Water quality assessment and trophic state classification of Tasik Ilmu, UTM

Abstract

Freshwater lakes are valuable natural asset to humans for their significant functions. Unfortunately, exposure of the lakes with anthropogenic pollutants creates concern on the occurrence of enhanced eutrophication which further degrade the water quality. In this study, water quality of UTM’s lake and river was characterized according the six water quality parameter of Malysian Department of Environment Water Quality Index (DOE-WQI), total phosphorus, fecal coliform, chl-a, transparency and turbidity. The impact of the oxidation pond (OP) on the lake water quality was also investigated and meanwhile, the trophic state of UTM’s lake was evaluated using Carlson index. Water samples were collected at seven locations including river, OP and lake for three times. The samples were analyzed for DO, BOD, COD, AN, total phosphorus and fecal coliform. The study found that, the WQI calculated for the lake was ranging from 69.5 to 70 which falls under Class III indicating that the water is slightly polluted and unsuitable for recreational use with body contact. The Trophic State Index (TSI) of Tasik Ilmu revealed that mean values of TSI(SD), TSI(chl-a) and TSI (TP) were 71.6, 65.4 and 100.2 respectively which reflect the eutrophic condition of the lake water. From the removal profile of OP it was found that, the COD removal was 60%, ammonical nitrogen and fecal coliform were only ranging between 30-33%, the total phosphorus and BOD were significant with 70% of removal. The classification of river water quality before the OP effluent falls under Class II with WQI 78 while, after the effluent it falls under Class III. In conclusion, the two indices TSI and WQI used for water quality assessment process confirmed that Tasik Ilmu is in a deteriorating state and effluents from the OP contributed to its deterioration.