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Sewage sludge and bagasse were used as raw materials to produce cheap and efficient adsorbent with great adsorption capacity of Pb 2+ . By pyrolysis at 800 °C for 0.5 h, the largest surface area (806.57 m 2 /g) of the adsorbent was obtained, enriched with organic functional groups. The optimal conditions for production of the adsorbent and adsorption of Pb 2+ were investigated. The results of adsorb-ability fitted the Langmuir isotherm and pseudo-second-order model well. The highest Pb 2+ (at pH = 4.0) adsorption capacity was achieved by treating with 60% (v/v) HNO 3 . This is a promising approach for metal removal from wastewater, as well as recycling sewage sludge and bagasse to ease their disposal pressure. [ABSTRACT FROM AUTHOR]

Heavy metal contamination has become a worldwide environmental concern due to its toxicity, non-degradability and food-chain bioaccumulation. Conventional physical and chemical treatment methods for heavy metal removal have disadvantages such as cost-intensiveness, incomplete removal, secondary pollution and the lack of metal specificity. Microbial biomass-based biosorption is one of the approaches gaining increasing attention because it is effective, cheap, and environmental friendly and can work well at low concentrations. To enhance the adsorption properties of microbial cells to heavy metal ions, the cell surface display of various metal-binding proteins/peptides have been performed using a cell surface engineering approach. The surface engineering of Gram-negative bacteria, Gram-positive bacteria and yeast towards the adsorption of heavy metals are reviewed in this article. The problems and future perspectives of this technology are discussed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Heavy metals removal from MSWI fly ash with BES and electrolysis was confirmed. [•] 98.5% of Cu(II), 95.4% of Zn(II) and 98.1% of Pb(II) removal were achieved in reactors. [•] BESs can remove some heavy metals in fly ash with energy saving. [Copyright &y& Elsevier]

Highlights: [•] Feasibility of natural limonite as iron catalyst in BES-Fenton system was confirmed. [•] With natural limonite, 96% of PNP removal efficiency was achieved within 6h. [•] PNP removal efficiency is kept above 94% for 7 periods with adding limonite only once. [ABSTRACT FROM AUTHOR]

Abstract: The cathodic reduction of complex-state copper(II) was investigated in a dual chamber microbial fuel cell (MFC). The inner resistance of MFC system could be reduced in the presence of ionizing , however, mass transfer was hindered at higher ammonia concentration. Thermodynamic and electrochemical analyses indicated that the processes of complex dissociation and copper reduction were governed by the ratio of T[Cu]:T[NH3] and the pH of solution. The reduction of could be achieved via two possible pathways: (1) releasing Cu2+ from , then reducing Cu2+ to Cu or Cu2O and (2) accepting an electron and forming , and depositing as Cu or Cu2O consequently. At initial concentration of 350mg T[Cu] L−1, copper removal efficiency of 96% was obtained at pH=9.0 within 12h (with △Cu/△COD=1.24), 84% was obtained at pH=3.0 within 8h (with △Cu/△COD=1.72). was reduced as polyhedral deposits on the cathode. [Copyright &y& Elsevier]

Abstract: A novel approach was tested for metallic silver recovery and power generation by using cathodic reduction in bioelectrochemical systems (BESs). In dual-chamber BESs (130mL volume) with acetate as electron donor on anode, both Ag+ ions and Ag(I) thiosulfate complex in catholyte were reduced on cathode. The reduction rate of Ag+ was more rapid than the Ag(I) complex as expected by energetic analysis. X-ray diffraction (XRD) analysis indicated that electrodeposits on cathodes from both catholyte were metallic silver with >91% purity. The feasibility of metallic silver recovery with the BESs was confirmed using simulated photographic wastewater and up to 95% of Ag(I) removal was achieved. [Copyright &y& Elsevier]

