ANALYSIS OF THE TREATMENT EFFICIENCY OF WASTEWATER FROM TWO BEVERAGE PRODUCING INDUSTRIES

8/10/2019 ANALYSIS OF THE TREATMENT EFFICIENCY OF WASTEWATER FROM TWO BEVERAGE PRODUCING INDUSTRIES

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ABSTRACT

Two industries in Kumasi were identified to possess Wastewater Treatment Plants (WWTP) totreat the large volumes of wastewater they generate on a daily basis before it was discharged into

a nearby river. This research examined the efficiency of treatment of these two wastewater

treatment plants. Samples were collected from the WWTP of both companies at the point of

entry into the plant, during the treatment process and after the treatment process. Laboratoryanalysis was performed for each sample collected to determine the BOD5, COD, TDS, pH,

Nitrate and Nitrite contents of the water. Also, further data was obtained from both companies.

This data contained information on the quality of wastewater before and after treatment for a

period of three months. Results from our analysis revealed that the efficiency of treatment of theWWTP of one company was 93.4, 94, 61.2, -127.3% for BOD, COD, Turbidity and TDS

respectively but failed to produce water that generally met the EPA standards for wastewater

discharge. The second companys WWTP on the other hand recorded efficiency levels of 90,56.7, 54.1, 22.6, and 93.3% for Nitrite, BOD, COD, Turbidity, and TDS respectively but

managed to produce wastewater that generally met the EPA standards for wastewater discharge.

100% efficiency meant all of the pollutant was removed from the waste water while 0%efficiency meant no pollutant was removed. Negative percentage efficiency meant that

wastewater became more polluted after passing through wastewater treatment plant (WWTP).


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CONTENTSABSTRACT ..................................................................................................... I

CHAPTER ONE: ................................................................................................. 1

INTRODUCTION ................................................................................................ 1

1.1 BACKGROUND ............................................................................................ 1

1.2 PROBLEM STATEMENT ..................................................................................... 3

1.3 JUSTIFICATION ......................................................................................... 3

1.4 AIMS AND SPECIFIC OBJECTIVES: ......................................................................... 4

CHAPTER TWO: ................................................................................................. 5

2.0 LITREATURE REVIEW ....................................................................................... 5

2.1 Wastewater treatment .................................................................................. 5

2.2 Wastewater Treatment Plants ........................................................................... 5

2.3 DESIGN OF COMPANY A AND COMPANY B PLANTS.......................................................... 9

2.4 Parameters of interest ............................................................................... 11

CHAPTER THREE: .............................................................................................. 16

MATERIALS AND METHODS ...................................................................................... 16

3.1 STUDY SITES .......................................................................................... 16

3.2 SAMPLING SITES ....................................................................................... 18

3.3 SAMPLING: ............................................................................................ 25

3.4 SAMPLE ANALYSIS: ..................................................................................... 25

CHAPTER FOUR: ............................................................................................... 29

4.0 RESULTS ................................................................................................ 29

4.1 LABOURATORY RESULTS FOR WASTEWATER SAMPLES COLLECTED FROM COMPANY A AND COMPANY B WWTP........... 29

CHAPTER FIVE: ............................................................................................... 42

5.0 DISCUSSION ............................................................................................. 42

5.1 OVERALL TREATMENT EFFICIENCY OF THE TWO TREATMENT PLANTS ............................................. 42

CHAPTER SIX: ................................................................................................ 53

6.0 CONCLUSION AND RECOMMENDATION .......................................................................... 53

6.1 Conclusion ........................................................................................... 53

6.2 Recommendation ....................................................................................... 54

REFERENCES .................................................................................................. 55

APPENDIXES .................................................................................................. 57

APPENDIX 1 : EPA Standards ................................................................................. 57

APPENDIX 2 :Paired t-test for Company A .................................................................... 58

APPENDIX 3 : Paired t-test for Company B ................................................................... 59

APPENDIX 4 : simple t-test for company A and company B Effluent ............................................ 60

APPENDIX 5 : Simple t-test for company A and company B influent ............................................ 60

APPENDIX 6 : Post hoc results for three month analysis of efficiency of Company A WWTP ..................... 61

APPENDIX 7 : Post hoc results for three month analysis of efficiency of Company B WWTP ..................... 61

APPENDIX 8 ................................................................................................. 62

LIST OF PLATES

PLATE 1: Areal view of the premises and layout of WWPT at Company A ...16

PLATE 2: Areal view of the premises and layout of WWPT at Company B ...17


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LIST OF FIGURES

FIGURE 3.1: Basic design of Company A plant .. ..21

FIGURE 3.2: Basic design of Company B plant .....24

FIGURE 4.11: TDS results for CompanyA' and 'Company B' WWTP ....30

FIGURE 4.12: pH results for 'Company A' and 'Company B' WWTP ...31

FIGURE 4.13: Turbidity results for 'Company A' and 'Company B' WWTP .....32

FIGURE 4.14: COD results for 'Company A' and 'Company B' WWTP ....33

FIGURE 4.15: BOD5 results for 'Company A' and 'Company B' WWTP .34

LIST OF TABLES

TABLE 2.1: Design specifications of Company A WWTP from WWTP manufacturer ..9TABLE 2.2: Design specifications of Company B WWTP from WWTP manufacturer .10

TABLE 4.1: Results for nitrate and nitrite analysis of wastewater from both companies ..35

Table 4.2: Efficiency during the treatment process of wastewater from both WWTPs..35

Table 4.3: Results of the mean wastewater quality and standard deviation over three

Months from Company A .......37

Table 4.4: Results of the mean wastewater quality and standard deviation over three months

from Company B. ...38Table 4.5: Efficiency after the treatment process of wastewater from both WWTPs.......39

Table 4.6: Quantity that was removed and remained after the entire treatment process from both

Companies...40


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CHAPTER ONE:INTRODUCTION

1.1 BACKGROUND

Wastewater is any water that has been adversely affected in quality by anthropogenic

influence that goes down the drain or sewage system. It comprises liquid waste discharged by

domestic residences, commercial properties, industries, and agricultural facilities. It can

encompass a wide range of potential contaminants at variable concentrations. In the most

common usage, it refers to the municipal wastewater that contains a broad spectrum of

contaminants resulting from the mixing of wastewater from homes, businesses, industrial

areas and often storm drains, especially in older sewer systems. Municipal wastewater is

usually treated in a combined sewer, sanitary sewer, effluent sewer or septic tank.

The composition of wastewater varies widely. Most commonly found in wastewater include

water (about 90%) which is often added during flushing to carry waste down a drain;

pathogens such as bacteria, viruses, prions and parasitic worms; non-pathogenic bacteria;

organic particles such as faeces, hairs, food, vomit, paper fibers, plant material, humus, etc.;

soluble organic material such as urea, fruit sugars, soluble proteins, drugs, pharmaceuticals,

etc.; inorganic particles such as sand, grit, metal particles, ceramics, etc.; soluble inorganic

material such as ammonia, road-salt, sea-salt, cyanide, hydrogen sulfide, thiocyanates,

thiosulfates, etc.; animals such as protozoa, insects, arthropods, small fish, etc.; macro-solids

such as sanitary napkins, nappies/diapers, condoms, needles, children's toys, dead animals or

plants, etc.; gases such as hydrogen sulfide, carbon dioxide, methane, etc.; emulsions such as


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paints, adhesives, mayonnaise, hair colorants, emulsified oils, etc.; toxins such as pesticides,

poisons, herbicides, etc.

Wastewater quality may be defined by its physical and chemical characteristics. Physical

parameters include colour, odour, temperature, and turbidity. Insoluble contents such as total

solids (TS), oil and grease also fall into this category. Chemical parameters associated with

the organic content of wastewater include biochemical oxygen demand (BOD5), chemical

oxygen demand (COD), and total organic carbon (TOC).

There are numerous processes that can be used to clean up wastewaters depending on the

type and extent of contamination. Most wastewater is treated in industrial-scale wastewater

treatment plants (WWTPs) which may include physical, chemical and biological treatment

processes.

