Contribution of washing bays toward urban aquatic pollution a case study of Techiman and Nkoranza Municipalities

Abstract

Washing bays businesses have gained popularity in urban Ghana. These washing bays use huge volumes of water and discharge dangerous chemicals into the environment through their activities. There is therefore the need to regulate the operations of the vehicle washing bays to ensure water conservation and its associated environmental and social impacts. This study estimated the water quantities used to wash different vehicles types and the pollution loads of the resulting wastewater in Techiman and Nkoranza Municipalities, Ghana. Twenty-two functional washing bays were purposively selected and monitored to estimate the water used to wash six different categories of vehicles and wastewater generated. Composite wastewater samples from two washing bays were analysed for concentrations of different contaminants which were used to calculate pollution loads. Data was entered on excel sheet and transported to SPSS for analysis. Frequencies and percentages were developed. The level of significance was set at P ≤ 0.05. The study showed that average volume of water used for washing each category of vehicle per day were as follow: Motorbike/Mopeds 107 L, Saloon car 162 L, Pickups 249 L, Buses/Coaches 266 L, Graders/Loaders 1159 L, Heavy articulators 1246 L. The wastewater was characterized by pH (7.4-7.6), TSS (857-2624 mg/L), TDS (125.5-148.6 mg/L), SO4 2- (66-68 mg/L), PO4 3- (0.37-0.41 mg/L) and turbidity (1190-1680 NTU). Pollutant loads for BOD up to 0.9 tons from Techiman and 0.8 tons from Nkoranza could be released in a year. COD up to 2 tons from Techiman and 2 tons from Nkoranza could also be released in a year. The wastewater has a low biodegradability index of 0.4. The study therefore concluded that, activities of washing bays in Techiman and Nkoranza pollute water bodies. It was recommended that washing bays adopt recycling method so that wastewater can be reused.