SESSION-16: College Students
PAPER-10: Study on the Natural Decay of Bacteria in a River System
Kavitha B.V., Harsha G Chachadi, Karthik M.K., and Lokesh Mahadevaiah

Abstract:

Water quality analysis in rivers has been considered important in our country during the recent years. The deterioration of the river water quality is due to pollution from different activities related to economic development. In order to maintain desirable levels of water quality parameters related to river, the probable impact of pollutant loads on river ecosystem has to be analysed.

Several studies related to this have been conducted and analysed. One important parameter is the natural decay of bacteria in the river Cauvery under different flow regimes due to the release of domestic waste and due to bathing activities.

The study area is river Cauvery located near Srirangapatna town, which is 15 km away from Mysore city. The study segment in the river is between Wellesley road bridge and Nimishamba temple, which is 1.6 km apart. The untreated wastewater outlet of Srirangapatna town is just located below the bridge. The study segment has been divided into 8 study tangents located 15m, 35m, 50m, 150m, 47m, 825m, 1150m and 1550 m downstream from outfall. In addition to the above, one more sampling station has been selected just upstream of the water of the outfall to know the background river water quality. The survey was conducted on the 4 th , 9 th and 18 th February 2000. The river flow rate, sewage flow rate and river water quality was monitored.

For the data analysis modelling studies, the available computer programmes MIXANDT and MIXCALBN were used to analyse the data collected from the field survey. MIXCALBN model is the water quality prediction model and is applicable to mixing zone below a pipe outfall.

From the modelling studies it was observed that at a high flow and high temperature conditions the decay was slower and consequently the bacterial concentration was not equal to background concentration at 1.6 km from the outfall in the latter case.