A Promising Practice in Disinfection Treatment for Reuse: Chemical plus Natural Systems,

Abstract

An experimental campaign has been conducted on a pilot plant which consists of a two-stage disinfection system for a secondary effluent: a chemical treatment, by means of low dosages of NaClO, followed by a natural one, in a horizontal subsurface flow bed. The aim is to analyse, during a hot period, the microrganisms removal achievable by the two stages and to compare the polished effluent quality with the Italian severe law limits for agricultural reuse of reclaimed wastewaters. The investigations has shown that in presence of high ambient temperatures, just a well designed final subsurface flow system is able to respect reuse quality limits. In this case, for safety reasons, a further UV treatment, after the only natural step, may be suggested, as it may prudentially switch on, only in case of emergencies that may occasionally occur