title: Urban water reuse: microbial pathogens control by direct filtration and ultraviolet disinfection.
abstract: Physicochemical treatment efficiency for unrestricted urban water reuse was evaluated at a conventional activated-sludge wastewater treatment plant (WWTP). Pilot plant set-up consisted of an alum coagulation step, granular media upflow flocculation and direct downflow dual-media filtration followed by ultraviolet disinfection (dose of 95 mJ cm⁻²). Optimum aluminum sulfate dosage of 10 mg L⁻¹ and coagulation pH 7.0 were preset based on bench scale tests. Under WWTP stable operation, water quality met United States Environmental Protection Agency (USEPA) suggested guidelines for unrestricted urban reuse regarding turbidity (mean value 1.3 NTU) and suspended solids (mean value 2.1 mg L⁻¹). When WWTP overall plant performance dropped from 90 to 80% (although BOD value stayed below 6 mg O₂ L⁻¹, suggesting unrestricted reuse), solids breakthrough in filtrate was observed. Microorganism removal rates were: total coliforms 60.0%, Escherichia coli 63.0%, Giardia spp. 81.0%, and helminth eggs 62.5%; thus organisms still remained in filtrate. Ultraviolet (UV) disinfection efficiency was 4.1- and 3.8-log for total coliforms and E. coli, respectively. Considering low UV efficiency obtained for helminths and the survival of protozoa and helminths in the environment, effluent quality presents risk to public health if destined for unrestricted urban reuse.
authors.affiliation: Department of Sanitation and Environment, School of Civil Engineering, Architecture and Urban Design, University of Campinas, UNICAMP - P.O. Box 6021, ZIP Code 13083-852, Campinas, Sao Paulo State, Brazil E-mail: isaac@fec.unicamp.br.
authors.forename: Ricardo
authors.initials: R
authors.lastname: de Lima Isaac
authors.affiliation: Department of Sanitation and Environment, School of Civil Engineering, Architecture and Urban Design, University of Campinas, UNICAMP - P.O. Box 6021, ZIP Code 13083-852, Campinas, Sao Paulo State, Brazil E-mail: isaac@fec.unicamp.br; Padre Anchieta University Center, UNIANCHIETA - Rua Bom Jesus de Pirapora, 100/140, ZIP Code 13207-270, Jundiaí, SP, Brazil.
authors.forename: Luciana Urbano
authors.initials: LU
authors.lastname: Dos Santos
authors.affiliation: Department of Sanitation and Environment, School of Civil Engineering, Architecture and Urban Design, University of Campinas, UNICAMP - P.O. Box 6021, ZIP Code 13083-852, Campinas, Sao Paulo State, Brazil E-mail: isaac@fec.unicamp.br.
authors.forename: Mariana S
authors.initials: MS
authors.lastname: Tosetto
authors.affiliation: Laboratory of Protozoology, Department of Animal Biology, Biology Institute, University of Campinas, UNICAMP - P.O. Box 6109, ZIP Code 13083-970, Campinas, Sao Paulo State, Brazil.
authors.forename: Regina Maura Bueno
authors.initials: RM
authors.lastname: Franco
authors.affiliation: Department of Sanitation and Environment, School of Civil Engineering, Architecture and Urban Design, University of Campinas, UNICAMP - P.O. Box 6021, ZIP Code 13083-852, Campinas, Sao Paulo State, Brazil E-mail: isaac@fec.unicamp.br.
authors.forename: José Roberto
authors.initials: JR
authors.lastname: Guimarães
mesh_terms: D000818:Animals; D001419:Bacteria / Q000302:isolation & purification / Q000528:radiation effects*; D001938:Brazil; D003458:Cryptosporidium / Q000302:isolation & purification / Q000528:radiation effects*; D004203:Disinfection / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D005374:Filtration; D005872:Giardia / Q000302:isolation & purification / Q000528:radiation effects*; D006376:Helminths / Q000254:growth & development / Q000302:isolation & purification / Q000528:radiation effects*; D033661:Oocysts / Q000528:radiation effects; D010063:Ovum / Q000528:radiation effects; D010865:Pilot Projects; D014466:Ultraviolet Rays; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*