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Reduction of Acid-Fast and Non-Acid-Fast Bacteria by Point of Use Coagulation-Flocculation-Disinfection

by Lisa M. Casanova 1,*,† and Mark D. Sobsey 2,†
Division of Environmental Health, School of Public Health, Georgia State University, P.O. Box 3995 Atlanta, GA 30302, USA
Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina Chapel Hill, Rosenau Hall, Room 148, 135 Dauer Drive, Campus Box 7431, Chapel Hill, NC 27599, USA
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Academic Editor: Miklas Scholz
Int. J. Environ. Res. Public Health 2015, 12(11), 14420-14428;
Received: 25 September 2015 / Revised: 1 November 2015 / Accepted: 9 November 2015 / Published: 13 November 2015
Point of use (POU) household water treatment is increasingly being adopted as a solution for access to safe water. Non-tuberculous Mycobacteria (NTM) are found in water, but there is little research on whether NTM survive POU treatment. Mycobacteria may be removed by multi-barrier treatment systems that combine processes such as coagulation, settling and disinfection. This work evaluated removal of a non-tuberculous Mycobacterium (Mycobaterium terrae) and a Gram-negative non-acid-fast environmental bacterium (Aeromonas hydrophila) by combined coagulation-flocculation disinfection POU treatment. Aeromonas hydrophila showed 7.7 log10 reduction in demand free buffer, 6.8 log10 in natural surface water, and 4 log10 reduction in fecally contaminated surface water. Turbidity after treatment was <1 NTU. There was almost no reduction in levels of viable M. terrae by coagulant-flocculant-disinfectant in natural water after 30 minutes. The lack of Mycobacteria reduction was similar for both combined coagulant-flocculant-disinfectant and hypochlorite alone. A POU coagulant-flocculant-disinfectant treatment effectively reduced A. hydrophila from natural surface waters but not Mycobacteria. These results reinforce previous findings that POU coagulation-flocculation-disinfection is effective against gram-negative enteric bacteria. POU treatment and safe storage interventions may need to take into account risks from viable NTM in treated stored water and consider alternative treatment processes to achieve NTM reductions. View Full-Text
Keywords: coagulation; flocculation; disinfection; Mycobacterium; point-of-use; water treatment coagulation; flocculation; disinfection; Mycobacterium; point-of-use; water treatment
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Casanova, L.M.; Sobsey, M.D. Reduction of Acid-Fast and Non-Acid-Fast Bacteria by Point of Use Coagulation-Flocculation-Disinfection. Int. J. Environ. Res. Public Health 2015, 12, 14420-14428.

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