding requirements (be they ionic, covalent, or metallic) of the constituent atoms of

the material are filled by other atoms in the material. However, atoms on the surface of the

adsorbent are not wholly surrounded by other adsorbent atoms and therefore can attract

adsorbates. The exact nature of the bonding depends on the details of the species involved,

but the adsorption process is generally classified as physisorption (characteristic of weak van

der Waals forces) or chemisorption (characteristic of covalent bonding). It may also occur

due to electrostatic attraction [45]

.

Adsorption is present in many natural, physical, biological, and chemical systems, and is

widely used in industrial applications such as activated charcoal, capturing and using waste

heat to provide cold water for air conditioning and other process requirements, synthetic

resins, increase storage capacity of carbide-derived carbons, and water purification.

Adsorption, ion exchange, and chromatography are sorption processes in which certain

adsorbates are selectively transferred from the fluid phase to the surface of insoluble, rigid

particles suspended in a vessel or packed in a column [46]

.

1.1.7.1 IUPAC Definition of Adsorption

Increase in the concentration of a substance at the interface of a condensed and a liquid or

gaseous layer owing to the operation of surface forces.

Adsorption of proteins is of great importance when a material is in contact with blood or

body fluids. In the case of blood, albumin, which is largely predominant, is generally

adsorbed first, and then rearrangements occur in favor of other minor proteins according to

surface affinity against mass law selection (Vroman effect) [47]

.

Adsorbed molecules are those that are resistant to washing with the same solvent medium in

the case of adsorption from solutions. The washing conditions can thus modify the

measurement results, particularly when the interaction energy is low [47]

.

Adsorption is a surface phenomenon with common mechanism for organic and inorganic

pollutants removal. When a solution containing absorbable solute comes into contact with a

[22]

solid with a highly porous surface structure, liquid–solid intermolecular forces of attraction

cause some of the solute molecules from the solution to be concentrated or deposited at the

solid surface. The solute retained (on the solid surface) in adsorption processes is called

adsorbate, whereas, the solid on which it is retained is called as an adsorbent. This surface

accumulation of adsorbate on adsorbent is called adsorption. This creation of an adsorbed

phase having a composition different from that of the bulk fluid phase forms the basis of

separation by adsorption technology [34]

.

Different types of adsorbents are classified into natural adsorbents and synthetic adsorbents.

Natural adsorbents include charcoal, clays, clay minerals, zeolites, and ores. These natural

materials, in many instances are relatively cheap, abundant in supply and have significant

potential for modification and ultimately enhancement of their adsorption capabilities.

Synthetic adsorbents are adsorbents prepared from Agricultural products and wastes, house

hold wastes, Industrial wastes, sewage sludge and polymeric adsorbents. Each adsorbent has

its own characteristics such as porosity, pore structure and nature of its adsorbing surfaces.

Many waste materials used include fruit wastes, coconut shell, scrap tyres, bark and other

tannin-rich materials, sawdust, rice husk, petroleum wastes, fertilizer wastes, fly ash, sugar

industry wastes blast furnace slag, chitosan and seafood processing wastes, seaweed and

algae, peat moss, clays, red mud, zeolites, sediment and soil, ore minerals etc.

Activated carbons as an adsorbent for organic pollutants consists in their adsorption a

complex process and there still exists considerable difficulty. The main cause of this

difficulty results from the large number of variables involved. These include, for example,

electrostatic, dispersive and chemical interactions, intrinsic properties of the solute (solubility

and ionization constant), intrinsic properties of the adsorbent (pore size distribution), solution

properties (pH) and the temperature of the system [48]

.

1.1.7.2 Adsorption by using Industrial Waste Material as an Adsorbent

Large amount of solid waste materials are producing due to widespread industrial activities.

Some of these materials are being put to use while others find no proper utilization & are

dumped elsewhere. The industrial waste material is available almost free of cost & causes

major disposal problem. If the solid wastes could be used as low cost adsorbents, it will

provide a two-fold advantage in reducing the pollution. Firstly, the volume of waste materials

could be partly reduced & secondly the developed low cost adsorbent can reduce the

[23]

pollution of wastewaters at a reasonable cost. In view of the low cost adsorbents, it would not

be necessary to regenerate the spent materials. With this view, a number of industrial wastes

have been investigated with or without treatment as adsorbents for the removal of pollutants

from wastewater [49]

.

The major solid waste byproduct of thermal power plants based on coal burning is fly ash.

Fly ash is produced as a fine, non-combustible residue carried off in the flue gas with

relatively uniform particle size distribution in the 1 – 10 µm range. The annual production of

fly ash from coal burning power plants has continued to increase, yet its overall utilization is

marginal. Currently, the main uses of fly as include construction of roads, bricks, cement, etc.

the high percentage of silica & alumina in fly ash make it a good material for utilization as an

inexpensive adsorbent for bulk use. Some studies on this aspect have been carried out [49]

.

The use of fly ash was investigated for the removal of phenol & Chlorophenols & found the

process to be endothermic with first order kinetics [50]

.

1.1.7.3 Types of Adsorbents

Different types of adsorbents are classified into natural adsorbents and synthetic adsorbents.

Natural adsorbents include charcoal, clays, clay minerals, zeolites, and ores. These natural

materials, in many instances are relatively cheap, abundant in supply and have significant

potential for modification and ultimately enhancement of their adsorption capabilities.

Synthetic adsorbents are adsorbents prepared from Agricultural products and wastes, house

hold wastes, Industrial wastes, sewage sludge and polymeric adsorbents. Each adsorbent has

its own characteristics such as porosity, pore structure and nature of its adsorbing surfaces.

Many waste materials used include fruit wastes, coconut shell, scrap tyres, bark and other

tannin-rich materials, sawdust, rice husk, petroleum wastes, fertilizer wastes, fly ash, sugar

industry wastes blast furnace slag, chitosan and seafood processing wastes, seaweed and

algae, peat moss, clays, red mud, zeolites, sediment and soil, ore minerals etc [34]

.

1.1.7.4 Characteristics and General Requirements of Adsorbents

Adsorbents are used usually in the form of spherical pellets, rods, moldings, or monoliths

with hydrodynamic diameters between 0.5 and 10 mm. They must have high abrasion

resistance, high thermal stability and small pore diameters, which results in higher exposed

surface area and hence high capacity for adsorption. The adsorbents must also have a distinct

pore structure that enables fast transport of the gaseous vapors.

[24]

Most industrial adsorbents fall into one of three classes:

Oxygen-containing compounds – Are typically hydrophilic and polar, including materials

such as silica gel and zeolites.

Carbon-based compounds – Are typically hydrophobic and non-polar, including materials

such as activated carbon and graphite.

Polymer-based compounds – Are polar or non-polar functional groups in a porous polymer

matrix [46]

.

1. Silica gel

Silica gel is a chemically inert, nontoxic, polar and dimensionally stable (< 400 °C or 750 °F)

amorphous form of SiO2. It is prepared by the reaction between sodium silicate and acetic

acid, which is followed by a series of after-treatment processes such as aging, pickling, etc.

