Can this portable robot end septic tank deaths once it is deployed?

A group of researchers from IIT Madras develops a robot that can help clean septic tanks without people having to enter the tanks

November 20, 2021 08:32 pm | Updated November 22, 2021 12:38 pm IST

Tech boon:  The robot can be integrated with a tractor, explains Divanshu Kumar, CEO Solinas Integrity.

Tech boon: The robot can be integrated with a tractor, explains Divanshu Kumar, CEO Solinas Integrity.

A statement by the Social Justice and Empowerment Ministry in the Lok Sabha, which was reported in The Hindu, conveyed that in the five years till December 31, 2020, there have been 340 deaths due to manual scavenging in sewers and septic tanks in 19 States and Union Territories, with Uttar Pradesh (52), Tamil Nadu (43) and Delhi (36) leading the list. Maharashtra had 34 and Gujarat and Haryana had 31 each, according to the statement. This is despite bans and prohibitory orders.

A group from Mechanical Engineering Department and Center for Non-Destructive Testing (CNDE) of IIT Madras has developed a robot that can, if deployed extensively, put an end to this practice of sending people into septic tanks. The robot, named HomoSEP (“homogeniser of septic tanks”) has taken the group about three years to develop.

The idea of making a robot that can wade through sewers and septic tanks initially led the group to attempt a fish-like model that could provide an inside look into the contents. However, on discussing with workers, they realised that a simpler device more focussed on homogenising the contents of a septic tank would be of greater help and then they set upon the journey of developing HomoSEP.

Inverted umbrella

HomoSEP has a shaft attached to blades that can open like an inverted umbrella when introduced into a septic tank. This is helpful as the openings of the septic tanks are small and the tank interiors are bigger. The sludge inside a septic tank contains faecal matter that has thickened like hard clay and settled at the bottom. This needs to be shredded and homogenised, so that it can be sucked out and the septic tank cleaned. The whirring blades of the robot achieve precisely this.

Further, the latest version of the robot is a lightweight model that can be attached to a tractor and wheeled off to remote and inaccessible areas. The robot is attached to the axis of the tractor and can be run using the power from the tractor’s engine. When needed, it can be detached from the tractor.

“The first version [of the robot] was very bulky and entirely made of steel. It was also a stationary unit and needed external power… from the mains or a battery source. It had to be lifted using a fork lift, placed on top of a tank and then you could perform the operation,” says Divanshu Kumar, an alumnus of the Mechanical Engineering group of IIT Madras and CEO of Solinas Integrity Private Limited, which is a startup that develops the robot. “At the time, we did not understand about the nature of the contents of the septic tanks so the blade profile was quite simplistic.”

Key innovations

Over the three years since 2019 and the pandemic with its associated hurdles, the group worked on this zeroth model, honing its properties, spiralling from concept to computer design, to simulation, to trials and back to the drawing board, until they developed the latest version. “We made some significant innovations to the first proof of concept model: we first improved the blade design to suit the fluid in the septic tank; then we achieved a miniaturisation so that just two people can carry the robot; lastly, we integrated it with a tractor so that it can be portable and run using the power of the engine,” says Prabhu Rajagopal, from the Department of Mechanical Engineering at IIT Madras and the Principal Investigator who has anchored the development of the robot.

Feedback and validation

To mimic the qualities of the contents of the septic tank, they generated material with similar properties which they tested with the help of Prof. Abhijit Deshpande of the Chemical Engineering Department. In the process of development, they also took along with them members of Safai Karamchari Andolan, asking for feedback and validation.

The present model has been tried in a set of septic tanks near the department, in a campaign of field trials in March. One more set of field trials is due, after which plans are afoot to deploy the robot following a pilot testing by the workers themselves. The project has been carried out with Corporate Social Responsibility funding from GAIL foundation, CapGemini, WIN foundation, and more recently from National Stock Exchange foundation.

The researchers plan to distribute eight units in Tamil Nadu, and are in touch with Safai Karamchari Andolan to identify the locations. They are also considering locations in Gujarat and Maharashtra. “Many people ask me why manual scavenging is still there 70 years after independence… It is not sufficient to sit in your homes and wish it will go away. Pious intentions are good, but beyond that we need someone to actually do the work of developing a solution, and people who will support those who do this.,” says Prof. Rajagopal. “I am not saying our group will solve the problem. Our country is too vast and the challenges are too many. But what I hope is to set an example.”

“It may not win rewards in the short term, such as a paper in Nature, or being feted for groundbreaking technology, but this is a problem that needs people to stick their neck out and develop a practical, viable technological solution. It is a question of intention,” he concludes.

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