Chlorination of Indicator Bacteria and Viruses in Primary Sewage Effluent

Abstract

Wastewater disinfection is used in many countries for reducing fecal coliform levels in effluents. Disinfection is therefore frequently used to improve recreational bathing waters which do not comply with microbiological standards. It is unknown whether human enteric viruses (which are responsible for waterborne disease) are simultaneously inactivated alongside fecal coliforms. This laboratory study focused on the chlorination of primary treated effluent with three doses (8, 16, and 30 mg/liter) of free chlorine as sodium hypochlorite. Seeding experiments showed that inactivation (>5 log 10 units) of Escherichia coli and Enterococcus faecalis was rapid and complete but that there was poor inactivation (0.2 to 1.0 log 10 unit) of F ؉ -specific RNA (FRNA) bacteriophage (MS2) (a potential virus indicator) at all three doses. However, seeded poliovirus was significantly more susceptible (2.8 log 10 units) to inactivation by chlorine than was the FRNA bacteriophage. To ensure that these results were not artifacts of the seeding process, comparisons were made between inactivation rates of laboratory-seeded organisms in sterilized sewage and inactivation rates of organisms occurring naturally in sewage. Multifactorial analysis of variance showed that there was no significant difference (P > 0.05) between the inactivation rates for seeded and naturally occurring FRNA bacteriophage. However, laboratory-grown poliovirus was inactivated much more rapidly than were naturally occurring, indigenous enteroviruses (P < 0.001). This may reflect differences in the way indigenous virus is presented to the disinfectant. Inactivation rates for indigenous enteroviruses were quite similar to those seen for FRNA bacteriophage at lower doses of chlorine. These results have significance for the effectiveness of chlorination as a sewage treatment process, particularly where virus contamination is of concern, and suggest that FRNA bacteriophage would be an appropriate indicator of such viral inactivation under field conditions.

Use of coliphages to evaluate water treatment processes and determine faecal contamination origin of source waters

“…The results also indicated the sources of pollution of the raw water source and the persistence of FRNA coliphage genotypes during water treatment. These results agree with the findings by previous investigators, who also pointed out the resistance of enteric viruses to water treatment processes Tree et al 2003). They confirm the results of previous studies (Ogorzaly and Gantzer 2006;Ogorzaly et al 2010), which concluded that FRNA phages can be used as a special tool to provide information on sources of faecal pollution in water sources.…”

Spatialand Temporal Variation in Concentration of F-Specific Rna Bacteriophages in an Open Channel Receiving Johkasou Effluents

“…This indicates the virus-reducing effect of gappei johkasou. However, low concentration of F-RNA bacteriophages could still be detected in the effluents of gappei johkasou because the solid particles to which the viruses are attached may protect them from the inactivation by disinfection 32) . The slight increase in the concentration of F-RNA bacteriophages in the sediment of Site 5 could be obtained due to the effects of effluents from upstream and gappei johkasou at Site 4.…”

Inactivation Effect of Antibiotic-Resistant Gene Using Chlorine Disinfection

“…In contrast, the maximum inactivation ratio at 0.5, 1.0, and 3.0 mg Cl2/L were above 7.5log. Like these results, fecal bacteria (fecal coliform and fecal streptococci) were destroyed at more than 99.999% in primary sewage effluent by chlorine disinfection [23]. Bacterial DNA was extracted from each chlorinated suspension of VRE.…”