In a bid to tackle Bengaluru’s waste problem, the Bruhat Bengaluru Mahanagara Palike (BBMP) is planning to make it mandatory for homes and hotels to install a pulveriser in their kitchen sinks. If this is implemented, however, it will lead to the city dealing with a severely clogged drainage system, experts claim.
“The kitchen waste will be put into the pulveriser, which will crush the waste and liquefy it. The liquid waste then flows out of the drain. With this, we can avoid sending around 1,000 tonnes of garbage to the dumping zone,” Bengaluru Mayor Sampath Raj told TNM.
According to the Mayor, on an average, Bengaluru generates 4,500 tonnes of garbage every day and around 3,000 tonnes is generated by homes and apartments alone.
With the garbage menace destroying the city, the BBMP’s Solid Waste Management and Town Planning Departments have come up with the idea to install pulverisers, the Mayor said.
Why the plan won’t work
According to Ramprasad, convenor of a citizens’ group Friends of Lakes, Bengaluru’s sewage system is not equipped to handle liquid waste flowing into it.
“We will need anywhere between 10-20 litres of water to push the pulverised garbage from the source. Further, pushing the liquid waste through the drain network will require more water. With Bengaluru depending on water which is brought from hundred kilometres, it is costing the city Rs 62 per kilolitre. Imagine wasting this precious water to just push this waste around?” asked Ramprasad.
“The total cost of handling wet waste, which is pegged at approximately Rs 7/kg, will simply go up by at least 5 times. The sewage treatment plant (STP) set up by the Bengaluru Water Supply and Sewerage Board (BWSSB) is nowhere near handling this kind of sewage,” Ramprasad added.
He also said the drain pipes aren’t strong enough to withstand the liquid waste flowing through them.
According to InSinkErator, the company which manufactures waste pulverisers, 70% of food scraps are water, but the remaining 30% are solids which are currently being screened out at the entrance to the waste water treatment plant. In most cases, this material is also sent to the landfills.
“If solids are dissolved in water by crushing them, when they reach the STP, they are either turned into carbon dioxide or methane. This will increase biological oxygen demand and dissolved solids levels increase the amount of treatment required, meaning more energy and more chemicals,” Ramprasad said.
Another issue is that pulverised food waste is bound to clog drains. This is because the food waste contains unsaturated fats, which solidify at room temperature and can build up inside pipes the pipes.
In September this year, The Guardian reported on a “fatberg weighing the same as 11 double decker buses and stretching the length of two football pitches” which had clogged London’s sewage network.
The report stated that the government was spending 1 million pounds every month to clear blockages caused by the fat content in the pulverised waste.
“Do we have a good system of drains? No! The BWSSB has not yet installed sewage connection in so many areas. Besides, untreated water from sewage pipes is flowing into the lakes. Look what happened to cities like London and San Francisco. They are grappling with a problem of clogged drains because of the pulverisers. The San Francisco Public Utility Commission spends about $3.5 million per year just to solve grease-related blockages. They have roughly 900 miles of pipeline, so that's about almost $4000 per mile,” Ramprasad added.