Tech No Craft

8/7/2019 Tech No Craft

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Water Harvesting

Living creatures of the universe are made of five basic elements, viz., Earth, Water, Fire, Air

and Sky, Obviously, water is one of the most important elements and no creature can survive

without it. Despite having a great regard for water, we seem to have failed to address this sector

seriously. Human being could not save and conserve water and it sources, probably because of its

availability in abundance. But this irresponsible attitude resulted in deterioration of water bodies

with respect to quantity and quality both. Now, situation has arrived when even a single drop of

water matters. However better late than never", we have not realized the seriousness of this issue

and initiated efforts to overcome those problems.

Problem?

Although India occupies only 3.29 million km geographical area, which forms 2.4% of the

world's land area, it supports over 15% of world's population. The population of India as of March 1,

2001 was 1,027,015,247 persons (Census, 2001). India also has a livestock population of 500 million,

which is about 20% of world's total livestock. However total annual utilizable water resources of the

country are 1086 km which is only 4% of world's water resources. Total annual utilizable resources of

surface water and ground water are 690 km and 396 km respectively (Ministry of Water Resources,

1999). Consequent to rapid growth in population and increasing water demand, stress on water

resources in India is increasing and per capita water availability is reducing day by day. In India per

capita surface water availability in the years 1991 and 2001 were 2300 m (6.3 m /day) and 1980 m

(5.7 m /day) respectively and these are projected to reduce to 1401 and 1191 m by the years 2025

and 2050 respectively. Total water requirement of the country in 2050 is estimated to be 1450 km

which is higher than the current availability of 1086 km. various options including rainwater

harvesting and wastewater reuse will have to be considered to meet the anticipated deficit.

As the water crisis continues to become severe, there is a need of reform in water

management system and revival of traditional systems. A scientific and technological study needs to

be carried out to assess present status so as to suggest suitable measures for the revival to

traditional system/wisdom. Revival process should necessarily be backed by people's initiative and

active public participation.

In the present scenario management and distribution of water has become centralized.

People depend on government system, which has resulted in disruption of community participation

in water management and collapse of traditional water harvesting system.


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The future water condition

Water availability will be to 1 person out of 3. Water quality will become unsafe in majority of the places. No food to 1/3 of the population. Many water borne diseases like Fluorosis, Dementia, Diarrhea, Cancer etc. will be order

of the day.

There will be fight for water between Man to man. City to city. State to state. Country to country Possible third world war?

Solution -

The simple cost, effective solution is water harvesting. There is much quantity of water

which can be harvested to a very large extent. It is the need of today that not a single drop of water

should be wasted and let down into the soil unused.

Water that can be harvested

Rain water- Water received by earth by natural precipitation and infiltrating into the soildirectly.

Storm water- Water received by natural precipitation and flowing through storm waterdrains which are ultimately let into the river, polluting the river to a large extent.

Grey water- Domestic water which flows through the drains of residential buildings.


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Rainwater Harvesting

Introduction

Water is an elixir of life on earth. Water is the worlds most precious natural source. It is

the support of life. The source of all water is Rain. Rain is Living water.

Falling rain is at risk only from airborne particles and from man-made pollution caused by

the smoke and ash of ires and industrial processes, particularly those which burn fossil fuels.

Most modern technologies for obtaining drinking water are related to the exploitation of

surface water from rivers, streams and lakes, and groundwater from wells and boreholes. However,

these sources account for only 40% of total precipitation. It is evident, therefore, that there is

considerable scope for the collection of rainwater when it falls, before huge losses occur due to

evaporation and transpiration and before it becomes contaminated by natural means or man-madeactivities. Where there is no surface water, or where groundwater is deep or inaccessible due to

hard ground conditions, or where it is too salty, acidic or otherwise unpleasant or unit to drink,

another source must be sought. In areas which have regular rainfall the most appropriate alternative

is the collection of rainwater, called rainwater harvesting. The term rainwater harvesting is

usually taken to mean the immediate collection of rainwater running off surfaces upon which it has

fallen directly. This definition excludes run-off from land watersheds into streams, rivers, lakes, etc.

Thus Rainwater Harvesting is the capture, diversion, and storage of rainwater for a

number of different purposes including landscape irrigation, drinking and domestic use, aquifer

recharge, and storm water abatement.

