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Use of a pilot-scale fixed-film bioreactor was investigated for remediation of bromate contamination within groundwater. Bromate reduction with stoichiometric production of bromide was observed, providing supporting evidence for complete reduction of bromate with no production of stable intermediates. Reduction of 87-90% bromate from an influent concentration of 1.1 mg L(-1) was observed with retention times of 40-80 h. Lower retention times led to decreases in bromate reduction capability, with 11.5% removal at a 10 h retention time. Nitrate reduction of 76-99% from a 30.7 mg L(-1) as NO(3)(-) influent was observed at retention times of 10-80 h, although an increase in nitrite production to 2.7 mg L(-1) occurred with a 10 h retention time. Backwashing was not required, with the large plastic packing media able to accommodate biomass accumulation without decreases in operational efficiency. This study has provided proof of concept and demonstrated the potential of biological bromate reduction by fixed-film processes for remediation of a bromate contaminated groundwater source.

The phosphate (P) fertilizer industry generates a highly hazardous and acidic wastewater. The present study reports the evaluation of an integrated precipitation and Enhanced Biological Phosphorus Removal (EBPR) process for the treatment of fertilizer plant wastewater and effluent detoxification, assessed by microtoxicity and seed germination tests. Effluent samples were collected from a local P fertilizer industry and were characterized by their high fluoride and P content. First, the samples were pre‐treated by precipitation of P and fluoride ions using hydrated lime. The resulting low‐fluoride and phosphorus effluent was then treated with the EBPR process to monitor the simultaneous removal of carbon, nitrogen, and phosphorus. Phosphorus removal included a two‐stage anaerobic/aerobic system operating under continuous flow. Pre‐treated wastewater was added to the activated sludge and operated for 160 days in the reactor. The operating strategy included increasing the organic loading rate from 0.3 to 1.2 g chemical oxygen demand (COD)/L day. The stable and high removal rates of COD, NH4+‐N, and PO43−‐P were then recorded. The mean concentrations of the influent were approximately 3600 mg COD/L, 60 mg N/L and 14 mg P/L, which corresponded to removal efficiencies of approximately 98%, 86%, and 92%, respectively. The microtoxicity of the treated wastewater was then monitored by LUMIStox and its phytotoxicity was investigated on cress, tomato, wheat, maize, ryegrass, and alfalfa seed germination. LUMIStox tests showed that treatment allowed a significant toxicity removal. Moreover, the untreated wastewater inhibited the species germination even when diluted 10 times, whereas a positive effect of treated wastewater was noticed. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 463–471, 2014

