Abstract:
Kombolcha leather industry produces huge amounts of inorganic and organic wastes which pollute the adjacent environment including Abba Sharo River. This study was focused on characterizing the physic-chemical parameters of Kombolcha tannery effluent and evaluates its impact on the water quality of receiving Abba Sharo River water. Accordingly, two tannery effluent samples along wastewater channel at different distances have been taken and three river water samples were collected along the river to evaluate its impact on the river and samples were collected and examined according to standard methods during period of dry season. The analyzed parameters were pH, EC, TDS, To, COD, NH3-N, Cl-, S-2 and Cr6+. The observed mean values for the above parameters revealed that except for pH, To, COD and the observed mean values for the remaining all parameters analyzed were beyond the EEPA standard limit values and pH, To and Cl-, values detected in the downstream of the river were within the permissible limit of the WHO guidelines (2013) and Ethiopian recommended values (QSAE, 2013) whereas EC, TDS, NH3-N, S-2 and Cr6+ were beyond the permissible limit of the WHO guidelines (2013) and Ethiopian recommended values (QSAE, 2013). The T- test also showed that, except for pH the variation between tannery effluents sampling points were statistically significant (p < 0.05). ANOVA also indicated that variation among the sampling points of river water samples were highly statistically significant (p < 0.05). In addition to this, the observed mean values for all analyzed parameters in downstream of the river were greater than the values obtained at upstream of the river that were considered to be free of Kombolcha tannery effluent. This shows that the downstream of the river is polluted, indicating the need to remediate the contaminated river due to direct discharge of tannery effluent by launching treatment plant and implementing rules and regulations.
