conducted, which found that concentrations at the top of active, acclimated biofilters typically were in the range of 10 2 to 10 3 ng ATP/cm 3 media. The effect of various biofilter parameters (source water characteristics and quality, pretreatment, hydraulic loading rate, temperature, and sampling depth) on ATP levels is discussed and evaluated using published ATP data. The authors also assess the relationship between ATP and biofilter performance in terms of carbon removal and identify a need for further research in this area.Pharand et al | http://dx.

Performance of full‐scale ozone–biofiltration was investigated over 14 months to determine the potential effects of seasonally related changes in water temperature and quality on the removal of natural organic matter fractions. The biofilters removed on average 12% of dissolved organic carbon, 31% of biopolymers, 6% of humic substances, 10% of humic building blocks, 31% of low‐molecular‐weight (LMW) acids/LMW humics, 14% of LMW neutrals, and 52% of assimilable organic carbon. The biofilters exhibited an increase in removal of dissolved organic carbon, biopolymers, LMW acids/LMW humics, and assimilable organic carbon as temperature increased from 3 to 28°C, even though filter contact time was somewhat shorter at higher temperatures. Although phosphorus concentrations were reduced by coagulation pretreatment, the biofilters effectively removed the LMW compounds generated from ozonation. Filter biomass levels were not related to temperature, empty bed contact time, time during the filter cycle, or removal of natural organic matter.

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