Basic Components

Regardless of the complexity of the system, the domestic rainwater harvesting system

comprises six basic components:

Catchment surface: the collectionsurface from which rainfall runs off.

Gutters and downspouts: channel waterfrom the roof to the tank.

Leaf screens, first-flush diverters, androof washers: components which

remove debris and dust.

One or more storage tanks, also calledcisterns.

Delivery system: gravity-fed or pumpedto the end use.

Treatment/purification: for potablesystems, filters and other methods to

make the water safe to drink.

Fig: Typical Components of Rainwater Harvesting


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Leaf Screens

To remove debris that gathers on the catchment surface, and ensure high quality water for

either potable use or to work well without clogging irrigation emitters, a series of filters are

necessary. Essentially, mesh screens remove debris both before and after the storage tank. The

defense in keeping debris out of a rainwater harvesting system is some type of leaf screen along the

gutter or in the downspout.

Depending upon the amount and type of tree litter and dust accumulation, the homeowner

may have to experiment to find the method that works best. Leaf screens must be regularly cleaned

to be effective. If not maintained, leaf screens can become clogged and prevent rainwater from

flowing into a tank. Built-up debris can also harbour bacteria and the products of leaf decay.

Leaf guards are usually -inch mesh screens in wire frames that fit along the length of the

gutter. Leaf guards/screens are usually necessary only in locations with tree overhang. Guards withprofiles conducive to allowing leaf litter to slide off are also available.

The funnel-type downspout filter is made of

PVC or galvanized steel fitted with a stainless

steel or brass screen. This type of filter offers

the advantage of easy accessibility for cleaning.

The funnel is cut into the downspout pipe at the

same height or slightly higher than the highest

water level in the storage tank.

Strainer baskets are spherical cage-like

strainers that slip into the drop outlet of the

downspout.

A cylinder of rolled screen inserted into the

Fig: Cylindrical Rolled Screen Filter

Fig: Leaf Guard Fig: Funnel type Downspout Filter


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drop outlet serves as another method of filtering debris. The homeowner may need to experiment

with various grid sizes, from insect screen to hardware cloth.

Filter socks of nylon mesh can be installed on the PVC pipe at the tank inflow.

First-Flush Diverters

A roof can be a natural collection surface for dust, leaves, blooms, twigs, insect bodies,

animal faeces, pesticides, and other airborne residues. The first-flush diverter routes the first flow of

water from the catchment surface away from the storage tank. The flushed water can be routed to a

planted area. While leaf screens remove the larger debris, such as leaves, twigs, and blooms that fall

on the roof, the first-flush diverter gives the system a chance to rid itself of the smaller

contaminants, such as dust, pollen, and bird and rodent faeces.

The simplest first-flush diverter is a PVC standpipe. The standpipe fills with water first during

a rainfall event; the balance of water is routed to the tank. The standpipe is drained continuously via

a pinhole or by leaving the screw closure slightly loose. In any case, cleaning of the standpipe isaccomplished by removing the PVC cover with a wrench and removing collected debris after each

rainfall event.

There are several other types of first-flush diverters. The ball valve type consists of a floating

ball that seals off the top of the diverter pipe when the pipe files with water. Opinions vary on the

volume of rainwater to divert. The number of dry days, amount of debris, and roof surface are all

variables to consider.

One rule of thumb for first-flush diversion is to divert a minimum of 10 gallons for every1,000 square feet of collection surface. However, first-flush volumes vary with the amount of dust

Fig: Simple first flush diverter Fig: First Flush Diverter with Ball


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on the roof surface, which is a function of the number of dry days, the amount and type of debris,

tree overhang, and season.

A preliminary study by Rain Water Harvesting and Waste Water Systems Pty Ltd., a

rainwater harvesting component vendor in Australia, recommends that between 13 and 49 gallons

be diverted per 1,000 square feet.

The primary reason for the wide variation in estimates is that there is no exact calculation to

determine how much initial water needs to be diverted because there are many variables that would

determine the effectiveness of washing the contaminants off the collection surface, just as there are

many variables determining the makeup of the contaminants themselves. For example, the slope

and smoothness of the collection surface, the intensity of the rain event, the length of time between

events (which adds to the amount of accumulated contaminants), and the nature of the

contaminants themselves add to the difficulty of determining just how much rain should be diverted

during first flush. In order to effectively wash a collection surface, a rain intensity of one-tenth of an

inch of rain per hour is needed to wash a sloped roof. A flat or near-flat collection surface requires

0.18 inches of rain per hour for an effective washing of the surface.

