Grey Water

Recycling & Reuse By

K.V. RAMAN

MANAGING DIRECTOR

NATURE HAS GIVEN US CLEAR & CLEAN WATER

LET US RETURN BACK THIS, AS WE RECEIVED IT!

WATER OF FACTS! • GROWING POPULATION NEEDS MORE FRESH WATER

• INDUSTRIAL GROWTH – NEEDS MORE WATER

• AGRICULTURE GROWTH – NEEDS MORE WATER

• UNPREDICTABLE RAINFALL – WATER SCARCITY

• LESS GROUND WATER RECHARGE – WATER SCARCITY

• OVER DRAWING FROM GROUND WATER SOURCE

• POOR / CONTAMINATED GROUND WATER QUALITY –

HIGHER TREATMENT COST

• HIGH COST OF TANKER WATER – Rs.70/m3 ( location

dependent)

What will happen if we don’t act now?

1. Threat to our existence!

2. Quality of life affected!

3. Threat to business !- e.g – Closure / Migration of

business/ Limitation of expansion / Higher Capex &

Opex

4. Limitation on agriculture growth for want of water!

Why Grey Water Recycling??

• Treated grey water will act as a substitute to those application

which do not require drinking water quality so directly it will

reduce & save fresh water requirement.

• Grey water recycling is not dependent on season or variability

of rainfall and as such is a continuous and a reliable water

resource.

• As the treated water is high in nutrient Content(i.e. Nitrogen,

Phosphorous) we can use it for irrigation purpose, so it will

lead to an increase in agricultural productivity.

• Grey water recycling will reduce load on Sewage treatment

plant therefore tangential benefit is there.

• Infiltration of treated Grey water will help to increase ground

water table level.

What are benefits of grey water recycling? Water saving potential :

• Each person water requirement is 135-150 lit/day so grey water

generated will be about 72 lit/day. we can recycle about 60 lit/day

which cost around Rs.21/- . Each person can save Rs.21/- per day.

It will reduce water bill so financial saving on price of water.

• Environmental benefits :

• Reduction in generation of waste water will reduce potential of

environmental pollution.

• Reduction in surface and ground water pollution.

• Sustainable Development.

• Treated water is valuable resource for landscaping and plant

growth especially in arid climates(Low rainfall).

• It is rich in phosphorous, potassium, and nitrogen, making it a

good nutrient or fertilizer source for irrigation.

What is Grey water & its Source???

• Grey water is all wastewater that is discharged from a house,

excluding black water (Toilet Wastewater).

• It includes waste water from Showers, Bathtubs Sinks,

Kitchen, Floor Cleaning, Dishwashers, Laundry tubs&

Washing machines.

Low-load

Showers, bathtubs

hand washbasins

Grey Water

High-load

Kitchen (dish

washers),

washing machines

What Grey Water Contains??

• Grey water generation is dependent on living standard of people

& it’s a result of personal hygiene, detergents used, cosmetics

used as well as dirty cloths,.

• Grey water contain Soap, Shampoo, Toothpaste, Food scraps,

Cooking oils, Detergents and Hairs, Kitchen waste, water from

Floor Cleaning.

• Dishwashing & Floor cleaning mainly contain phosphorous ,

Sodium Bicarbonate.

• Kitchen waste contribute to Organic loading so increase in BOD

Load.

12.5 % Bathing

56 % Washing

Machine & floor

Cleaning

31 % Kitchen waste

Grey Water Characteristics

Parameter Unit Raw Grey water

(range)

Suspended Solids mg/L 10-100

Turbidity NTU 20-100

BOD5 mg/L 50-150

Ammonia mg/L 1-10

Total Phosphorous mg/L 0.5-5

Sulphate mg/L

10-50

pH mg/L 6.5-8.5

Total Hardness as

CaCO3

mg/L 30-150

Conductivity µs/cm 150-500

TOC mg/L 50-100

Other

applications:

- car washing

- fire fighting

- industrial use

Grey Water Recycling

Surface &

Ground

water

Recharge

Gardening ,

Irrigation

Toilet flushing,

Washing

machine

What are the Factors Influencing Grey Water Reuse??

• Budget: It is dependent on which type of treatment we are

providing. It may vary from low cost to expansive treatment.

