Assessment of wastewater effluent quality in Thessaly region, Greece, for determining its irrigation reuse potential

Abstract

The objective of the present study is to assess wastewater effluent quality in Thessaly region Greece in relation to its physicochemical and microbiological burden as well as its toxic potential on a number of organisms Wastewater may be used for agricultural as well as for landscape irrigation purposes therefore its toxicity potential is quite important Thessaly region has been chosen since this region suffers from a distinct water shortage in summer period necessitating alternative water resources During our research treated effluents from four wastewater treatment plants operating in the region (Larissa Volos Karditsa and Tirnavos) were tested for specific physicochemical and microbiological parameters [biochemical oxygen demand (BOD(5)) chemical oxygen demand (COD) total suspended solids (TSS) pH electrical conductivity selected metals presence (Cd Co Cr Cu Fe Mn Ni Pb Zn As) and fecal coliforms (FC) number] The effluents were also tested for their toxicity using two different bioassays (Daphnia magna immobilization test and Phytotoxkit microbiotest) The findings were compared to relative regulations and guidelines regarding wastewater reuse for irrigation The results overall show that secondary effluents in Thessaly region are generally acceptable for reuse for irrigation purposes according to limits set by legislation if effective advanced treatment methods are applied prior to reuse However their potential toxicity should be closely monitored since it was found that it may vary significantly in relation to season and location when indicator plant and zooplankton organisms are used (C) 2010 Elsevier Inc All rights reserved