Abstract: A pilot-scale, membrane-free, bioelectrochemical system (BES) reactor (16L in volume) installed by five cathodes with different distance to anode was tested for the removal of copper. CuSO4 solution was used as catholyte and anaerobic microorganisms grew as anodic biocatalyst. In the reactor, Cu(II) was reduced and recovered as solid-state copper deposits on cathodes accompanied with power production. When 600 and 2000mg of Cu2+ were added into the cathode chamber, removal efficiency of 92% over 480h and 48% over 672h period with electric quantities of 2724C and 8703C, and cathodic efficiencies of 61.92% and 45.60% were achieved, respectively. The reduction reaction rate depended on the initial average Cu2+ concentration. The internal resistance decreased and voltage output increased as the distance of each cathode to anode decreased. The mass of metal Cu crystals and Cu(I) compounds deposited on each cathode was dependent on current intensity. [Copyright &y& Elsevier]

Abstract: Based on energetic analysis, a novel approach for copper electrodeposition via cathodic reduction in microbial fuel cells (MFCs) was proposed for the removal of copper and recovery of copper solids as metal copper and/or Cu2O in a cathode with simultaneous electricity generation with organic matter. This was examined by using dual-chamber MFCs (chamber volume, 1L) with different concentrations of CuSO4 solution (50.3±5.8, 183.3±0.4, 482.4±9.6, 1007.9±52.0 and 6412.5±26.7mg Cu2+/L) as catholyte at pH 4.7, and different resistors (0, 15, 390 and 1000Ω) as external load. With glucose as a substrate and anaerobic sludge as an inoculum, the maximum power density generated was 339mW/m3 at an initial 6412.5±26.7mg Cu2+/L concentration. High Cu2+ removal efficiency (>99%) and final Cu2+ concentration below the USA EPA maximum contaminant level (MCL) for drinking water (1.3mg/L) was observed at an initial 196.2±0.4mg Cu2+/L concentration with an external resistor of 15Ω, or without an external resistor. X-ray diffraction analysis confirmed that Cu2+ was reduced to cuprous oxide (Cu2O) and metal copper (Cu) on the cathodes. Non-reduced brochantite precipitates were observed as major copper precipitates in the MFC with a high initial Cu2+ concentration (0.1M) but not in the others. The sustainability of high Cu2+ removal (>96%) by MFC was further examined by fed-batch mode for eight cycles. [Copyright &y& Elsevier]

Abstract: A membrane-free baffled microbial fuel cell (MFC) was developed to treat synthetic Cu(II) sulfate containing wastewater in cathode chamber and synthetic glucose-containing wastewater fed to anode chamber. Maximum power density of 314mW/m3 with columbic efficiency of 5.3% was obtained using initial Cu2+ concentration of 6400mg/L. Higher current density favored the cathodic reduction of Cu2+, and removal of Cu2+ by 70% was observed within 144h using initial concentration of 500mg/L. Powder X-ray diffraction (XRD) analysis indicated that the Cu2+ was reduced to Cu2O or Cu2O plus Cu which deposited on the cathode, and the deficient cathodic reducibility resulted in the formation of Cu4(OH)6SO4 at high initial Cu2+ concentration (500–6400mg/L). This study suggested a novel low-cost approach to remove and recover Cu(II) from Cu2+-containing wastewater using MFC-type reactor. [Copyright &y& Elsevier]

Based on the structure related to the high-temperature superconductor yttrium-barium-copper oxide, two novel high-efficiency visible light photocatalysts were created in this study. The yttrium-barium oxide (YBO) semiconductors Y 2 Ba 3 O 6 (YB3O) and Y 2 Ba 4 O 7 (YB4O) were prepared by a copper-free solid-phase sintering method. They were applied for the effective treatment of dye-containing wastewater by photocatalysis under visible light irradiation. The degradation efficiency of methylene blue (MB) reached more than 95% within 10 min. Stable visible light degradation of methyl orange (MO) was achieved in the presence of YB3O and YB4O. The electron spin resonance technique and active substance capture technique confirmed the presence of superoxide radicals (·O 2 −), hydroxyl radicals (·OH) and holes (h VB +) under visible light illumination. UV–Vis diffuse reflectance spectroscopy analysis showed that the direct optical band gaps of YB3O and YB4O were 2.550 eV and 2.583 eV, respectively, which resulted in their high visible absorption at 486.27 nm and 480.06 nm. After five cycles, the recoveries of YB3O and YB4O reached 67.15% and 72.98%. Therefore, YB3O and YB4O are considered as powerful semiconductor catalysts for the photocatalytic degradation of organic dyes in wastewater. • Synthesis of yttrium -barium oxide (YBO) visible light catalyst. • Y 2 Ba 3 O 6 (YB3O) and Y 2 Ba 4 O 7 (YB4O) show a forbidden band width of 2.550 eV and 2.583 eV respectively. • The effective degradation of methylene blue was achieved within 10 min under visible light. • The mineralization of the total organic carbon in the degraded solutions of both dyes reached close to 80%. [ABSTRACT FROM AUTHOR]

