Soil Aquifer Treatment as Disinfection Unit

Abstract

AbstractThe Shafdan wastewater treatment system treats the municipal wastewater of the Tel-Aviv metropolitan area, which contains 22 cities with a population of about two million. The conventional mechanical–biological treatment is followed by managed groundwater recharge. The effluent undergoes soil aquifer treatment (SAT) by controlled passage through the unsaturated zone and an average retention time of 960 days in the aquifer. The SAT provides effluent polishing treatment as well as seasonal and multiannual storage, which are much needed in the semiarid Mediterranean climate. The Shafdan SAT operates without disinfection prior to the land spreading of the secondary effluents or after the water is reclaimed from the aquifer. Despite that, since 1995 there has not been even a single positive test of fecal coliforms (FC) in any of the reclamation wells, and since 2001, all of the enterovirus tests in an observation well located midway between the infiltration basins and the reclamation wells were negativ...