Assessment of industrial waste load of River Borkena and its effect on Kombolcha town and the surrounding communities

Abstract

Water pollution is a major threat to human population and dumping of pollutants into water body result in rapid deterioration of water quality and affect the ecological balance in the long run. The present study was undertaken to assess pollution load from river Borkena. In urban and suburban parts of Kombolcha, the use of industrial wastewater for irrigation purpose is a common practice. Local farmers in Borkena watershed use the wastewater to irrigate their agricultural fields for cultivation of vegetables. But they suffered from loss of productivity of leafy vegetables and skin injury because of their exposure to the wastewater during irrigation practices. That is why this study focused on assessing the amount of industrial waste load on river Borkena and its effects on communities in the watershed. The main aim of this study was: to assess the physico-chemical characteristics of River Borkena before and after industrial waste discharges mixed to it by the waste carrier small streams; and its environmental impact on the surrounding communities and vegetable farms. The methodology consisted: 1) Basic survey in order to assess the physical and chemical characteristics of the river water, and 2) a case study performed by focus group discussions with the community authorities and farmers in the study area who used the river water mainly for irrigation purposes. Sampling was conducted at 6 sites in the study area during low and high flow periods with an interval of three months for a period of one year in order to account for the seasonal hydrological cycle of the river water. Laboratory measurements of river water and leafy vegetables for metal concentration were also determined to investigate the effect of the use of the river water for growing vegetables and other personal cases. The findings of this dissertation showed metal concentrations in leafy vegetables and irrigation water are within the permissible limits of FAO/WHO standards and not significant for the time being, but is expected to be a challenge in the near future if not well addressed. The concentrations of metals in leafy vegetables will provide baseline data and it shows that, in the current situation consumption of leafy vegetables grown in the study area may not have health risks in the context of metal concentrations. To avoid the entrance of metals into the food chain, municipal or industrial wastes should not be drained into the river and farmlands without prior treatment. The continuous monitoring of the soil, vegetable plant and irrigation water quality are prerequisites for the prevention of potential river water. Laboratory measurements of river water and leafy vegetables for metal concentration were also determined to investigate the effect of the use of the river water for growing vegetables and other personal cases. The findings of this dissertation showed metal concentrations in leafy vegetables and irrigation water are within the permissible limits of FAO/WHO standards and not significant for the time being, but is expected to be a challenge in the near future if not well addressed. The concentrations of metals in leafy vegetables will provide baseline data and it shows that, in the current situation consumption of leafy vegetables grown in the study area may not have health risks in the context of metal concentrations. To avoid the entrance of metals into the food chain, municipal or industrial wastes should not be drained into the river and farmlands without prior treatment. The continuous monitoring of the soil, vegetable plant and irrigation water quality are prerequisites for the prevention of potential health hazards to human beings. Finally this study fills the gaps in information for concerned regional and federal governmental offices and may use it as an input to design regulations and policies which benefits the communities in the watershed.