The recommended diversion of first flush ranges from one to two gallons of first-flush

diversion for each 100 square feet of collection area. If using a roof for a collection area that drains

into gutters, calculate the amount of rainfall area that will be drained into every gutter feeding your

system. Remember to calculate the horizontal equivalent of the roof footprint when calculating

your catchment area. If a gutter receives the quantity of runoff that require multiple downspouts,

first-flush diversion devices will be required for each downspout.

Filter System

The filter bed which we have designed is

inspired from ancient water harvesting structure in

Gujrat called Adlaj. Our filter system consists of

three stages which have different combinations of

filtering and adsorbing materials. Three stage

filtering system enhances the quality of the water.

The whole structure is made out of pre fabricated

concrete panels and has an octagonal shape. Pre

fabricated octagonal base plates and eight pre

fabricated rectangular panels are installed. The

installation process involves use of ball bearing and

water proofing solvents. The whole structure lies

beneath the ground level or above the ground level

as the requirement may be.

Fig: 3 Stage Filtering Assembly


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The first stage consists of layer of material in following order:

Sr no. Material Specification Thickness

1 Pebbles

According to

IS 2386 1963 Part I

5.0 cm

2 Brick Powder 3.0 cm

3 Fine Ennor 3.0 cm

4 Cotton 1.0 cm

5 Coal Pieces 3.0 cm

The second stage consists of layers of material in following order:

Sr. No. Material Specification Thickness

1 Coarse Aggregates

According to

IS 2386 1963 Part I

1.5 cm

2 Cotton 1.0 cm

3 Fine Ennor 3.0 cm

4 Small Pebbles 2.0 cm

5 Saw Dust 3.0 cm

6 Small Pebbles 3.0 cm

7 Coal Powder 2.0 cm

8 Coarse Aggregates 1.5 cm

The third stage consists of layers of material in following order:


1 Pebbles

According toIS 2386 1963 Part I

4.0 cm

2 Corse Ennor 3.0 cm

3 Fine Ennor 3.0 cm

4 Pebbles 5.0 cm

In this system the functions of the materials are as follows:

Sr. no. Material Function

1 Pebbles To slow down the velocity of the water.

2 Coarse Aggregates To slow down and evenly distribute the flow of water.

3 Ennor Sand To filter out particulate and suspended matter.

4 Coal To adsorb specific contaminants over its surface.

5 Brick Powder To adsorb specific contaminants from water.

6 Saw Dust To adsorb the oil and grease form the water.


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Applications:

This system can be used in residential building and colleges. Especially, places where large

area of roof is left unused can be used for rain water harvesting and this filter bed will certainly

prove to be useful. Places where major area is covered with pavement and concrete can also be

used for this type of rain water harvesting using this model. In this case the whole assembly would

be under the ground level and the filtration will take place due to gravity. Places like playing

grounds, stadiums and parks, gardens, resorts, golf course etc can be very well used for rain water

harvesting as much of the rainfall falling on these terrain generally flow away as runoff. Much

quantity of water can be harvested from these places.

Fig: Schematic showing different applications of the rainwater harvesting technique


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Storm Water Harvesting

Introduction

The infiltration in the city is very less so all the water flow as runoff and go to sever line. By

this a lot of good water is wasted as it get mixed with the sewage water thus if we stop the water

going to the drain line we can store this water, which can be used for domestic purpose like car

washing, gardening, etc. If this water is given some treatment we can even use the water for

drinking purpose. The storm water passed through filter bed before reaching the storage tank the

cost of water treatment also reduces to a very large extent.

In tropical countries like India where we receive heavy rainfall during the four month of

monsoon. This technique will be quite useful as the stored water can be then used during the next

four month of winter season so that the water availability during the summer will be more.

Technique is simple as that of rain water harvesting but there are some changes in it due to

large quantity of water. The storage tank required for this should be large in size. From proper

planning the mezzanine floor can be used for this purpose. So the water further supplied will be

under gravity so the electricity required for the pumping will decrease having a cost efficient

working.

The present scenario.

The storm water during rainy season causes drainage problem and often roads are damagedby rainfall runoff.

This problem is serious in big cities and industries, where most of the open area is coveredby roads or some concrete structures without proper drainage.

The water on roads during rains remains stagnant for hours, together due to poor stormwater management and results into erosion of roads.

