Technical evaluation of tertiary treatment processes for wastewater reuse

摘要

Water stress is a major issue in the Mediterranean region. In touristic areas, drinking water uses may compete with recreational or agricultural uses due to the overexploitation of water resources. In this context, treated wastewater reuse is a relevant alternative by addressing quantitative (protection of water resources) and qualitative (protection of the environment) issues. The tertiary treatment chains studied during this project take into account technical, economical and health risk management aspects related to the use for irrigation purposes as defined by the French decree of August 2, 2010 amended in June 25, 2014. Two treatment chains are implemented on industrial pilot scale downstream a wastewater treatment plant (24,000 population equivalents): "ultrafiltration - storage" and "sand filtration - storage then UV disinfection". This article aims to provide technical assessment of these treatment processes, taking into account three aspects: effluent quality, O&M needs, and consistency with intended uses. All the treatment chains studied allow to achieve the highest quality standard defined by French regulations. However, some point deviations to this quality may result in rapid clogging of the ultrafiltration membranes or in UV lamp fouling, and thus the need for higher maintenance.