The most important aerobic treatment system is the activated sludge process, based on the

maintenance and recirculation of a complex biomass composed by micro-organisms able to

adsorb the organic matter carried in the wastewater. Anaerobic processes are widely applied

in the treatment of industrial wastewaters and biological sludge (Burton et al, 2003). Some

wastewater may be highly treated and reused as reclaimed water. For some wastewaters

ecological approaches using reed bed systems such as constructed wetlands may be

appropriate. Modern systems include tertiary treatment by micro filtration or synthetic

membranes. After membrane filtration, the treated wastewater is indistinguishable from

waters of natural origin of drinking quality. Nitrates can be removed from wastewater by

microbial denitrification, for which a small amount of methanol is typically added to provide

the bacteria with a source of carbon. Ozone Wastewater Treatment is also growing in


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popularity, and requires the use of an ozone generator, which decontaminates the water as

ozone bubbles percolate through the tank (Burtonet al., 2003).

1.2 PROBLEM STATEMENT

Two industries have been identified in the Kaasi industrial area in Kumasi to generate large

quantities of wastewater as a result of their manufacturing processes. Both industries are in

the food production sector and for the purpose of this project would be addressed as

CompanyA and CompanyB. Both industries have modern wastewater treatment facilities

that treat wastewater generated through rigorous cleaning of machinery to prevent the growth

of microbes, the pasteurization process, and heating and cooling, Residual material from

bottles broken or rejected in the packaging areas along with liquid in the process tanks, also

contributes to wastewater.

Treated wastewater from these companies is discharged into the RiverSisa (which forms a

part of the Sisa-Oda catchment area of the eastern part of Kumasi) which is a few meters

away from the company sites. Improperly treated wastewater has negative effects on surface

waters. These effects include increase in Oxygen demand, escalated microbial growth, dying

of aquatic organisms due to O2-deficiency and possibly toxic compounds accumulating and

polluting the river water.

1.3 JUSTIFICATION

Around 90% of wastewater produced globally remains untreated, causing widespread water

pollution, especially in low-income countries such as Ghana. Increasingly, agriculture is

using untreated wastewater for irrigation. Cities provide lucrative markets for fresh produce,

so are attractive to farmers. However, because agriculture has to compete for increasingly


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scarce water resources with industry and municipal users, there is often no alternative for

farmers but to use water polluted with urban and industrial waste directly to water their crops

(Drechselet al., 2010). Communities downstream of the river also use the water for domestic

purposes such as cooking, drinking, bathing and washing.

The practice whereby wastewater from manufacturing industries is released into water bodies

is a potential for national disaster when proper care and attention is not given to the treatment

of the wastewater before releasing into our rivers. This project seeks to identify the pollution

load on the river Sisa from the two companies by determining the treatment efficiency of the

WWTP of both companies.

1.4 AIMS AND SPECIFIC OBJECTIVES:

The aim of this project was to determine the treatment efficiency of wastewater from

two different beverage producing industries in Kumasi.

The specific objectives were as follows:

To determine the physico-chemical properties (BOD5, COD, Total Dissolved Solids,

Turbidity, Nitrates, Nitrites and pH) of raw wastewater from the two companies.

To determine the reduction in levels of contamination in the wastewater after

treatment by comparing the wastewater quality before treatment to the quality after

treatment.

To determine potential problems in the wastewater treatment procedure/plant that

may be affecting its efficiency for improving wastewater treatment and to make

appropriate recommendations to remediate such problems.


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CHAPTER TWO:

2.0 LITREATURE REVIEW

2.1 Wastewater treatment

Wastewater is water that has come into contact with any of a variety of contaminants and is

not fit for human consumption. Wastewater has its source in domestic settings, commercial

operations, industry and agriculture (The FreeDictionary, 2013). To ensure the safe discharge

and use of wastewater it seems fairly obvious that we need to treat wastewater not only to

recycle the water and nutrients but also to protect human and environmental health.

2.2 Wastewater Treatment Plants

Generally WWTP are constructed to ensure that wastewater generated is remediated to meet

the requirements set by local and governmental regulators and environmental protection

agencies. The assessment of the efficiency of sewage treatment plants in Nagasandra and

Nailasandra in Bangalore, India by Ravi et al (2010) provides a typical example of how

important wastewater treatment plants are. Bangalore city hosts two Urban Wastewater

Treatment Plants (UWTPS) towards the periphery of Vrishabhavathi valley, located in

Nellakedaranahalli village of Nagasandra and Mailasandra Village, Karnataka, India. These

plants were designed and constructed with an aim to manage wastewater so as to minimize

and/or remove organic matter, solids, nutrients, disease-causing organisms and other

pollutants, before it reenters a water body. It was revealed from the performance study that

efficiency of the two treatment plants was poor with respect to removal of total dissolved

solids in contrast to the removal/reduction in other parameters like total suspended solids,

BOD5and COD (Raviet al., 2010).


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Wastewater treatment plants should be designed so that the effluent standards and reuse

objectives, and biosolids regulations can be met with reasonable ease and cost. The design

should incorporate flexibility for dealing with seasonal changes, as well as long-term changes

in wastewater quality and future regulations (Syed, 1999). Before the construction of a

wastewater treatment plant, analysis is always performed on the quality of the raw

wastewater that is required to be treated. The determination of the quality aids in identifying

which treatment processes are capable of improving the quality of the wastewater and finally

selecting the best treatment process among all the options.

The operation and maintenance of the completed facility requires expertise from various

fields in engineering and science. Principles from a wide range of disciplines: engineering,

chemistry, microbiology, geology, architecture, and economics are required to carry out the

responsibilities of designing, constructing, operating and maintaining a wastewater treatment

plant (Syed, 1999).

For every industry type there is a peculiar configuration of effluent treatment plant setups.

For example, brewery industries have a peculiar setup for a WWTP. Similarly, the leather

industry has its own, the dairy industry has its own, and the textile dyeing industry also has

its own setup. But the general processes of treatment are:

1. Pretreatment: This removes materials that can be easily collected from the raw

sewage before they damage or clog the pumps and sewage lines. It may include

activities such as:

o Screening: sewage water passes through a bar screen to remove all large objects like

cans, rags, sticks, plastic packets.


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o Grit Removal: This involves a sand or grit channel or chamber, where the velocity of

the incoming sewage is adjusted to allow the settlement of sand, grit, stones, and

broken glass.

o Flow Equalization: Equalization basins may be used for temporary storage of diurnal

or wet-weather flow peaks. Basins provide a place to temporarily hold incoming

sewage during plant maintenance and a means of diluting and distributing batch

discharges of toxic or high-strength waste which might otherwise inhibit biological

treatment

o Fat and Grease Removal: According to Roy(1971), in some larger plants, fat and

grease are removed by passing the sewage through a small tank where skimmers

collect the fat floating on the surface.

2. Primary Treatment: In the primary sedimentation stage, sewage flows through large

tanks, commonly called "pre-settling basins", "primary sedimentation tanks" or

"primary clarifiers". The tanks are used to settle sludge while grease and oils rise to

the surface and are skimmed off (Roy, 1971).

3. Secondary Treatment: It is essentially designed to substantially degrade the

biological content of the wastewater. Secondary treatment systems are classified as

fixed-film or suspended-growth systems.

Fixed-film or attached growth systems include Trickling Filters, Biotowers, and

Rotating Biological Contactors, where the biomass grows on media and the

wastewater passes over its surface. The fixed-film principle has further developed into

Moving Bed Biofilm Reactors (MBBR), and Integrated Fixed-Film Activated Sludge

(IFAS) processes.

Suspended-growth systems include activated sludge, where the biomass is mixed with

the sewage and can be operated in a smaller space than trickling filters that treat the

same amount of water.


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However, fixed-film systems are more able to cope with drastic changes in the

amount of biological material and can provide higher removal rates for organic

material and suspended solids than suspended growth systems (USEPA, 2004).

4. Tertiary Treatment:The purpose of tertiary treatment is to provide a final treatment

stage to further improve the effluent quality before it is discharged to the receiving

environment (sea, river, lake, and ground). More than one tertiary treatment process

may be used at any treatment plant. If disinfection is practiced, it is always the final

process. Tertiary treatment processes include sand filtration, nutrient removal

(nitrogen and phosphorus) and disinfection (chlorination, ozonation, ultra-violent)

(USEPA, 2004).

5. Odour Control: Odours are emitted by wastewater treatment and are typically an

indication of an anaerobic or "septic" condition. Early stages of processing will tend

to produce foul smelling gases, with hydrogen sulfide being most common. Most

industrial WWTP will often treat the odours with carbon reactors, a contact media

with bio-slimes, small doses of chlorine, or circulating fluids to biologically capture

and metabolize the obnoxious gases. Other methods of odour control exist, including

addition of iron salts, hydrogen peroxide, and calcium nitrate (Harshmanand

Barnette., 2000)


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2.3 DESIGN OF COMPANY A AND COMPANY B PLANTS

2.3.1 WWTP at COMPANY A

The WWTP at company A was constructed in the year 2004. The plant was desi gned to

handle an average wastewater of 2100 m3/day and a peak flow of 105m3/hour. According to

the specifications of the design, the plant could handle incoming wastewater with the

following characteristics.

