A novel clean and energy-saving system for urea-formaldehyde resin wastewater treatment: Combination of a low-aeration-pressure plate membrane-aerated biofilm reactor and a biological aerated filter

Abstract Urea-formaldehyde resin (UFR) wastewater containing formaldehyde (FA) and urea generated from UFR production and utilization is harmful to humans and the environment. To improve the energy efficiency of treating toxic UFR wastewater without generating secondary pollution, a novel low-aeration-pressure plate membrane-aerated biofilm reactor (PMABR) was developed, and a combined system composed of a PMABR and a biological aerated filter (BAF) was constructed. In the combined system, the PMABR realized FA conversion and urea hydrolysis, the ammonium nitrogen (NH4+-N) in the PMABR effluent was efficiently nitrified in the BAF, and the intermediate products methanol and volatile fatty acids (VFAs) in the PMABR were used as organic carbon sources to denitrify nitrate nitrogen (NO3−-N). When the membrane aeration pressure was 0.50 kPa and the influent pollutant membrane area loadings of PMABR were 11.24 g FA/(m2 d) and 11.98 g urea/(m2 d), the removal rates of FA, chemical oxygen demand (COD) and total nitrogen (TN) in the combined system reached 100%, 96.68% and 81.84%, respectively. The low-aeration-pressure PMABR largely reduced aeration energy consumption and provided an organic carbon source and environmental conditions for denitrification. The combination of a PMABR and a BAF can realize the cleaner treatment of toxic UFR wastewater in an economical manner.