Surface water quality deterioration is the impact of anthropogenic activities at the study areas due to rapid industrialization. The study was done to know the spatial variation of the water quality of the Tunggak River and surrounding area because of industrial activities. In-situ parameters and ex-situ data of chemical, bio-chemical parameters and heavy metals were collected monthly to fulfill the objectives. The samples were collected from 10 selected stations and analyses were carried out using standard methods. Heavy metals were determined by using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). SPSS statistical software was used for data analysis. The results of the study revealed that industrial effluents were the major source of pollutants and caused of spatial variation among the stations. Less amount of Dissolved Oxygen (DO) and higher concentration of Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), ammoniacal-nitrogen and heavy metals made the water un-usable except irrigation. Analyzed surface water was classified based on Department of Environment-Water Quality Index (DOE-WQI) Malaysia and found that the maximum stations except lower and uppermost were in class IV (highly polluted). Pollution rate was higher in the middle stations due to large number of industries were located in the middle and they discharged all their effluents in the river stream. Due to tidal interference in the lower stream and minimum industry in the upper stream pollution was less in those stations

The pH of the water of the studied stations was slightly acidic to neutral, while EC was included within recommended standard. The contamination intensity, pollution level, classification of water indicated that the wastewater having higher contamination level, especially, BOD, COD, NH3-N, PO4, Pb, Cd, Cr, Cu, Co, Ni and Hg concentration were high in all samples with lower DO value. The high COD content indicated that the wastewater of Gebeng area contains higher wastes. However, the results were differed on the basis of seasons and types of industries. It was also found that Pb and Hg concentrations were higher in wet season in comparison to dry, while Cd, Co, Cr, Cu, Zn, Ni, Ba and As concentrations were higher in dry season in comparison to wet. All sampling sites were categorized as highly polluted. DOI: http://dx.doi.org/10.3329/bjb.v44i1.22731 Bangladesh J. Bot. 44(1): 103-110, 2015 (March)

Two-step treatment technique was developed for the treatment of water by Pseudomonas aeroginosa in a bioreactor in a first phase and then the bacterial treated water was treated with the vetiver grass, cattails and water hyacinth in second phase. Two-step process of bioremediation of 13 days was found to be satisfactory for As, Ba, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn in compared to the direct treatments with vetiver grass, cattails and water hyacinth in 20 days. As the plants cannot work or tolerate the higher concentrations of heavy metals, so with the first step on an average 52.48% reduction of heavy metals were done within 5 days. It was observed that 100% removal of Pb was found by two-step process of Pseudomas aeroginosa with cattails and water hyacinth, respectively in 13 days, while 98.16% removal of Pb was found by direct plant treatment of water hyacinth in 20 days. It was clear that the two-step treatment for vetiver grass, cattails and water hyacinth were found as the most effective treatments.

Gebeng is a rapidly growing industrial area in Pahang, Malaysia. The study was conducted to explore the pollution level and to find out the human interference on surface water quality. The highly polluted parameters were BOD, COD, DO, ammonical nitrogen, phosphate, Pb, Cu, Cd, Co and As and most of the stations categorized as polluted (Class III and IV). Heavy metals like Pb, Cu, Co, Cd and As were higher at upstream river zone and highly polluted nevertheless the downstream zone and surface water were comparatively less polluted. Industrial wastes and effluents increased the contamination levels of the studied water.