Table 2.3.1: Design specifications of Company A Wastewater Treatment Plant from WWTP

manufacturer

The discharge parameters of the plant design are also listed below:

Flow m3/hr (peak) 105

pH range 6-9

TSS 50mg/l

BOD5 50mg/l

COD 250mg/l

Nitrate 50mg/l

Source: Environmental Department Of Company A.

COD (mg/l) TSS (mg/l) BOD5(mg/l) NITRATE (mg/l)

MAX 5813 713 3328 0.86

MIN 1967 195 1453 0.36

AVERAGE 3783 310 2322 0.61


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2.3.2 WWTP at COMPANY B

Company Bs WWTP was also constructed in the year 2004. The plant was designed to

handle an average of 1400m3/day of wastewater and a peak flow of 95m3/hour. According to

the specifications of the design, the plant could handle incoming wastewater with the

following characteristics:

Table 2.3.2: Design specifications of Company B Wastewater Treatment Plant from WWTP

manufacturer

The discharge parameters of the plant design are also listed below:

Flow m3/hr (peak) 95

pH range 6-9

TSS 50mg/l

BOD5 50mg/l

COD 150mg/l

Nitrate 5mg/l

Phosphate 2 mg/l

Source: Wastewater Treatment Department Of Company B.

COD

(mg/l)

TSS

(mg/l)

BOD5

(mg/l)

NITRATE

(mg/l)

pH PHOSPHATE

(mg/l)

MAX 2,500 100 1,500 4 11.8 3.5


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2.4 Parameters of interest

There are numerous parameters that may be used in determining the quality of water, whether

drinking water or wastewater. These parameters include alkalinity, colour, COD, BOD5,

conductivity, pH, TDS, total phosphorus, TSS, turbidity, nitrate, total coliforms, heavy metal

content, E. coli. For each kind of water analysis that is performed, parameters are selected

based on a number of factors which include the intended use of the water, the source of the

water, the kind of treatment which the water may have already undergone, the likely sources

of contamination of the water. Analysis of water which is intended for drinking purposes for

example must definitely include bacteriological analysis of total coliforms and E. coli.

Wastewater from an industry such as a mining industry must definitely include in its

analytical parameters heavy metal concentration.

For the purposes of this project, which examined wastewater from beverage production

companies, the following parameters were identified and analysis was done based on them;

BOD5, COD, total dissolved solids, turbidity, nitrates, nitrites and pH. Each parameter was

chosen considering its impact on the environment as the wastewater was discharged directly

into the surrounding environment. Also these parameters were selected because both

WWTPs were designed for the treatment of such parameters in wastewater.

2.4.1 BOD5

Biochemical oxygen demand or BOD5is the amount of dissolved oxygen needed by aerobic

microorganisms in a body of water to break down organic material present in a given water

sample at certain temperature over a specific time period. The BOD5 value is measured in


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milligrams of oxygen consumed per litre of sample in 5 days of incubation at 20 C and it

indicates the degree of organic pollution of water (Sawyeret al.,2003).

Most natural waters contain small quantities of organic compounds. Aquatic microorganisms

have evolved to use some of these compounds as food. Microorganisms living in oxygenated

waters use dissolved oxygen to convert the organic compounds into energy for growth and

reproduction. Populations of these microorganisms tend to increase in proportion to the

amount of food available. This microbial metabolism creates an oxygen demand proportional

to the amount of organic compounds useful as food. Under some circumstances, microbial

metabolism can consume dissolved oxygen faster than atmospheric oxygen can dissolve into

the water or the autotrophic community (algae, cyanobacteria and macrophytes) can produce.

Fish and aquatic insects may die when oxygen is depleted by microbial metabolism

(GoldmanandHorne,1983).

2.4.2 COD

Chemical Oxygen Demand is the amount of oxygen required to chemically oxidize organic

matter in water. It is expressed in milligrams per litre (mg/L) also referred to as ppm (parts

per million), which indicates the mass of oxygen consumed per litre of solution (Sawyeretal,

2003).

Though BOD5 and CODall measure the organic content of water, COD values are far larger

than BOD5 as not all organic material can be oxidized biologically. High COD values have

similar environmental effects as high BOD5 values


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2.4.3 TDS

Total Dissolved Solids is a measure of the combined content of all inorganic and organic

substances contained in a liquid in: molecular, ionized or micro-granular suspended form.

Generally the operational definition is that the solids must be small enough to survive

filtration through a sieve the size of two micrometer. Although TDS is not generally

considered a primary pollutant (e.g. it is not deemed to be associated with health effects) it is

used as an indication of aesthetic characteristics of water and as an aggregate indicator of the

presence of a broad array of chemical contaminants.

High TDS levels generally indicate hard water. A number of studies have been conducted and

indicate various species' reactions to high levels of TDS range from intolerance to outright

toxicity. Most aquatic ecosystems involving mixed fish fauna can tolerate TDS levels of 1000

mg/l (Boyd, 1999).

Research has shown that exposure to TDS is compounded in toxicity when other stressors

are present, such as abnormal pH, high turbidity, or reduced dissolved oxygen (Hoganetal.,

1973).

2.4.4 TURBIDITY

Turbidity is the cloudiness or haziness of a fluid caused by individual particles (suspended

solids) that are generally invisible to the naked eye. Fluids can contain suspended solid matter

consisting of particles of many different sizes. While some suspended material will be large

enough and heavy enough to settle rapidly to the bottom of the container if a liquid sample is

left to stand, very small particles will settle only very slowly or not at all if the sample is


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regularly agitated or the particles are colloidal. These small solid particles cause the liquid to

appear turbid. The most widely used measurement unit for turbidity is the NTU

(Nephelometric Turbidity Unit) (Baton, 2007).

In water bodies such as lakes, rivers and reservoirs, high turbidity levels can reduce the

amount of light reaching lower depths, which can inhibit growth of submerged aquatic plants

and consequently affect species which are dependent on them, such as fish and shellfish.

High turbidity levels can also affect the ability of fish gills to absorb dissolved oxygen (Court

etal., 1979).

2.4.5 pH

pH approximates the concentration of hydrogen ions in a solution. The pH value is the

negative logarithm (base 10) of the concentration of Hydrogen ions in the solution. pH is

measured on a scale of 0 to 14 with the lower values indicating high hydrogen ion activity

(more acidic) and high values indicating low hydrogen ion activity (less acidic). A pH of 7 is

neutral. Every whole unit of pH change represents a ten-fold change in the hydrogen ion

activity. For example, a pH of 5 is ten times more active than a pH of 6 and a pH of 4 is one

hundred times more active than a pH of 6. In the laboratory pH is measured by electrometric

pH measurement which is the determination of the activity of the hydrogen ions by

potentiometric measurement using a standard hydrogen electrode and a reference electrode.

The pH of the environment has a profound effect on the rate of microbial growth. pH affects

the function of metabolic enzymes. Acidic conditions (low pH) or basic conditions (high pH)

alter the structure of the enzyme and stop growth. Most microorganisms do well within a pH

range of 6.5 to 8.5. However, some enzyme systems can tolerate extreme pHs and will thrive

in acidic or basic environments. Abnormal or irregular pH in biological treatment processes


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can result in a significant decrease in the rate of removal of organic compounds from the

environment, which will affect the biochemical oxygen demand (BOD5) measurements

(Bates, 1973).

2.4.6 NITRATE / NITRITE

Nitrates and nitrites are nitrogen-oxygen chemical units which combine with various organic

and inorganic compounds. Unlike dissolved oxygen and TDS, the presence of normal levels

of nitrates usually does not have a direct effect on aquatic insects or fish. However, excess

levels of nitrates in water can create conditions that make it difficult for aquatic insects or fish

to survive.

