Uma Krishnan Residence DWWT

We designed a 800 litres/day capacity grey water treatment system for a private residence at Thirvanmiyur, Chennai. The system treats all water from the bath, kitchen and washing areas to tertiary standards. The treated water is reused for irrigation and flushing purposes.

The system is a one of its kind as it uses the best practises from water treatment methods propagated by Centre of Science and Environment, the Auroville and ideas from a well know water expert Mr. Indukant Ragade. The water treatment takes place in a four component system consisting of a Grease Trap, a Bio-Gravel Filter, a Planted Filter and finally a Polishing Pond.

Decentralised Waste Water Treatment System

Decentralised Grey Water Treatment System

  • The grease trap separates the scum and oil generated from dish washing. This floats on top and can be easily removed manually.
  • The bio-gravel filter performs the primary treatment by providing the surface area for beneficial micro-organisms to thrive. The principle here is very similar to the bio-sand filter used in the rural parts of India and Africa. See below a video showing the working of a bio-sand filter.
  • Our planted filter uses a combination of vertical and horizontal filtration to remove any remaining solids in the water. The roots of plants growing within the filter quickly oxidises the water thereby reducing the biological oxygen demand and increasing the dissolved oxygen.
  • The polishing pond provides tertiary treatment by using the suns UV rays to rid the water of any remaining smells, soaps and traces of grey colour. The pond can be used as an aesthetic water body for fish and aquatic plants.

The output water has just the right nutrients for plants and is ideal for irrigation purposes. The treated water can also be used for flushing purposes in toilets with tank-less flush systems.

Shreya Krishnan - 09.03.2018.pdf