This study evaluated uranium sequestration performance in iron-rich (30 g/kg) sediment via bioreduction followed by reoxidation. Field tests (1383 days) at Oak Ridge, Tennessee demonstrated that uranium contents in sediments increased after bioreduced sediments were re-exposed to nitrate and oxygen in contaminated groundwater. Bioreduction of contaminated sediments (1200 mg/kg U) with ethanol in microcosm reduced aqueous U from 0.37 to 0.023 mg/L. Aliquots of the bioreduced sediment were reoxidized with O 2 , H 2 O 2 , and NaNO 3 , respectively, over 285 days, resulting in aqueous U of 0.024, 1.58 and 14.4 mg/L at pH 6.30, 6.63 and 7.62, respectively. The source- and the three reoxidized sediments showed different desorption and adsorption behaviors of U, but all fit a Freundlich model. The adsorption capacities increased sharply at pH 4.5 to 5.5, plateaued at pH 5.5 to 7.0, then decreased sharply as pH increased from 7.0 to 8.0. The O 2 -reoxidized sediment retained a lower desorption efficiency at pH over 6.0. The NO 3 −-reoxidized sediment exhibited higher adsorption capacity at pH 5.5 to 6.0. The pH-dependent adsorption onto Fe(III) oxides and formation of U coated particles and precipitates resulted in U sequestration, and bioreduction followed by reoxidation can enhance the U sequestration in sediment. Unlabelled Image [ABSTRACT FROM AUTHOR]

In this study, bacterial mercury (Hg) methylation was investigated under the influence of red-tide algae of Skeletonema costatum (S. costatum). The distribution and speciation of total mercury (THg) and methylmercury (MeHg) were profiled by employing Geobacter metallireducens (G. metallireducens GS-15) as the methylating bacteria. G. metallireducens GS-15 showed different capabilities in methylating different inorganic forms of Hg(II) (HgCl 2) and Hg(II)-Algae (HgCl 2 captured by S. costatum) to MeHg. In the absence of S. costatum , a maximum methylation efficiency of 4.31 ± 0.47% was achieved with Hg(II) of 1–100 μg L−1, while accelerated MeHg formation rate was detected at a higher initial Hg(II) concentration. In the presence of S. costatum , there were distinct changes in the distribution of THg and MeHg by altering the bioavailability of Hg(II) and Hg(II)-Algae. A larger proportion of THg tended to be retained by a higher algal biomass, resulting in decreased methylation efficiencies. The methylation efficiency of Hg(II) decreased from 3.01 ± 0.10% to 1.01 ± 0.01% with 10-mL and 250-mL algal media, and that of Hg(II)-Algae decreased from 0.83 ± 0.13% to 0.22 ± 0.01% with 10-mL and 250-mL Hg(II)-Algae media. Fourier transform infrared spectrometry, surface charge properties and elemental compositions of S. costatum were used to infer that amine, carboxyl and sulfonate functional groups were most likely to interact with Hg(II) through complexation and/or electrostatic attraction. These results suggest that red-tide algae may be an influencing factor on bacterial Hg methylation in eutrophic water bodies. Unlabelled Image • Bacterial Hg methylation was investigated in the Hg-algae-bacteria system. • Bacterial MeHg yield and methylation efficiency depended on algal biomass. • Higher algal biomass reduced the potential risk of bacterial Hg methylation. • S. costatum exerted significant influences on Hg distribution and speciation. • Various functional groups in algal cells were involved in Hg-algae interactions. [ABSTRACT FROM AUTHOR]