Algae and other plants use nitrates as a source of food. If algae have an unlimited source of

nitrates, their growth is unchecked. Large amounts of algae can cause extreme fluctuations in

dissolved oxygen. Photosynthesis by algae and other plants can generate oxygen during the

day. However, at night, dissolved oxygen may decrease to very low levels as a result of large

numbers of oxygen consuming bacteria feeding on dead or decaying algae and other plants

(Madhab and Satya, 2009). Nitrates, when present with phosphates in water bodies, could

cause a condition known as eutrophication, which could further result in an anoxic event

(lack of oxygen).

Nitrate is a soluble nutrient found in fertilizers and sewage that percolates through the ground

and into aquifers. People who use aquifers as their source of drinking water are at a risk as

high nitrate (NO3) levels cause methemoglobinemia, or Blue Baby Syndrome, which can be

fatal to infants


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CHAPTER THREE:

MATERIALS AND METHODS

3.1 STUDY SITES

Two industries have been identified in the Kaasi industrial area in Kumasi to generate large

quantities of wastewater which ends up in the river Sisa. Both industries are in the food

production sector.

Plate 1: Areal view of the premises and layout of WWPT at Company A.

Company A is a Ghana-based company that is principally engaged in brewing. The

company was founded more than 40 years ago and is based in Kumasi, Ghana. The company

produces three alcoholic beverages and three non-alcoholic beverages.


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Sampling from Company A was done at the wastewater treatment plant. The image at the

top shows the layout of the company site with the area marked blue indicating the production

site and the area marked red indicating the wastewater treatment site of the company. The

wastewater treatment plant of Company A is based on two separate proprietary biological

processes. Both processes incorporate a random packed media system, which is also a

propriety product:

1. Hybrid technology (Anaerobic)

2. Submerged Aerobic filter (Aerobic)

Plate 2: Areal view of the premises and layout of WWPT at Company B

Company B is located atAsokwa in Kumasi, Ghana. The Company produces and markets

seven main brands, five carbonated soft drinks and two water brands.


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Sampling from Company B was done at the wastewater treatment plant. The image at the

top shows the layout of the company site with the area marked blue indicating the production

site and the area marked red indicating the wastewater treatment site of the company.

The wastewater treatment plant of Company B is based on one principal biological process

which is the Activated Sludge Process (Aerobic). This process is repeated in three tanks

during the process of treatment.

3.2 SAMPLING SITES

3.2.1 COMPANY A

The plant has a concrete inlet sump designed as two sections within a common structure. It is

covered to contain odour which is directed to the odour control unit for treatment. The

influent flows by gravity through a 25mm manually raked bar screen into the second section

of the inlet sump. Submerged pumps then transfer the wastewater from the secondary section

to a rotary screen. The rotary screen has a 2mm wedge wire screen and particles larger than

2mm were removed from the wastewater.

The screened wastewater passes out through a drum via gravity, into the balancing tank. If

the wastewater is outside the normal operation conditions, it is directed to the divert tank. The

plant has a balancing tank of 8 hours maximum retention time for influent load equalization

through the process of fermentation. It also has a divert tank with a 2 hour retention time

capacity. Both the balancing tank and the divert tank were constructed of glass coated

sectional steel. The balancing tank however was designed to include a pre-acidification stage


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for pH control and also has a vented roof for odour collecting to the odour control unit. The

content of the divert tank was fed back to the inlet sump in a controlled manner for treatment.

Variable speed pumps then transferred the water from the balancing tank to the anaerobic

reactor. The reactor was constructed from glass coated sectional steal and has a sealed roof.

The upper zone of the reactor contained randomly packed plastic media to a depth of two (2)

meters. On entering the reactor, the wastewater immediately mixed with the anaerobic

biomass. The reactor converts the COD content of the wastewater to methane, CO2and new

biomass. C6H12O6 3CH4 + 3CO2. The treated wastewater, biogas and some of the

anaerobic biomass flowed up into the packed media zone. At this point, three-phase

separation took place, dividing the liquid, gas and biomass into their separate constituents.

The treated wastewater flowed through the media and out from the reactor via a peripheral

launder channel into the degassing column. The anaerobic biomass was detached from the

biogas and separated from the treated wastewater as it passed through the packed media zone.

The biomass then fell back into the reactor and the biogas rose into the roof space above the

packed media zone.

From the degassing column, the wastewater flowed under gravity to the submerged aerated

filter where the second stage of the biological treatment took place via an aerobic process.

The reactor was constructed with glass coated sectional steel. The reactor contained randomly

packed plastic media, elevated and separated from the base of the reactor by a media support

platform but submerged in the anaerobically treated wastewater. The media provided a large

surface area on which the bacteria attached themselves. Air was pumped into the reactor by

blowers and was controlled via a dissolved oxygen probe located in the reactor. The air and

wastewater mixed and rose slowly to the packed media zone where it made contact with the


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aerobic biomass on the media surface. The aerobic bacteria further degraded the COD content

of the wastewater to produce more water, new aerobic biomass and CO2

The aerobically treated wastewater then moved from the aerobic tank to the clarifier tank.

The clarifier tank was constructed of glass coated sectional steel with a sloping concrete base.

The effluent from the submerged aerated filter (SAF) gravitates to the central diffuser drum

to allow the solids in the effluent to be separated. The clarified effluent flowed to a peripheral

launder and gravitate over a v-notch weir. The solid deposited at the base of the clarifier

were transferred to a central hopper by a half bridge scraper. The sludge was then pumped to

the aerobic sludge holding tank.

The clarified effluent then gravitates through the service water tank to the discharge point to

be discharged from the facility.


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Wastewater from the brewery

Manual screenS1002

Screen press

Bypass

Divert Tank

pH correction tank

Acid Caustic

Anaerobic Effluent tank

Pre-Treatment

Influent Pit

Buffering

FIG 3.1: Basic design of Company A plant and sampling points

Buffer tankT2001

Divert tank

T2002Clarifier

acid

Submerged Aerated

Filter

FINAL EFFLUENT

DISCHARGE

Balancing Tank

POST

TREATMENT

AEROBIC

TREATMENT

FIG 3.1: Basic design of Company A plant and sampling points

Wastewater from brewery


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3.2.2 COMPANY B

Wastewater from the production hall or any other place reached the treatment plant by first

passing through the bar screens. The bar screen is a manually operated two step bar installed

in the existing drain from the pumping station inlet. Its main purpose is to remove large

particles in the wastewater such as crown caps and drinking straws.

From there the wastewater flowed into a Sand-Oil trap (Grit chamber). This chamber serves

as a sand and oil trap to separate coarse matter like broken bottles, sand and stone. The pre-

clearified water passed the overflow into the neutralization chamber.

In the neutralization chamber, there was an agitator that constantly mixed the wastewater

while the water was being dosed with acid (HCl). The constant agitation of the water

prevented sedimentation and bad odour. The pH of the wastewater was controlled by a pH

measurement unit which automatically checks the pH of the wastewater and then dosed the

water in other to attain optimum pH for treatment.

The neutralized water flowed by gravity into a pump pit where two submerged pumps were

installed. These pumps pumped the water into the biological treatment unit BENB (Balancing

Equalization and Neutralization Basin).

The BENB was constructed from glass coated sectional steal and has a maximum capacity of

780m3. Water was pumped into this basin at a rate of 180m3/h. The BENBuses biological

means through an activated sludge process to partially treat the water. After a fixed time of

aeration and settlement, the clear water is pumped into the SBR1 . The SBR1 (Sequencing

Batch Reactor 1) was constructed from glass coated sectional steal and has a maximum


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capacity of 780m3. The neutralized and treated wastewater from the BENB having settled,

was pumped into the SBR1 where treatment was same as in the BENB. The treated

wastewater from the SBR1 was pumped into the SBR2 where treatment was same as in the

SBR1. The SBR2(Sequencing Batch Reactor 2)was constructed from glass coated sectional

steal and has a maximum capacity of 780m3. With the aid of oxygen in compressed air from

blowers into the tanks, microorganisms reduce BOD and COD in the water.

After treatment of the water in the SBR2the wastewater was transferred into storage tanks.

The storage tanks act as temporary storage of the effluent before it was discharged into drains

out of the premises of the company.


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Wastewater from the production hall

FIG 3.2: Basic design of Company B plant and sampling points

PRE-TREATMENTBar Screen

Sand-Oil trap

BUFFERINGNeutralization chamber

AEROBIC TREATMENT

BENB

SBR1

SBR2

STORAGE POST

TREATMENT

FINAL EFFLUENT DISCHARGE

PUMP

PUMP

PUMP


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3.3 SAMPLING:

Sampling for this project was conducted in two separate groups. One group of samples was

obtained from the wastewater treatment facility on the premises of Company A, while the

other group of samples was obtained from the wastewater treatment facility on the premises

of Company B. Composite samples were collected for this project and were collected at

intervals of 2hrs for a 24 hour period. Sampling for this project was done once.

