摘要 :
Onsite treatment of leachate was implemented at the Tveta Landfill, adjacent to the city of Sodertalje, Sweden. The system consists of leachate collection in a pond, precipitation of metals with chemicals, a constructed wetland, a...
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Onsite treatment of leachate was implemented at the Tveta Landfill, adjacent to the city of Sodertalje, Sweden. The system consists of leachate collection in a pond, precipitation of metals with chemicals, a constructed wetland, and forest irrigation. This article describes the constructed wetland and its effectiveness at removing ammonia in the system. Pulsed-discharge hydrology and wetland ecology formed the basis for the development of a compact constructed wetland (CCW). The system presented here has most design similarities with vertical sub-surface flow wetlands, though this system is run in batch mode. Chemically purified leachate and untreated leachate were applied to separate sections of the CCW using a filling and emptying schedule. A leachate treatment cycle of about 14 days duration was used, involving a 7 day submerged phase followed by a 7 day drained period. The removal efficiency varied between 40 and 75% on a mass basis. A maximum mass removal rate of up to 5.1 g m~(-2) d~(-1) was achieved in wetlands receiving leachate after chemical pretreatment. In wetlands receiving non-treated leachate a net release of up to 18 g m~(-2) N occurred in the form of nitrate. This indicated a considerable nitrification but limited denitrification in those systems. It was unclear whether the chemical treatment enhanced the nitrogen removal efficiency because of lower toxicity and/or content of fewer competing cations, or other mechanisms. Mechanisms responsible for the NH_4-N removal in the CCW system have to be further investigated.
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摘要 :
Landfill leachate is commonly treated offsite with municipal wastewater. This offsite leachate treatment may be limited or no longer applicable due to the increasingly stringent regulations and concerns related to per- and polyflu...
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Landfill leachate is commonly treated offsite with municipal wastewater. This offsite leachate treatment may be limited or no longer applicable due to the increasingly stringent regulations and concerns related to per- and polyfluoroalkyl substance (PFAS) discharge into the environment, resulting in development of full-scale, onsite leachate treatment facilities. To help landfills prepare for the potential shift from offsite to onsite leachate treatment for PFAS compliance, this study analyzed and compared the environmental, human health, and economic performances of a typical onsite and a typical offsite leachate treatment alternative through life cycle assessment (LCA) and life cycle cost assessment (LCCA) using a landfill site located in Zhuzhou, China as a testbed. Two distinct functional units (FUs) were investigated: 1 m3 of leachate treated and 1 g of PFAS removed. Our results show that the onsite scenario offered benefits from human health and economic perspectives, while the offsite scenario generally performed better from the environmental perspective when a leachate PFAS concentration of 150,704 ng/L was assumed. The extent of this tradeoff varied when different functional units were adopted. The onsite scenario will not be competitive from all three perspectives when PFAS concentration in the raw leachate is less than 1666 ng/L.
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