Advanced treatment for municipal wastewater reuse in agriculture. UV disinfection: bacteria inactivation

A 100 m(3) h(-1) pilot plant was built at West Bari (southern Italy) Wastewater Treatment Plant and operated from 1996 to 1998 to compare bacteria inactivation parasite removal disinfection,, by-products formation and cost effectiveness of advanced disinfection methods such as UV rays, peracetic acid and ozone, alone or in proper combination, on differently treated municipal effluents. This paper reports the bacteria inactivation effectiveness of UV disinfection of secondary secondary-clarified (CL) or secondary-clarified-filtered (F) effluent for meeting the Italian microbial standard for unrestricted reuse of municipal wastewater in agriculture (2 CFU 100 ml-1 of total coliforms). Such a 5 log inactivation target was effectively met With F and CL effluents at a dose of 100 and 160 MWS cm(-2) respectively, while it was only almost approached with effluent II at 430 mWs cm(-2) dose. Significant removal of disinfection-resistant bacteria like Pseudomonas aeruginosa as well as full compliance with local agronomic regulation also was achieved for both CL and F disinfected effluents.