Investigating the Availability of Domestic Wastewater Pollution Load Capacity in Brantas River, Malang

Department of Civil Engineering and Planning, Faculty of Engineering, Universitas Negeri Malang, Jalan Semarang No. 5, Malang, Indonesia

^* Corresponding author: ridwan.muhamadrifai.ft@um.ac.id

Abstract

The riverine system can recover itself to its balance once pollutant enters the water body. Nonetheless, this self-purification capability only applies when the concentration and magnitude of the pollutant do not exceed the pollution load capacity. As the main river in Malang, the Brantas River receives most of the pollutants from anthropogenic activities, especially domestic wastewater. A study was conducted to uncover the capacity of the pollution load of the Brantas River. Samples were obtained from surface water in five stations along the river and analysed according to the domestic wastewater parameters in the Permen LHK No. P.68/2016 against river water quality for Class II limit. A model was then constructed using QUAL2Kw software. The analysis showed that Brantas River does not have sufficient allocation for COD and BOD at all stations, and NH₃ at downstream stations. In contrast, the river remains able to accept TSS and coliform inputs. The model showed that only coliform contaminants can be self-purified despite all citizens discharging domestic wastewater containing coliform at the maximum concentration and flow. It is clear that to make the pollution load for domestic wastewater available in Malang, river quality must be managed before the stream enters the city.