These after treatment methods results in various pore size distributions.

Silica is used for drying of process air (e.g. oxygen, natural gas) and adsorption of heavy

(polar) hydrocarbons from natural gas [46]

.

2. Zeolites

Zeolites are natural or synthetic crystalline aluminosilicates, which have a repeating pore

network and release water at high temperature. Zeolites are polar in nature.

They are manufactured by hydrothermal synthesis of sodium aluminosilicate or another silica

source in an autoclave followed by ion exchange with certain cations (Na+, Li+, Ca

2+, K

+,

NH4+). The channel diameter of zeolite cages usually ranges from 2 to 9 Å (200 to 900 pm).

The ion exchange process is followed by drying of the crystals, which can be pelletized with

a binder to form macroporous pellets.

Zeolites are applied in drying of process air, CO2 removal from natural gas, CO removal from

reforming gas, air separation, catalytic cracking, and catalytic synthesis and reforming.

Non-polar (siliceous) zeolites are synthesized from aluminum-free silica sources or by

dealumination of aluminum-containing zeolites. The dealumination process is done by

treating the zeolite with steam at elevated temperatures, typically greater than 500 °C (930

[25]

°F). This high temperature heat treatment breaks the aluminum-oxygen bonds and the

aluminum atom is expelled from the zeolite framework [46]

.

3. Activated carbon

Activated carbon is a highly porous, amorphous solid consisting of microcrystallites with a

graphite lattice, usually prepared in small pellets or a powder. It is non-polar and cheap. One

of its main drawbacks is that it reacts with oxygen at moderate temperatures (over 300 °C).

Activated carbon can be manufactured from carbonaceous material, including coal

(bituminous, subbituminous, and lignite), peat, wood, or nutshells (e.g., coconut). The

manufacturing process consists of two phases, carbonization and activation. The

carbonization process includes drying and then heating to separate by-products, including tars

and other hydrocarbons from the raw material, as well as to drive off any gases generated.

The process is completed by heating the material over 400 °C (750 °F) in an oxygen-free

atmosphere that cannot support combustion. The carbonized particles are then "activated" by

exposing them to an oxidizing agent, usually steam or carbon dioxide at high temperature.

This agent burns off the pore blocking structures created during the carbonization phase and

so, they develop a porous, three-dimensional graphite lattice structure. The size of the pores

developed during activation is a function of the time that they spend in this stage. Longer

exposure times result in larger pore sizes. The most popular aqueous phase carbons are

bituminous based because of their hardness, abrasion resistance, pore size distribution, and

low cost, but their effectiveness needs to be tested in each application to determine the

optimal product.

Activated carbon is used for adsorption of organic substances and non-polar adsorbates and it

is also usually used for waste gas (and waste water) treatment. It is the most widely used

adsorbent since most of its chemical (e.g. surface groups) and physical properties (e.g. pore

size distribution and surface area) can be tuned according to what is needed. Its usefulness

also derives from its large micropore (and sometimes mesopore) volume and the resulting

high surface area [46]

.

1.1.8 Removal of Organic Pollutants by Adsolubilization Technique

Separation process, based on the use of surfactants, have several advantages over traditional

methods. They have usually low-energy requirements, & as many of the surfactants are bio-

[26]

degradable, these separation processes can avoid serious environmental problems. Some of

the applications of these techniques are in wastewater cleanup & ground water treatment.

They are also important in biotechnology & hydrometallurgy.

Among the surfactant based separations worthy of mention are micellar enhanced

ultrafiltration (MEUF) & admicellar chromatography. The first one takes the advantage

of solubilization of organic molecules in spontaneously formed aggregated surfactants known

as micelle (in aqueous phase), & the second one uses the admicelle i.e. the bilayer surfactant

molecules adsorbed on the solid surfaces. The word ―Admicelle‖ comes from the adsorbed

micelle. The solubilization occurring in admicelle is called Adsolubilization. An innovative

separation process based on adsolubilization is admicellar process based on adsolubilization

is ―admicellar chromatography‖. The separation thus occurs in a fixed-bed adsorbent. When a

process stream with a solute into the admicelle results.

The advantages of such processes are not only separating the target molecules but also

concentrating or extracting them in smaller volumes of solvents. Thus surfactant-enhanced

carbon regeneration (SECR) can be employed to desorb organic compounds, which is

otherwise a difficult task.

In the present day scenario, when one of the key point of ―Prevention & Minimization‖ of

pollution is ―Recycling of Staring materials‖, these separation processes may not only solve

the economy but it will potentially help keeping the environment clean.

[27]

Figure 1.1: (A) Schematic Representation of a Spherical Micelle, (B) Structures of adsorbed surfactants

on smooth thin-film surfaces of mineral oxides, (C) Schematic Diagram of Solubilization &

Adsolubilization Process

(B) (A)

(C)

[28]

The concept of adsolubilization & the formation & structure of admicelles is best represented

by the adsorption isotherm.

Figure 1.2: Schematic Diagram of Typical Surfactant Adsorption Isotherm

These isotherms are commonly divided into four regions.

Region I is a region of low adsorption densities. In this region, the surfactants are adsorbed as

monomers & do not interact with one another. The adsorption in this zone results primarily

from electrostatic forces between surfactant ions & the charged solid surface. Region II is

indicated by the sharp increase in the slope of the isotherm. The monolayered structure

formed in this region is called hemimicelle. In this region, the adsorption is due to the

electrostatic attraction between the ions & the charged solid surface & hemimicelles

association of hydrocarbon chains. When surfactant molecules/ions equivalent in number to

the surface sites have been adsorbed, the contribution due to the electrostatic attraction

disappears & the further increase in adsorption will be only due to association between the

hydrocarbon chains. The transition from region I to region II has been given designations

analogous to the critical micelle concentration (CMC) such as critical admicelles

concentration (CAC) or hemimicelle concentration (HMC). The transition from region II to

region III is marked by the decrease in the slope of the isotherm. In region III the surfactant

ions are probably adsorbed by a slightly different mechanism. The adsorption in this zone is

[29]

due to the association between the hydrocarbon chains as double layer & is known as an

admicelle. Region IV is called the plateau adsorption region. In most systems the transition

from region III to region IV occurs above the CMC of the surfactant. Micelle-like aggregates

are formed on the solid surface.

Depending on the target molecule to be removed, the surfactant & the adsorbent can be

selected. The adsorbent of choice may be alumina, silica, various minerals such as zeolite,

bentonite, etc. Another factor, which greatly influences the adsorption of ionic surfactant on

to oppositely charged surfaces, is the pH of the solution. The organic chlorinated (viz.

perchloroethylene), pesticides, aromatic hydrocarbons, dyes, etc. are suitable targets which

can be removed from wastewater using these techniques.

The adsolubilization process has been suggested as a viable alternative to carbon adsorption.

