This study was aimed to investigate the chromium removal from the tannery wastewater through electrocoagulation. The zinc and copper plates were used as electrodes for the electrocoagulation process. The effectiveness of the electrocoagulation for chromium removal efficiency was examined investigating various parameters: applied voltage, time, and current density. In batch experiment, 500 mL chromium-containing wastewater was used for electrocoagulation. Chromium content in the raw wastewater and after treatment at optimized conditions was 340.1 and 6.9 mg/L, respectively. The efficiency of chromium removal and reduction of biochemical oxygen demand (BOD) was at 98.0 and 64.6%, accordingly. Although total dissolved solids (TDS) was slightly increased. The increment of current density enhances forming zinc hydroxide which causes the damage of electrodes. Electrocoagulation is an effective technique to remove chromium from the wastewater especially from the tannery wastewater. Journal of Engineering Science 12(1), 2021, 29-34

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Wet salting preservation is commonly practiced to preserve raw hide/skin which discharges high salinity wastewater during soaking operation of hide/skin processing.The saline wastewater significantly pollutes the environment. In this study, a novel plant-based approach has been made to preserve the goatskin to reduce pollution in tannery wastewater. The Ficus hispida plant leaf paste with a minimal amount of common salt was applied on the flesh side of raw goatskin. Efficacy of the method was evaluated by scrutinizing thermal stability, hair slip, odor, moistness percentage, Total Kjeldahl Nitrogen, and bacterial count in comparison with the conventional wet salting preservation method for 28 days. Pollution load in the wastewater, for example, total dissolved solids (TDS), total suspended solids (TSS), chloride (Cl À ), biochemical oxygen demand (BOD), and chemical oxygen demand (COD) was measured following the APHA method. Results indicate that the novel plant-based method has decreased the pollution load of Cl À , TDS, TSS, BOD, and COD in the tannery wastewater by 51.02%, 41.6%, 37.1%, 2.9%, and 14.6%, respectively. Leather produced from the experimentally preserved goatskin illustrates similar physical properties in comparison to the leather produced from conventionally preserved goatskin. The proposed preservation technique of goatskin in combination with lower salt might be an ecological alternative that could decrease the pollution load especially in soaking operation.