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Static leaching experiments lasting 480 h were performed to investigate the release of dissolved organic matter (DOM) and inorganic nitrogen from coal gangues collected from the Jurassic Middle-Lower Yan′an formation in the Bulianta coal mine (CG1) and the Permian Shanxi formation in the Baode coal mine (CG2) in North China. The amounts of dissolved organic carbon (DOC), NH4+–N, NO3−–N, and NO2−–N released from CG1 were all much higher than those from CG2, as was the electrical conductivity. These were highly correlated with the mineral and chemical composition and lithology. The fluorescence, biological, and humification indices for the leachates were indicative of autochthonous microbial processes that occurred during DOM formation. In addition, the specific ultraviolet absorbance at 254 nm (SUVA254) and fluorescence intensities (divided by DOC) of peaks B1, B2, T2, and A indicated that more microbial and less plant precursors in the DOM were released from CG2 than from CG1. Adsorption and denitrification of NH4+–N and NO3−–N released from CG1 and CG2 were observed. These results should be useful in assessing the environmental impacts caused by the DOM and nitrogen released from coal gangue. [ABSTRACT FROM AUTHOR]

Because of demand uncertainties, a build-operate-transfer (BOT) project may lead a concessionaire either to realize an excessive profit or suffer a loss. The object of this paper is to establish an adjustment mechanism to automatically balance the risks and rewards between public and private sectors under the fixed preset concession period. Using a revised net present value (NPV) financial evaluation model and the Monte Carlo simulation technique, the authors construct a model that can determine the optimum solution of the minimum revenue guarantee (MRG) level and the collect rate of royalty for BOT projects. The MRG and royalty collection combination (G&R) is shown, via a reduction in the decision variables, to be a more effective scheme than those in previous studies. The results of a sensitivity analysis based on a wastewater treatment BOT project prove that Scheme M of MRG based on 90% volume combined with a 20% royalty rate is the leading option because it guarantees that the concessionaire will always earn a reasonable anticipated return under the fixed term. The main contribution of this paper is to provide a simple tool for balancing the risks and benefits for the government and investors. [ABSTRACT FROM AUTHOR]