The process is advantageous over ordinary adsorption. The solute can be removed from

concentrated mixture by this process. The regeneration problems of carbon have been solved

in this process. The reuse & recycle of both surfactants & adsorbent can be done for several

treatment cycles. While the phenomenon of solubilization has been extensively studied & has

important applications in numerous technologies, adsolubilization is hardly recognized as an

important phenomenon. Almost all the studies occurred since mid-eighties are on the

physico-chemical aspects & the technological utilization of the process is only beginning.

Implementation of this method for real-field application is also waiting [51]

.

[30]

1.2 Literature Review

Wangchareansak T., Craig V. et. al. have studied the adsorption isotherms and aggregate

structures of adsorbed surfactants on smooth thin-film surfaces of mineral oxides have been

studied by optical reflectometry and atomic force microscopy (AFM). Films of the mineral

oxides of titania, alumina, hafnia, and zirconia were produced by atomic layer deposition

(ALD) with low roughness. We find that the surface strongly influences the admicelle

organization on the surface. At high concentrations (2 × CMC) of cetyltrimethylammonium

bromide (CTAB), the surfactant aggregates on a titania surface exhibit a flattened admicelle

structure with an average repeat distance of 8.0 ± 1.0 nm whereas aggregates on alumina

substrates exhibit a larger admicelle with an average separation distance of 10.5 ± 1.0 nm. A

wormlike admicelle structure with an average separation distance of 7.0 ± 1.0 nm can be

observed on zirconia substrates whereas a bilayered aggregate structure on hafnia substrates

was observed. The change in the surface aggregate structure can be related to an increase in

the critical packing parameter through a reduction in the effective headgroup area of the

surfactant. The templating strength of the surfaces are found to be hafnia > alumina >

zirconia > titania. Weakly templating surfaces are expected to have superior biocompatibility

[52].

Pausa S. et. al. has studied Micellar-enhanced ultrafiltration (MEUF) process is one of the

promising technologies in separating the low molecular weight substance from the

wastewater. The MEUF process involves the combination use of surfactant and ultrafiltration

membrane. The selection of surfactant is very important which depends on the nature of

contaminants (i.e organic, inorganic). Critical micelle concentration of surfactant plays an

important role in selection of surfactant concentration for MEUF process. Many researchers

have reported that MEUF and nanofiltration process has the same removal capacity of

contaminants from wastewater but the uniqueness of MEUF is, it requires less energy due to

low operating pressure [53]

Robert S. et. al. has studied the effect of selected counter ions (Cl-, Br

- & HSO4

-) on the

cationic surfactant Hexadecyl Trimethyl Ammonium (HDTMA) on clinoptilolite zeolite & on

the subsequent sorption of chromate by HDTMA – zeolite. The HDTMA sorption on the

zeolite, as characterized by the Langmuir sorption maximum, followed the trend HDTMA-Br

> HDTMA-Cl > HDTMA – HSO4- (208, 151 & 132 mmol/kg, respectively). The same

[31]

counter ion trend was observed for HDTMA sorption on KGA-1 kaolinite. Measurement of

counterion sorption indicated that HDTMA-Br & HDTMA-Cl formed complete bilayers on

the zeolite, whereas HDTMA-HSO4- showed less than full bilayer formation. Competitive

sorption between HDTMA-Br & HDTMA-Cl on the zeolite also showed a preference for the

Br- counter ion. The counter ion stabilization of HDTMA admicelles on the zeolite surface

follows the same trends as the counter ion stabilization of micelles in solution. Chromate

sorption was also strongly influenced by the HDTMA-zeolite counterion, with chromate

sorption maxima decreasing in the order HDTMA-HSO4- > HDTMA-Cl

- >HDTMA-Br

- (28,

16 & 11 mmol/kg, respectively). The sorption of chromate & other divalent anions on

HDTMA-zeolite results from a combination of entropic, coulombic & hydrophobic effects,

all of which are functions of the initial HDTMA counter ion. In the design of surfactant

modified clays & zeolites for environmental applications, the strong influence of the

surfactant counterion must be considered [54]

.

Patel N. et. al. has studied the removal of Cr+6

from aqueous solution by Moringa oleifera.

Hexavalent chromium is considered a serious environmental pollutant through some

industries. In the present investigation, Moringa oleifera leaf, seed and bark powder were

used as an adsorbent for the removal of Cr+6

from aqueous solutions. The maximum removal

was observed at pH 2, contact time of 30 minutes in a jar test apparatus with 120 rpm and

initial concentration of 25mg/L. Adsorption behavior is found to follow Langmuir , BET and

Freundlich, Temkin isotherms. The study showed that Moringa oleifera seeds were more

favorable than leaves and bark in removing Cr+6

from the aqueous solution with Langmuir

and BET adsorption model with a correlation coefficient equal to 0.981. Moringa oleifera

leaf and bark studies showed that the Freundlich adsorption model better en suite with value

of n obtained is 2.040 and 2.044 respectively. The Moringa oleifera Bark and leaves show

good agreement with Temkin isotherm with value of b is 3.153 and 1.868 respectively. The

results showed that the maximum adsorption capacity of Cr+6

on Moringa oleifera leaves

(2.375 mg/g), Moringa oleifera seeds (2.489mg/g), Moringa oleifera bark (2.483 mg/g) were

at pH of 2 after 30 min. The natural water/wastewater/effluent can be treated by adding

suitable dose of low cost, natural adsorbent - Moringa oleifera leaf, seed and bark powder

and by application of flocculator /instrument with 120 rpm. Maintain pH of 2 and contact

time 30 minutes for optimum results. The settled residue/ sludge remained at the bottom of

clarifier can be taken out by rotating scraper with pump .The adsorbent and Cr+6

can be

[32]

recovered by giving H2SO4 treatment to this sludge. The sludge of Moringa oleifera seeds,

leaves and bark is biodegradable. By using this cost effective, eco friendly technique we can

get rid of the hazardous sludge disposal problem – generated by chemical treatment for

Chromium removal/recovery [55]

.

Toowoomba would have been the first city in Australia to use recycled sewage for drinking

water after necessary treatment. In Toowoomba, the wastewater would have been treated

using ultra filtration, R.O., U.V. disinfection & oxidation process to destroy microorganisms.

Using the process called ―Indirect Potable Reuse‖ the recycled wastewater then top up

existing drinking water supplies to be stored at the nearby dam and then undergo

conventional water treatments. It would then become part of resident’s daily drinking

supplies. But there are two common concerns with such water purification projects; 1st

require considerable amounts of energy, 2nd

environmental concerns about what to do with

the concentrated salty wastewater that is made during the process [56]

.

Puthiya V. et. al. described adsorption of Crystal Violet (CV) by bottom ash in fixed-bed

column mode. Equilibrium of adsorption was studied in batch mode for finding adsorption

capacity of bottom ash. In fixed bed column adsorption, the effects of bed height, feed flow

rate, and initial concentration were studied by assessing breakthrough curve. The slope of the

breakthrough curve decreased with increasing bed height. The breakthrough time and

exhaustion time were decreased with increasing influent CV concentration and flow rates.