In our country, industries and cities are facing water crises due to over exploitation ofunderground water and no provision for recharge of aquifers.

Declining water levels are also consuming more energy in lifting the water and reduction ingreen coverage.

Methodology:

We have designed a technique through which we will be able to harvest the storm water

and at the same time treat it to some extent. Our model consists of sedimentation tank and a

filter bed. This assembly is beneath the pavement along both sides of the road. The assembly

consists of a sedimentation tank and a filter bed through which water passes to get into a

channel. Through this channel the filtered water will flow and will get collected into a tank from

where it can pumped out and be sent for treatment purpose or can be directly used for various

purposes like landscaping and gardening purposes by Municipal Corporation.


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The function of sedimentation tank is to reduce the velocity of the flowing water.

Sedimentation process requires very less velocity. In fact the settling time required by a particle

depends upon its size as well as its velocity. Sedimentation process helps to remove the

suspended matter and thereby reduces the chances of filter bed of getting clogged.

The second stage is that of filter bed. The filter bed consists of the following materials:


1 Pebbles

According to

IS 2386 1963 Part I

2.5 cm


3 Ennor sand 1.5 cm

4 Muslin Cloth 0.5 cm

5 Coal Powder 1.5 cm

6 Ennor sand 1.5 cm

7 Brick Powder 1.5 cm

8 Ennor sand 2.5 cm

9 Muslin Cloth 1.0 cm


Fig: Schematic Diagram for Storm water harvesting technique


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Functions of the materials:

Sr. no. Material Function

1 Pebbles To slow down the velocity of the water.

2 Coarse Aggregates To slow down and evenly distribute the flow of water.

3 Ennor Sand To filter out particulate and suspended matter.

4 Coal To adsorb specific contaminants over its surface.

5 Brick Powder To adsorb specific contaminants from water.

6 Muslin Cloth To avoid the mixing of fine aggregates this can lead to

clogging.

Some advantages of this system;

The filtration takes place due to gravity and hence power is not required for the same. Filters the water and hence reduces the treatment cost of this water. Most of the STPs are inefficient and require more maintenance as they are loaded to highly

turbid waste water. This will indirectly reduce the maintenance cost of the STPs.

Solution of managing storm water on roads in urban and industrial areas is channelizing thesame to ground water system in hygienic manner.

This method not only helps in controlling the devastating effects of storm water, but wouldimprove ground water regime both in terms of rising of water levels and increase in ground

water availability.

The techniques will also increase life of roads and reduce cost on maintenance and repairs.Besides, better plant growth is envisaged with less water requirement due to moist

condition of surface soil through percolation structures.

Applications

This system can be applied to the internal roads of societies and residential projects, where

the traffic density is low and hence less contamination of water would take place. The water

harvested can be used for various purposes like flushing at public places and if treated can be very

well used for construction purposes and gardening etc.

This system can also be applied in schools and colleges where traffic density is already low.

Using this system schools and colleges can cater their daily needs of gardening and flushing in wash

rooms.

Depending upon the extent of treatment, this water can also be used for drinking purpose inareas where there is acute shortage of water or at places like construction site where the ground

water table is low and hence it cannot be used.


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Grey Water Harvesting

Grey water is commonly defined as wastewater generated from bathroom, laundry and

kitchen. Due to rapid industrialization and development, there is an increased opportunity for grey

water reuse in developing countries such as India. The present scenario in case of grey water is as

follows.

This shows that there is much grey water that can be treated, recycled and reused. Grey

water is generated on a large scale at places like airports, schools and colleges, restaurants,

commercial complexes etc.

Methodology

The system consists of three stages viz. Septic Tank, Sand Filter, Planter Bed. The

functions of the three stages are stated as follows:

Fig: Pie Chart showing Grey water statistic

Fig: Schematic diagram showing the processes of Grey water Treatment.


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Root Zone Treatment Technique

A constructed wetland or wetpark is an artificial marsh or swamp, created for

anthropogenic discharge such as wastewater, storm water runoff or sewage treatment, and as

habitat for wildlife, or for land reclamation after mining or other disturbance. Natural wetlands act

as biofilters, removing sediments and pollutants such as heavy metals from the water.

