Abstract
This study intends to assess the removal efficiency of the chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total suspended solids (TSS) from raw tannery wastewater using electrocoagulation by aluminum electrodes as well as to determine the effects of its main operating factors. Therefore, the response surface methodology was applied through an experimental Box-Behnken design by considering the current intensity (I), treatment time (T), and pH levels as the factors. In addition, the BOD, COD, and TSS removal percentages were considered to be the response variables. The results indicate that the treatment time, current intensity, and pH level were significant for COD and TSS, whereas only the treatment time was significant at a confidence level of p-value < 0.05 for BOD. For COD, the optimal operating conditions were I = 3 A, T = 24 min, and pH = 8.4; for BOD, the optimal operating conditions were I = 3 A, T = 24 min, and pH = 5.5; and for TSS, the optimal operating conditions were I = 2.7 A, T = 19 min, and pH = 7.4. Under these conditions, removal efficiencies of 56.8%, 69.2%, 99.9% were observed for COD, BOD, and TSS, respectively. The results suggest that electrocoagulation is an effective method for removing the parameters under study; therefore, it is a viable alternative for reducing the pollution issues caused by the tannery industry.
Highlights
The tannery industry is an important activity in the economic development of Peru and this is due to the diversity of articles that are generated from leather and the international demand of tanned skins until wet blue state
Our study focuses on assessing the efficiency of the electrocoagulation process for removing the pollutants generated by the tannery industry expressed as biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total suspended solids (TSS) and on optimizing the process through the Box–Behnken (BBD) response surface methodology
This is caused when a high current intensity is supplied to the reactor, generating a large number of monomeric and polymeric species according to Faraday’s law, which reduces the amount of wastewater pollutants [8]
Summary
The tannery industry is an important activity in the economic development of Peru and this is due to the diversity of articles that are generated from leather and the international demand of tanned skins until wet blue state (wet tanned skin). When high COD and BOD contents are reported in organic matter, water bodies lose a considerable amount of dissolved oxygen This is harmful to aquatic organisms because it results in anaerobic activity that may release harmful gases. Estimates from the Center for Technological Innovation in Leather, Footwear, and Related Industries (CITEccal Lima) identified approximately 100 different tanneries in Lima. Most of these tanneries have not yet implemented an effluent treatment system, which can ensure their compliance with the current environmental regulations, putting the environmental health and the very existence of the industry at constant risk. In 2017, Ufuk Durmaz et al [4] determined the optimum operating values for COD and TSS removal through aluminum electrodes to be 18.9 mA/cm min of electrolysis time, and a pH level of 6
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