The effect of bed depth, flow rate and CV concentration on the adsorption column design

parameters were analyzed. Bed depth service time (BDST) model was applied for analysis of

crystal violet adsorption in the column. The adsorption capacity of bottom ash was calculated

at 10% breakthrough point for different flow rates and concentrations. Desorption studies

reveals that recovery of CV from bottom ash was effective by using CH3COOH than H2SO4,

NaOH, HCl and NaCl solutions [57]

.

Many non-conventional low cost adsorbents, including natural materials, biosorbents & waste

materials from industry & agriculture, have been proposed by several researchers. These

materials could be used as sorbents for the removal of dyes from waste water. Some of the

reported sorbents include clay materials (bentonite, kaolinite), zeolite, siliceous material

(Silica beads, alunite, perlite), agricultural wastes (bagasse pith, maize cob, rice husk,

[33]

coconut shell), industrial waste products (waste carbon slurries, metal hydroxide, sludge,

biosorbents (chitosan, peat, biomass), etc. [58]

.

Sing B. et. al.’s study covers sorption of toxic metal ions (Pb+2

& Zn+2

) on synthesized

Sodium Aluminosilicate (NAS) in the presence & absence of humic acid (Aldrich) at

different pH (3 to 10). The material was synthesized by solution route method. This powder

of sodium aluminosilicate is of amorphous nature. The surface area of the synthesized

material was measured by BET analysis & found to be 457m2/gm. The point of zero charge

was obtained by zeta potential measurement & was found to be 1.70, which is very close to

the zeta potential of silica (2.0). Site density was observed to be 4.22 × 10-5

mole/gm from the

titration data. A series of experiments were carried out to study the effect of ionic strength,

calcium ions, sorbent dose, metal ions concentration & temperature. The sorption was found

to be pH dependent. Humic Acid found to affect sorption. It was observed that at lower pH

(<5) HA enhanced sorption, whereas at higher pH (>5) sorption was decreased which can be

attributed to greater interaction between the metal ions & mineral bound HA at lower pH &

HA in solution at higher pH. At lower pH, HA strongly bound to positive surface of

aluminosilicate resulting in enhanced sorption. Sorption was enhanced at higher temperature

[59].

Shrivastava R. et. al. have studied the use of zero – valent iron (ZVI) as a reductive medium

is receiving increased interest due to its easy availability, low operation & maintenance costs.

ZVI acts as a reducing agent for the reduction of highly toxic Cr (VI) to Cr (III), while itself

being oxidized to Fe (II) & Fe (III) [60]

.

Continuous extraction of water has resulted in depletion of available water sources in and

around the industrial areas. In addition, wastewater discharge into natural watercourses has

caused surface and groundwater pollution, leaving water unsafe for potable use and impairing

industrial use without major and costly treatment. The current low cost end-of-pipe treatment

approach will become increasingly expensive as effluent discharge standards become more

stringent. Meanwhile, technological advancements now make it possible to treat wastewater

for variety of industrial reuse. Most industries in even developing countries are already

moving towards wastewater reuse and source separation and treatment of separated effluents

is gaining more attention. Wastewater reuse potential in different industries depends on waste

volume, concentration and characteristics, best available treatment technologies, operation

[34]

and maintenance costs, availability of raw water, and effluent standards. Radical changes in

industrial wastewater reuse have to take into consideration rapidly depleting resources,

environmental degradation, public attitude and health risks to workers and consumers [31]

.

Harnandez M. et. al. have studied the adsorption of four organophosphorous insecticides,

diazinon, dimethoate, malathion and methidathion, on nine soils representative of the

Mediterranean area. The sorption of the organophosphorous pesticides was slightly

influenced by soil texture and organic matter content. Pesticide sorption was ranked

according to their hydrophobicity, except for the pair diazinon/malathion. Pesticide sorption

was also examined in aqueous solutions in the presence of surfactants. Three different

surfactants were selected: a cationic (hexadecyl trimethyl ammonium bromide), a non-ionic

(Tween 80) and an anionic surfactant (Aerosol 22), to verify the effect of their presence on

pesticide retention by the different soils. The addition of Tween 80 and Aerosol did not

modify the pesticide sorption and no correlation was found between soil organic matter and

clay content and pesticides sorption coefficients. The presence of the cationic surfactant

increased pesticide retention, especially when the surfactant was present at a concentration

between 100 and 200% of the soil cation exchange capacity. In the presence of the cationic

surfactant, the distribution coefficients were significantly correlated with soil cation exchange

capacity. The competition between the weakly retained dimethoate and the other insecticides

was tested in the presence or absence of the cationic surfactant. Dimethoate has showed a

higher retention when examined alone than when the rest of the insecticides competed for

sorption sites [61]

.

Singh V. et. al. have used fly ash as an adsorbent for removal of malathion from aqueous

solution. Fly ash, obtained from a thermal power plant, Anpara, Sonebhadra, India has been

used as an effective adsorbent for the removal of malathion from aqueous solutions. The time

required to attain equilibrium was found to increase from 40 to 60 minutes as the initial

malathion concentration increases from 1 to 10 mg/L. The optimum pH value for adsorption

was 4.5. The removal of malathion increased by increasing the temperature indicating

endothermic nature of removal process. The fly ash exhibited first order rate kinetics and

followed both Langmuir and Freundlich isotherm models. Endothermic nature of adsorption

process was further supported from increasing values of Langmuir and Freundlich constants

with increase in temperature. The adsorbent can be used as an economical product for the

removal of malathion from wastewater also. A comparison of the adsorption capacity of fly

[35]

ash with other adsorbents shows that fly ash can be used for the removal of malathion from

aqueous solutions [62]

.

Paria S. et. al. have studied the progresses of understanding of the surfactant adsorption at the

hydrophilic solid–liquid interface from extensive experimental studies are reviewed here. In

this respect the kinetic and equilibrium studies involves anionic, cationic, non-ionic and

mixed surfactants at the solid surface from the solution. Kinetics and equilibrium adsorption

of surfactants at the solid–liquid interface depend on the nature of surfactants and the nature

of the solid surface. Studies have been reported on adsorption kinetics at the solid–liquid

interface primarily on the adsorption of non-ionic surfactant on silica and limited studies on

cationic surfactant on silica and anionic surfactant on cotton and cellulose. The typical

isotherm of surfactants in general, can be subdivided into four regions. Four-regime isotherm

was mainly observed for adsorption of ionic surfactant on oppositely charged solid surface

and adsorption of non-ionic surfactant on silica surface. Region IV of the adsorption isotherm

is commonly a plateau region above the CMC, it may also show a maximum above the CMC.

