Treatment and remediation of a wastewater lagoon using microelectrolysis and modified DAT/IAT method

To examine treatment and remediation of a wastewater lagoon with poor biodegradability, a typical wastewater lagoon in Tianjin,China, was treated and remedied using microelectrolysis and modified demand aeration tank (DAT)/intermittent aeration tank (IAT)methods. After pretreatment by microelectrolysis, the removal efficiency of chemical oxygen demand (COD) was up to 64.6% and the ratio of BOC/COD in the effluent increased from 0.013 to 0.609. The removal rates of CODCr and NH+4-N were affected by sludge backfiow rate, mixed liquor suspended solids (MLSS), and hydraulic retention time (HRT) in the modified DAT/IAT reactor. The highest removal rates of CODCr and NH+4-N were up to 78.9% and 62.6%, respectively, when the sludge backflow rate was 38.0 mL/min, the total HRT was 8.0 hr and MLSS was 4088.0 mg/L. In this case, some protozoa and metazoa were observed in activated sludge and biofilm carriers. Most of chrominance was removed by microelectrolysis treatment, while the modified DAT/IAT methods were more effective for CODCr and NH+4-N removal.