Description:
The discharge of secondary effluent from wastewater treatment plants (WWTP) containing nitrogen (N), phosphorus (P), and partially soluble refractory organic compounds poses a threat to surface water quality and limits its reuse. To address this problem, macroporous ion exchange resin adsorption was investigated as an alternative to single biochemical nitrogen removal processes in this work. Various conditions were examined to optimize adsorption performance, and the adsorption mechanism was explored through isotherm fitting, thermodynamic parameter calculation, and kinetic analysis. The experiment demonstrated that the resin exhibited strong selectivity for nitrate (NO3−) and achieved an equilibrium adsorption amount of 9.8924 mg/g and an equilibrium adsorption time of 60 min at 25°C. The resin's adsorption of NO3− was mainly dominated by energy-uniform monolayer adsorption, and the internal diffusion effect during the adsorption process was weak. The resin denitrification pilot plant demonstrated stable operation for two months and achieved COD<20 mg/L, TN<1.5 mg/L, and NH4+-N<0.5 mg/L. The removal rates of COD, TP, NH4+-N, NO3−-N, and TN were 41.65%, 42.96%, 55.37%, 91.8%, and 90.81%, respectively. This study presents a practical, low-cost, and efficient treatment method for the deep treatment of secondary effluent from WWTP in practical engineering, providing new ideas and theoretical guidance