Feasibility of bioremediation of a ground water polluted with alkylpyridines

The potential for bioremediation of ground water polluted with various alkylpyridines was investigated. Aerobic bacteria, indigenous to the ground-water aquifer, were utilized for biodegradation of the various contaminants. Laboratory experiments demonstrated that biodegradation occurred only under aerobic and not under anaerobic conditions. Analysis of the ground water in the site indicated that levels of oxygen were below 1 mg/l. Thus, it is suggested that oxygen limitation prevented the biodegradation of pollutants in the aquifer. Phosphate amendment (5 mg/l) into slurries of contaminated sediment and ground water resulted in enhanced degradation rates. Columns filled with aquifer material and leached with contaminated ground water were used to simulate possible in situ bioremediation. Reduction in concentration of the different compounds in column effluents ranged between 40 and 80%, with 2,3-, 2,6-, and 3,5-lutidine degrading at lower rates than other contaminants. In addition to in situ treatment, the potential of using aboveground systems for treatment was explored. A mixed culture capable of degrading 14 different alkylpyridines was isolated from the subsurface sediment. This culture was used to seed a two-stage fixed film reactor. The reactor was fed with a mixture of organic acids and alkylpyridines that simulated the ground-water composition. The reactors were very effective in removing the pollutants from the waste stream. The efficiency of alkylpyridine removal was between 98 and 100% and overall COD removal was 97%, when operating at a loading rate of 4.32 g COD/L-h and hydraulic retention time of 3 h. These results imply that a combined approach which utilizes both in situ and aboveground treatments should be used for the bioremediation of polluted ground water.