Tannery Wastewater Treatment Using Activated Sludge Process with Aluminum and Ferric Sulfates for Irrigation Purposes

Abstract

Leather tanning industry is one of the most polluting industries which produce wide varieties of high-polluted wastewater. in order to reuse tannery wastewater effluent for restricted irrigation, many technologies can be employed for wastewater treatment such as activated sludge method (AS) and membrane biofilm reactor (MBR). This study was performed to evaluate the feasibility of using ASP with chemical additives to provide high treatment performance. Tannery wastewater was collected from a leather tanning factory in Cairo. Pilot-model consists of a primary sedimentation tank, aeration tank equipped with an air blower and a final settling tank was performed as a simulation of ASP process. Due to the high-strength toxic residues, a modification was performed to the ASP by adding ferric and aluminum sulfates to improve the treatment efficiency. In this experimental study, 4 trials were performed. The 4 experimental trials were 8 hours aeration cycle without additives, 12 hours aeration cycle without additives, 12 hours aeration cycle with ferric sulfate, and 12 hours aeration cycle with aluminum sulfate. The physicochemical properties of tannery wastewater such as BOD, COD, TSS, NH3-N, TKN, and TP were measured at the national research center in Cairo. During 12-hours aeration cycle with aluminum sulfate, the removal efficiency of COD, BOD, TSS, NH3-N, TKN, and TP were 98.65%, 98.95%, 99.35%, 93.67%, 90.11%, and 64.71%, respectively. It can be concluded that the 12 h aeration cycle with aluminum sulfate was the most effective for tannery wastewater treatment and its final effluent was suitable for reuse in irrigation purposes.