Citation:

Smith, M., S. Stuntz, Y. Xing, M. Magnuson, R. Phillips, AND W. Harper. Functional resilience of activated sludge exposed to Bacillus globigii and bacteriophage MS2. Water and Environment Journal. John Wiley & Sons, Inc., Hoboken, NJ, 35(3):930-936, (2021). https://doi.org/10.1111/wej.12682

Impact/Purpose:

Biocontaminants are present in infectious wastes that may be discharged to a water reclamation facility. This study evaluated the effect of two biocontaminant surrogates on the activity and performance of activated sludge. In the presence of bacteriophage MS2 at 3.2 x 108 PFU/mL, the peak respiration rates varied between 9.1 - 10.5 mg O2/gVSS/hr, generally similar to the rates observed in negative controls. MS2 did not alter the molar CO2 produced-to-O2 consumed stoichiometry observed during respiration. Similar results were observed when Bacillus globigii (BG) was injected into activated sludge over a concentration range from 2x101 colony forming units per mL (CFU/mL) to 2x107 CFU/mL. Ethanol, a potential co-contaminant associated with biocontamination incidents, can inhibit initial oxygen uptake but eventually drives respiration rates significantly higher than those of the negative controls. MS2 and BG both adsorbed to activated sludge; post-exposure viability was confirmed for BG but not for MS2. These results provide the first evidence of the functional resistance of activated sludge to MS2 and BG, leading to science-based decisions for treatment plant operators who are considering requests to process biohazardous waste.

Description:

This study evaluated the effect of two biocontaminant surrogates on the activity and performance of activated sludge. In the presence of bacteriophage MS2 at 3.2 × 108 PFU/ml, the peak respiration rates varied between 9.1 and 10.5 mg O2/gVSS/hr, generally similar to the rates observed in negative controls. MS2 did not alter the molar CO2-produced-to-O2 consumed stoichiometry observed during respiration. Similar results were observed for Bacillus globigii (BG). Ethanol, a potential co-contaminant associated with biocontamination incidents, can inhibit initial oxygen uptake. MS2 and BG both adsorbed to activated sludge; post-exposure viability was confirmed for BG but not for MS2. This study is the first to evaluate the effects of BG and MS2 on activated sludge, and it presents a protocol that can be used in operational situations.

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