BIOREMEDIATION FEASIBILITY STUDY FOR THE AVENUE COKING WORKS, CHESTERFIELD, UK

摘要

Three locations of the former Avenue Coking Works have been sampled for bioremediation feasibility testing. In a first stage, slurry biodegradation tests were performed to assess the potential for biodegradation and optimal treatment conditions. Treatment conditions included dead and live controls, addition of inorganic fertiliser, a commercial nutrient mixture and inorganic fertilisers with adapted bacteria. Bioremediation was monitored by respiration measurents and by chemical analyses of pollutants after 8 and 17 weeks. For all soil samples but the Tar Pit, BTEX, phenol, cresols, C2-alkylphenols, NSO-heterocyclic compounds and naphtalene were removed to a significant extent. 3-ring PAH and mineral oil was also degraded in some, not all, samples. Higher ring PAH, C3-alkylphenols and mineral oil in some samples did not degrade. Slightly better microbial activity and pollutant removal appeared to result from the addition of inorganic fertilisers, albeit in combination with a bacterial inoculum. In a second stage, biodegradation kinetics were determined in two solid phase bioreactors for two soils, each receiving a commercial nutrient supplement. An 80-day monitoring of respiration activity and pollutants in soil and off-gas samples enabled mass balancing. For the soil highly polluted with tar, similar biodegradation was observed for BTEX, naphtalene and mineral oil as for the batch tests, without biodegradation of higher ring PAH. Phenolic compounds were not degraded. Significant volatilisation of VOC as well as cyanide was observed, most of the decrease in VOC concentrations in the soil was however due to biodegradation. For moderately polluted soil, similar results were observed as in the batch tests, I.e. a good removal of naphtalene and a decrease of approximately 50% of mineral oil and total PAH. PCR-analysis demonstrated the presence of Sphingomonas sp. Which could grow on pyrene as a unique source of carbon. Finally a full scale biopile was set up at the site to determine the achievable end points in real environment. After bioremediation of the plant area and waste tip material a soil is produced with only the heavier PAH’s remaining. The leachability for PAH’s, phenols and cyanides was largely reduced after treatment. C3-alkylphenols showed to be resistant for bioremediation.