Abstract Algae and mercury (Hg) are ubiquitous in marine environments. In this study, we investigated the effects of a typical marine algae of diatom Skeletonema costatum on Hg methylation by an iron-reducing bacterium of Geobacter sulfurreducens (G. sulfurreducens) PCA. In the absence of Skeletonema costatum , the bacterial MeHg production rate maximized at 104.06 ± 11.7 ng L−1 h−1 with a high Hg level, while the highest methylation efficiency was achieved at a low Hg concentration. The existence of Skeletonema costatum greatly inhibited the capability of G. sulfurreducens PCA to methylate Hg. With the increase in algal biomass, there was a significant mitigation of MeHg formation and Hg0 release, leaving a considerable proportion of immobilized Hg2+ species (up to 47%) associated with algal cell materials. These results suggest that marine algae are crucial in determining the bioavailability of Hg contaminants and the methylating potential of G. sulfurreducens PCA. Highlights • Marine algae of Skeletonema costatum was insignificant in Hg methylation. • G. Sulfurreducens PCA was capable of bacterial methylation of Hg. • Bacterial methylation depended on initial Hg level and active algal biomass. • Bacterial methylation of Hg was inhibited by Skeletonema costatum. • Algal biomass was crucial in determining the distribution and transformation of Hg. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two novel yttrium-barium oxide photocatalysts, YBO, were discovered based on YBCO. • The energy band, density of states and charge density difference of YB3O and YB4O were analyzed and compared. • Electron spin polarization enables efficient separation of photogenerated carriers generated by YBO. • YB3O and YB4O had good semiconductor properties and photocatalytic potentials. Novel semiconductor photocatalysts are currently a hot research topic. We are inspired by the phenomenon that high-temperature superconductors can achieve superconductivity only under certain conditions (e.g., liquid nitrogen temperature). Here, based on the analysis of the energy band structure of the high-temperature superconductor YBCO (YBa 2 Cu 3 O 7-x , YBCO), two new yttrium barium oxide (YBO) semiconductor materials, Y 2 Ba 3 O 6 (YB3O) and Y 2 Ba 4 O 7 (YB4O), are reported in this study. According to first-principles calculations, we find that YB4O and YB3O have stable formation energies, as well as forbidden band gaps, which are suitable for the visible light response. In addition, YB4O possesses a larger effective mass difference of carrier and stronger electron delocalization in various directions than that of YB3O, while YB3O possesses a larger light absorption threshold than that of YB4O. These two innovative yttrium-barium oxide materials show strong semiconducting properties and have great potential as photocatalysts. [ABSTRACT FROM AUTHOR]

Highlights: [•] Pseudomonas sp. WYZ-2 was isolated from biocathode in bioelectrochemical system. [•] WYZ-2 accelerated the electrons transfer taking electrode as sole electrons donor. [•] WYZ-2 modified electrode played a catalytic role for azo dye decolorization. [ABSTRACT FROM AUTHOR]

Ideonella sp. TH17, an autotrophic hydrogen-oxidizing bacterium (HOB), was successfully enriched and isolated from activated sludge in a domestic wastewater treatment plant (WWTP). Batch experiments were conducted to identify the cell growth and ammonium (NH 4 +-N) removal, and to verify the pathways of nitrogen utilization under different conditions. At a representative NH 4 +-N concentration of 100 mg/L in domestic wastewater, it was the first time that a HOB strain achieved a nearly 100% ammonium removal. More than 90% of NH 4 +-N was assimilated to biomass nitrogen by strain TH17. Only a little of N 2 (<10% of initial NH 4 +-N) was detected without N 2 O emission in aerobic denitrification process. Autotrophic NH 4 +-N assimilation contributed predominantly to biomass nitrogen production, supplemented by assimilatory nitrate (NO 3 −-N) reduction under aerobic conditions. A total of 17 amino acids, accounting for 54.25 ± 1.98% of the dry biomass, were detected in the bacterial biomass harvested at 72 h. These results demonstrated that the newly isolated strain TH17 was capable of removing NH 4 +-N and recovering nutrients from wastewater efficiently. A new solution was thus provided by this HOB strain for ammonium treatment in sustainable WWTPs of future. • A novel HOB strain was enriched and isolated for rapid NH 4 +-N removal. • High-quality microbial proteins were produced with simultaneous NH 4 +-N removal. • NH 4 +-N removal was contributed predominantly by autotrophic assimilation. • NH 4 +-N removal was supplemented by aerobic denitrification with zero N 2 O emission. [ABSTRACT FROM AUTHOR]