Enhancing treatability of tannery wastewater by integrated process of electrocoagulation and fungal via using RSM in an economic perspective

Abstract The wastewater from tannery industry, using single treatment technology has not been enough to remove the chromium (Cr 6+ ) or high organic content (COD). Electrocoagulation (EC) and Biological Fungal Treatment (BFT) which endure against toxic and/or highly organic content, are promising technologies to eliminate impurities of tannery wastewaters. In this study, the treatment performance of integrated EC and BFT processes via response surface methodology (RSM) was investigated for the tannery wastewater to determine the effects of operating variables. The factors of electrode combination (Al–Fe), pH (4–8), current density (0.54 – 0.81 A), and electrolysis time (15–60 min) are investigated for EC and inoculum rate (0.5-2%) reaction time (6-36 h) and pH (4-6) are also investigated for BFT. The operating cost of the combined process was calculated as 1.73 $.m −3 . It was determined that efficient COD (63.8% ) and Cr 6+ (90%) removal were achieved via EC (pH 8.0, 60 min reaction time and 0.81 A current). The optimum condition of BFT for COD and Cr 6+ removal are at pH 5.0, 36 h reaction time and 2% inoculum rate. Total efficient COD (96%) and Cr 6+ (97%) removal were achieved at EC and BFT with the combined system.