Combining Chemical Coagulation Process and Innovative Aerobic Reactor for the Treatment of De-Hairing Wastewater

Abstract

The tanning industry causes great damage and pollution to the environment. It generates tanning effluents and solid waste which, without pretreatment, discharged directly into the environment. Beam-house operations are among the important process of this industry which generates the biggest amount of toxic effluents. These wastes are considered as the most odious materials in the leather industry. The effluent is characterized by alkaline pH value, high loads of oil&grease, sulfides, total suspended solids, chemical oxygen demands and biological oxygen demands. Integration of chemical coagulation using ferric chloride aided with lime and down flow hanging non-woven (DHNW) reactor was applied in the present study. Coagulation was performed using a continuous coagulation reactor (CCT). The DHNW was packed with non-woven poly ethylene terephthalate (PET) fabric produced from waste plastic bottles. The efficiency of the integrated treatment system was assessed using the reduction of sulfide, chemical and biological oxygen demands (COD & BOD), total Kjeldahl nitrogen (TKN) and total suspended solids (TSS). Residual concentrations of COD, BOD and TSS in the CCT effluent were 985, 440 and 25 mg/L (96.1%, 85.2% and 99.3% removal), respectively. The effluent of CCT reactor was feed to the DHNW reactor. Concentrations of COD, BOD and TSS were 145, 55 and 4 mg/L, respectively in the final treated effluent. While, the sulfide concentration had been greatly reduced to 0.5 mg/L. With respect to the parameters studied, the treated effluent might meet the National regulatory standards for discharging into the sewerage systems.