Abstract The Marshland Upwelling System (MUS) is an alternative method for coastal dwellers to treat their wastewater. Past studies have dealt with the removal of fecal pathogens from wastewater. However the objectives of this research were to: 1) evaluate the treatment capability of the MUS under high hydraulic loadings and cool temperatures with respect to CBOD5, TKN, TAN, NO2--N, NO3--N, TP, and PO4-P, and 2) determine the ideal flowrate and injection frequency to achieve satisfactory nitrogen removal without hydraulic failure. The artificial wastewater study was performed to evaluate the treatment of CBOD5, TKN, TAN, TP, and PO4-P under high hydraulic loadings and cold temperatures. According to the pressure data, there were no signs of hydraulic dysfunction (clogging and/or channelization) during the study. CBOD5 was reduced from an influent value of 227 mg/l to an effluent value of 19 mg/l. TKN was reduced from 120 to 3 mg/l-N. The concentration of TAN was reduced from 110 to 1.5 mg/l. The influent TP and PO4-P concentrations were 14 and 7.2 mg/l-P, respectively. However, the effluent concentrations of TP and PO4-P were 0.3 and 0.7 mg/l-P. A flow rate of 2.8 L/min injecting for 30 minutes every 3 hours provided effective reduction of nitrogen. The concentrations of TKN in the influent were reduced from 168 to 1.8 mg/l-N. The influent TAN concentrations were reduced from 160 to 1.1 mg/l-N. Laboratory studies demonstrated the importance macrophytes have on the redox potential of the underlying media. By increasing the redox potential, the macrophytes also accelerated the production/reduction of NO2--N.
