Rain water harvesting & greywater management

RAIN WATER HARVESTING& GREYWATER MANAGEMENT

Vivek Kumar,St. Vincent Pallotti

College of Engineering and Technology, Nagpur

RAIN WATER HARVESTINGRAIN WATER HARVESTING

REASONS OF SHORTAGE OF WATER

Population increase Industrialization Urbanization

(a) Increase in per capita utilization(b) Less peculation area

In places where rain fed/ irrigation based crops are cultivated through ground water

Decrease in surface area of Lakes, talab, tanks etc.

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REASONS OF SHOTRAGE OF WATER

Deforestation(i) Less precipitation(ii) Absence of Barriers

(a) Rain drops checked by leaves of tree(b) Water slowly descends through twigs & trunk © Humus – acts as reservoir(d) Tiny creatures – helps percolation

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1 hectare of forest-6-7 Lac ton of water

(after filtering) top layer can hold 1.2 Lac tons of water

WHAT IS THE SOLUTION ?

Rain water is the ultimate source of fresh water Potential of rain to meet water demand is

tremendous Rain water harvesting helps to overcome water

scarcity To conserve ground water the aquifers must be

recharged with rain water Rain water harvesting is the ultimate answer

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WHY RAIN WATER BE HARVESTED

To conserve & augment the storage of ground water

To reduce water table depletionTo improve the quality of ground

water To arrest sea water intrusion in

coastal areas To avoid flood & water stagnation in

urban areas

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WHAT IS RAIN WATER HARVESTING ?

It is the activity of direct collection of rain water Rain water can be stored for direct use or can be recharged into the ground water aquifer

The roof catchment are selectively cleaner when compared to the ground level catchmentThe roof catchment are selectively cleaner when compared to the ground level catchment

Losses from roof catchment are minimum Built & Maintained by local communities No Chemical contamination & only required filtration Available at door step with least cost

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THE TYPICAL ROOF TOP RAIN WATER HARVESTING SYSTEM COMPRISES

Roof catchment Gutters Down pipe & first flushing pipe Filter Unit Storage Tank

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ROOF CATCHMENT

The roof of the house is used as the catchment for collecting rain water. The style construction and material of the roof effect its suitability as a catchment, Roofs made of corrugated iron sheet , asbestos sheet, Tiles or Concrete can be utilized for harvesting the rain water

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GUTTERS

Gutters are channels fixed to the edges of roof all around to collect & transport the rainwater from the roof. Gutters can be made in semi-circular and rectangular shape with cement pipe, plain galvanized iron sheet, PVC pipes, bamboos etc. Use of locally available material reduce the overall cost of the system.

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DOWN PIPE

It is the pipe which carries the rainwater from the gutters to the filter & storage tank. Down pipe is joined with the gutters at one end & the other end is connected to the filter unit of the storage tank. PVC or GI pipe of 50mm to 75mm (2 to”) are commonly used for down pipe. Bamboo can be also used wherever available and possible

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FIRST FLUSH PIPE

Debris, dust & dirt collect on the roof during non rainy periods when the first rain arrive. A first flush system arrangement is made to avoid the entering unwanted material into the Filter media & storage tank. This is a simple manually operated arrangement or semi-automatic system with a valve below the ‘T’ junction

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FILTER UNIT

The filter unit is a container or chamber filled with filter media such as coarse sand, charcoal, coconut fiber, pebbles & gravels to remove the debris & dirt from water that enters the tank. The filter unit is placed over the storage tank or separately. It may be of Ferro cement filter unit, Aluminum, Cement rings or Plastic bucket etc.

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STORAGE TANKIt is used to store the water that is collected from the roof through filter. For small scale water storage plastic buckets, jerry cans, clay or cement jars, ceramic jars,

drums may be used. For larger quantities of water, the system will require a bigger tank with cylindrical or rectangular or square in shape constructed with Ferro cement or cement rings or plain cement concrete or reinforced cement concrete or brick or stone etc. The storage tank is provided with a cover on the top to avoid

the contamination of water from external sources. The storage tank is provided with pipe fixtures at appropriate places to draw the water to clean the tank & to dispose of extra water. A provision for keeping the vessel to collect

the water is to be made.

