Analysis of heavy metals, physicochemical parameters and effect of blending on treatability of wastewaters in Northern Ethiopia

Abstract

The present study monitored textile factory, distillery, and domestic wastewaters and investigated the effects of blending on the physicochemical properties of these wastes. Findings revealed that distillery wastewaters had the highest values of all tested parameters, including heavy metals, biodegradable organics, and nutrients. Biological and chemical oxygen demands in the textile wastewater were higher than domestic wastewater, while total phosphorus, total nitrogen, and sulfate were higher in the domestic wastewater. Likewise, while higher mean concentrations of zinc, copper, iron, and manganese were found in the domestic wastewater, the rest studied heavy metals did not show statistical differences (p < 0.05). This study concluded that blending improves biological treatability and effectively neutralizes the alkaline textile, acidic distillery, and domestic wastewaters at volumetric ratios of 3:1:18, respectively. This methodology will help to avoid the use of chemicals for neutralization and can be a useful entry point to establish sustainable wastewater management strategy in the developing countries. The results suggest the need for inclusion of the tested nine heavy metals in the Ethiopian standards for discharge from the distillery and domestic effluents.