Isotherms of four different regions are discussed in detail. Influences of different parameters

such as molecular structure, temperature, salt concentration that are very important in

surfactant adsorption are reviewed here. Atomic force microscopy study of different

surfactants show the self-assembly and mechanism of adsorption at the solid–liquid interface.

Adsorption behaviour and mechanism of different mixed surfactant systems such as anionic–

cationic, anionic–non-ionic and cationic–non-ionic are reviewed. Mixture of surface-active

materials can show synergistic interactions, which can be manifested as enhanced surface

activity, spreading, foaming, detergency and many other phenomena [63]

.

Jain R. et. al. have studied the potential of de-oiled mustard in removal of dyes from waste

water. De-oiled mustard, a bio-sorbent, was successfully utilized in removing a water soluble

azo dye, congo – red from waste water. Kinetic studies of adsorption of congo red to de-oiled

mustard were conducted in batch conditions at 30˚C. Specific rate of the processes were

calculated by kinetic measurements & a first order adsorption kinetic was observed in each

case. The equilibrium process showed to be well described by both Freundlich & Langmuir

models, at 30 ˚C, 40 ˚C & 50 ˚C. Desorption studies indicate that elution by dilute NaOH

through the fixed bed of the adsorbents columns could be regenerated & a quantitative

recovery of congo red can be achieved. In order to observe the quality of wastewater COD

measurements were also carried out & a significant decrease in the COD values was

[36]

observed, which clearly indicates that adsorption method offer good potential to remove

congo red from wastewater [64]

.

Saravanan V. et. al. have studied Chromium removal from tannery effluent based on high

gradient Magnetic Separation Technology with magnetic nano particles (magnetite) used as

an adsorbent. Magnetite is prepared from Iron (III) Chloride & Iron (II) Chloride. The

adsorbent has received a considerable attention due to their small size, large surface area, low

cost, ease of preparation, non-toxicity, negligible mass transfer resistance etc. it was found

that – (i) Adsorption follows second order kinetics, (ii) Rate of adsorption at room

temperature was 0.0002 mg/L.min, (iii) Adsorption was spontaneous & favored by increase

in temperature as Gibbs free energy was possible, (iv) Langmuir isotherm fits well to

experimental data, (v) Adsorption capacity increases with increase in temperature, increases

with decrease in pH, slightly increase with increase in feed concentration, decreases with

increase in adsorbent dosage. U.V visible spectrophotometer was used throughout the study

for determination of concentration Cr of solution [65]

.

Safarik I. et. al. have studied a simple procedure for the detection of low concentrations of

malachite green and crystal violet in water is presented. The dyes were preconcentrated from

1000 ml of water samples with magnetic solid phase extraction using magnetic affinity

adsorbent (magnetite with immobilized copper phthalocyanine dye).Due to the magnetic

properties of the adsorbent the preconcentration process can also be performed in water

samples containing suspended solids. After elution of the captured dyes, their presence in

eluates was detected spectrophotometrically.Concentrations of both dyes in the range 0.5–1.0

µg/L of water could be reproducibly detected.The dyes can be detected not only in potable

water, but also in river ones [66]

.

Swarankar V. et. al. have studied that Chromium in natural water is found in the oxidation

states Cr(III) & Cr(VI). Arsenic occurs in 2 oxidation states that form oxyanions; arsenate

As(V) & Arsenite (III); Arsenite is more mobile & toxic than AsO4. Zeolites are crystalline,

hydrated alumino-silicate containing exchangeable alkaline & alkaline earth cations in their

structural frame works. Since zeolites have permanent negative charge on their surfaces, they

have no affinities for anions. However recent studies have shown that modification of zeolite

with certain surfactants or metal cations yield sorbents with a strong affinity for many anions.

Zeolite has high internal & external surface areas & high internal & external cation exchange

[37]

capacities suitable for the surface modification by cationic surfactants. When the initial

surfactant concentration is less than the Critical Micellar Concentration (CMC), the sorbed

surfactant molecules primarily form a monolayer, limited chromate & arsenate sorption

indicates that the patchy bilayer may also be formed. When the surfactant concentration is

greater than the critical micellar concentration & enough surfactant exist in the system, the

sorbed surfactant molecules from bilayer, producing maximum chromate & arsenate sorption

[67].

Joshi K. et. al. studied that the semiconductors like (TiO2) Titanium oxide & (ZnO2) Zinc

Oxide with commercial activated carbon were investigated regarding its potential as an

adsorbent for removal of adsorbent, which are Acid Blue – 29, Methylen Blue, Rhodamine

6G, Indigo Caramine & Congo Red from textile wastewater. The batch mode adsorption

experiments were carried out using various concentrations of dyes to test the sorption basic &

acid dyes from textile wastewater. The influence of various parameters & the rate process

involved in the removal of dye for initial dye concentration, agitation time, carbon dosage &

pH has been studied at the room temperature. The adsorption process followed second order

rate kinetics. The experimental data fitted reasonable well to Langmuir & Freundlich

adsorption isotherm. The amount of dye adsorbed increases with increase in initial

concentration. It was also found that Kad—

of dye adsorption process decreases with increase

in initial concentration. Characterization of carbon was studied. The morphology of activated

carbon was characterized by SEM analysis of activated carbon. The % of adsorption of acid

blue – 29, methylene blue, congo red from wastewater was found to be 85.67% & 93.5%,

92.4% respectively [68]

.

Salari Z. et. al. have studied that adsorption is a unit operation in which dissolved constituents

is removed from the solvent (water) by interphase transfer to the surfaces of an adsorbent

particle. The basic objective of this paper is calculating adsorption density and modeling of

the equilibria of adsorption processes on carbonate rocks. There has been very little study of

surfactant adsorption on carbonate minerals. This paper describes the equilibrium adsorption

was investigated by examining adsorption behavior in a system of solid phase carbonate and

of an aqueous phase of surfactant. Effects on surfactant adsorption density for different

surfactant concentration were conducted on crushed rock as well as circulation tests through

core samples. The range of initial surfactant concentrations were from 50 to 600 ppm in the

crushed cores. CTAB surfactant used as a cationic surfactant. An adsorption isotherm is used

[38]

to characterize the equilibria between the amount of adsorbate that accumulates on the

adsorbent and the concentration of the dissolved adsorbate. The Langmuir adsorption

isotherm, Freundlich isotherm used to describe equilibria. The equilibrium time was

approximately one day. The rate of adsorption dependent on availability of surfactant in the

system, it was found that the adsorption of surfactant increased with increasing surfactant

concentration. The phenomenon of adsorption at solid/liquid interface is of major importance

in the process of enhanced oil recovery with the application of surfactant [69]

.

Koner S. et. al. have studied the adsorption of cetyltrimethylammonium bromide (CTAB), a

well known cationic surfactant on silica gel and its application for organic bearing

wastewater treatment. The study was conducted for both CTAB-spiked distilled water and

real wastewater. The studies on adsorbent dose variation and removal kinetics were

conducted to find the optimum dose and equilibrium contact time for CTAB removal.

