Biotransformation of Organics in Soil Columns and an Infiltration Area

Abstract

Laboratory column experiments were performed to evaluate the fate of a series of chlorinated and nonchlorinated organic contaminants in Rhine sediment and in sediment from the infiltration area of the Municipal Water Works of Amsterdam, near Zandvoort, The Netherlands. Columns were operated under aerobic, denitrifying, and methanogenic conditions. All nonchlorinated and few chlorinated compounds were aerobically transformed. Of the compounds tested under denitrifying conditions, only 1,2‐dichloro‐4‐nitrobenzene was partially transformed. Methanogenic conditions favored the transformation of chlorinated substances by reductive dechlorination. Toluene was the only nonhalogenated compound that was transformed under methanogenic conditions. Steady‐state effluent concentrations after biotransformation were at least 10 times lower than the drinking water limit of 1 μg/l except in the case of 1,2,4‐trichlorobenzene which had a steady‐state effluent concentration of 2.6 μg/l. Steady‐state effluent concentrations did not depend on the influent concentration applied. Most transformations proceeded at the same steady‐state rates at a temperature of 4° C, although the process of reductive dechlorination was slower at 4° C than at 20° C. Hydrological calculations revealed that the combined action of hydrology and sorption to organic matter in the infiltration system can reduce the concentrations of 2 week pulses of polar and nonpolar contaminants by at least 80 and 95%, respectively. There was a good qualitative agreement between removals observed in column experiments and in the dune infiltration area.

Microbial degradation of chlorinated benzenes

“…The column, which operated with a hydraulic retention time of 1.5 days, was highly effective in the removal of CB, reducing the influent concentration of 25-30 mg CB l -1 to 0.04 mg CB l -1 or less. Degradation of mixtures of chlorinated benzenes has also been studied in slow sand filter columns under aerobic conditions (Zacharias et al 1995;Bosma et al 1996). In one study, contaminated water was filtered through 40 kg of sand placed in 32-l columns with a hydraulic retention time of 3.2 h. The sum of all CBs in the influent and effluent was 3.81 and 0.014 mg l -1 , respectively, corresponding to a removal efficiency of 99.6%.…”

“…As evidence of biodegradation, the inorganic chloride concentration was shown to increase in the column. In another study, the removal of CBs during infiltration of water into sand dunes as part of a drinking water treatment scheme was evaluated with laboratory-scale columns (V = 0.6 or 5.7 l) filled with sand (Bosma et al 1996). Under aerobic conditions, CB, 1,2-DCB, 1,3-DCB, 1,4-DCB, and 1,2,4-TCB were removed by [99, 90, 30, 90, and 40%, respectively. Several studies considered the removal of CB in waste gases in biological trickling reactors (Oh and Bartha 1994;Mpanias and Baltzis 1998;Seignez et al 2004;Mathur et al 2006).…”

Towards improved instrumentation for assessing river-groundwater interactions in a restored river corridor

“…Open water bodies may be polluted by pathogens or dissolved contaminants, which are introduced into running waters by the effluent of sewage treatment plants, stormwater overflow, and agricultural drainage, among others. The passage through the riverbed, the hyporheic zone, and the alluvial aquifer -summarized as bank filtration -acts as filter and reactor for contaminants, nutrients, and pathogens (Bosma et al, 1996;Bourg and Bertin, 1993;Merkli, 1975;Schwarzenbach et al, 1983Schwarzenbach et al, , 2006Schwarzenbach and Westall, 1981). The actual biogeochemical interactions sustaining the quality of the pumped bank filtrate depend on numerous factors including aquifer mineralogy and structure, oxygen and nitrate concentrations in the surface water, types of organic matter in the surface and groundwater environments, and land use in the local catchment area (Hiscock and Grischek, 2002).…”

Degradation of linear alkylbenzene sulfonate in soil columns

“…To compare the actual magnitude of the dispersion in the columns, the Peclet number for each column was calculated [10,11];…”