Advanced treatment and disinfection for municipal wastewater reuse in agriculture

In a 3-year joint research project, approved in 1995 by the European Commis sion, methods for advanced treatment and disinfection of municipal wastewat er to permit reuse in agriculture were investigated. Pathogen inactivation, disinfection by-products (DBP) formation and the cost effectiveness of dis infection methods involving UV rays, ozone (O-3) and peracetic acid (PAA we re evaluated. The investigation was carried out on municipal effluents whic h had received different degrees of treatment (secondary, clarified, clarif ied-filtered) in a 100 m(3)/h pilot plant that was designed, built and oper ated at West Bari (S. Italy) municipal wastewater treatment plant. Under th e experimental conditions investigated, the WHO microbial guideline for unr estricted reuse of wastewater in agriculture (1,000 CFU/100ml for Faecal Co liforms) was easily achieved with all three disinfectants, while the corres ponding Italian standard (2 CFU/100ml) was effectively met only with UV at an O&M cost in the range 17.5-35 EURO/1000m(3). Log-inactivation values gre ater than or equal to 5 for both UV and PAA and greater than or equal to 3 for O-3 were obtained; selected pathogens were affected by UV and, in part, by O-3. No DBPs were detected with UV and PAA, while limited formation of aldehydes was found with O-3. (C) 1999 IAWQ Published by Elsevier Science L td. All rights reserved.