Interestingly, the adsorption capacity was found to be very high for real wastewater and the

reaction occurred very rapidly compared to that of CTAB-spiked distilled water samples. The

kinetic study revealed that the reaction followed the pseudo-second order reaction kinetics

model. The isotherm followed four region isotherm models. The effects of various parameters

such as pH, presence of electrolytes and operating conditions on the adsorption process were

studied. High adsorption capacity was observed in presence of electrolytes and in alkaline

condition. Kinetic study determined the rate limiting to be chemisorption. Regeneration of

silica gel after its complete exhaustion was efficiently done using hydrochloric acid (18%).

After the surfactant removal, the surfactant modified silica gel (SMSG) was efficiently used

for the removal of dyes and herbicide from water environment through the process called

adsolubilization. Therefore, this would be a simple and efficient process for treatment of

organic bearing wastewater especially textile wastewater [70]

.

Pasha C. et. al. have proposed a simple, selective and sensitive spectrophotometric method

for the determination of widely used organochlorine pesticide endosulfan using thionin and

methylene blue as chromogenic reagents. The method is based on the liberation of sulfur

dioxide from endosulfan by adding acid reagent and alcoholic potassium hydroxide. The

liberated sulfur dioxide is passed through potassium iodate solution and the iodine so

liberated bleaches the violet color of thionin and blue color of methylene blue and is

measured at 600 nm and 665 nm respectively. This decrease in absorbance is directly

proportional to the endosulfan concentration. The Beer’s law is obeyed in the range of 0.4–

[39]

7.0 and 0.2–9.0 µg/ml of endosulfan using thionin and methylene blue as reagents

respectively. The molar absorptivity and Sandell’s sensitivity were found to be 1.05 x 105 and

5.03 x 104 L mol

-1 cm

-1, 3.85 x 10

-3 and 8.10 x 10

-3 µg cm

-2 of endosulfan using thionin and

methylene blue as reagents respectively. The method has been applied for the determination

of endosulfan in water, soil and vegetables [71]

.

Rao Y. et. al. have studied a novel method for the determination of carbosulfan in

environmental samples using oxidative coupling. The method comprises of alkaline

hydrolysis of the pesticide and the resulting phenol is reacted with 2,4-di-methoxy aniline in

presence of acidified K2Cr207. The dye product formed is extracted into CHCl3 and the

absorbance measured at 430nm [72]

.

Janghel E. et. at. Have studied a new and highly sensitive spectophotometric method for the

determination of parts per million levels of widely used organophosphorus pesticide

monocrotophos. The method is based on alkaline hydrolysis of monocrotophos to N-

methylacetoacetamide followed by coupling with diazotized p-amino acetophenone in

alkaline medium. The absorption maxima of the reddish-violet coloured compound formed is

measured at 560 nm. Beer’s law is obeyed over the concentration range of 1.2 to 6.8 µg in a

final solution volume of 25 mL. The molar absorptivity and Sandell’s sensitivity were found

to be 7.1 x 105 (+100) L mole-1 cm-1 and 0.008 µg cm-2, respectively. The standard

deviation and relative standard deviation were found to be + 0.005 and 2.05%, respectively.

The method is simple, sensitive and free from interferences of other pesticides and diverse

ions. The method has been satisfactorily applied to the determination of monocrotophos in

environmental, agricultural and biological samples [73]

.

Rasuljan M. et. al. have studied a new decomposition method for the release of phosphorus

and the molybdenum blue method for phosphorus determination in organics was modified.

The modified method was applied for the determination of organophosphorus pesticide

(dimecron) in its commercial samples. The commercial samples were found to contain 0.2

gm/ml of pesticide instead of 1.0 gm/ml as shown by the label. Limit of detection of the

method was investigated & was found to be 0.282 ppm for dimecro. The method was applied

successfully to other organophosphorus pesticides [74]

.

Bestamin O. et. al. have studied the potential of activated carbon for phenol adsorption from

aqueous solution. Batch kinetics and isotherm studies were carried out to evaluate the effect

[40]

of contact time, initial concentration, and desorption characteristics of activated carbon. The

equilibrium data in aqueous solutions was represented by the isotherm models. Desorption

studies to recover the adsorbed phenol from activated carbon performed with NaOH solution.

It is necessary to propose a suitable model to gain a better understanding on the mechanism

of phenol desorption. For this purpose, pore diffusion and 1rst-order kinetic models were

compared. The diffusivity rate (D/r2 ) and 1rst-order desorption rate (kD ) constants were

determined. The two- and three-parameter in the adopted adsorption isotherm models were

obtained using a non-linear regression with the help of MATLAB package program. It was

determined that best adsorption isotherm models were determined to be in the order:

Langmiur > Toth > Redlich¨CPeterson > Freundlich isotherms [75]

.

Goel A. et. al. have studied Bagasse fly ash, a waste from the sugar industry, as a replacement

for the current expensive methods for the removal of fluoride from wastewater. The batch

study indicated that initially the removal of fluoride increases with the increase of pH, while

the adsorption capacity decreased with increasing initial concentration of fluoride & it

increased with increasing adsorbent concentration. The maximum equilibrium time was

found to be 90 minutes. The optimum adsorption was obtained under condition of 5 mg/L

concentration of fluoride at pH 6. About 75% removal of fluoride is possible in 90 minutes.

The adsorption data were analyzed using the Langmuir & Freundlich adsorption models to

determine the mechanistic parameters at three different temperature ranges – 20 ˚C, 30 ˚C &

40 ˚C [76]

.

Tilaki D. et. al. have studied that Bentonite is such mineral sorbents which is naturally

available. Organo-Bentonite can be prepared by contacting Bentonite & cationic detergent.

Cationic detergent molecules are bounded between Bentonite layers & long hydrophobic tail

of these molecules can adsorb the hydrophobic molecules. So organo-Bentonite has more

adsorptive capacity than ordinary Bentonite. Textile colored waste water was added into the

activated sludge system continuously. In this study, municipal type wastewater from

university campus was used as wastewater entering into the activated sludge laboratory pilot

plant model. The color removal efficiency was determined by COD measurement in the

filtered samples. Before dosage, the average color removal was 25%. In this study ordinary

clay soil, bentonite & organically modified Bentonite were directly added into the system.

Clay soil, Bentonite & Organo-Bentonite were added to the activated sludge system at 0.5,

1.0 & 2.0 gm/L dose rate separately. The addition of clay soil did not change color removal

[41]

significantly at different dose rate. The average color removal efficiency by addition of

Bentonite in this three different dose rate was 45%. Increasing the Bentonite dose rate did not

increase color removal efficiency meaningfully. The most effective materials were found to

be organically modified Bentonite for Color removal. While the color removal efficiency for

0.5 gm/L organo-Bentonite addition was 55%, it was 68% for 1.0 g/L & 75% for 2 g/L [77]

.

