SALT ENRICHMENT OF MUNICIPAL SEWAGE - NEW PREVENTION APPROACHES IN ISRAEL

Wastewater irrigation is an environmentally sound wastewater disposal practice, but sewage is more saline than the supplied fresh water and the salts are recycled together with the water. Salts have negative en vironmental effects on crops, soils, and groundwater. There are no ine xpensive ways to remove the salts once they enter sewage, and the prev ention of sewage salt enrichment is the most immediately available sol ution. The body of initiatives presently structured by the Ministry of the Environment of Israel are herein described, with the aim to contr ibute to the search for a long-term solution of salinity problems in a rid countries. The new initiatives are based on: (1) search for new te chnologies to reduce salt consumption and discharge into sewage; (2) d ifferent technologies to cope with different situations; (3) raising t he awareness of the public and industry on the environmental implicati ons of salinity pollution; and (4) an elastic legal approach expressed through new state-of-the-art regulations. The main contributor to the salinity of sewage in Israel is the water-softening process followed by the meat koshering process. Some of the adopted technical solutions are: the discharge of the brine into the sea, the substitution of sod ium by potassium salts in the ion-exchangers, the construction of cent ralized systems for the supply of soft water in industrial areas, the precipitation of Ca and Mg in the effluents from ion-exchangers and re cycling of the NaCl solution, a reduction of the discharge oi salts by the meat koshering process, and new membrane technology for salt reco very.