title: Microbial reduction in wastewater treatment using Fe(3+) and Al(3+) coagulants and PAA disinfectant.
abstract: Wastewater is an important source of pathogenic enteric microorganisms in surface water and a major contaminating agent of drinking water. Although primary and secondary wastewater treatments reduce the numbers of microorganisms in wastewater, significant numbers of microbes can still be present in the effluent. The aim of this study was to test the feasibility of tertiary treatment for municipal wastewater treatment plants (WWTPs) using PIX (FeCl3) or PAX (AlCl3) coagulants and peracetic acid (PAA) the disinfectant to reduce microbial load in effluent. Our study showed that both PIX and PAX efficiently reduced microbial numbers. PAA disinfection greatly reduced the numbers of culturable indicator microorganisms (Escherichia coli, intestinal enterococci, F-specific RNA coliphages and somatic DNA coliphages). In addition, pathogenic microorganisms, thermotolerant Campylobacter, Salmonella and norovirus GI, were successfully reduced using the tertiary treatments. In contrast, clostridia, Legionella, rotavirus, norovirus GII and adenovirus showed better resistance against PAA compared to the other microorganisms. However, interpretation of polymerase chain reaction (PCR) analysis results will need further studies to clarify the infectivity of the pathogenic microbes. In conclusion, PIX and PAX flocculants followed by PAA disinfectant can be used as a tertiary treatment for municipal WWTP effluents to reduce the numbers of indicator and pathogenic microorganisms.
authors: International Water Management Institute, PMB, CT 112, Cantonments, Accra, Ghana E-mail: s.k.pradhan@cgiar.org.
authors: Surendra K
authors: SK
authors: Pradhan
authors: Water and Health Unit, National Institute for Health and Welfare, PO Box 95, FI-70701 Kuopio, Finland.
authors: Ari
authors: A
authors: Kauppinen
authors: Department of Environmental Science, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland.
authors: Kati
authors: K
authors: Martikainen
authors: Water and Health Unit, National Institute for Health and Welfare, PO Box 95, FI-70701 Kuopio, Finland.
authors: Tarja
authors: T
authors: Pitkänen
authors: Water and Health Unit, National Institute for Health and Welfare, PO Box 95, FI-70701 Kuopio, Finland.
authors: Jaana
authors: J
authors: Kusnetsov
authors: Water and Health Unit, National Institute for Health and Welfare, PO Box 95, FI-70701 Kuopio, Finland.
authors: Ilkka T
authors: IT
authors: Miettinen
authors: Department of Environmental Science, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland.
authors: Matti
authors: M
authors: Pessi
authors: Department of Environmental Science, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland.
authors: Hannu
authors: H
authors: Poutiainen
authors: Department of Environmental Science, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland.
authors: Helvi
authors: H
authors: Heinonen-Tanski
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D005591:Chemical Fractionation; D003090:Coliphages / Q000187:drug effects; D004202:Disinfectants / Q000494:pharmacology; D007501:Iron / Q000737:chemistry*; D010463:Peracetic Acid / Q000494:pharmacology*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods
chemical_list: D004202:Disinfectants; D000535:Aluminum; D007501:Iron; D010463:Peracetic Acid