dewats decentralised natural waste water treatment system

Decentralised waste water treatment systemsDecentralised waste water treatment systemsAuroville Centre for Scientific Research

Decentralised waste water treatment principles and devices

Treatment for organic wastewater from domestic and industrial sources

Treatment of wastewater flows from 1-1000 m3/d

Achievement of discharge standards

Tolerance to inflow fluctuationMinimal dependence on external energy, minimal maintenance

Using gravity instead of pumps, avoiding valves

Aiming towards reliable and long-lasting devices

Priority given to anaerobic technology in warm climatesand aerobic technology in cold climates

Reuse of wastewater

Pre-treatment deviceSettler

Pre-treatment

Settler

1st treatment

Baffled tank reactor

Anaerobic filter

RawSewage

OutletSettler

OutletBaffledReactor

OutletGravelFilter

OutletPond

BOD5

COD

457

0

200

400

600

800

1000

1200

RawSewage

OutletSettler

OutletBaffledReactor

OutletGravelFilter

OutletPond

BOD5

COD 0

200

400

600

800

1000

1200

RawSewage

OutletSettler

OutletBaffledReactor

OutletGravelFilter

OutletPond

BOD5

COD 0

200

400

600

800

1000

1200

RawSewage

OutletSettler

OutletBaffledReactor

OutletGravelFilter

OutletPond

BOD5

COD 0

200

400

600

800

1000

1200

Planted gravel filter

Polishing pond

Pre-treatment is done in a Settler

A device which separates the liquid from the solid, retention time is only 2 hours. Pollution reduction is around 30%

First treatment takes place in a Baffled Tank

A device with several identical chambersthrough which the effluent moves from top to bottom.Retention time is 24 hours.Pollution reduction is around 80%

Natural treatment of waste water occurs by channeling the effluent through several devices:

Second treatment takes place in a anaerobic filter

A device filled with a filter material (cinder) throughWhich the effluent moves from top to bottom.

Retention time is around 8 hours.Total pollution reduction is around 90%At this stage CPCB standards are metbut the effluent still has an odour

Third treatment takes place in a planted gravel filter

A structure filled with gravel material and planted with water resistant plants, who provide oxygen to the passing effluent.Retention time is 1½ day.Pollution reduction is around 90%

RawSewage

OutletSettler

OutletBaffledReactor

OutletGravelFilter

OutletPond

BOD5

COD 0

200

400

600

800

1000

1200

RawSewage

OutletSettler

OutletBaffledReactor

OutletGravelFilter

OutletPond

BOD5

COD 0

200

400

600

800

1000

1200

RawSewage

OutletSettler

OutletBaffledReactor

OutletGravelFilter

OutletPond

BOD5

COD 0

200

400

600

800

1000

1200

RawSewage

OutletSettler

OutletBaffledReactor

OutletGravelFilter

OutletPond

BOD5

COD 0

200

400

600

800

1000

1200

Post treatment takes place in polishing pondsfitted with aquatic plants and fishes.It is through this device that the water transformsfrom a lifeless state into living water again.

Ponds with aquatic plants are an efficient way to combine wastewater treatment,landscaping, aesthetics and water reuse, the pond can also act as a storage device.

Underground anaerobic process Above ground level aerobic process

CPCB standards are met at this point, except for the smell control

Overview of the different devices

Surya Nivas, 2003 – 12 users

Samasiti, 2009 - 25 PE

Solar Kitchen, 1998 – 40 m³

Surya Nepal Pvt Ltd(subsidiary of ITC)

125 m³/day

Surya Nivas, Nepal60 m³ /day

Kadambadi settlementNagipattinam

Post Tsunami Dewats projects

Vortex systemsfor waste water treatment

ATS – Algal Turf Scrubbers Treating toxic waste water

Algal are grow in shallow basins for cleaning water pollution, including heavy metals

In the process Biomass is grown and harvested for Energy - gas methane/ethanol/butanol - Bio-diesel – bio-aviation fuel

Note: solar energy absorption by algal is 45 to 50%, increase in biomass doubles/24 hrs, during the process algal absorbs CO2 and gives off oxygen

ATS needs Start up investment Land area is required for installing the basins

Integrating ATS – Algal Turf Scrubbers

the use of algae for cleaning toxic

waste water

Auromode

“And justify the light on Nature’s face.”