Sewage treatment plants have no standard design

Waste treatment crisis in HSR Layout

By MANASI PARESH KUMAR
Three people died while they were cleaning the collection tank of the Sewage Treatment Plant (STP) in ND Sepal Apartments in HSR Layout recently. This has triggered questions about what goes into the maintenance of the STPs which go beyond just setting up these systems. “There is no set standard by the Karnataka State Pollution Control Board (KSPCB) on approved technologies for STPs. Whether you go for batch reactors or septic tanks, they will be approved. There are no defined parameters on the kind of technology to be deployed in proportion to the scale,” says Dr Ananth Kodavasal of EcoTech Engineering Consultancy.

“The effluent water that first comes into the collection tank is a mix of liquid and solid waste. This tank is continuously aerated with diffusers or air blowers to avoid the build-up of methane gas from anaerobic bacteria when the tank lacks enough ventilation. A well-ventilated tank is where aerobic bacteria thrives and carbon dioxide is the byproduct. The air blowers are connected to pipes that constantly push fresh air,” says Dr Ananth.

But with the options of mechanised cleaning available, why would men go down into the tank at all? “Even in the most serviced and well maintained STPs, where the tank is cleaned thoroughly every two years, mechanised cleaning does not work completely. One man has to go inside the tank to remove the sludge that allows the mechanised action to then do its job,” says Dr Ananth. Safety is therefore paramount. “No man should go into these spaces without protective gear like gumboots, harness, air masks… every precaution needs to be taken. No one can stay inside these spaces for more than 10 minutes, even though there are air pipes constantly pushing in fresh air. Ventilation is vital. Single entrances will not work. You need at least two or more openings depending on the size of the tank,” explains Dr Ananth.

Most apartments try to cut corners. “Mechanised cleaning costs Rs 4,000-5,000 for every tank. To remove 10 tanks of sludge, the cost will be substantial. Here, they paid with three human lives instead,” says Dr Ananth.

The rules specify that the KSPCB officials need to conduct annual checks of these STPs to ensure their proper functioning. Most often, this remains only on paper. Even as the government mandates STPs for upcoming apartment complexes, with no set guidelines on technology to be used and its maintenance, the problem may continue to trigger tragic repercussions every time a sewage line is blocked.

© Oorvani Foundation/Open Media Initiative. Also available online at citizenmatters.in