Impacts and Policy Implications of Metals Effluent Discharge into Rivers within Industrial Zones: A Sub-Saharan Perspective from Ethiopia

Abstract

Kombolcha, a city in Ethiopia, exemplifies the challenges and problems of the sub-Saharan countries where industrialization is growing fast but monitoring resources are poor and information on pollution unknown. This study monitored metals Cr, Cu, Zn, and Pb concentrations in five factories’ effluents, and in the effluent mixing zones of two rivers receiving discharges during the rainy seasons of 2013 and 2014. The results indicate that median concentrations of Cr in the tannery effluents and Zn in the steel processing effluents were as high as 26,600 and 155,750 µg/L, respectively, much exceeding both the USEPA and Ethiopian emission guidelines. Cu concentrations were low in all effluents. Pb concentrations were high in the tannery effluent, but did not exceed emission guidelines. As expected, no metal emission guidelines were exceeded for the brewery, textile and meat processing effluents. Median Cr and Zn concentrations in the Leyole river in the effluent mixing zones downstream of the tannery and steel processing plant increased by factors of 52 (2660 compared with 51 µg Cr/L) and 5 (520 compared with 110 µg Zn/L), respectively, compared with stations further upstream. This poses substantial ecological risks downstream. Comparison with emission guidelines indicates poor environmental management by industries and regulating institutions. Despite appropriate legislation, no clear measures have yet been taken to control industrial discharges, with apparent mismatch between environmental enforcement and investment policies. Effluent management, treatment technologies and operational capacity of environmental institutions were identified as key improvement areas to adopt progressive sustainable development.

Evaluating the effect of diffuse and point source nutrient transfers on water quality in the Kombolcha River Basin, an industrializing Ethiopian catchment

“…Sampling of nutrients from factory emissions was done concurrently with that of the rivers. The factories show typical year‐round emissions (Zinabu, Kelderman, van der Kwast, & Irvine, ). River water samples were collected at the outlet of four sub‐catchments and two catchments (Figure ).…”

Characteristics and Assessment of Toxic Metal Contamination in Surface Water and Sediments Near a Uranium Mining Area

“…As an important type of environmental pollutant, toxic metals can enter water bodies through various natural or anthropogenic pathways and occur in the water phases, sediments, and organisms, and exhibit different environmental geochemical behaviors and biological toxic effects. Human activities, such as mining and disposal of waste water containing toxic metals and industrial metal chelates from tanneries, steel mills, etc., are the main sources of metals in water and sediments, which lead to a decline in water quality [6][7][8].…”

Estimating combined loads of diffuse and point-source pollutants into the Borkena River, Ethiopia

“…The concentrations of Pb were highest in the downstream zone of the Leyole river, likely due to the tannery discharges (Zinabu et al, 2017a). Though the industrial sources in the upstream parts of the rivers were found low in Pb emissions (Zinabu et al, 2017a), the relatively high Pb accumulation in the riverbed sediments (Figure 3.4.) probably shows the incidence of Pb pollution from other source(s) such as vehicles that are washed beside the river (Karrari et al, 2012).…”

“…Policies regarding water protection are, however, limited to regulation of pollutants emission into waters through a "polluter pays" principle to be implemented by regional and local water bureaus, rather than a country-wide approach for preventive management. The city of Kombolcha in north-central Ethiopia is a typical example of a conurbation with extensive pollution from industrial and municipal discharges, as well as agricultural intensification (Zinabu et al, 2017a). While it is visually apparent that some stretches of the rivers running…”

“…Estimating combined loads of diffuse and point-source 42 pollutants into the Borkena River, Ethiopia through the city are polluted, with recognition by city authorities of likely impact on, especially, human health, information on river water and sediment quality is scant. The rivers receive discharges from multiple industrial sources using heavy metals in their processing (Zinabu et al, 2017a), and surface water pollution is likely exacerbated by recurrent regional drought.…”