Effect of Grain Size and Nutrient Feeding on the Treatment Potential of Biofilters for Treatment of   De-Icing Chemicals

Abstract

Abstract:Biofilter application for treatment of stormwater containing de-icing chemicals commonly applied in airports, propylene glycol and potassium formate, was investigated. Lab-scale adsorption tests using filter media made of crushed clay (Filtralite) and granular activated carbon showed that adsorption was unsuitable for removal of propylene glycol and potassium formate. Column filtration experiment testing two different crushed clay size ranges was conducted. The results showed that DOC removal was dependent on a number of factors. This study investigated the impact of filter depth, nutrients addition, and filtration rate. DOC removal suggested that DOC degradation occurred on the top filter layer. It was shown that the most active separation occurred in the first ~20 cm of filter depth. This was confirmed by results from water quality analysis (i.e. DOC removal and ATP measurement) and calculations based on a filtration performance analysis (Iwasaki model) and filter hydraulic evaluation (Lindquist diagram). It was shown that for the highest C:N:P ratio tested (molar ratio of 24:7:1), 50-60% DOC removal was achieved. Addition of nutrients was found important and determining the biofilter performance.

Full-Scale Manipulation of the Empty Bed Contact Time to Optimize Dissolved Organic Matter Removal by Drinking Water Biofilters

“…14,15 Studies of first-stage full-scale biofilters with expanded clay media are rare. 16 Filtralite is an expanded clay medium used for many years in Scandinavia in various applications, including for treatment of drinking water, stormwater, industrial wastewaters, 17 deicing chemicals, 18 and wastewater. 19 A majority of studies with a Scandinavian perspective focused on comparing Filtralite filters with anthracite/sand or GAC filters at equal filter depths.…”

“…Published studies of direct biofiltration involved adsorptive media like granular activated carbon (GAC) or common non-adsorptive filter media, like sand/anthracite. , Studies of first-stage full-scale biofilters with expanded clay media are rare . Filtralite is an expanded clay medium used for many years in Scandinavia in various applications, including for treatment of drinking water, stormwater, industrial wastewaters, deicing chemicals, and wastewater . A majority of studies with a Scandinavian perspective focused on comparing Filtralite filters with anthracite/sand or GAC filters at equal filter depths. − We are unaware of any full-scale studies to optimize DOM removal by Filtralite biofilters.…”