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  • RESEARCH HIGHLIGHT

Robot helps clean waste from septic tanks

The septic tank cleaning robot. Credit: IIT Madras

A robot that is able to clean decomposed domestic waste from septic tanks might put an end to manual scavenging that exposes cleaners to toxic gases in septic tanks.

Septic tank wastes generate harmful gases such as methane, hydrogen sulphide, carbon dioxide, sulphur dioxide, ammonia, nitrogen dioxide and traces of carbon monoxide.

Hydrogen sulphide at low concentrations causes eye irritation, sore throat, breathing problems and coughs, and at high concentrations can lead to loss of consciousness and even death. Methane causes oxygen deficiency by depleting oxygen levels in the air.

The robot, called ‘HomoSep’, invented by scientists at the Indian Institute of Technology in Madras has a set of rotary cutters. These function like the blades in a domestic kitchen mixer-blender to homogenise hard sludge in septic tanks.

The researchers, led by Prabhu Rajagopal and Divanshu Kumar, designed the cutters like an inverted umbrella. This allows the blades to enter the narrow manhole of a septic tank in a retracted position. Once inside, they open up like an umbrella. The robot is operated using pedals.

The robot homogenises septic tank-mimicking materials and septic tank waste. The resulting sludge can be transferred for recycling using a suction pump.

The researchers integrated the robot with a tractor to power it and transport it to remote locations.

doi: https://doi.org/10.1038/d44151-022-00063-z

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