Impact of wastewater effluents from a sugar industry and a molasses based distillery on water quality of River Musamya in Lugazi, Uganda

Abstract

The sugar industry in Uganda and East Africa is of economic importance in terms of employment opportunities, government revenue, and sugar production for export and domestic consumption. However, there is a problem of environmental pollution due to its wastewater disposal without proper treatment. Sugar Corporation of Uganda Ltd (SCOUL) is one of the major sugar industries in Uganda milling over 1,583 tons of sugar cane per day and generating over 1000m3 of wastewater per day. Wastewater disposed by SCOUL is in septic conditions and causes serious pollution to the nearby river water source. However, there is little information regarding ecological studies to examine water quality of river Musamya after receiving effluents from SCOUL. This study therefore assessed the impact of wastewater effluents from SCOUL on the water quality of River Musamya so that environmental pollution mitigation measures can be put in place. Physico-chemical characteristics of wastewater from SCOUL and water from River Musamya at the point of discharge, upstream and downstream of the river were determined using standard methods for the examination of water and wastewater. Impact of wastewater from SCOUL on River Musamya was evaluated and results showed that pollutant concentration in effluent from SCOUL were above permissible discharge limits by NEMA. River Musamya received 2,523±728 m3/day of wastewater with a high organic matter and nutrient load of 20,346 ± 4,449 kg COD/day, 5,692±1,666 kg BOD/day, 121±29 kg TN/day and 40±14 kg TP/day. The pH, TDS, EC, T-Fe, Na+, Ca2+, TN, TP, Turbidity, Temperature, BOD, COD, DO of the upstream and downstream river after wastewater discharge varied from 7.1 to 5.6, 88 to 1007mg/l, 108 to 1524μs/cm, 3.2 to 10.5mg/l, 5.5 to 8.0mg/l, 8.5 to 25mg/l, 1.4 to 6.8mg/l, 0.8 to 2.7mg/l, 49 to 616NTU, 24.8 to 25.7˚C, 3.8 to 184mg/l, 13 to 675mg/l, 6.5 to 2.83mg/l, respectively, and the difference was significant (P < 0.05). Therefore, despite the sugar processing industry (SCOUL) being economically important, the impact of its effluent wastewaters on the environment is significant. Hence there is urgent need for intervention by employing technologies that reduce the quantity of waste effluents generated and also by installing a wastewater treatment system that impacts less on the environment.