Full‐Scale Ozone–Biofiltration: Seasonally Related Effects on NOM Removal

Abstract

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.

Biomass Evolution in Full‐Scale Anthracite‐Sand Drinking Water Filters Following Conversion to Biofiltration

“…These concentrations fell outside the typical range of ATP concentrations (i.e., 100–1,000 ng ATP/cm 3 media) identified for drinking water biofilters (Pharand et al 2014). In that work, Pharand et al (2015) sampled biomass during an individual filter cycle as opposed to concentrated sampling at the start of a filter cycle. The current study highlighted that determining ATP concentration at the start of a filter cycle and within a filter cycle was important for understanding the range of expected ATP concentrations in biofiltration.…”

“…In GAC filters undergoing conversion to biologically activated carbon biofiltration, biofilters reached steady state with respect to DOC removal at the same time that biomass steady state, as measured by ATP, was reached (Velten et al 2011). In contrast, other analyses have shown that biomass concentration in the top media layer in drinking water biofilters, as measured by phospholipids, ATP, and/or fluorescein diacetate (FDA) hydrolysis, is not directly related to biodegradable organic matter (BOM) (Emelko et al 2006) or DOC removal (Pharand et al 2015, 2014; Stoddart & Gagnon 2015) in pilot‐ or full‐scale biofilters.…”

“…ATP can be monitored in aqueous or bulk water (i.e., raw water, filter influents, filter effluents) (Lautenschlager et al 2014, Hammes et al 2010) to estimate planktonic or bulk water biomass, as well as on granular media such as anthracite (Pharand et al 2015), sand (Lautenschlager et al 2014, Magic‐Knezev & van der Kooij 2004), and granular activated carbon (GAC) (Velten et al 2011, 2007; Magic‐Knezev & van der Kooij 2004) to estimate biofilm biomass. ATP has been shown to correlate reasonably well ( R 2 = 0.69) with total cell concentration (i.e., as measured using flow cytometry) in distributed drinking water (Siebel et al 2008) and correlate significantly ( p < 0.05) with total direct bacterial cell counts for biomass detached from drinking water biofilter media (Magic‐Knezev & van der Kooij 2004).…”

State and Provincial Perspectives on the Regulation of Biological Filtration

“…Rapid rate gravity biofiltration has been practiced in major Western European waterworks since the 1970s (Heilker 1979, Sontheimer et al 1978). During the last decade, biological filtration has been gaining popularity in drinking water treatment in the United States and Canada, and its benefits are being recognized (Hallé et al 2015, Pharand et al 2015, Schulz 2014). Biofiltration is aerobic, rapid rate filtration through traditional granular media (e.g., granular activated carbon [GAC], anthracite, sand) that have developed a biofilm capable of degrading organic matter.…”

Evaluation of a side‐by‐side, full‐scale conversion to biological filtration

“…Several studies have concluded that nutrient supplementation could be beneficial in optimizing the performance of biofilters (Granger, Stoddart, & Gagnon, ; Lauderdale et al, ), whereas others have found no significant benefit (Azzeh, Taylor‐Edmonds, & Andrews, ; McKie et al, ; Pharand, Van Dyke, Anderson, Yohannes, & Huck, ). These contradictory results emphasize that more information is needed to better understand the potential benefits of nutrient augmentation.…”