20150151994 | SINGLE-TANK NUTRIENT REMOVAL SYSTEM USING IMMOBILIZED BIOMASS - A method and system are provided for treating water, such as wastewater, landfill leachate, or contaminated groundwater. A single tank is used. A structure with a unique design within the tank promotes growth of immobilized biomass. A recycle stream transports some of the fluid output from near the top of the tank back to the bottom of the tank, the rest of the fluid output leaving the water treatment system as effluent. Oxygenation means within the tank cause fluid to flow upwards, and this together with the recycle stream causes fluid to circulate through the immobilized biomass. The oxygenation means result in the formation of an aerobic zone, and the location and/or aeration flow rate of the oxygenation means result in an oxygen-depleted zone. Different processes occur in the aerobic and oxygen-depleted zones, removing a variety of contaminants. The use of a recycle stream and of immobilized biomass results in efficient water treatment, even though a single tank is used, and the water treatment system can have a low footprint and cost. | 06-04-2015 |