Effective enzyme activity: A proposed monitoring methodology for biofiltration systems with or without ozone

Addition of GAC caps and ozonation to conventional filters for improved organics and disinfection by-product reduction

“…DBP control). 33 As such, coagulant dosing targeting DBP precursors, especially in combination with the GAC caps, may improve DBP FP removal beyond what was observed during this study.…”

“…6) based on previous studies which evaluated GAC and anthracite biofilters at this location (75–100 ng g −1 media ATP in unchlorinated anthracite biofilters, 175–270 ng g −1 -media in unchlorinated GAC biofilters). 33 Anthracite filters (in service >20 years) overall exhibited slightly higher ATP values than the corresponding GAC filters (virgin GAC; 28–65 ng ATP g −1 -media).…”

“…36,37 However, an optimal ozone dosage is dependent on source water composition, upstream treatment processes and the level of bioactivity associated with filtration. 9 A previous study at the same facility using GAC pilot filters demonstrated almost twice the DOC removal at a target ozone residual of 0.5 mg L −1 , 33 providing further evidence regarding the importance of site-specific studies to target organics.…”

“…This was anticipated based on previous studies which attributed ozone to an increase in availability of phosphate and carbon in the influent, thus promoting subsequent biological activity. 33 Phosphatase activity in the TMFs increased between the August (25 °C) and September (23 °C) sampling events, decreasing thereafter. No relationship with water temperature was observed, similar to previous results at this facility.…”

“…These results follow that of previous studies, which suggest that ATP is not an effective or meaningful indicator of organics removal and should be used instead as an indicator of biofilm development. 12,33,39…”