Disinfection of Membrane Bioreactor Permeate Using Free Chlorine: Virus Inactivation and Disinfection Byproducts Formation

Free Chlorine Disinfection of Full‐Scale MBR Effluent to Achieve 5‐Log Virus Inactivation

“…This indicates that the MS2 inactivation was very rapid in the CTF MBR effluent and did not require a high NaOCl dose to meet the 5-log inactivation goal. This observation is consistent with the previous reports on bench-and pilot-scale free chlorine disinfection studies with MBR effluents (Hirani et al, 2014;Mansell et al, 2008;Mansell, et al, 2009), as well as those granular media-filtered tertiary effluents (Adelman et al, 2016;Huitric et al, 2013).…”

“…The Ct value obtained in this study was one magnitude smaller than the values reported in earlier pilot-scale free chlorine disinfection studies in which mixed liquor from the aeration tank was added to the permeate to simulate the ''worst case scenario'' (Mansell et al, 2008;Mansell et al, 2009) and was comparable to the reported values for the disinfection of the effluents from normal and cleaned MBR membranes (Hirani et al, 2014) as shown in Table 7. The turbidity values measured in this study are also very similar to what Hirani et al (2014) reported for the effluent from cleaned MBR membranes (i.e., 0.2 NTU).…”

“…This result indicates that the ultrafiltration membranes at the CTF were in very good condition owing to the effective membrane cleaning with NaOCl and citric acid (see Treatment Facility Descriptions) and produced recycled water suitable for free chlorine disinfection. This also suggests that proper membrane cleaning to maintain the integrity of the MBR membranes is very important because impaired membranes would deteriorate the water quality and cause turbidity spikes, which could lead to Ct requirement to increase as demonstrated by the earlier works (Hirani et al, 2014;Mansell et al, 2008;Mansell et al, 2009). The minimum Ct value determined in this study was also comparable to the reported values for the free chlorine disinfection of granular media-filtered tertiary effluent in pilotand full-scale studies conducted to aim at the conditional approval of free chlorine disinfection at full-scale water reclamation facilities in California (Adelman et al, 2016;Huitric et al, 2013).…”

“…A number of research papers have been published in the past 10 years on the free chlorine disinfection of tertiary effluent to revisit the Ct value determination for effective disinfection of nitrified recycled water in California (Adelman et al, 2016;Hirani et al, 2014;Huitric et al, 2013;Mansell et al, 2008;Mansell et al, 2009). The researchers in the Sanitation Districts of Los Angeles County (LACSD) have conducted a series of pioneering work at their Whittier Narrows Water Reclamation Plant (Mansell et al, 2008;Mansell et al, 2009) and San Jose Creek East Water Reclamation Plant (Huitric et al, 2013). Mansell et al (2008) reported that Ct values above 30 and 40 mgÁmin/L were sufficient to achieve 5-log MS2 inactivation and less than 2.2 MPN/100 mL total coliform goal, respectively, in a series of bench-and pilot-scale experiments of free chlorine disinfection of membrane bioreactor (MBR) effluent spiked with mixed liquor from the aeration tank to simulate the effluent from damaged hollow fiber membranes.…”

“…The researchers in the Sanitation Districts of Los Angeles County (LACSD) have conducted a series of pioneering work at their Whittier Narrows Water Reclamation Plant (Mansell et al, 2008;Mansell et al, 2009) and San Jose Creek East Water Reclamation Plant (Huitric et al, 2013). Mansell et al (2008) reported that Ct values above 30 and 40 mgÁmin/L were sufficient to achieve 5-log MS2 inactivation and less than 2.2 MPN/100 mL total coliform goal, respectively, in a series of bench-and pilot-scale experiments of free chlorine disinfection of membrane bioreactor (MBR) effluent spiked with mixed liquor from the aeration tank to simulate the effluent from damaged hollow fiber membranes. Mansell et al (2009) also confirmed that more than 5-log inactivation of poliovirus could be achieved with a similar free chlorine disinfection in a bench-scale experiment, whereas chloramine was much less effective than free chlorine.…”