Geochemical processes in recharge basin soils used for municipal effluents reclamation by the soil-aquifer treatment (SAT) system

摘要

Soil Aquifer Treatment (SAT) of secondary effluents activates biogeochemical processes in the soil and aquifer environment to accomplish large-scale reclamation of municipal wastewater. We studied in detail the long-term geochemical processes of SAT soils in the Dan Region Reclamation Project, near Tel Aviv, Israel. Soil redox potential shifts between the anoxic/reduced stale during the recharge stage and oxic/oxidized state following drainage. Extensive geochemical changes have occurred in the soils over the 23 yr period of operation during which 1650 m cumulative hydraulic load of effluents has been recharged. Organic matter accumulated in the top horizon of the soil profile while Ca carbonate and Mn oxide were dissolved and leached. Minor and trace elements typically enriched in municipal effluents, accumulated in the topsoil. A conceptual model was developed to describe the array of biogeochemical processes al the upper soil horizons of the SAT system.