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Trinitrotoluene (TNT), a commonly used explosive for military and industrial applications, can cause serious environmental pollution. 28-day laboratory pot experiment was carried out applying bioaugmentation using laboratory selected bacterial strains as inoculum, biostimulation with molasses and cabbage leaf extract, and phytoremediation using rye and blue fenugreek to study the effect of these treatments on TNT removal and changes in soil microbial community responsible for contaminant degradation. Chemical analyses revealed significant decreases in TNT concentrations, including reduction of some of the TNT to its amino derivates during the 28-day tests. The combination of bioaugmentation-biostimulation approach coupled with rye cultivation had the most profound effect on TNT degradation. Although plants enhanced the total microbial community abundance, blue fenugreek cultivation did not significantly affect the TNT degradation rate. The results from molecular analyses suggested the survival and elevation of the introduced bacterial strains throughout the experiment. Reference to this paper should be made as follows: Nõ lvak, H.; Truu, J.; Limane, B.; Truu, M.; Cepurnieks, G.; Bartkevičs, V.; Juhanson, J.; Muter, O. 2013. Microbial community changes in TNT spiked soil bioremediation trial using biostimulation, phytoremediation and bioaugmentation, Journal of Environmental Engineering and Landscape Management 21(3): 153Á162. http://dx.Abstract. This study compared treatment methods that utilised a liquid carrier of hydrogen peroxide and a solid carrier, percarbonate, for p-dichlorobenzene, p-chloro-m-cresol and p-chlorothymol degradation in the soil. The targeted chlorinated aromatic contaminants in the soil degraded to a certain level when treated with the liquid hydrogen peroxide, but the removal efficacy was not dependent on the dosage. In contrast, an increase in the percarbonate dosage enhanced the contaminant removal. Supplementary ferrous iron was more effective for the treatment that employed the liquid carrier of hydrogen peroxide than the treatment employing the solid carrier. Although acidic pH conditions (initial pH of 2.5) favoured contaminant degradation using liquid hydrogen peroxide, the treatment involving percarbonate resulted in more effective contaminant removal without any soil pH preadjustment. Therefore, the solid carrier of hydrogen peroxide, percarbonate, was concluded to be an effective alternative to the liquid carrier, resulting in greater contaminant removal at natural soil pH values.

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In this research, various combinations of physicochemical (coagulation, Fenton process and ozonation) and biological (aerobic oxidation) treatment methods were used to purify wastewater originating from wood soaking basins in plywood production industry. Although the wastewater has good biodegradability (92 %), there is a high fraction of organic material expressed as recalcitrant chemical oxygen demand (COD) of approximately 360 mg L -1 . High fraction of organics is caused by woodoriginating water-soluble material, i.e. extractives, including lignin and tannins. It was found that optimal treatment method for hardwood soaking basin wastewater is the combination of biological pre-treatment, chemical treatment with Fenton reagent and biological post-treatment. Under optimal conditions of combined process performance, up to 99 % removal of the organic loads, nitrogen and phenols was achieved. Besides achieving target discharge limits stated for industrial wastewater, the effluent met the requirements set for municipal wastewater treatment plants, making the treated water acceptable for subsequent discharge into natural water bodies: treated water COD = 90 ± 3 mg L -1 ; BOD 7 = 10 ± 1 mg L -1 . The main result of the present work was the establishment of sustainable, efficient and economically feasible process to treat the wastewater with minimised chemicals consumption. This differs considerably from approaches such as coagulation or wet oxidation, used to treat similar water types according to the literature, and is readily applicable for the production facilities of various scales, including small and medium enterprises, without the need to make changes in existing technological schemes.