Three samples were collected from each treatment plant using water sampling bottles as seen

in Fig 3.1 and Fig 3.2. The three samples collected from each plant were taken from:

1. Wastewater entering the treatment facility (influent). These samples were labeled

A1 for Company A and B1 for Company B.

2. Wastewater in the treatment plant which was undergoing treatment. These samples

were labeled A2 for Company A and B2 for Company B.

3.

Treated wastewater being released from the treatment plant into a drainage system

(effluent). These samples were labeled A3 for Company A and B3 for

Company B.

3.4 SAMPLE ANALYSIS:

All six samples collected (A1, A2, A3, B1, B2, B3) were transported in an ice chest to the

laboratory at Ghana Water Company office at Suame. Laboratory analyses of the samples

were conducted there to identify chemical and physical properties of all the samples

collected.


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3.4.1 PHYSICAL PARAMETERS

Physical parameters analyzed were total dissolved solids (TDS), pH, and turbidity. The pH

analysis was done using a pH meter, while the turbidity was done using the turbidimeter.

Analysis of total dissolved solids in the samples was done using a conductivity Meter.

3.4.2 CHEMICAL PARAMETERS

Chemical parameters of the samples analyzed where COD, BOD, Nitrates and Nitrite. The

COD test was done using a COD reactor, where 2ml of each sample was put in a test tube

containing a reacting agent (Potassium dichromate) and then the test tube put into the reactor

for 2 hours.

The BOD5 test was carried out by diluting each sample with oxygen saturated dilution water,

measuring the dissolved oxygen (DO) and then sealing the sample to prevent further oxygen

dissolving in. The samples were kept at 20 C in the dark to prevent photosynthesis (and

thereby the addition of oxygen) for five days, and the dissolved oxygen was measured again.

The difference between the final DO and initial DO was the BOD5.

The nitrate test was carried out by taking 20ml of each sample and putting in separate

containers. Each sample was digested using PalintestNitratestpowder. The digested solution

was shaken to properly mix. The solution was then allowed to stand for a while to settle and

decant. A portion of the decanted solution was collected into a round test tube and put into a

Palintest Photometer. A wavelength of 570nm on the photometer was used to determine the

presence of nitrate in the samples.


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The nitrite test was carried out by collecting 50ml of each sample into test tubes. 2ml of

ILOSVAYsN21solution was added to each sample in the test tube. This was followed by

adding 2ml of ILOSVAYsN22 solution to each test tube. After 15 minutes the samples

were filtered into another container using a filter paper and then analysed with a Nessleriser

for presence of nitrite.

3.4.3 STATISTICAL ANALYSIS

A number of statistical analysis were conducted on the results obtained from our laboratory

analysis of wastewater from both companies WWTP. These analysis were:

1. Paired t-test: This analysis was done by comparing the mean values of the wastewater

characteristics before treatment and after the treatment processes to determine if there

was any statistically significant difference between them.

2. Simple t-test: This analysis was done by comparing the mean values of wastewater

characteristics of the influent of both companies to determine if there was any

significant difference between them. Similarly, the analysis was done for the effluents

of both companies to determine if there was any significant difference between them.

3. Post hoc: This analysis was done by comparing the mean values of wastewater

treatment efficiency over a period of three months to determine if there was any

significant differences in efficiency between the three months. This analysis was done

for each company separately. The analysis was conducted for data obtained from the

laboratories of the two companies.


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A table is represented in the appendix that summarise the results of the statistical

analysis that was conducted. The statistical software that was used was SPSS version

16.0 and also a Graphical representation software (Microsoft Excel) was used to

generate graphs of the results we obtained.


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CHAPTER FOUR:

4.0 RESULTSThe results obtained from laboratory analysis of the samples collected from Company A

and Company B are presented in this chapter.

4.1 LABOURATORY RESULTS FOR WASTEWATER SAMPLES

COLLECTED FROM COMPANY A AND COMPANY B WWTP

Laboratory results that were obtained from Company A samples revealed some level of

improvement in wastewater quality. Parameters such as pH, nitrate content and nitrite content

remained fairly the same after the treatment of the water. Total dissolved solid in the

wastewater on the other hand increased in concentration after the treatment of the wastewater.

Turbidity, BOD5 and COD recorded some level of reduction after treatment. Initial

concentrations of COD and BOD5before treatment of the wastewater were very high.

Results from Company B wastewater analysis also showed varying degrees of treatment.

Generally every other parameter experienced some level of improvement after the treatment

process. Total dissolved solid were in large quantities before the commencement of the

treatment process but after the treatment the amount was greatly reduced.

pH, Turbidity, COD and BOD5 were in low concentrations before the commencement of

treatment as compared to that of Company A. These parameters of the wastewater were also

reduced after the treatment process. However turbidity of the water during treatment of the

water increases significantly by 328.93% of the initial level before treatment. Nitrate and


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Nitrite had low initial concentrations and were undetectable in the wastewater after the

treatment process.

Laboratory analysis of the wastewater quality over the last three months was also obtained

from the two companies and presented in a table 4.3. The data from the past three months

were obtained so as to compare with the results we obtained from our laboratory analysis, and

also to analyze the level of consistency in the treatment of the wastewater from the WWTP of

both companies.

Fig 4.11: TDS results for 'Company A' and 'Company B' WWTP

TDS for Company A wastewater increased throughout the treatment process from 725mg/l to

1358mg/l and further increased to 1648mg/l after the entire treatment process (Fig 4.11).


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TDS of Company B on the other hand dropped from 1056mg/l to 187.2mg/l during the

treatment process and then finally dropped to 70.7 mg/l after the treatment process (Fig 4.11).

Fig 4.12: pH results for 'Company A' and 'Company B' WWTP

pH for Company A wastewater increased from 8 to 10 during the treatment process but

reduced to 8.1 after the entire treatment process (Fig 4.12).

pH for Company B reduced from an initial point of 9.4 to 8.1 during the treatment process.

But it further reduced to 7.9 after the treatment process (Fig 4 12).


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Fig 4.13: Turbidity results for 'Company A' and 'Company B' WWTP

Turbidity for Company A reduced from an initial 240.3ntu to 136.2ntu during the treatment

process. It further reduced from 136.2ntu to 93.3ntu after the treatment process was completed

(Fig 4.13)

Company B however recorded an increase in turbidity from an initial point of 23.85ntu to

102.3ntu during the treatment process. The turbidity finally dropped from 102.3ntu to 18.45ntu

(Fig 4.13).

ntu


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4.14: COD results for 'Company A' and 'Company B' WWTP

COD of wastewater at Company A before treatment began was very high, but it reduced

drastically from the initial 15850mg/l to 4050 during the treatment process. After the entire

treatment process, the COD had further reduced from 4050mg/l to 1030mg/l (Fig 4.14).

COD of wastewater for Company Bincreased from an initial 305mg/l to 2450mg/l during the

treatment process but reduced to 140mg/l after the treatment was over (Fig 4.14).


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Fig 4.15: BOD5 results for 'Company A' and 'Company B' WWTP

BOD for Company A wastewater recorded a large reduction from an initial amount of

8242mg/l to 2146.50mg/l during the treatment process. It further reduced to 545.5mg/l after

the treatment process (Fig 4.15).

BOD of Company B wastewater increased from an initial of 161.65mg/l to 1250mg/l during

the treatment process but reduce to 70mg/l after the treatment process (Fig 4.15).


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Table 4.1: Results for nitrate and nitrite analysis of wastewater from both companies

COMPANY A

NITRITE (mg/l)

COMPANY B

NITRITE (mg/l)

COMPANY A

NITRATE (mg/l)

COMPANY B

NITRATE (mg/l)

BEFORE bdl 0.15 bdl 0.01

DURING bdl bdl bdl bdl

AFTER bdl bdl bdl 0.001

From the results that were obtained and presented in the Table 4.1 above, nitrate and nitrite

were below detection level (bdl) in the influent and effluent of Company A wastewater.

Company B however recorded 0.15mg/l and 0.01mg/l for Nitrite and Nitrate respectively in

influent entering the treatment plant. Nitrate and nitrite levels were not detected in Company

B WWTP during the treatment process but an amount of 0.001mg/l of nitrate was detected

after the treatment of wastewater from Company B WWTP.

