Date of Award

Spring 1-1-2012

Document Type

Thesis

Degree Name

Master of Science (MS)

First Advisor

R. Scott Summers

Second Advisor

Karl Linden

Third Advisor

Joann Silverstein

Abstract

Biofiltration is a growing field within drinking water treatment. Biological filters, or biofilters, are capable of removing organic matter, including a variety of trace organic contaminants. Using biomass attached to media from a source water that was wastewater-impacted and media from an unimpacted source, bench-scale filters were run under carbonaceous and nitrogen-supplemented conditions to determine the impact on the removal of trace organics. The majority of contaminants evaluated in the study were best removed by the wastewater-impacted biomass filter media that was operated under carbonaceous conditions. Unimpacted biomass media showed comparable removals to the impacted biomass media under nitrogen-supplemented conditions. Filter media with higher biomass levels was also generally more effective at removing trace organics. Results of this study can be used in conjunction with Zearley and Summers (2012) and future work to enable engineers and operators to better predict how biofilter removal of trace organic compounds will change over time.

An important factor in the operation of biofilters is the biomass, which can often be linked to the filter's ability to remove organic compounds. This second study was designed to develop a relationship between an ATP based method and a phospholipids based method, two common biomass analysis techniques. The two biomass analysis methods were linearly related with a correlation coefficient of 0.91 when applied to media from similar source waters. Media samples taken from filters exposed to pre-oxidized water and media from new filters exhibited lower ATP per nmol of phospholipids ratios. Using the ATP and phospholipids cell count approximation methods yields cell ATP cell counts that are only one-quarter of the count predicted by the phospholipids approximation method. Both ATP and phospholipids relationships with depth are best fit using logarithmic regressions. However, the slopes of the depth versus biomass curves may depend on media type or filter influent. The holding time study results showed that if samples cannot be immediately tested for ATP, the cell activity remains closer to initial levels when media is held unextracted.

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