Operation:

Vegetation in a wetland provides a substrate (roots, stems, and leaves) upon which

microorganisms can grow as they break down organic materials. This community of microorganisms

is known as the periphyton. The periphyton and natural chemical processes are responsible for

approximately 90 percent of pollutant removal and waste breakdown. The plants remove about

seven to ten percent of pollutants, and act as a carbon source for the microbes when they decay.

Different species of aquatic plants have different rates of heavy metal uptake, a consideration forplant selection in a constructed wetland used for water treatment.

Physical, chemical, and biological processes combine in wetlands to remove contaminants

from wastewater. An understanding of these processes is fundamental not only to designing

wetland systems but to understanding the fate of chemicals once they have entered the wetland.

Theoretically, treatment of wastewater within a constructed wetland occurs as it passes through the

wetland medium and the plant rhizosphere. A thin aerobic film around each root hair is aerobic due

to the leakage of oxygen from the rhizomes, roots, and rootlets.Decomposition of organic matter is

facilitated by aerobic and anaerobic micro-organisms present. Microbial nitrification and subsequent

denitrification releases nitrogen as gas to the atmosphere. Phosphorus is co precipitated with iron,aluminum, and calcium compounds located in the root-bed medium. Suspended solids are filtered

out as they settle in the water column in surface flow wetlands or are physically filtered out by the

medium within subsurface flow wetland cells. Harmful bacteria and viruses are reduced by filtration

and adsorption by biofilms on the rock media in subsurface flow and vertical flow systems.

Rootzone Treatment System (decentralized):

The Rootzone Treatment System (RZTS) is an important element for decentralization of

wastewater treatment and water recycling. RZTS consists of sealed filter beds comprising of sand,

gravel, soil system occasionally with a cohesive element, planted with vegetation which can grow in

wetlands. After removal of coarse and floating material, the wastewater passes through the filter

bed where biodegradation of the wastewater takes place.

Sr.

No.

Stage Function

1 Septic Tank The main function of this stage is to separate out the solid

waste if any from the grey water and to reduce the velocity and

control the discharge of grey water in wetland bed.

2 Wetland Bed The main function of the wetland bed is to filter out the

particulate matter from the grey water and to treat it by root

zone treatment technique.


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How a reed bed mechanism works?

The treatment processes are based essentially on the activity of microorganisms present in

the soil. Smaller the grain size of the filter material and consequently larger the internal surface of

the filter bed higher would be the content of microorganisms. Therefore the efficiency should be

higher with finer bed material. This process is however limited by the hydraulic properties of the

filter bed; finer the bed material, lower the hydraulic load and higher the clogging tendency. The

optimization of the finer material in terms of hydraulic load and biodegradation intensity is

therefore the most important factor in designing RZTS. The reed bed system is divided into two

categories based on the arrangement of the filtering materials like vertical filtering system or

horizontal filtering system.

Horizontal Flow Reed Beds (tertiary but sometimes secondary)

There are two main types, subsurface flow and overland flow. The subsurface flow type is

often used, in which sewage flows horizontally through the gravels. The arrangement is like a tub

bath, filled with gravels and planted with aquatic plants. As one pours water from one end of the tub

bath, water overflows at the far end. A depth of some 30-60 cm is maintained in the bed, unlike

vertical flow beds which are free draining. This means less oxygen is available for aerobic treatment.

The lower levels of oxygen create ideal condition for nitrogen removal from treated effluents. Whilst

such reed beds are occasionally used for secondary treatment of sewage, the presence of high levels

of organic matter, the low levels of oxygen make horizontal flow reed beds better suited for tertiary

treatment. In this situation they do an excellent job removing fine particles of organic matter that

are too small to be removed in settlement tank. Adequate settlement before the horizontal flow bed

will extend the beds life.

Applications

This system can be used in mainly in villages and residential complexes. The grey water from

the houses can be treated through this system. The treatment process is fully natural and no energy

is required for treatment. Since it is a natural process very less maintenance is required. The treated

water has improved qualities and is even drinkable. This would solve the problem of scarcity of

water in drought prone areas.

Advantages of all the three systems:

The materials used in all the three systems are locally available. The working of all the three systems is so simple that even a lay man can

understand.

All the three systems are cost effective and efficiency is quite good. All the three systems are easy to install and require very less maintenance.

Maintenance is yearly i.e. after monsoon period the systems needs to be checked

once.

The main purpose of these systems is to reduce the load coming on the conventionaltechniques of water treatment there by reducing the treatment cost and

maintenance cost.

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