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The problem of wastewater has long been ubiquitous and has great consequences for the environment and its inhabitants. Microbial fuel cells (MFCs) have enormous potential for the treatment of wastewaters polluted with azo dyes. The amount of energy that can be produced from a single-chamber MFC is sufficient to perform decolorization and degradation of such dyes, which are widely used in the textile industry. This study on the azo dye, reactive black 5 (RB5), provides an alternative method through three parallel-connected MFCs to obtain electricity that directly serves for the dye's electrochemical degradation. We examined degradation followed by decolorization of RB5 using Fe and Pt electrodes, together with H2O2, to achieve the electro-Fenton process. The amount of voltage produced (295 mV), the current density (276 mA m-3) and the power density (50 mW m-3) were sufficient to degrade 25 mg L-1 RB5 dye with 0.5 mM H2O2 in just 2 h. The dye degradation mechanism was investigated using UV-VIS, FT-IR and HPLC-MS/MS. The ecotoxicity of the degradation products was assessed using a bacterial model, Aliivibrio fischeri. These tests showed that there was successful degradation of the dye to products whose toxicity is less than that of RB5.

AbstractMowing, as a common grassland utilization strategy, affects nutrient status in soil by plant biomass removal. Phosphorus (P) cycle plays an important role in determining grassland productivity. However, few studies have addressed the impacts of mowing on P cycling in grassland ecosystems. Here, we investigated the effects of various mowing regimes on soil P fractions and P accumulation in plants and litters. We specifically explored the mechanisms by which mowing regulates ecosystem P cycling by linking aboveground community with soil properties. Our results showed that mowing increased soil dissolvable P concentrations, which probably met the demand for P absorption and utilization by plants, thus contributing to an increased P accumulation by plants. Mowing promoted grassland P cycling by a reciprocal relationship between plants and microbes. Short‐term mowing enhanced P cycling mainly through increased root exudation‐evoked the extracellular enzyme activity of microbes rather than the alternations in microbial biomass and community composition. Long‐term mowing increased P cycling mainly by promoting carbon allocation to roots, thereby leading to greater microbial metabolic activity. Although mowing‐stimulation of organic P mineralization lasted for 15 consecutive years, mowing did not result in soil P depletion. These results demonstrate that P removal by mowing will not necessarily lead to soil P limitation. Our findings would advance the knowledge on soil P dynamic under mowing and contribute to resource‐efficient grassland management.

Understanding the spatial variability of CO2 emissions among and within cities and its driving factors is a prerequisite for emission reductions. Using 10 × 10 km national grid emission data (circa 2007), we quantified the spatial distribution of total CO2 emissions and emission efficiency of Chinese cities at the prefectural city scale. The emission efficiency was measured according to the emission intensity, CO2 emissions per capita, residential CO2 emissions per capita and industrial CO2 emissions per unit area. We found substantial variability in the total CO2 emissions among cities ranging from <0.1 to 214.3 million tons. High total CO2 emissions were mostly concentrated in northern, eastern and northeastern China. An overall analysis of the total CO2 emissions and emission intensity revealed that 75% of the cities in northern China had higher total emissions and lower efficiencies than the national average, and these cities shall be the main targeted cities for CO2 emissions reduction and emission intensity improvement. Additionally, urban districts had higher total CO2 emissions and emissions per capita than their surrounding regions for the majority of the prefectural cities. Four indicators, including the industrial structure, gross domestic product (GDP), total population, and size of the built-up area, were significantly related to the CO2 emissions and emission efficiency. Industrial structure was the most important driving force. Our results underscore the need to design region- and/or city-specific reduction strategies instead of a one-size-fits-all policy, and provide strategic information to public and private decision makers on controlling total emissions and improving emission efficiency.

Abstract Top-spray configurations are widely used in pharmaceutical fluidized beds for particle coating and granulation. The process is complex due to the change of particle moisture as well as particle density. It is important to investigate the flow hydrodynamics in the process. In this paper, electrical capacitance tomography (ECT) combined with pressure transducers are used to investigate the flow hydrodynamics of gas-solids flow in a top-spray fluidized bed for wetting and drying. The flow characteristics investigated include bubble size, dominant frequency and standard deviation. Discrete wavelet transforms (DWT) and Fast Fourier Transform (FFT) are used to analyze the capacitance and pressure signals. The effects of key process parameters, including superficial velocity, particle size and spraying conduction on the flow hydrodynamics, are analyzed. The result indicates that both the material moisture and particle size influence the minimum fluidized velocity and bubble characteristics during the wetting and drying process. The result also indicates that the moisture content of particles and superficial fluidization velocity are two main factors, which determine the bubble characteristics in the top-spray process. The bubble size presents a complex trend, which is influenced by the spray pressure. The fluctuation frequency of bubbles presents a different trend in the wetting and drying stage.

