Constructed Wetlands and Groundwater Infiltration Treating Industrial Wastewater, Treatment Efficiency, and Pollution Tracing

Three treatment systems for wastewater from two landfills, one active and one closed, and an industrial location including a quarry have been monitored continuously for over a decade. The wastewater from the active landfill is infiltrated through an extensive unsaturated zone into groundwater and subsequently into a large river system. The wastewater from the closed landfill is treated in a constructed wetland (CW) and the industrial low-grade wastewater in filter dams. The treatment systems operate well with the specific wastewaters, high-concentration leachate from waste in infiltration systems, low-concentration leachate in constructed wetlands, and wastewater from inert waste in filter dams. The landfilling of organic waste was restricted to low limit values for more than a decade ago, but it is hard to see any changes in leachate due to changes in waste landfilling regulations. The heavy carbon stable isotope 13C is useful in tracing landfill leachate and to evaluate dilution into other water bodies. The adding of P to the aeration pond treating low-concentration leachate did not help in the removal of N; on the contrary, the concentration of ammonia was sharply decreased when the adding of P was discontinued.