(The Effect of Inflow and Infiltration on the Strength of Municipal Wastewater)

Abstract

Inflows and infiltrations are a common phenomenon in the sewerage system in our country. This is due to weather factors and high rainfall distribution in Malaysia. Therefore, infiltration rates are also expected to be high through manholes. The purpose of this study is to identify the effects of infiltration and inflow on wastewater strength from municipal areas with a population of 1000 PE. Modeling using the Storm Water Management Model (SWMM) software is used to determine the rate of infiltration and inflow of rainwater into sewers as well as the rate of decay of pollutant loads such as Chemical Oxygen Demand (COD) and Ammonia (NH3) in a sewer system involving 17 manholes. The results in this modeling are the infiltration rate for each catchment area and the decay rate of the total pollutant load. As for the infiltration rate, the catchment area is divided into three, namely S1, S2 and S3, where S1 contains the lowest amount of infiltration compared to S2 and S3 which is 1.27 mm/h for 10%, 1.36 mm/h for 15% and 1.45 mm/h for 20%. In addition, the total pollutant load produced for the 12 hours of simulation conducted for COD is 160-180 kg with a total decay occurring around 0.10-0.29% while Ammonia produces a pollutant load of 140-160 kg with a consistent decay rate and does not give substantial reduction to Ammonia. The results show that the infiltration that occurs does not affect the velocity of wastewater but affects the strength of wastewater which can cause the concentration of wastewater to decrease.