YONIK MEILAWATI YUSTIANI
Abstract
The deoxygenation coefficient is the use of oxygen in the process of organic matter decomposition and nitrification. The deoxygenation process for highly polluted rivers mainly crossing the urban areas has rarely been determined, therefore, this research aims to specify the range of the rate which can later be used for modeling purposes. Water samples were taken from 2 rivers in Indonesia, Cikapundung and Citepus. Dissolved oxygen (DO) usage was then being analyzed daily for 10 days. Slope method, proposed by Thomas was used to calculate the deoxygenation rate. The laboratory analyses and calculation results show that Cikapundung River and Citepus River have deoxygenation rate ranges between 0.010-0.370 day-1 and 0.031-0.480 day-1 respectively, while the BOD (Biochemical Oxygen Demand) ultimate concentration range are 1.17-75.08 mg/L and 14.80-80.80 mg/L respectively. The rates acquired are relatively low compared to that of empirical equation results. It indicates that the degradation process is not optimal, probably due to the high concentration of pollutants that inhibit the degradation process. It will give a strong recommendation on controlling the heavy metals, toxic, and chemical pollutants discharged into the river, especially at the point that has low flow rate. Improvement of river water quality needs to be held concerning those kinds of pollutants.