A Visit to Faecal Sludge Treatment Plant in Devanahalli

Information Board at FSTP, Devanalli

On 30th June, some of us interns had the opportunity to have a look at the faecal sludge treatment plant in the Devanahalli TMC. It was quite interesting to know and understand the mechanism behind how human waste is recycled and thereby used as manure.

As we reached the plant, one of the workers introduced us to the basic functioning of the plant. He patiently explained all the details to us and answered our questions as well. It was an engaging conversation with him. Firstly, he began by showing us the main component, the Feeding Tank. This tank receives the load which is collected by a tanker. The feeding tank receives around three to four loads every day. The tank comprises two sub-tanks or chambers having a capacity of 3500 litres and 3000 litres each. Once the first sub-tank is loaded, the sludge is then fed into the next one.

The sludge is then allowed to settle for a minimum of 2 hours where the solid and liquid components separate. Once this occurs, the liquid is extracted from the sludge and sent to the biogas chamber. In this chamber, the liquid gives rise to biogas as a byproduct. Biogas produced in this plant is used by the workers for cooking. The solid remnants from the sludge then go to the stabilisation tanks where anaerobic reactions take place. There are two stabilisation tanks present in the plant. One of them is movable and is present underground. Apart from this, there were other parts of the plant such as planted gravel filters and an anaerobic baffle reactor. Lastly, the after going through all these processes, the sludge is sent to the drying bed. It is allowed to dry for 10-15 days after which is collected. The dried sludge is then mixed with household wet waste. It is mixed in batches and allowed to decompose for about 45 days. Lastly, it is sieved and the final product is sold as manure or compost.

 Diagram of the Treatment System

Our visit to the FSTP was much needed considering our exposure to Sanitation Safety Planning. This set the context for us to understand this concept better. It was quite surprising to see no foul odour in any of the chambers. There was no chance of humans coming into contact with the faecal sludge. The ambience of the place was calm and peaceful. A lot of trees and plants were present. The manure produced by the plant is also used to grow these trees. There were jamun, pomelo, and roses among others. Birds were chirping even at that hour. A birdhouse was also present in the plant. It was made out of recycled wood. The entire plant was an eco-friendly, low-waste, energy-conserving system. It was great to see this place maintained so well.

View of FSTP

View of FSTP Site

- Srija J & Arunraj,
  Interns at Biome Environmental Trust (Summer 2023)