NOVEL GAC SYSTEM DESIGN ELIMINATES SLUDGE GENERATION AND REINFILTRATES GROUNDWATER

摘要

Both in situ and pump and treat technologies for groundwater containing high levels of dissolvedrniron (>100 mg/l) are often overly expensive and difficult to maintain due to the sludge generationrnand iron fouling. The increasing popularity and economics of in situ remediation, and therndifficulty of adequately treating the groundwater in situ to low clean-up levels, has necessitatedrnthe development of novel groundwater remediation technologies for the physical, and/orrnbiological treatment of organic compounds. Treatability testing, pilot testing, and scale-uprndesign at two separate sites resulted in successfully operating activated carbon treatment systemsrnwith no-metals pretreatment or filtration, and subsequent groundwater recirculation. Thernoperating systems:rn1. Remove parts per million (ppm) levels of volatile organic compounds (VOCs)rnand semi-volatile organic compounds (SVOCs) to treatment goals;rn2. Maintain high concentration of dissolved metals in solution, during both the lowrnlevel and high level loading of the activated carbon columns, thereby eliminatingrnsludge generations and disposal costs; and,rn3. Maintain dissolved metals in solution and allow the treated groundwater to bernreinfiltrated into the aquifer for reuse and natural resource maintenance.rnGroundwater associated with the first site contains high dissolved iron and calciumrnconcentrations (200-400 milligrams per liter [mg/l] each), VOCs including benzene, 1,2-rndichloroethane, and high total organic carbon (100 mg/l). The second site also contains high ironrnand calcium concentrations (20-100 mg/l each), VOCs including benzene, chlorobenzene, andrntoluene, and SVOCs including nitrobenzene, and 4-chloroanaline. Groundwater at both sitesrnexhibit low dissolved oxygen levels and low oxidation/reduction potentials.rnBased on the operational results of several full scale carbon columns exhaustion/changeoutrncycles, this novel technology application has been shown to treat groundwater to lowrnconcentrations, circumvent significant iron sludge generation and management costs, eliminaterncosts associated with publicly owned treatment works (POTW) and national pollutant dischargernelimination system (NPDES) discharge, while recirculating groundwater back into the aquifer forrnnatural resource maintenance and reuse.