An integrated approach to document high anammox activity and biodiversity in a constructed wetland (CW) was performed and showed that substantial anammox activity could mitigate undesirable N(2)O emission. The enhanced anammox bacterial abundance, biodiversity and activity were achieved by supplementing activated sludge to the CW. Up to 3.38 × 10(7) gene copies g(-1) dry soil of anammox bacteria were enriched in the CW. The activity measured by isotope pairing technique increased from 1.6 nmol N g(-1) sludge h(-1) in the original activated sludge to 18 nmol N g(-1) soil h(-1) in the CW, with the specific cellular activity increased from 5.1 to 12.8 fmol cell(-1) d(-1). Up to 33% of produced N(2) could be attributed to anammox process in the CW, with the remainder being due to denitrification. Phylogenetic analysis of anammox bacterial 16S rRNA genes indicated a shift of community from single Candidatus "Brocadia fulgida" in sludge to multiple "Jettenia", "Brocadia", and "Anammoxoglobus" species in the CW. With static chambers and control experiments, the CW with supplemented sludge had a 30% reduced N(2)O emission flux compared with the tests without adding biomass during an 8 month testing period.

Aim of this study is to quantify the impacts of climate change on phenology and yield of winter wheat in rainfed and irrigated regions of Pakistan by using integration of two well-known crop models including STICS and APSIM with CORDEX-SA regional climate models (RCMs). A number of different adaptation strategies based on early sowing (i.e. S1:10 and S2:20 days), irrigation (I1:15% and I2:30% additional water) and a combination of sowing and irrigation adaptations were examined to recover the potential losses that would occur due to climate change. The data for the wheat phenology, biomass (t/ha) at different stages and yield (t/ha) was obtained from several experiments at national research institutes in Pakistan under both rainfed and irrigated conditions. After calibration and validation of both crop models (STICS and APSIM), the current climate data were replaced with the CORDEX-SA RCM-projections for climate change impact analysis. A significant rising and declining trends were observed in temperature and precipitation patterns, respectively, for the selected study regions. Consequently, a substantial impact of climate change on wheat phenology (anthesis stage, maturity stage, growing length), biomass (t/ha) and yield (t/ha) was observed under scenario periods for RCP4.5 and RCP8.5. Additionally, the adaptation strategies on wheat for rainfed regions showed a substantial improvement in wheat biomass and yield simulated by STICS model particularly for sowing-2 under RCP4.5. Irrigated regions showed more improvement for irrigation-2 (I2) and combination of sowing-1 + irrigation-2 (S1 + I2) using the STICS model under both RCPs. Overall, it was observed that changes in crop phenology had a stronger impact in terms of crop yield for RCP8.5 as compare to RCP4.5. This study provides a valuable understanding and way forward for the better wheat management under changes in precipitation and temperature patterns. The study also discuss in detail, the adaptation strategies to cope with potential damage, over two different irrigation zones (rainfed and irrigated) in Pakistan.

Low cost zeolites with incorporated silver show high activity for both oxygen reduction and borohydride oxidation reaction.

Wastewater is rich in nutrients, while desert regions often suffer from severe nutrient shortages, potentially leading to eutrophication and desertification in respective landscapes. Cyanobacterial cultivation emerges as a promising solution by extracting nutrients from wastewater and transferring them to deserts using cyanobacteria-induced biocrust technology. In this study, two biocrust inducing cyanobacteria, Microcoleus vaginatus and Scytonema javanicum were cultivated in synthetic and municipal wastewater, respectively, to assess their capabilities of nutrient removal and biocrust induction. Both cyanobacteria demonstrated effective removal of nitrogen and phosphorus from either synthetic or municipal wastewater, achieving removal rates exceeding 90 %. Sterilization experiments on the municipal wastewater confirmed that indigenous microorganisms did not influence cyanobacterial performance, though the two cyanobacteira exhibited contrasting growth and metabolic behaviors. Specifically, S. javanicum achieved higher biomass accumulation, reaching up to 6.05 ± 0.87 mg Chl-a L−1, whereas M. vaginatus produced more exopolysaccharides, up to 40.98 ± 2.96 mg L−1 in the municipal wastewater. The cyanobacteria harvested from the municipal wastewater effectively promoted biocrust formation, validating the feasibility of transferring nutrients from wastewater to deserts through cyanobacteria-induced biocrusts. Considering their varied growth behaviors, our findings advocate for the use of a combination of diverse cyanobacteria strains to optimize cultivation and inoculation technologies. Fil: Fernandez, Mariela Alejandra. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina Fil: Montes, María Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina Fil: Zhang, Cheng. Chinese Academy of Sciences; República de China Fil: Song, Shaoxian. Wuhan University of Technology; China Fil: Vadiveloo, Ashiwin. Murdoch University; Australia Fil: Xia, Ling. Wuhan University of Technology; China Fil: Lan, Shubin. Northeast Normal University; China Fil: Wu, Li. Northeast Normal University; China