Reaction kinetics and validity of BOD test for domestic wastewater released in marine ecosystems

With urbanization of coastal cities, marine pollution is becoming a severe problem. The rates of biodegradation, decomposition, and ratification of pollutants get slowed down due to salinity. The higher temperatures prevalent in tropical regions significantly affect reaction rates. Multiple factors influence the rate of biodegradation, making the process complex. Hence, prediction and evaluation of the assimilative capacity of the marine environment due to wastewater discharges is becoming a difficult task. Biochemical oxygen demand (BOD) is a wet oxidation process, which follows first-order kinetics. The values of kinetic rate constants are expected to differ with varying salinities and temperatures. Research is carried out using glucose-glutamic acid and domestic wastewater to evaluate the impact of salinity on biodegradation of carbonaceous waste at 20°C and 27°C. The findings confirm the hypothesis of slow biodegradation of carbonaceous organic matter in marine waters. An inverse relationship between rate of biodegradation and salinity was observed. BOD exertion at 20°C (5 days) and 27°C (3 days) for the marine environment is comparable at selected salinities thereby confirming the validity of BOD test of shorter duration at elevated temperature.