title: Reducing pathogens in combined sewer overflows using performic acid.
abstract: Combined sewer overflows contribute significantly to pathogen loads in surface water. Some chemical disinfectants such as chlorine have proved to reduce the levels of microorganisms even in complex matrices such as wastewater in combined sewer systems; however, some of them release toxic by-products into water bodies and increase costs of plant maintenance and repair. In this study, we determined if performic acid (PFA) disinfection units can be operated at decentralized treatment facilities and reduce bacteria, viruses, and protozoan parasites in combined sewer overflows (CSOs). The PFA dosing unit at the inflow of a CSO storage tank dosed a fixed flow volume into the inflowing stormwater and, thus, concentrations varied between approximately 12-24mgl-1. The results showed a reduction of most hygienically relevant bacteria with mean removal efficiencies of 1.8log10for Aeromonas spp. and 3.1log10for E. coli. For viruses, however, reduction was only observed for somatic coliphages with 2.7log10. In this setting, PFA does not seem to be suitable to remove e.g. protozoan parasites such as Giardia lamblia. In terms of operation, dosing the substance is uncritical in decentralized facilities, but the PFA needs too much time to react with pathogens after being dosed into the overflow of CSO storage tanks and before dilution with surface water in most facilities.
authors.affiliation: Institute of Environmental Engineering of RWTH Aachen University (ISA), 52056 Aachen, Germany. Electronic address: tondera@isa.rwth-aachen.de.
authors.forename: Katharina
authors.initials: K
authors.lastname: Tondera
authors.affiliation: Institute of Environmental Engineering of RWTH Aachen University (ISA), 52056 Aachen, Germany.
authors.forename: Kassandra
authors.initials: K
authors.lastname: Klaer
authors.affiliation: Institute for Hygiene and Public Health (IHPH), University of Bonn, Sigmund-Freud-Str. 25, 53105 Bonn, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Koch
authors.affiliation: Department of Hygiene, Social and Environmental Medicine, Ruhr-University Bochum (RUB), Universitaetsstr. 150, 44801 Bochum, Germany.
authors.forename: Ibrahim Ahmed
authors.initials: IA
authors.lastname: Hamza
authors.affiliation: Institute of Environmental Engineering of RWTH Aachen University (ISA), 52056 Aachen, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Pinnekamp
mesh_terms: D001419:Bacteria / Q000187:drug effects* / Q000302:isolation & purification; D016785:Cryptosporidium parvum / Q000187:drug effects* / Q000302:isolation & purification; D004279:DNA, Viral / Q000032:analysis; D004202:Disinfectants / Q000494:pharmacology*; D004203:Disinfection; D004323:Drainage, Sanitary; D004784:Environmental Monitoring; D005561:Formates / Q000494:pharmacology*; D005872:Giardia / Q000187:drug effects* / Q000302:isolation & purification; D012722:Sewage / Q000382:microbiology / Q000469:parasitology / Q000821:virology; D014780:Viruses / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D014871:Water Microbiology
chemical_list: D004279:DNA, Viral; D004202:Disinfectants; D005561:Formates; D012722:Sewage; C008817:peroxyformic acid
keywords: Bacteria; Combined sewer overflows; Disinfection; Parasites; Performic acid; Viruses