Manual scavenging no more: IIT students develop robot to clean septic tanks and sewers

Manual scavenging was abolished in 1993, and the ban was again reinforced in 2013. Yet, it continues. In fact, according to a 2018 report by the National Commission for Safai Karamcharis (NCSK), one person loses their life every five days while cleaning sewers and septic tanks across the country. 

Even as states look to deploy mechanised systems to clean sewers and septic tanks, these are yet to be universally implemented. The Delhi government recently inducted 200 mechanised systems to clean sewage, but each one came at a hefty price tag of Rs 40 lakh. 

Now, students at IIT-Madras have come up with a feasible sanitation solution, priced between Rs 10 lakh and Rs 30 lakh. The Sepoy Septic Tank Robot uses high-velocity cutters to cut through the thick sludge in septic tanks and clear drains. Once the sludge is cut through, it is sucked out using a vacuum pump, according to a Financial Express report.

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Talking to The Hindu Dr Prabhu Rajagopal, from the Centre for Non-Destructive Evaluation at IIT-Madras and who has been working on the project for about four years, said,

“To move in the fluid, a robot needs to have a propeller, but the conditions in a septic tank pose specific problems. If you use a rotary propeller, like in an aircraft, the blades will get congested.”

To overcome this, the team used bio-inspired fins, and developed a six-fin propeller led by Srikanth, a masters’ student at the institute.

Dr Rajagopal said, “The propeller is retracted and put into the septic tank. It then opens up and we rotate it, and the contents of the septic tank are cut up. They can be sucked out using vacuum pumps,” reports The Hindu.

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The robot is still in the testing phase, and the team is trying to procure sludge from oil and gas companies as it would be thick and viscous - similar to sludge in septic tanks and drains. The team is also being guided by Professor Indumathi Nambi, of the Environmental Engineering group at IIT-Madras.

Deepti Sukumar, National Co-convener of the Safai Karamchari Andolan (SKA), said,

“This is excellent work. Under the Swachh Bharat scheme, many toilets are being built in remote areas that have narrow streets. Pumps cannot enter to clean these septic tanks. This invention will be very useful for these cases.”

The machine will have lab trials in April and May, after which the robots will undergo site trials in July-August. 

Interestingly, Thiruvananthapuram-based Genrobotics, is also addressing the same issue with Bandicoot, a spider-shaped robot that can clean sewers and drains. The 50-kg, pneumatic-powered, remote-controlled robot can be sent down a manhole where it spreads its limbs and removes sewage. The robotic arm uses 360-degree motion to sweep the manhole floor and collect the filth.

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