A cool breeze welcomes me at Kannan Pasupathiraj’s home in Muttukkadu. We sit down in the garden. Just as I am about to sip my tea, I hear the sound of water flowing beneath my feet.

Seeing my quizzical look, Pasupathiraj smiles and tells me I am sitting on top of a small waste water treatment plant. “Most people will immediately try to shut their nose, expecting a foul smell,” he says. To my surprise, absolutely no stench comes from the plant. Says Pasupathiraj: “We are sitting on a septic tank where waste water is treated using an environment-friendly German technology.”

According to him, the plant is designed on the tried and tested Sequencing Batch Reactor (SBR) method, where 98 per cent of purification is achieved in just six hours, and without any chemical treatment.

The waste water goes through a precise sequence of aeration, sedimentation and clear water removal, using gravity to separate waste particles of varying density. All three sequences happen in a single tank rather than three tanks. Aeration is the most important of the operations, and creates a suitable environment for natural bacteria to digest the waste in water.

Two separate chambers are used — one is where the waste water is collected and the other is the SBR tank where the water is transferred for the actual biological process to happen. Here, short cycles of aeration and rest happen alternatively, resulting in the production of millions of micro-organisms that treat the water thoroughly. The recycled water in Pasupathiraj’s house is used to raise his garden of fruit-bearing trees and other plants.

For a family of up to six people, the size of the entire plant with both tanks is about 3,600 litres, which is much smaller than the septic tanks in many homes. For apartment blocks with up to six families (about 35 people), the size of the plant required is about 22,000 litres. The power consumed by the plant is about 8W per person, in other words, it’s roughly equal to a family using one 40W bulb. The price ranges from about Rs 1 lakh for a small plant that services a family of six to Rs 65 lakh for a plant used for 1,000 people.

Called Klaro, the technology is apparently one of the few that offers fully automated sewage treatment for single homes, apart from being suitable for apartment and commercial complexes, colleges, hospitals and resorts. For more details, visit www.ecotec.in or call 98407 16526.