Table 4.2: Efficiency of the treatment process of wastewater from both WWTPs

Negative values in Table 4.2 are an indication that the wastewater became more polluted

during the treatment process. Positive values are an indication of a reduction in pollution in the

wastewater during the treatment process. Company B recorded the highest level of efficiency

of TDS removal (82.3%) while Company A recorded an increase in TDS addition of 87.3%

PARAMETER COMPANY A

(%)

COMPANY B

(%)Total dissolved solids

(mg/l)

-87.3 82.3

Turbidity (ntu) 43.4 -328.9

COD (mg/l) 74.4 -705.6

BOD5(mg/l) 73.9 -637.3

Nitrite (mg/l) 0 100


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during the treatment process due to the addition of Ammonium Sulphate (NH4)2SO4 as nutrient

for microbial growth in Company A WWTP.

The highest turbidity removal (43.4%) was recorded in Company A while Company B

recorded an increase of turbidity by 328.9% during the treatment process. COD and BOD

removal efficiency was also high in Company A at 74.4% and 73.9% respectively.Company

B recorded an increase in COD and BOD levels at 705.6% and 637.3% respectively. This was

expected because Company B used an activated sludge system. Company B recorded a 100%

reduction in Nitrite concentrations but in Company Anitrite was below detection limit during

the treatment process.


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Table 4.3: Results of the mean wastewater quality and standard deviation over three

months from Company A

MONTH PARAMETER BEFORE DURING AFTER

OCTOBER

COD (mg/l) 4,5481362.22 2,364935.63 711130.32

BOD5(mg/l) 614.75948.84 -- 483103.24

pH 111.3 6.90.3 7.60.2

TSS (mg/l) 24264.01 40872.09 19031.49

NITRATE (mg/l) 181.41 -- --

PHOSPHORUS (mg/l) 227.78 52.511.90 --

TEMPERATURE (oc) 361.39 35.90.53 32.40.87

N

OVEMBER

COD (mg/l) 6,7542709.03 1,180764.43 823212.29

BOD5(mg/l) 1,3311815.68 -- 30298.40

pH 110.6 70.2 80.3

TSS (mg/l) 344198.2 568146.45 355177.95

NITRATE (mg/l) 4237.48 -- --

PHOSPHORUS (mg/l) 223.54 6012.35 --

TEMPERATURE (oc) 35.10.8 36.70.9 32.55.7

DECEMBER

COD (mg/l) 9,2821928.87 61321265.83 978538.45

BOD5(mg/l) 8166022.78 -- 23638.22

pH 10.60.83 7.11.4 80.4

TSS (mg/l) 345201.15 462126.63 362116.87

NITRATE (mg/l) 251.13 -- --

PHOSPHORUS (mg/l) 445.22 6712.73 --

TEMPERATURE (oc) 36.71.09 37.31.7 33.40.9


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Table 4.4: Results of the mean wastewater quality and standard deviation over three months

from Company B.

MONTH PARAMETER BEFORE AFTER

OCTOBER

pH 9.10.3 7.90.4

TURBIDITY (ntu) 50.8514.7 4010.2

COD (mg/l) 3169 12020

BOD5(mg/l) 17025 4224.9

NITRATE (mg/l) 1.120.5 1.350.51

PHOSPHORUS (mg/l) 1.960.3 1.70.22

TEMPERATURE (oc) 32.51.4 291

NO

VEMBER

pH 9.50.22 8.90.2

TURBIDITY (ntu) 100.7340.5 15.112.4

COD (mg/l) 42015 3213.2

BOD5(mg/l) 25010 207.4

NITRATE (mg/l) 1.060.04 0.160.02

PHOSPHORUS (mg/l) 1.860.55 1.70.6

TEMPERATURE (oc) 301 28.91.5

DECEMBER

pH 8.80.4 90.2

TURBIDITY (ntu) 47.815.2 19.925.6

COD (mg/l) 30527 40.3216.1

BOD5(mg/l) 12525 28.65.4

NITRATE(mg/l) 1.150.01 0.160.04

PHOSPHORUS (mg/l) 0.970.66 1.70.02

TEMPERATURE (oc) 290.3 28.21.3


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Table 4.5: Efficiency of the treatment process of wastewater from both WWTPs

Company A recorded a negative value for efficiency of removal of TDS (-127.3%) as it

rather increased the amount of dissolved solid present in the wastewater after the treatment

process due to the addition of nutrients for microbial growth. Company B on the other hand

recorded a positive efficiency value (93.3%) since it succeeded in removing much of the

dissolved solids in the wastewater after the treatment process.

Company A recorded a 61.2% reduction in turbidity as compared to Company Bs 22.6%

reduction in turbidity after the treatment process. Company A also recorded the highest

percentage of efficiency for COD and BOD (94% and 93.4% respectively) as compared to

Company B which recorded 54.1% and 56.7% respectively for COD and BOD.

PARAMETER COMPANY A

(%)

COMPANY B

(%)

Total dissolved solids (mg/l) -127.3 93.3

Turbidity (ntu) 61.2 22.6

COD (mg/l) 94 54.1

BOD5(mg/l) 93.4 56.7

Nitrite (mg/l) 0 90


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Nitrite was below detection limit in Company As wastewater, hence, there was no efficiency

of removal determined. Company B on the other hand recorded 90% efficiency in nitrite

removal.

Table 4.6: Quantity that was removed and remained after the entire treatment process

from both Companies

COMPANY TDS

(mg/l)

TURBIDITY

(ntu)

COD

(mg/l)

BOD

(mg/l)

A REMOVED -923 147 14820 7696.5REMAINED 1648 93.3 1030 545.5

BREMOVED 985.3 4.5 165 91.65

REMAINED 70.7 18.45 140 70

Table 4.6 above shows the actual values of how much of contamination were removed from

the wastewater and also how much of it remained in the wastewater after treatment in the

WWTP of both companies. Negative values in Table 4.6 are an indication that more

contamination were added to the wastewater after the treatment process and the wastewater

became more polluted while positive values indicate that waste was removed from the

wastewater after the treatment process and the wastewater became less polluted

After the treatment process, 923 mg/l of TDS was added to Company A wastewater

resulting in a total of 1648 mg/l of TDS in the final effluent. Company B recorded a

removal of 985.5 mg/l of TDS resulting in a final effluent of 70.7 mg/l of TDS.

147 ntu was removed from Company A wastewater after treatment, thus producing an

effluent with 93.3 ntu. Only 4.5 ntu was removed from Company B wastewater after

treatment, hence resulting in a final effluent of 18.45 ntu.


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14820 mg/l of COD was removed from Company A wastewater and 1030 mg/l of COD

remained after treatment. 165 mg/l of COD was also removed from Company B wastewater

after treatment, while 140 mg/l remained in the wastewater after the treatment process.

7696.5 mg/l of BOD was removed from Company A wastewater while 545.5 mg/l of BOD

remained in the wastewater after the treatment process.

Company B recorded 91.65mg/l of BOD removal while 70mg/l of BOD remained in the

wastewater after the treatment process.


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CHAPTER FIVE:

5.0 DISCUSSION

5.1 OVERALL TREATMENT EFFICIENCY OF THE TWO

TREATMENT PLANTS

The overall efficiency of each plant was calculated by considering the TDS, pH, Turbidity,

COD, BOD, Nitrate and Nitrite of the influent and final effluent (Table 4.4).

5.1.1 TOTAL DISSOLVED SOLIDS

Results from the laboratory analysis on Total Dissolved Solids showed that great variations

existed in the treatment of TDS in wastewater from both companies (Fig 4.11). Company B

recorded a 93.3% efficiency in TDS removal (Table 4.5). In other words , Company B

treatment plant successfully removed an average of 985.3 mg per every litter of wastewater

that flowed through it (Table 4.6). This meant that an average of 70.7 mg of dissolved

material remained in the wastewater after treatment representing 6.7% of the initial amount of

TDS present before treatment. With an effluent of TDS 70.7 mg/l, it falls within the Ghana

EPAs standards for TDS (1000mg/l) (Fig 4.11). Hence company B effluent TDS level was

14 times lower than what was expected from them by the Ghana EPA.

