Hydrogen autotrophic reduction of perchlorate have advantages of high removal efficiency and harmless to drinking water. But so far the reported information about the microbial community structure was comparatively limited, changes in the biodiversity and the dominant bacteria during acclimation process required detailed study. In this study, perchlorate-reducing hydrogen autotrophic bacteria were acclimated by hydrogen aeration from activated sludge. For the first time, high-throughput sequencing was applied to analyze changes in biodiversity and the dominant bacteria during acclimation process. The Michaelis-Menten model described the perchlorate reduction kinetics well. Model parameters q(max) and K(s) were 2.521-3.245 (mg ClO4(-)/gVSS h) and 5.44-8.23 (mg/l), respectively. Microbial perchlorate reduction occurred across at pH range 5.0-11.0; removal was highest at pH 9.0. The enriched mixed bacteria could use perchlorate, nitrate and sulfate as electron accepter, and the sequence of preference was: NO3(-) > ClO4(-) > SO4(2-). Compared to the feed culture, biodiversity decreased greatly during acclimation process, the microbial community structure gradually stabilized after 9 acclimation cycles. The Thauera genus related to Rhodocyclales was the dominated perchlorate reducing bacteria (PRB) in the mixed culture.

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Graphite tailings were used as the raw materials for the preparation of foamed ceramics via a high-temperature self-foaming method. The residual carbon in the tailings acted as the foaming agent and no additional foaming agents were required. The residual carbon reacted with Fe2O3 and produced gas that was wrapped by the liquid phase to form a porous structure. The effects of sintering temperature, holding time, carbon content, flux on the bulk density, water absorption, and mean pore size of the foamed ceramics were investigated. The bulk density, compressive strength, thermal conductivity, and water absorption of the foamed ceramic prepared using the optimal sample D100 (100 wt% graphite tailings) and sintered at 1200 °C for 20 min were 1.36 g/cm3, 0.35%, 12.03 MPa, and 0.51 W/(m·K), respectively. The raw material contained CaO, Fe2O3, and SiO2, which formed augite with a low fusibility point. In contrast, the molten decomposition products of potassium feldspar and CaSiO3 ions formed anorthite, which has a high fusibility point. Therefore, potassium feldspar is not recommended for use as a flux in tailing systems with high calcium content. Foamed ceramics were prepared using up to 100 wt% graphite tailings. This is a new approach for the economical disposal of graphite tailings.

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S-doped TiO 2 as a novel adsorbent for Cu 2þ cations removal from aqueous solutions was synthesized by simple sol-gel process. Removal of Cu 2þ cations from aqueous solutions was investigated with particular reference to the effects of initial Cu 2þ cations concentration, pH-value, adsorbent dosage, and temperature on adsorption. It was found that the maximum adsorption capacity was 96.35 mg g À1 at 328 K. The adsorption equilibrium isotherms and the kinetic data were well described by the Langmuir and pseudo-second-order kinetic models, respectively. The high uptake capability of S-doped TiO 2 makes it a potentially attractive adsorbent for the removal of heavy metal pollutants from aqueous solution.