Assessment of the level of chromium species in the discharged effluents of Haik and Debre Berhan tanneries in the Amhara Region using ICP-OES and UV-VIS spectrometry

Abstract

The purpose of this study was to assess the level of chromium species in the discharged effluents of selected tanneries in the Amhara Region; Haik and Debre Berhan tanneries. The level of total chromium, and hexavalent chromium in the discharged effluent of the studied tanneries were determined using the ICP-OES, and UVVis spectrometry, respectively. The level of trivalent chromium species in the samples was then estimated by difference. Recovery results in the range 96.3 to 103.3% verified the applicability of the methods for the determination of the chromium species in the effluent samples. One way ANOVA statistical analysis was used to check whether the results between sampling months were statistically different or not. The mean concentration of Chromium (VI) before and after treatment in the effluent of Haik tannery was 0.618±0.076 and 0.123±0.064 ppm while in the effluent of Debre Berhan tannery, 0.070±0.009 and 0.039±0.005 ppm, respectively. Similarly, the average total chromium concentration before and after treatment in the discharged effluents of Haik and Debre Berhan tannery was 4,772.3±2.4 and 392.7±1.7 ppm, and 512.8±1.1 and 325.0±0.3 ppm, respectively. Although the average levels of chromium species over the sampling times looked not much higher than the permitted levels, some of the results indicated that the factories release effluent which is extremely loaded with chromium species including the most toxic form of chromium (hexavalent chromium). The assessment results in general showed the pollution of the river waters into which the studied tanneries are discharging their effluent.

Key Words/Phrases: Debre Berhan tannery, Inductively coupled plasma-optical emission spectrometry, Diphenylcarbazide, Recovery study, Tannery effluent, UV-Visible spectrophotometry