A strategic plan for reuse of treated municipal wastewater for crop irrigation on the Island of Crete

Abstract

► A methodology for planning water recycling on islands is presented. ► It is a tool to incorporate reclaimed water in the water management of islands. ► Reclaimed wastewater quantities are matched against specific irrigation needs. ► The exploitation of this water resource can relieve water stress in islands. This work presents a strategic plan on the feasibility of recycling treated municipal wastewater for agricultural irrigation on the Greek island of Crete. Three types of crops were investigated, namely olive trees, vineyards and lettuce as representative of raw-eaten vegetables. The Greek water reuse criteria were used as guidelines for the irrigation of the above mentioned types of crops. Qualitative and quantitative data regarding wastewater plant effluents were collected from 16 wastewater treatment plants (WWTPs) operated on Crete. Analysis of the collected data indicated that WWTPs did not meet the criteria for unrestricted irrigation of the crops, due to absence of tertiary treatment . In order to estimate the area of land that can be irrigated using treated effluents, the water requirements of each crop were estimated as the difference between evapotranspiration and effective precipitation using climatic data as input to CROPWAT software. Based on WWTPs capacity, the irrigated area was estimated and then was visualized and demonstrated using the CORINE 2000 database in ArcGIS. The present study showed that water recycling during summer could reserve approximately 19.16 Mm 3 of fresh water, which corresponds to 4.3% of total irrigation requirements . It is evident that the exploitation of this alternative water resource could be beneficial for Crete, relieving island's water shortage and stress.