Generation of acidic mine drainage is a major environmental problem in areas with mining waste. The cost-effective method for reclaiming of acid-generating mining wastes is a vegetation cover. Using plant growth-promoting bacteria (PGPR) and humic acid in remediation have several beneficial effects. The application of both humic substances and PGPR resulted in a decrease in Cu, Fe, Zn and sulfate concentrations in a variety of drainage water samples. Both PGPR and humic acid improve plant growth when used separately, however, the combination of both treatments has the most positive effect on fresh biomass yield – between 22% and 43 % and dry biomass of plants – between 31% and 41 %. Furthermore, addition of Bacillus and Pseudomonas bacteria, in combination with humic acids, to poor soil for reclamation improved grass mineral nutrition and reduced Cu and Zn uptake. The treatment with PGPR and humic acids significantly increased the uptake of nitrogen, phosphorus and potassium by plants.
The influence of hydraulic retention time (HRT) on the rate of sulphate-reduction and electricity generation of microbial fuel cell fed with ethanol was studied. The experiments were performed in the laboratory installation, consisting of an anaerobic fixed-bed reactor and a microbial fuel cell with air-cathode. An effective sulphate removal was achieved at hydraulic retention times 44 and 66 h. The effectiveness of COD removal raises with increasing the hydraulic retention time. The highest maximum power density of 258 mW/m2 was obtained at 22 h HRT. The use of ethanol as an electron donor had a great impact on the composition of the microbial community. The metagenomic data obtained showed that the most abundant phylum in bacterial community was Proteobacteria – 87.8 %, and particularly Gammaproteobacteria – 53,1%. The sulphate reducing bacteria that can incompletely oxidise organic compounds usually with acetate as an end product were presented in the microbial community in anodic chamber. The dominant microbial species among sulphate reducing bacteria was Desulfomicrobium mexicanus (19,79%).
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