NONIONIC SURFACTANTS IN REUSED WATER - ARE ACTIVATED SLUDGE/SOIL AQUIFER TREATMENTS SUFFICIENT

About 6 x 10(7) m(3) (20%) of the 3 x 10(8) m(3) of sewage water in Israel is recharged into the coastal groundwater aquifer in the Tel-Aviv region after an activated sludge treatment process. A subsequent pumping out of these effluents via recovery wells supplies reclaimed water, mainly for unrestricted irrigation, to the southern part of Israel, as part of the total 12 x 10(8) m(3)/year of water used in the country for irrigation. Although the soil/aquifer treatment (SAT) was shown to be efficient for the removal of BOD, COD, TOC and anionic surfactants (70-90%), an increase in the organic parameters of the reclaimed water compared with those of previous years, was observed. The effectiveness of non-ionic surfactants' removal via existing primary and secondary wastewater treatment plants and that of the combined activated sludge/soil aquifer treatment was shown to be 69-81 and 97% (96/92.5% in terms of CTAS), respectively. The concentrations of 22-25 ppb of ''hard'' non-ionic surfactants still found in the reused water constitute an issue of concern.