Abstract
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 × 10(8) PFU/ml, the peak respiration rates varied between 9.1 and 10.5 mg O(2)/gVSS/hr, generally similar to the rates observed in negative controls. MS2 did not alter the molar CO(2)-produced-to-O(2) 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.