The performance of batch stabilization reservoirs for wastewater treatment, storage and reuse in Israel

Stabilization reservoirs receive partially treated wastewater effluents for storage and controlled release. They are used in Israel for two purposes: a) to upgrade the quality of the effluents during the long residence time within the reservoirs and, b) to store the effluents during the rainy winter in order to perform agricultural irrigation during the dry summer. The improvement obtained in the quality of the effluents (i.e., the treatment capacity of the reservoirs) depends on the operational regime of the reservoirs as reactors: continuous flow, in series, batch, etc. The performance of the reservoirs as batch reactors for wastewater treatment is herein analyzed based on outdoor experiments carried out in real scale reservoirs with different hydraulic and organic loadings. The results of the experiments are compared with forecasts obtained through statistical and kinetic models. Stabilization reservoirs working in batch mode, when properly designed and operated, are able to remove GOD, BOD, TSS and detergents by up to one order of magnitude, and Faecal coliforms by up to five orders of magnitude (before chlorination). A significant removal of heavy metals, bacteriophages and other pollutants is also obtained. The quality of the effluents released from the reservoirs, added to the capabiblity for controlled release, permits both wide crop rotation and easy management of irrigation. Copyright (C) 1996 IAWQ.