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. Analys is of the ground water in the site indicated that levels of oxygen wer e 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 resul ted in enhanced degradation rates. Columns filled with aquifer materia l and leached with contaminated ground water were used to simulate pos sible in situ bioremediation. Reduction in concentration of the differ ent compounds in column effluents ranged between 40 and 80%, with 2,3- , 2,6-, and 3,5-lutidine degrading at lower rates than other contamina nts. In addition to in situ treatment, the potential of using abovegro und systems for treatment was explored. A mixed culture capable of deg rading 14 different alkylpyridines was isolated from the subsurface se diment. 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 e ffective in removing the pollutants from the waste stream. The efficie ncy of alkylpyridine removal was between 98 and 100% and overall COD r emoval 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.