Assessment of water quality characteristics during base and storm flow events on Sungai Langat Basin

Abstract

Rapid urbanization along the Sungai Langat plays an important role in the increase of point source (PS) and non-point source (NPS) pollutions. The water quality statistical analysis during the base and storm flow events outputs enables to identify the PS and NPS pollution impairing the river. Sungai Langat basin is deteriorated due to NPS pollution of BOD, COD, TSS, NH3-N, NO3 and E.Coli from year 2004-2008. The utmost and less most water constituents polluting Sungai Langat basin were ranked using the violation analysis during base and storm flow events. The overall rank from the most to less impacting pollutants impairing Sungai Langat basin are E.Coli (NPS)> E.Coli(PS)> TSS(NPS)> COD(NPS)> NH3-N(NPS)> BOD(NPS)> COD(PS)> TSS(PS)> NH3-N(PS)> BOD(PS). The longitudinal profile analysis (year 2008), show the BOD, COD, TSS, NH3-N, NO3 and E.Coli have similarity where the all of the studied water quality concentrations have increased at DOE station of 1L07 to 1L05 segment of river due to sewage. It also founded that the presence of E.Coli in Sungai Langat is at concerning level as the concentration of E.Coli can reach 44 times higher than limiting standard of 2000cfu/100mL. The presence of E.Coli in Sungai Langat is proved by the longitudinal concentration profiles illustrating the decreasing level of DO and pH at segment of IL07 to IL05. The strong concentrations of BOD and COD at the same segment of the Sungai Langat are related to anthropogenic pollution sources and are from sewage (PS) such as sewage treatment plants and industrial effluents. The GIS maps confirmed that there are numerous numbers of private and public sewage treatment plant, compare to other segments of the river. Another possibility is, the PS also suspected coming from the industry effluents which is responsible to the elevation of E.Coli in Sungai Langat basin. The failure of sewage treatment systems (overflow due to storm water) also may be the reason why the E.Coli level still high during storm flow events. Other sources (NPS) may be from municipal wastes, or animal husbandry of the segment of river.