Jayraj R. et. al. have studied the use of Aspergillus niger fungal strain for the bioremediation

of the heavy metals. This fungal strain was isolated from soil & found that this biosorbed

7.77 mg/L Cu++

from solution within 1 hr. a wastewater with a pH of 3.0 or above can be

effectively treated for metal ion removal & the wastewater with pH lower than 3.0 would

need pH adjustment. This method can be useful to remove heavy metals from polluted

industrial & domestic effluent on a large scale. These biosorbed ions can be eluted & the

biomass could be regenerated & used again. So, it represents an easy & cost effective

technology for the abatement of pollution. This method is not only economical, but also quick

& easy to operate [78]

.

Dorathi R. et. al. have studied the dichlorophenol (DCP), the precursor as well as the

derivative of 2,4 – Dichlorophenoxy acetic acid (2,4-D), is one among the priority pollutants

listed by USEPA. This paper presents a beningn method for degrading DCP using iron in its

hypervalent form (Fe+6

aq.). The oxidation potential of ferrate is higher than the common

chemical oxidants like ozone, hydrogen peroxide & Chlorine used in wastewater treatment.

Potassium ferrate was prepared by sacrificial anodic electrolysis & was used as such in

aqueous form for the study, instead of separating out in solid form as given in the literature.

Due to which, the addition of chemicals like hexane & methanol, for separation &

purification of solid potassium, ferrate was avoided. The concentration of DCP was taken as

100 mg/L to simulate waste water condition. The relevant parameters namely ferrate gets

converted into ferric which is an adsorbent, hence adsorption of DCP onto the ferric was also

studied [79]

.

Paul M. et. al. have studied that the waste water from the chemical laboratory causes a lot of

pollution in soil & water & is unavoidable. So measures can be taken to recycle at least the

metal ions & thereby reduce pollution due to them. Anions & other cations cannot be

recycled economically, but can be removed to a greater extent by a method of bio-treatment.

The lab wastewater is digested with dilute nitric acid for one hour so as to convert most of the

[42]

insoluble metal ions into soluble nitrate & also to decompose the sulphides into soluble metal

nitrates. From this solution metal ions are precipitated in their respective groups (as

mentioned in qualitative inorganic analysis), confirmed by qualitative analysis & dissolved

individually into soluble nitrates & chlorides. This solution is then provided for qualitative

analysis of cations in the lab since all metal ions cannot be recycled economically the left out

metal ions in the wastewater can be prevented from polluting soil & water sources by treating

it in a bed of balsam plants & a bed of saw dust. The extent to which the balsam plants can

remove metal salts from waste water has to be studied further. Thus chemical analysis being a

part of study in the branch of chemistry can be made less polluting to some extent if the bio

remedies suggested above is followed [80]

.

Celen I. et. al. have studied the effects of environmental conditions on ammonia removal as

struvite (Magnesium Ammonium Phosphate) i.e. MAP) in a laboratory scale batch reactor.

MAP precipitation was carried out by adding phosphoric acid & magnesium source either as

MgCl2 or MgO. The effect of temperature, pH, M:N:P ratios were studied. Temperature did

not significantly affect ammonia removal between 25 – 40 ˚C & over 90% removal was

obtained. The effect of pH, however, was significant & highest removal was reached at pH

8.5 – 9.0. The various stoichiometric ratios of ammonium to M & P have been tested slight

excess of M & P have been tested& slight excess of M & P was found to be beneficial for

higher recovery of ammonia as struvite. However, further increase in M & P ratios did not

result in further ammonia removal which is also costly for the practical application of the

process. When MgO was used as M source, the ammonia recovery was 60-70% whereas the

use of MgCl2 has increased this figure up to 95 %. In addition 2 steps purification process

was developed to recover MAP crystals from impurities of anaerobic digester. Firstly,

precipitates were dissolved in acid & impurities were removed by centrifugation. The

clarified supernatant was re-precipitated by adjusting its pH with caustic. It was shown that in

2 steps process white MAP crystals could be used for another application [81]

.

Zhang W. et. al. have studied the adsorption equilibria of Phenol & aniline on non-polar

polymer adsorbents (NDA – 100, XAD – 4, NDA – 16 & NDA – 1800) in single & binary

solute adsorption system at 313 K. The results showed that all the adsorbents can be well

fitted by Freundlich & Langmuir equation & the experimental uptake of phenol & aniline in

all binary component systems is obviously higher than predicted by the extended Langmuir

model, arising presumably from the synergistic effect caused by laterally acid-base

[43]

interaction between the adsorbed phenol & aniline molecules. A new model was developed to

quantitatively describe the synergistic adsorption behavior of phenol/aniline equimolar in the

binary solute systems & showed a marked improvement in correlating the binary solute

adsorption of phenol & aniline by comparison with the widely used extended Langmuir

model [82]

.

Desai B. & Desai H. studied the removal of heavy metals (Copper, Zinc and Iron) from

ground water (Udhna Gam) sample was done by using the natural adsorbent Moringa oleifera

seed powder (MOSP). The variables for pH were decided at pH 4, 6, 7, 8 and 10 to find out

optimum pH for further treatment. The variables for contact time were decided as ½ hour, 1

hour, 1.5 hours, 2 hours and 2.5 hours to find out optimum contact time for further treatment.

The pH 8.7 and 2.5 hours contact time were considered as optimum pH and optimum contact

time respectively because maximum %removal efficiency of water pollutants was observed at

pH 8.7 and at 2.5 hours contact time. The variables for MOSP dosage were decided as 2000

ppm, 3000 ppm, 4000 ppm, 5000 ppm and 6000 ppm to find out optimum MOSP dosage to

get maximum % removal efficiency of heavy metals from the Udhna Gam ground water

sample. The MOSP dosage of 6000 ppm (6 g/l) had established good chemistry with drinking

water Indian standard. Maximum reduction of Copper (99.94%), Zinc (95.38 %) and Iron (96

%) was observed at pH 8.7, 2.5 hour contact time and at 6000 ppm MOSP dosage [83]

.

Patel I., Desai H. studied the landfill leachate in The Khajod Solid Waste Disposal Site, Surat

usually contains quite high NH4+ -

N concentration, which is well known to inhibit nitrification

in biological treatment processes. A common pre-treatment for reducing high strength of

ammonium (NH4+ -

N) is by an air-stripping process. However, there are some operational

problems such as carbonate scaling in the process of stripping. For this reason, some

technical alternatives for NH4+ -

N removal from leachate need to be studied. In this study, a

bench-scale experiment was initiated to investigate the feasibility of selectively precipitating

NH4+ -

N in the leachate collected from a local landfill in Surat as magnesium ammonium

phosphate (MAP). In the experiment, three combinations of chemicals, MgCl2.6H2O +

Na2HPO4.12H2O, MgO + 85% H3PO4, and MgO + Na5P3O10, were used with the different

stoichiometric ratios to generate the MAP precipitate effectively. The results indicated that

NH4+-N contained in the leachate could be quickly reduced from 1108 mg/l to 40 mg/l

within short period of time, when MgCl2.6H2O + Na2HPO4.12H2O were applied with a

Mg2+:NH4

+:PO4

3- mole ratio of 1:1:1. The pH range of the minimum MAP solubility was

[44]

discovered to be between 8.5 and 9.0. Attention should be given to the high salinity formed in

the treated leachate by using MgCl2.6H2O + Na2HPO4.12H2O, which may affect microbial

activity in the following biological treatment processes. The other two combinations of

chemicals [MgO + 85% H3PO4 and MgO + Na5P3O10] could minimize salinity after

precipitation, but they were less efficient for NH4+-N removal, compared with MgCl2.6H2O +

Na2HPO4.12H2O. COD had reduced up to 50% during this precipitation. It was found that the

sludge of MAP generated was easily settled within 30 minutes to reach its solids content up

to 50% [84]

.

