Evaluation of Sparta's municipal wastewater treatment plant's effluent as an irrigation water source according to Greek Legislation

A project co-funded by the Greek Ministry of Rural Development and Food and by the Prefecture of Laconia has been undertaken aiming at the investigation of the influence of irrigating olive orchards with treated municipal wastewater (TMWW) on crop productivity and the quality of olive oil produced as well as on the soil chemical and physical characteristics, bearing its influence on the environment in general. According to this project, a two-year experiment was conducted in a 0.5ha olive orchard with two different irrigation water sources. The first source was a water borehole and the second source was the Sparta's municipal wastewater treatment plant. As regards the aim of the project, comparisons between the effects of these two sources had to be made concerning olive trees productivity and nutritional status, olive oil quantity and quality, soil chemical and physical properties, etc. In the summers of 2011 and 2012, we irrigated the olive trees 7 and 12 times, respectively. At the same time we conducted all the statutory chemical analysis of both fresh water and TMWW at every irrigation event, excluding the microbial analysis for technical reasons. In this paper, we present the chemical analysis results concerning both irrigation water sources and their characterization according to the Greek legislation. Furthermore, we discuss issues concerning the possibility of reusing the Sparta's TMWW plant effluent for irrigation based on the analysis of the data and the Greek legislation.