Chlorine disinfection of Pseudomonas aeruginosa, total coliforms, Escherichia coli and Enterococcus faecalis: revisiting reclaimed water regulations

• Published in: Water science and technology 2011-01, Vol.64 (11), p.2151-2157
• Main Authors: Coronel-Olivares, Claudia, Reyes-Gómez, Lidia María, Hernández-Muñoz, Aurelio, Martínez-Falcón, Ana Paola, Vázquez-Rodríguez, Gabriela A, Iturbe, Ulises
• Format: Article
• Language: English
• Subjects: Aquatic environment; Bacteria; Chlorine; Chlorine - pharmacology; Coliforms; Detection; Disinfectants; Disinfectants - chemistry; Disinfection; Disinfection - standards; Drinking water; E coli; Effluents; Enterobacteriaceae - drug effects; Enterococcus faecalis; Enterococcus faecalis - drug effects; Environmental regulations; Escherichia coli; Escherichia coli - drug effects; Indicators; Microorganisms; Opportunist infection; Pathogens; Pseudomonas aeruginosa; Pseudomonas aeruginosa - drug effects; Public health; Reclaimed water; Regulations; Skin; Sodium; Sodium hypochlorite; Sodium Hypochlorite - chemistry; Sodium Hypochlorite - pharmacology; Wastewater; Wastewater treatment; Wastewater treatment plants; Water Microbiology - standards; Water Purification - methods; Water Purification - standards
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2011.691

Pathogenic organisms can be transmitted orally through drinking water or through skin and mucosae by both direct and indirect contact, and their presence in water thus has a negative impact on public health. In wastewater treatment plants (WWTP), water is disinfected to inactivate pathogens. The quantification of several microbial indicators in aquatic systems is required to estimate the biological quality of such systems. So far, coliform bacteria have been used as traditional indicators world-wide. This study has assessed the resistance of total coliforms, Escherichia coli, Pseudomonas aeruginosa and Enterococcus faecalis to three dosages of sodium hypochlorite (NaClO) at two exposure times. The bacteria were isolated from secondary effluents of a WWTP located in Hidalgo, Mexico. The results show that the number of colony-forming units of all studied bacterial types decreased when both the NaClO concentration and exposure times increased. However, they were not eliminated. The inclusion of the species Pseudomonas aeruginosa in regulations for treated wastewater quality as a new indicator is highly recommended due to its importance as an opportunistic pathogen. The detection of this species along with the traditional organisms could be particulary significant for reclaimed water to be used with direct human contact.