Abstract

A study was carried out in Polash and Ghorasal Urea fertilizer factories to assess the impact of effluent on water quality of the Lakhya River. Comprehensive waste water sampling by grab sampling method and flow measurement by float velocity method were carried out for five weeks (one sample per week) at five sampling stations at Polash and Ghorasal Urea fertilizer factories during June to July, 2007. Water quality samplings by grab sampling method were also carried out for five weeks (one sample per week) at four stations in the Lakhya River at the same time and River flows on the period of October 2006 to September 2007 were collected from Institute of Water Modelling. Effluents at both the factories and water sample from selected points in the river were analysed for pH, temperature, DO, BOD₅, COD, NH₃-N, NH₄-N, TS, TSS, and TDS during June to July, 2007 at the Environmental Engineering Laboratory of Bangladesh University of Engineering and Technology, Bangladesh. The results showed that the effluents were alkaline while the level of DO, BOD₅, COD, NH₃-N, NH₄-N, TS, TSS, and TDS relatively high and 17425-20012 kg/day Ammonia load discharged from fertilizer factories into the Lakhya River. The upstream water was near to neutral pH (average pH, 7.66 ± 0.102) with high dissolved oxygen but low in the levels of the other parameters. The river water after the effluent receiving points was basic (average pH, 8.16 ± 0.08) and the levels of other parameters were high due to heavy pollution load especially Ammonia discharged from fertilizer factories. The results suggested that water in the river was polluted and not good for human consumption. It is therefore recommended that the disposal of improperly treated or untreated wastes should be stopped to save the river water from further deterioration.

Key words: Industrial effluents, Impact, river water, pollution, water quality.