FIXED-FILM DENITRIFICATION COUPLED WITH IN-SITU REMEDIATION OF NITRATECONTAMINATED GROUNDWATER

摘要

This investigation studied the potential of coupling a two-stage, reversible flow systemrnwith an in-situ polishing step to determine overall performance and sustainability of therntreatment strategy. Effluent water from the reversible flow system was pumped throughrnan artificial aquifer to determine the polishing potential of the aquifer. Aquifer backpressurernwas measured to monitor the extent of injection port plugging. Performancernwas measured by effluent water nitrate-, nitrite-nitrogen and soluble chemical oxygenrndemand concentrations. The aquifer influent was the reversible flow system effluent.rnThe reversible flow reactor system was fed water containing 50 mg NO_3-N L~(-1) forrnapproximately nine months at a hydraulic retention time of 1 hour. The feed waterrncarbon-to-nitrogen ratio was 1:1 with ethanol as the carbon source. Performance datarncollected during this study demonstrate the sustainability of the integrated system. Thernintegrated system effectively reduced the nitrate-, nitrite-nitrogen, soluble COD andrnTSS concentrations to near zero levels. The aquifer column was operated for 150rndays and resulted in only 250 mm of water increase in back-pressure at the influentrnof the column. This back-pressure increase occurred in the first 300 mm of columnrnlength.