Ganesh festival 2017 was much greener than last year, with the rivers in Pune recording lesser pollution levels. Detailed analysis of river water at various locations carried out by the Maharashtra Pollution Control Board (MPCB) shows lesser measure of pollutants in the water a day after the immersion as comared to the same day last year. Civic officials and social organisations attribute this to the increased levels of awareness among the general public who now increasingly immerse their idols in the tanks rather than the river.
Other than the measure of sound pollution, the pollution control board also monitors the water quality in the river a day after the immersion. Officials of the board take samples from more than 20 popular visarjan ghats and test them on a variety of parameters like chemical oxygen demand (COD), biochemical oxygen demand (BOD), dissolved oxygen (DO), total dissolved solids (TDS) and presence of heavy metals like lead, nickel iron etc.
Historically, the river pollution levels touch a dangerous high a day after immersion as majority of idols are made from Plaster of Paris and have heavy metal-based paints. Due to the non-biodegradable nature of the material the idols tend to remain in the riverbed for longer time there by increasing the pollution levels.
For the last many years the Pune Municipal Corporation (PMC) and several social organisations have been urging people to immerse their idols in immersion tanks rather than in the river. More than 200 such tanks have been constructed along the river bank for the general public. For Mula river, the board collects samples for testing near Aundh and Harrish Bridge while for Mutha samples are collected from Vitthalwadi and Deccan. Samples are also collected from the area near the Sangam bridge after the confluence of Mula and Mutha. Samples collected at Deccan always have the worst readings given the higher number of visarjan ghats in the area.
Barring the samples collected at Deccan, the dissolved oxygen levels this year hovered between 5.7 to 5.4 parts per million (ppm) which was between 4.7 to 1.9 ppm last year. The samples collected near Bund Garden had recorded 3.9 ppm of DO in 2016, but it was at a healthy 6 ppm this year. Samples collected at Vitthalwadi and Deccan had recorded 25 and 28 ppm of BOD last year while this year only the sample collected at Vitthalwadi had a reading of 32 ppm. The Central Pollution Control Board had mandated the maximum BOD limit for surface water at 30 ppm while COD should be below the 250 ppm limit. The COD limits both year were within the range, but the readings from Vitthalwadi and Deccan were on a higher side. By far, the biggest difference was the decrease in the TDS levels which this year was almost one third of last year’s levels. Also, unlike last year, nickel was not detected in the river water this year (see box).
Suchismita Pai, function head (outreach) of the waste pickers cooperative Swach, said this dip in the river pollution levels was a direct result of increased awareness among the people about the relation between river pollution and idol immersion. PMC had recorded a total of 2.19 lakh idols being immersed in the tanks this year as compared to the 2.02 lakh idols immersed last year. “This year, we had conducted drives on two days and more than 46,000 idols were diverted to the tanks,” she said. Pai also attributed this awareness to the role played by the social media. “Since the run-up to the festival, social media was agog with messages asking people to use the immersion tanks rather than the river. That too played an important role,” she said.