Comba wells contamination not due to petroleum factor: Expert

MARGAO, MARCH 1
In a new twist to the Comba well water contamination row, the Assistant Professor, Biological Sciences, BITS Pilani Dr Srikanth Mutnuri has concluded that the scum that is seen on top of well waters in Comba area is not due to any petroleum products, but is due to iron bacteria and iron content in water.
In his observations submitted to inquiry officer, Deputy Collector, Margao Johnson Fernandes after a day-long inspection of the wells on Monday, Dr Mutnuri has recommended treatment of the affected wells by aeration and shock chlorination as the initial step, adding that the affected wells can be analysed again after above initial treatment to decide upon requirement of further treatment.
Saying that the problem is not very serious as initially thought and can be resolved easily, Dr Mutnuri observed that oil like layer was found in well not in use in recent times, while no oily layer was noticed in wells which are in use.
“When samples were taken in sampling bottles, precipitate was observed after 20-30 minutes. The precipitate was found in the samples from unused wells and not in used wells”, he said.
Reasons: “The above observation indicates the presence of iron bacteria which was observed as slime on the ouster walls of the container with which water from contaminated wells were drawn”, he said, adding that iron bacteria are red orange in colour and caused smell that resembles fuel oil or sewage or that of some decaying matter and are greasy to touch. These bacteria are common in wells which has been idle for a while”.
Saying that the source of iron in these wells might be due to laterite soil, Dr Mutnuri said this might occur naturally as part of rock weathering process, adding “The walls of the wells are laterite which are rich in iron”.
“The reason for observing precipitate in sample bottles when well water (contaminated) was drawn is due to oxidation of dissolved iron which settled down as precipitate”, he observed.
Inquiry officer, Johnson said the panel appointed to probe the well contamination will treat the wells as recommended by the Dr Mutnuri, adding that the panel is also  awaiting report from the Goa State Pollution Control Board on the joint inspection early next week.