Dissolved oxygen dynamic system model for the determination of the waste assimilating capacity at Brantas river Malang city

摘要

River quality standard in Indonesia still determined normatively.It apply for all river with various conditions.This is not appropriate for water quality management because each river have different characteristics to keep the optimal condition for the life in water body.With dynamic system model of dissolved oxygen(DO),DO's changes can be approached.DO is the most important parameter to know the quality of water body.Furthermore,it could be used for estimate waste assimilating capacity(WAC)for organic waste to be discharged to water body for optimal DO's condition.This research is to make dynamic system model of DO's river using Stella v9.1.3 application.Object research located on Brantas River at Malang city.The behaviors of DO's kinetics for each monitoring point at Brantas river Malang city are approached with the dynamic system model of DO that had done verified and validated with the constrain;(1)reaeration rate of the river for typical rivers as much 1.5/day;(2)SOD's deoxygenation rate is assumed as much 5 grO2/m~2 for Brantas river with moderately pollution.From the result of sensitivity analysis of DO's dynamic system model can be determined range value for optimal DO for fish's life.The WAC for pollutant of BOD,NH3 and NO2 can be determined also.For rainy season in 2015,the WAC for the river pollutant of BOD have used almost all.Different condition of used WAC for NH3 and NO2.The remaining WAC for NH3 and NO2 are still near the available WAC.