Pollution effect of wastewater discharged from Hawassa Textile factory on tikur wuha river, southern Ethiopia

Abstract

Industrial pollution to water body is one of the serious problems if there is no well established wastewater treatment facility. The main focus of this study was to investigate the effects of wastewater generated from Hawassa Textile Factory on Tikur Wuha River. Composite wastewater samples were taken from the factory outlet and the outlet of lagoon and a grab water sample was collected from each selected ten sampling stations on Tikur Wuha River once per month from April to May 2011. A habitat score was made for each established sampling stations by using habitat assessment checklist. Macroinvertebrate sample was collected together with water sample from each selected sampling sites by using surber sampling method from Tikur Wuha River. The wastewater and river water physicochemical parameters such as Chemical oxygen demand (COD), biological oxygen demand (BOD), total organic nitrogen (TON), nitrate nitrogen (NO3-N), ammonia nitrogen (NH3–N), Phosphate (PO4 3-), Sulphate (SO4 2-) and total suspended solids (TSS) were analyzed. Percent comparability of habitat score showed that both upstream and downstream study sites were categorized to good habitat conditions. Multi metric index of Tikur Wuha River was developed using selected metrics. Based on the multi metric score sites such (U1 – U5) fall to very good biological integrity, while the downstream sites such as (D1 & D2) categorized under very poor biological integrity. The results from this finding reveal that the downstream study sites such as (D1 & D2) were categorized as severely impaired than upstream sites. From the correlation matrices metrics that expected to decrease with perturbation had a strong negative relationship with pH, COD, BOD5 & orthophosphorus at (r= - 0.839, -0.889, -0.887 & -0.722 respectively with %EPT) on the other hand metrics that expected to increase with perturbation is % Chironomidae, has strong positive correlation with pH, COD, BOD5 and orthophosphorus respectively. The study showed that the water qualities of the downstream study sites on Tikur Wuha River were adversely affected and its aquatic biota was impaired due to the strong wastewater or poorly treated wastewater discharged from the textile factory. For sustainable management of this water resource, regional environmental protection agencies in cooperation with the factory manager should take technical measures to alleviate the problem. The environmentalist in the factory should continuously monitor the textile effluents and take necessary actions to change wastewater to environmentally friendly form before discharging it