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SIZE OF STORAGE TANK

Based on No. of person in the House hold Per capita water requirement No. of days for which water is requiredExampleDrinking water requirement for a household with 5 family

members, period 8 months & 6 lpcd= 5x 180x 6= 7200 Liters

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GREYWATER GREYWATER MANAGEMENTMANAGEMENT

GREYWATER DEFINITION Greywater is wastewater generated by

household processes such as washing dishes, laundry and bathing. Greywater is distinct from wastewater that has been contaminated with sewage, which is known as blackwater .

CHARACTERISTICS OF DIFFERENT SOURCES OF GREYWATER PRODUCTION kitchen: kitchen greywater contains food residues, high amounts of

oil and fat, including dishwashing detergents. In addition, it occasionally contains drain cleaners and bleach. Kitchen greywater is high in nutrients and suspended solids. Dishwasher greywater may be very alkaline (due to builders), show high suspended solids and salt concentrations.

bathroom: bathroom greywater is regarded as the least contaminated greywater source within a household. It contains soaps, shampoos, toothpaste, and other body care products. Bathroom greywater also contains shaving waste, skin, hair, body-fats, lint, and traces of urine and faeces. Greywater originating from shower and bath may thus be contaminated with pathogenic microorganisms.

laundry: laundry greywater contains high concentrations of chemicals from soap powders (such as sodium, phosphorous, surfactants, nitrogen) as well as bleaches, suspended solids and possibly oils, paints, solvents, and non-biodegradable fibres from clothing. Laundry greywater can contain high amounts of pathogens when nappies are washed

Greywater GardensGreywater Gardens

• drain greywater (without any pre-treatment) to swales or trenches, which are filled with mulch material;

• Sub-mulch or above the surface of mulch application;

• periodical replacement of decomposing mulch (wood chips, bark chips, rice husk, etc.);

• simple greywater management systems;

• direct utilisation of greywater;

• facilitate breakdown of organic compounds and recover nutrients;

Advantages & Limitations of Greywater Advantages & Limitations of Greywater GardensGardens

ADVANTAGES LIMITATIONS

• no external energy required (no pumping) due to gravity flow;

• not suitable for densly populated areas with high greywater production if space for establishing greywater gardens is limited;

• hair, soap residues etc. will be retained (at the point of greywater application) by the mulch material;

• use of locally available organics (e.g. rice husk, etc.) as mulch material;

• no use of inorganic material (e.g. gravel, perforated pipes, etc.) for distribution of greywater;

• greywater garden can be redesigned easily by simply plowing the soil (organic material will be mixed with the soil);

Examples of Greywater Gardens, India

Greywater Towers

Horizontal (HFCW) & Vertical Flow Constructed Wetlands (VFCW)

• preliminary treatment of greywater in e.g. settlement tank for solid-liquid separation (oil and fat, hair, lint, food residues, etc.);

• subsequent treatment of greywater in reed beds also known as horizontal flow constructed wetlands (HFCW) or vertical flow planted gravel filters (VFPGF) also known as vertical flow constructed wetlands (VFCW);

• application of pretreated greywater happens continously by gravity flow (HFCW) and intermittently by means of siphons or (solar-operated) pumps (VFCW);

• HFCW differ from VFCW as part of the filter is permanently soaked and operated aerobically, anoxically (no free oxygen present but nitrates) and anaerobically;

Advantages & Limitations of HFCW and VFCW

HORIZONTAL FLOW CONSTRUCTED WETLANDS

ADVANTAGES LIMITATIONS

• feeding by gravity flow is possible; • required surface area;

• treated water is fit for non-potable purposes (e.g. surface application);

VERTICAL FLOW CONSTRUCTED WETLANDS

ADVANTAGES LIMITATIONS

• reduced surface area in comparision to HFCW

• intermittent feeding requires either a (solar-operated) pump or sufficient vertical distance for installation of siphon tank

• treated water is fit for non-potable purposes (e.g. surface application);

Sizing of Small-Scale Horizontal Flow Constructed Wetlands

Sizing of Small-Scale Vertical Flow Constructed Wetlands

Examples of VFCW, Nepal

Examples of HFCW, Nepal

THANK YOU

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