Performance evaluation and chemical oxygen demand removal of tannery wastewater through the aerobic-anaerobic route

With characterized for complex and maximum substance (suspended solids, broke up oil, a mixture of inorganic and chromium sulfides), tannery wastewater was subjected to a treatment process on removal of chemical oxygen demand (COD) via upstream anaerobic sludge blanket reactor where we found reduced departure efficiencies and that process limits were affected by the assortments in regular stacking rates, closeness of chromium, and sulfides. Hence, a combination of the aerobic-anaerobic hybrid reactor was set up for sequential treatment to determine possible COD reduction. This study investigated the biological degradation of tannery wastewater in a laboratory-scale sequential up-flow aerobic-anaerobic reactor. The aerobic zone at the top was packed with spherical ball-shaped polyhedral polypropylene, and the anaerobic zone at the bottom was packed medium with granular media. The aeration flow rate varied by 2 L/min, 4 L/min, and 6 L/min in the aerobic zone, and the reactor maintained an organic loading rate (OLR) of 5 kg COD/m³/d. Parameters like COD and gas yield assess the performance of the reactor. The maximum COD of 86% is removed in the anaerobic zone with an aeration rate of 6 L/min, and the 1800-mL methane gas yield is measured by the 29th day.