Desai A. & Desai H. studied removal of Cr+6 from aqueous solution by Azadirachta indica.

Hexavalent chromium is considered as a serious environmental pollutant through industries.

The main objective of present studies is to investigate the adsorption behaviour of Cr6+ ions

on to Azadirachta indica leaves. Main parameters considered are pH, contact time, adsorbent

dose and initial hexavalent chromium concentration during removal of Cr6+ using natural

adsorbent by adsorption technique with Batch mode experiments. Present study shows that

the Azadirachta indica leaves were found as an effective biosorbent for the removal of

hexavalent chromium from aqueous solution. The optimum percentage removal of

hexavalent chromium from aqueous solution obtained is 99.68 %, 99.63%, 98.79%, 98.99%

for initial Cr (VI) concentration 50 mg/L ,75 mg/L, 100 mg/L, 125 mg/L at pH 6 , adsorbent

dosage 5 g, contact time 4 hrs in jar test apparatus with 160 rpm. The results showed that the

maximum adsorption capacity of hexavalent chromium on Azadirachta indica leaves

observed is 6.202 (50mg/L), 8.307 (75mg/L), 9.546 (100mg/L) and 12.68 (125mg/L) at pH 6

after 4 hr. The values of coefficient of correlation (R2) obtained was nearer to 1 for

Azadirachta indica leaves are in good agreement with Langmuir, BET , Freundlich and

Temkin adsorption isotherm models. For Langmuir and BET adsorption isotherm the

adsorption capacity (Q0) is observed highest 10.194 mg/g and (qmax) 5.8754 mg/g for 125

mg/L initial Cr(VI) concentration. Rate of adsorption (b) was also observed highest 7.0469

L/mg and 344.82 L/mg in case of Langmuir and BET adsoption isotherm for 125 mg/L

initial Cr(VI) concentration, suggest better applicability of BET isotherm for Azadirachta

indica leaves as adsorbent for Cr(VI) from aqueous solution. Azadirachta indica leaves data

for all chromium concentration (50mg/L, 75mg/L, 100mg/L and 125mg/L) followed

Freundlich model due to value of n obtained is 3.690, 4.115, 3.875 and 4.975 respectively .

Freundlich adsorption isotherm is also better applicable for 125 mg/L initial Cr(VI)

[45]

concentration as the highest value of adsorption capacity (Kf) is obtained 4.518 mg/g and

intensity of adsorption (n) is 4.9751 L/mg. The Azadirachta indica leaves shows good

agreement with Temkin isotherm for all initial concentration of Cr (VI) = 50 mg/L, 75

mg/L ,100 mg/L, 125 mg/L as the value of rate of adsorption (b) = 1.049 , 1.292, 1.646, 1.580

L/mg respectively. Here also, the value of adsorption capacity (a) was observed highest 3.939

mg/g for initial Cr(VI) concentration of 125 mg/L. The natural water/wastewater/effluent can

be treated by adding suitable dose of low-cost, natural adsorbent Azadirachta indica leaf

powder and by application of flocculator/other instrument with 160 rpm. The settled residue

remained at the bottom can be taken out. The adsorbent and Cr6+ can be recovered by giving

H2SO4 treatment to this sludge. The sludge of Azadirachta indica leaves is biodegradable. By

using this cost effective, eco-friendly technique we can get rid of the hazardous sludge

disposal problem-generated by chemical treatment of Chromium removal/recovery [85]

.

[46]

1.3 Need, Aims & Objective of the Study

Biological stages in conventional wastewater treatment plants are not able to remove

organic pollutants such as Phenol, Dyes & Pesticides/Insecticides from industrial

wastewater.

Such persistent pollutants require a special attention by giving purifying treatment to

remove them from wastewater.

The present work aims the following objectives:

1. Alumina has been used for the removal of anionic surfactant Sodium Dodecyl

Sulphate (SDS) from aqueous solution – practically any wastewater containing

surfactants.

2. The exhausted Alumina thus produced after the removal of SDS is called the Anionic

Surfactant Modified Alumina (ASMA).

3. ASMA has also been used for the removal of Crystal Violet Dye from synthetic as

well as actual textile sample.

4. ASMA has also been used for the removal of Phenol from synthetic as well as actual

sample of pharmaceutical industry.

5. Regeneration of ASMA by organic solvent acetone as well as recovery of Crystal

Violet & Phenol.

6. Silica Gel (very cheap commodity – can be easily obtained as a waste material from

Silica Gel Manufacturing Industry) has been used as an adsorbent for the removal of

cationic surfactant Dodecyl Trimethyl Ammonium Chloride from aqueous solution –

practically any wastewater containing surfactants.

7. The Surfactant coated Silica Gel was reutilized to uptake other organic pollutants like

organophosphorous insecticide monocrotophos from synthetic & actual pesticide

manufacturing industry sample.

8. Regeneration of Silica gel as well as recovery of monocrotophos by using mixture of

two organic solvents Metahnol & Acetone.

[47]

1.4 Scope of the Study

Tremendous potential exists for wastewater recycling and reuse in India, as only 30 percent

of the wastewater generated is treated. Industrial segment is most attractive for recycle and

reuse, mainly for non- potable applications.

Industries such as power, textiles, dyeing units, tanneries, and refineries have more potential

for wastewater recycle and reuse. Commercial and residential segments can reduce their

freshwater intake by adopting wastewater recycling, thereby, easing the burden on the

municipalities.

Adsolubilization process could efficiently be used for the removal of different organic

pollutants like dyes, phenolic compounds, Insecticides/herbicides, etc. from water

environment. Implementing this technique in the conventional treatment plant shall save

energy as well as our environment.

Industrial solid waste can be used as an adsorbents & these adsorbents can be used to remove

waste of other industries. The pollutants, thus adsorbed, can be recovered. The recovered

material can be reused in the industry as a raw material or intermediate material. This will

save fresh raw material. These adsorbents can also be regenerated easily. Regeneration of

such adsorbent would reduce the fresh material consumption to a greater extent & thus would

become very cost-effective as well as environment friendly. We can use thus regenerated

adsorbent again to treat more & more such organic pollutants.

[48]

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