ABSTRACT
In the artificial groundwater recharge plant “Lange Erlen” near Basel, Switzerland, forested alluvial soils are used for water purification. 85% of the initial concentration of dissolved organic carbon (DOC) in the recharge water (1.7 mg/l) was removed during the passage through the forest soils and the fluvial sediments. Two third of the total DOC-decrease occurred in the unsaturated zone and the uppermost groundwater layer below the surface of the recharge basin and was caused by microbial degradation. The remaining DOC was removed during the aquifer passage (approx. 250 m horizontal flow). Here, beside biodegradation and intermediate sorption processes, particularly intermixing with cleaner natural groundwater was responsible for the DOC-decrease.