• Existing plumbing: Grey water & Black water collection

pipes should be separate.

• Existing garden area: Availability of space & choice of plant

is main aspect to calculate watering requirement.

• Elevation of garden beds: if Garden bed is having slope then

we can directly through gravitational force use treated water

for gardening if not then we have to go for some extra units

like pipe n pumps.

• Storage :We can have ready made tanks for storage of raw

grey water.

• Space : Sufficient space should be available to install plant.

How do I collect Grey water??

• Identification of water : Separation of the drinking water ,

grey water ,Black water pipes and clear labeling of the taps

and devices should be there for reuse.

• Diversions systems : Grey water can not be stored more than

24 hour. It has to be treated through filtration & disinfection.

What is Grey water reuse concept??

• Safety & Hygiene : Treated grey water should be hygienically Safe i.e. absence of E-Coil bacterial and viruses.

• Identification : Separate Grey water Plumbing & Labeling should be there and avoid cross connection between drinking water and grey water.

• Segregation between low & High Strength : Water from baths, showers and hand washbasin which is less polluted should be collected separately from high concentrated kitchen waste & washing machines

• Direct reuse : We can use low concentrated grey water directly for Toilet Flushing & Irrigation

• Treatment system: Grey water treatment should be Simple, Low Cost & Ecofriendly & Reliable and easy to operate and maintain

Grey water Treatment Technologies

Dependent On

• Planned site

• Available space

• User needs

• Investment and maintenance costs

Proposed Process

CAPEX & OPEX

CAPACITY 75 KLD POWER @ Rs.14 / Kwh 516110

CHEMICAL PAC & CLO2 @ 5 K/month 60000

CONSUMABLES - CARBON/Year 35000

MAINTENANCE @ 3% of Capex 125000

LABOUR @ Rs.40K /Month 480000

TOTAL OPEX 1216110

WATER PROCESSED /DAY in m3 75

WATER PROCESSED /YEAR (365 DAYS) in m3 27375

COST OF FRESH TANKER WATER /m3 70

COST OF FRESH TANKER WATER /YEAR 1916250

CAPEX 8000000

SIMPLE RETURN ON INVESTMENT

TOTAL SAVINGS BY WAY OF WATER PURCHASE 1916250

OPEX 1216110

NETT SAVINGS/YEAR 700140

Contribution

• Rs.40,000/ flat towards Capex when 200 residential units are considered which is just the cost of a refrigerator / LCD TV /or a high end washing machine.

What are treated grey water parameter should be??

A) Hygiene requirements (bathing water quality )

Sr No Parameter Standards

1 Total coliforms < 10.000 / 100 ml

2 E. coli < 1.000 / 100ml

3 Pseudomonas aeruginosa < 100 / 100 ml.

4 Faecal Streptococci 0 / 0.1 ml;

5 Candida albicans 0 / 0.1 ml;

6 Staphylococcus aureus 0/1 ml

7 Legionella sp. 0 / 10 ml;

8 BOD7 < 5 mg/l;

9 Oxygen Saturation > 50%;

10 UV-Transmission at 254nm (1 cm) 60%

B) Technical requirements

• Grey water Should not be source of bad odour. It must be free from colour & Suspended Solids.

• Grey water pipe should be permanently colour coded & Labeled.

• There should not be a Cross connection between Drinking and Treated water.

• Municipal Waste water should not enter in grey water recycling system.

• All mechanical equipment and treatment unit should be easily accessible for cleaning , repair & maintenance

• Skilled Installation of treatment plant should be done to avoid errors.

• Storage reservoirs should be away from direct sunlight to avoid possible growth of Algae.

How to install Grey water treatment system?

What are the precautionary care one should take while using treated grey water?

Health aspects: • System overload should be avoided. • Less polluted grey water sources such as from showers,

bath tubs and hand washbasins should be preferred for treatment and reuse over kitchen or laundry grey water

• Grey water should not be stored but used immediately or within 24 hours

• When used for gardening, grey water should be applied to the subsurface to avoid any contact with the grey water.

• Grey water should not be applied to fruits and vegetables that are eaten raw.

• When used to water the garden or for irrigation, no sprinklers should be used

thank you