Results for Company A wastewater analysis indicated that the treatment plant rather

increased the total amount of Dissolved Solids after the entire treatment process by 127.3%

of the initial amount of dissolved solids present (Table 4.5). In figures, an additional average

of 923 mg of dissolved material was added per litre of wastewater after the treatment process

(Table 4.6). The increase in the amount of total dissolved solids could be attributed to the


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addition of nutrients such as Ammonium Sulphate (NH4)2SO4 to the treatment tanks so as to

sustain microbial growth. Also, occasional foaming occurs in the tanks and anti-foaming

chemicals were added to mitigate the foaming effect. The final effluent from Company A

does not meet EPA standards for TDS because it was 1.65 times higher than what was

expected from them by the EPA.

5.1.2pH

pH was a very crucial property of wastewater that may determine the degree to which it may

be treated. pH may directly or indirectly affect the levels of removal of BOD, COD,

Dissolved solids and nutrients. Influent entering the treatment plants was generally

characterized by high pH. This was due to the use of Caustic Soda in washing bottles that are

returned to the factory before refilling them. Caustic soda also known as Sodium Hydroxide

(NaOH) was a highly basic material which was white in colour

In the case of wastewater analysis of effluent from both companies, pH of influent and

effluent fell well within the optimum necessary for treatment (Fig 4.12). That was to say the

pH fell within a range of 6 9. However Company A recorded an increase pH to 10 during

the treatment process of the wastewater. This could most likely affect microbial growth in

both the aerobic and anaerobic tanks; thus affecting the efficiency of those tanks.

At a confidence level of 95%, a paired t-test on pH of Company A wastewater before

treatment and after treatment produced a p-value of 0.041. This indicated that the difference

between pH levels before treatment and after treatment of the wastewater was statistically

significant. At an alpha value () of 0.05, a paired t-test on pH of Company B wastewater

before and after treatment produced a p-value of 0.131. This indicated that the difference


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between pH levels before treatment and after treatment of the wastewater was not statistically

significant.

5.1.3 TURBIDITY

The turbidity of wastewater from Company B did not see much improvement (Fig 4.13)

Turbidity of the final effluent reduced by 22.64% from an initial of 23.85 ntu (Table 4.5). It

was also mentioned in our results that turbidity of the wastewater in Company B treatment

plant increase by 328.93% during the treatment process (Table 4.2). This was most likely due

to the mixing of the water with the aerobic bacteria present in the aerobic tank. The final

treated effluent from Company B meets the turbidity requirements of the EPA standards

because it was 4.06 times less than what was expected from them by the EPA.

Analysis of Company A wastewater for turbidity revealed a slightly different result from

the other company. In Company Asresults, turbidity reduced steadily from its initial point

of 240.3 ntu to 93.3 ntu (Fig 4.13). In other words, turbidity reduced by 61.17% (Table 4.5).

Company A did not experience an increase in turbidity during the treatment process (Fig

4.13) due to the possibility of a more effective system of separation of biomass from the

wastewater or poor mixing of the wastewater with the aerobic and anaerobic bacteria. Despite

the relatively high level of reduction of turbidity in wastewater from Company A, the

effluent did not meet EPA standards for turbidity because it was 1.24 times higher than what

was expected from them by the EPA (Fig 4.13).

At an alpha value () of 0.05, a paired t-test on turbidity of Company B wastewater before



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between turbidity before treatment and after treatment of the wastewater was not statistically

significant.

5.1.4 COD

Laboratory results on wastewater from Company A revealed 93.5% efficiency in the

removal of COD (Table 4.5). Only 6.5% of the initial amount of COD remained in the

wastewater after treatment. The treatment plant was able to remove 14820 mg of COD per

litre of wastewater that passed through it (Table 4.6). The remaining level of COD however

was higher than EPA required level. With a COD level of 1030 mg/l, it was four times higher

than EPA standard.

The treatment plant at Company B however managed 54.1 % efficiency in COD removal

with respect to results obtained from laboratory analysis of wastewater from the plant (Table

4.4). The plant successfully removed 165 mg of COD for every litre of wastewater that went

through it (Table 4.6). Despite the low level of efficiency of Company B treatment plant in

terms of COD removal, the final effluent met EPAs standard for COD in effluents as it was

1.78 times lower than what was expected from them by the EPA (Fig 4.14).

In comparison, Company A treatment plant was more efficient than Company B by a ratio

of 1.7: 1. However Company B final COD levels fall within the standard requirements for

discharge, while Company A does not (Fig 4.14).

At an alpha value () of 0.05, a paired t-test on COD of Company A wastewater before


between COD levels before treatment and after treatment of the wastewater was not


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statistically significant. At a confidence level of 95%, a paired t-test on COD levels of

Company B wastewater before treatment and after treatment produced a p-value of 0.014.

This indicated that the difference between COD levels before treatment and after treatment of

the wastewater was statistically significant.

5.1.5 BOD5

With respect to the results obtained from the laboratory, Company A treatment plant

managed to remove 93.38% of the total BOD that was present in the wastewater before

treatment (Table 4.5). This means that only 6.62% of the total BOD remained in the

wastewater after treatment. Initial amount of BOD was recorded to be 8242 mg/l, hence the

plant was able to remove 7696.5 mg of BOD per every litre of wastewater (Table 4.6). This

was quite a high level of efficiency; however the final BOD content of the treated effluent

does not meet the requirement of the EPA (50 mg/l). This means that the BOD content of

effluent from Company A was more than ten times the amount required by EPA standards

(Fig 4.15).

The treatment plant at Company B managed to remove 56.70% of BOD from the

wastewater after the treatment process (Table 4.5). 43.30% of the initial BOD was still

present after the treatment process. Initial BOD recorded before treatment was 161.65 mg/l

hence the plant was able to remove an average of 91.66 mg of BOD per litre of wastewater

passing through it (Table 4.6). With a final effluent with BOD of 70 mg/l, it still did not meet

the EPA requirement of 50 mg/l.

Comparing the initial BOD load on both plants, it was obvious that Company A BOD load

was far greater than Company B BOD load (8242 mg/l against 161.65 mg/l. Roughly 50: 1


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ratio) (Fig 4.15). Though Company B recorded a BOD value close to the EPA standard, its

plant recorded just 56.70% BOD removal efficiency. Company A on the other hand

recorded a much higher BOD removal efficiency of 93.38% though it was also very far from

meeting the EPA standards.

At an alpha value () of 0.05, apaired t-test on BOD5 of Company A wastewater before and

after treatment produced ap-value of 0.276. This indicated that the difference between BOD5

levels before treatment and after treatment of the wastewater was not statistically significant.

At a confidence interval of 95%, a paired t-test on BOD5 levels of Company B wastewater

before and after treatment produced a P-value of 0.023. This indicated that the difference

between BOD5 levels before treatment and after treatment of the wastewater was statistically

significant.

5.1.6 NITRATE AND NITRITE

Results we obtained from our analysis of wastewater from both companies revealed that both

nitrates and nitrites were below the minimum detection level of analytical methods we used

(Table 4.1). The lack of nitrates and nitrites could affect the degree to which microbial

populations in the treatment plant of Company A would break down and remove BOD in the

wastewater. This was because these compounds are nutrients for the microorganisms to be

able to act upon organic matter.

Company B results however showed some amount of nitrate and nitrite was present in the

influent entering the plant (Table 4.1). Though the amount of nutrient was quite insignificant,


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results on the finally treated effluent revealed that more than 90% (Table 4.5) of the nutrient

was used up during the treatment process most likely by microbes.

At a confidence level of 95%, a paired t-test on Nitrate/nitrite levels of Company B

wastewater before and after treatment produced a p-value of 0.212. This indicated that the

difference between Nitrate/nitrite levels before treatment and after treatment of the

wastewater was statistically insignificant.

5.1.7 TEMPERATURE

At an alpha value () of 0.05, apaired t-test on temperature of Company A wastewater before

and after treatment produced a p-value of 0.009. This indicated that the difference between

temperature levels before treatment and after treatment of the wastewater was statistically

significant.

At an alpha value () of 0.05, apaired t-test on temperature of Company B wastewater before

and after treatment produced a p-value of 0.17. This indicated that the difference between

temperature before treatment and after treatment of the wastewater was not statistically

significant.

5.1.8PHOSPHATE

At a confidence level of 95%, a paired t-test on phosphate levels of Company A wastewater


between phosphate levels before treatment and after treatment of the wastewater was

statistically significant


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At an alpha value () of 0.05, a paired t-test on phosphate levels of Company B wastewater


between phosphate levels before treatment and after treatment of the wastewater was not

statistically significant

5.1.9 TSS

At an alpha value () of 0.05, a paired t-test on Total Suspended Solid of Company A

wastewater before treatment and after treatment produced a p-value of 0.752. This indicated

that the difference between Total Suspended Solid levels before treatment and after treatment

of the wastewater was not statistically significant.

