Effects of bed depths and the ratio of aerobic to anaerobic zone on the performance of horizontal subsurface flow macrophyte‐assisted high‐rate vermifilters treating synthetic brewery wastewater

Abstract

Effects of total vermibed depth, as well as the ratio of aerobic (the unsubmerged) to anaerobic (the submerged) zone on the performance of the horizontal subsurface flow macrophyte‐assisted vermifilters (HSSF‐MAVFs) treating synthetic brewery wastewater at a higher hydraulic loading rate (HLR), were investigated for the first time. Results showed that the HSSF‐MAVF with a 50 cm total and 18 cm submerged vermibed depth yielded the optimum removal of the pollutants, ensuring a (91.2 ± 1.7)%, (81.8 ± 1.9)%, (67.4 ± 3.9)%, and (63.1 ± 2.3)% removal of chemical oxygen demand (COD), ammonium N (NH4+–N), total N (TN), and organic N, respectively, whereas there was an increase of (142 ± 6.3)% in the effluent nitrate–N (NO3−–N) than that in the influent. At the optimum condition, the effluent concentrations of all the pollutants including COD, NH4+–N, NO3−–N, TN, and organic N were well below the surface water discharge standards specified by the Central Pollution Control Board (CPCB), and thus, the effluent of the HSSF‐MAVF could be safely discharged into the surface water bodies.Practitioner Points Total vermibed depth of HSSF‐MAVFs was optimized for organic and nitrogen removal. HSSF‐MAVFs were subjected to the higher HLR of synthetic brewery wastewater. Removal of COD and NH4+–N was decreased with the increase in submerged bed depth. Removal of organic N and TN was increased with the increase in submerged bed depth. Total/unsubmerged bed depth had a positive impact on the organic and N removal.