With the pilot effort at cleansing the Mithi River using a microbial technology having purified a considerable amount of water and drastically reduced its odour, the city’s development authority has decided to continue the process and is scouting for newer technologies that may have come up in the market.
In 2011, the MMRDA had decided to try the use of a process known as bioremediation on a third of the river that falls under its jurisdiction. The rest is under the BMC’s care.
“We had a pilot contract with a company to implement this technology on the 6-km stretch of the Mithi that falls under the MMRDA’s jurisdiction. The contract is scheduled to end this year. The experiment was very successful and we have decided to continue using it.
We will see if there are more such technologies in the market at competitive rates. If not, then we will consider continuing with the same product,” said an MMRDA official who did not want to be named.
The development authority is now looking for a three-year contract for cleaning and odour control of the Mithi River, running along the plush Bandra Kurla Complex business district.
“We had been in touch with the BMC about the technology too, but there has been no progress,” the official said.
The 18-km-long Mithi is the suburbs’ main natural water drain and accommodates untreated waste from 43 side drains. With the levels of Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD) being too high, the river water had become akin
Through bioremediation, a US-based technology, the MMRDA had engaged a private company to use a biochemical, Persnickety 713, in the water to convert the anaerobic elements to aerobic elements and enable the sunlight to act as a natural disinfectant.
Laboratory readings obtained by the MMRDA show that the COD and BOD levels were as high as 1,015 mg/litre and 405 mg/litre respectively before using the technology, while the permissible limits are 100-150 mg/litre for COD and less than 50 mg/litre for BOD.
In less than a year of using the bioremediation technology, the COD and BOD levels had dropped to 42 mg/litre and 15 mg/litre, respectively.