5.1.10 Effect of plant design on efficiency

The design of the treatment plants of both companies influenced the degree to which

contaminants were efficiently removed from the wastewater. Generally Company As

WWTP was more efficient than Company Bs WWTP. A number of factors could be

attributed to why Company A was more efficient than Company B. These factors include:

1. Type of secondary treatment employed: Company A WWTP was designed to treat

wastewater using two different kinds of biological processes (anaerobic and aerobic).

Anaerobic decomposition requires less amount of energy as compared to aerobic

decomposition, hence more of the contamination in the wastewater was removed by

the anaerobic treatment stage of Company A WWTP. In Fig 4.14 and Fig 4.15, it

was observed that COD and BOD levels reduced by a large margin during the


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treatment process (after the first biological treatment processes which was anaerobic

in the case of Company A).The combination of anaerobic treatment followed by

aerobic treatment in Company A WWTP ensured higher efficiency of wastewater

treatment,

Company B WWTP was designed to treat wastewater using one kind of biological

process (aerobic). Due to the sole use of an activated sludge system, it was observed

that BOD, COD and turbidity levels increased during the treatment process (Fig 4.13

Fig 4.14 and Fig 4.15). This is because the addition of activated sludge increased the

biomass in the wastewater as well as making the wastewater more turbid.

2. The retention time of the treatment tanks: When wastewater spends more time in the

treatment tanks, it offers the microbes in the tanks more time to act upon the

contaminants in the wastewater and reduce the concentration of the contaminants. The

retention time of the treatment tanks in Company A WWTP was 3 hours while the

retention time of treatment tanks in Company B WWTP was 2 hours. Company A

WWTP provided more time for the treatment of wastewater as compared to

Company B WWTP, hence Company A had a more efficient treatment plant.

5.1.11 Effect of age of plant on efficiency

Both treatment plants were constructed in the year 2004 and have been in operation for the

past nine years. Comparing the design specifications of both plants (table 2.3.1 and table

2.3.2) and the current level of treatment efficiency (table 4.5), it was observed that the

efficiency of both treatment plants had reduced over the nine years period of operation. This

could be attributed to the influence of environmental conditions such as temperature changes


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and rain fall on the WWTPs. Also the degradation of mechanical parts of the WWTPs due to

the consistent use of the plants over the years could have affected the plants efficiency of

treatment.

5.1.12 Effect of raw wastewater characteristics on plant efficiency

High amounts of contamination in wastewater can affect the efficiency of treatment of the

wastewater. In the removal of COD and BOD for example, oxygen may be required,

however, if there is too much demand for oxygen in removing contaminants in the

wastewater, anoxic conditions may develop that would result in the death of aerobic microbes

in the wastewater. These microbes are responsible for the removal of contaminants in the

wastewater, hence their death will reduce the efficiency of treatment of the wastewater.

In comparing the wastewater generated by both companies as a result of their production

activities, Company A generated more load in their wastewater as compared to Company

B. Company A principally engaged in brewing which involves a lot of fermentation

processes. Raw materials used in production in Company A include malt extract, hops,

special grains (maize or rice) and yeast. These fermentation processes generate high amounts

of biomass waste which end up in the wastewater fed into the treatment plant. Company B

principally engages in the production of soft drinks. The production of soft drinks does not

involve fermentation. Hence Company Bs production activities did not generate much

contamination in their wastewater entering the treatment facility.

A second t-test was conducted to ascertain if there were similarities in the influents and

effluents that were fed into the WWPTs and released from the WWPTs of both companies.

The results however indicated that at a confidence interval of 95% and a P-value of 0.178,


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Company A WWTP received influents with statistically insignificant different

characteristics compared to the influent fed into Company B WWTP. The t-test results also

revealed that at a confidence interval of 95% and a p-value of 0.104, Company A and

Company B WWPTs produced effluents with differences which were statistically

insignificant from each other.

A Post Hoc analysis was conducted for the data received from both Company A and

Company B laboratories. Analysis on Company A data indicated that wastewater treatment

efficiency for the three months (October, November, and December) was not consistent. That

was to say that at a confidence interval of 95%, the P-values for monthly comparisons were

all greater than 0.05.

Post Hoc results on Company B indicated that there was no homogeneity in the treatment

efficiency of the WWTP over the three month period at a confidence interval of 95%. This

meant that the WWTP of Company B had experience varying degrees of efficiency over the

three month period, with some months recording higher levels of efficiency than others.

According to the research done by Ravi et al, (2010) on WWTPs in Nagasandra and

Mailasandra, TDS and COD removal efficiency was the least in both plants. In comparison to

our work, TDS removal efficiency was low for Company A but high for Company B while

COD removal efficiency was low for Company B but high for Company A.


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CHAPTER SIX:

6.0 CONCLUSION AND RECOMMENDATION

6.1 Conclusion

Results obtained from sample analysis and data obtained from both companies indicated that

wastewater treatment efficiency of both plants has decreased over the years since the time of

construction of both wastewater treatment plants. The efficiency of treatment however has

not been consistent even for short periods of time (three month period).

It was also observed that higher levels of efficiency of treatment did not necessarily translate

to the meeting of standards for discharge of effluent into the environment. This was mainly

due to the already high level of load in the influent before treatment, such that even a high

degree of treatment still produced effluent that did not meet the standard. This was observed

mostly in the results of Company A.

Though Company B produced relatively lower levels of efficiency of treatment, its final

effluents were within the required standards for discharge of effluent into the environment.

These phenomena could also be attributed to the amount of load contained in the influent

entering the plant for treatment.

The overall efficiency of treatment was in the order TDS< Turbidity< BOD< COD for

Company A WWTP and Turbidity < COD


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Hogan C. M., Patmore C. L. and Seidman H. (1973). Statistical Prediction of Dynamic

Thermal Equilibrium Temperatures using Standard Meteorological Data Bases. U.S.

Environmental Protection Agency. EPA-660/2-73-003.

Madhab C. D. and Satya P. D. (2009). Fundamentals of ecology. McGraw Hill, New

Delhi.

Ravi P. K., Pinto L. B. and Somashekar R.K. (2010). University Journal Of Science,

Engineering And Technology. Vol. 6, No. Ii, Pp 115-125

Roy F. W. (1971). Process Design Manual for Upgrading Existing Wastewater Treatment

Plants. Water Resources Scientific Information Center. Washington, D.C Chapter 3

Sawyer C. N., McCarty L.P. and Parkin G. F. (2003). Chemistry for Environmental

Engineering and Science (5th ed.). McGraw-Hill. New York

Syed R. Q. (1999). Wastewater Treatment Plants: Planning, Design and Operation.

Technomic Publishing Company.

The FreeDictionary. (2013). wastewater. Retrieved May 21, 2013 from

http://www.thefreedictionary.com/wastewater

USEPA. (2002). The Microbiology of Drinking WaterPart 1 - Water Quality and Public

Health

USEPA. (2004). Primer for Municipal Wastewater Treatment Systems. Document no.

EPA 832-R-04-001.


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APPENDIXES

APPENDIX 1 : EPA StandardsAlcoholic Beverage Industry

PARAMETERS MAXIMUM

PERMISSIBLELEVELS

1. Alkalinity(mg/l) 150

2. Color(TCU) 200

3. COD(mg/l) 250

4. BOD(mg/l) 50

5. Oil & Grease(mg/l) 5

6. Conductivity(mg/l) 1500

7.pH(mg/l) 6-9

8. TDS(mg/l) 1000

9. Total phosphorous(mg/l) 2

10.TSS(mg/l) 50

11.Turbidity(N.T.U.) 75


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APPENDIX 2 :Paired t-test for Company A

PARAMETER Standard

deviation

Standard

Errormean t df Sig.

BEFORE

BODAFTER

3673.11267

146.37701

1836.556

73.189

1.319 3 0.279

BEFORE

COD AFTER

4892.84

145.822

2446.42

72.911

3.454 3 0.041

BEFORE

pHAFTER

1.218

0

Documents

ANALYSIS OF THE TREATMENT EFFICIENCY OF WASTEWATER FROM TWO BEVERAGE PRODUCING INDUSTRIES