Mercury (Hg) represents a growing environmental and health major concern. It originates from natural sources and mainly from anthropogenic processes and it is widely distributed in the natural media. According to the last Global Mercury Assessment (2013), annual global emissions from both sources were estimated to be from 5,000 to 8,000 metric tons per year. Among the different mercury species released to the environment, methylmercury (MeHg) is considered as the most toxic form due to its ability to bioaccumulate, being then threatening even at very low concentrations.Its presence depends onHg(II) bioavailability and global amount.This explains the urgent need to ensure a continuous Hg(II) monitoring. Many efforts have been made in order to develop reliable systems able to deliver quick data and to comply with low detection limits, in accordance with the threshold value delivered by the World Health Organization (1µg L-1/ 5 nM). Spectroscopic techniques such as CV-AFS and CV-AAS are routinely used for Hg(II) determination. Although these methods can afford good sensitivity and low concentrations determination, they require sample preparation step, complex procedures and expensive material, which limits their use for on-site measurements. In this context, electrochemical sensors present excellent candidates for in situ Hg(II) trace analysis, taking in account their numerous advantages compared to spectroscopic techniques: easier handling, simple procedure, low energy consuming, low cost material and portability. In this work, we will propose a new electrochemical approach aiming to conceive and optimize an electrochemical Hg(II) sensor. The method consists in the functionalization of a glassy carbon electrode (GC) with gold nanoparticles (AuNPs) and Diazonium Salts. The main idea is to combine the interesting properties of both AuNPs and Diazonium salts. AuNPs were chosen for their electrocatalytic effect, large surface area, mass transport enhancement and for the strong affinity to mercury which will improve the sensor sensitivity. On the other hand, diazonium salts are used to improve the sensor stability by anchoring the AuNPs to the GC surface. First, nanometricorganic layer were grafted of the polished GC surface, by electrochemical reduction of 1.5 mM4-thiophenol diazonium (SH) using Constant Potential Electrolysis (CPE) in 0.1 M HCl solution at -0.55 V for 300 seconds. Electrochemical characterization performed by Cyclic Voltammetry (CV) and redox probes (ferricyanide and hexaamineruthenium(III)) revealed a total suppression of the signal, confirming the formation of a continuous blocking layer. This was confirmed by Atomic Force Microscopy (AFM)used to estimate the layer thickness, which was found to be 4 nm. Second, AuNPs were electrodeposited, for the first time, onto the diazonium multilayer by CPE in NaNO3 solution containing 0.25 mM HAuCl4for 300 seconds. Once more, redox probes were used to characterize the resulting interface and a total signal restauration and enhancement was observed after AuNPs electrodeposition, which highlights the effective AuNPs onto the organic layers. Field emission gun scanning microscopy (FEG-SEM) was used to provided further evidence and to quantify particle size and density of the AuNPs deposits. Both size and density are dependent on the CPE duration. Small homogeneous AuNPs with 27±3 nm average diameter and 158 NPs/µm2density were observed when the CPE was carried out during 300 seconds, while larger particles with 63±6 nm average diameter and lower density (63 NPs/µm2) were obtained when a longer CPE duration (600 seconds) is used. Finally, AuNPs were activated by cyclic voltammetry in H2SO4 prior to Hg(II) detection in order to homogenize the surface and to rearrange the crystallographic plans of the AuNPs. Herein, the well-known gold oxides reduction peak was observed and used to calculate the electroactive surface area (ESA) of the functionlized electrode. The electrochemical response of the final generated GC/SH/AuNPs interface towards Hg(II) was recorded by Square Wave Anodic Stripping Voltammetry (SWASV) in 0.01 M HCl solution containing different amounts of Hg(II). The SWASV procedure consists on the Hg(II) preconcentration at the electrode surface followed by the preconcentrated Hg(0) reoxidation in Hg(II). Under optimized conditions, and for a preconcentration time of 300 seconds, a well-defined peak, corresponding to Hg(0) reoxidation, was observed around 0.5 V/ECS. The sensor showed a linearity range from 1 up to 10 nM and allowed to reach picomolar level. The stability in HCl, phosphate buffer and air was also studied over several weeks: Once a week, the activation procedure was performed and followed by Hg(II) determination in order to evaluate the analytical performances of the sensor over time. Finally, Hg(II) detection assays were conducted in natural water samples collected from different sampling points. Figure 1

<p>High temperature aquifer thermal energy storage (HT-ATES) can play a key role for a sustainable interplay between different energy sources and in the overall reduction of CO<sub>2</sub>emission. In this study, we numerically investigate the thermo-hydraulic processes of an HT-ATES in the Greater Geneva Basin (Switzerland). The main objective is to investigate how to handle the yearly excess of heat produced by a nearby waste-to-energy plant. We consider potential aquifers located in different stratigraphic units and design the model from available geological and geophysical data. Aquifer properties, flow conditions and well strategies are successively tested to evaluate their influence on the HT-ATES economic performance and environmental impact. This was achieved using a new open-access, user-friendly and efficient code that we also introduce here as a possible tool for geothermal applications.</p><p> </p><p>The results highlight the importance of thorough numerical simulations based on more realistic exploitation when designing HT-ATES systems. We show that relations between thermal performance and the shape of the injected thermal volume are generally hard to derive when complex well schedules are imposed because the injected/produced volumes may not be equal. Despite more complex storage strategies to comply with legal regulations, the shallower group of investigated aquifers in this study remains economically more suitable for storage up to 90ºC. In average four well doublets will be required to store the yearly excess of energy. The deeper group of investigated aquifers, however, become interesting for storage at higher temperatures.</p>

The global energy demand is growing substantially. Clean and secure energy supply is a must for our civilization's sustainable development. Solar and wind energy is growing fast and can contribute significantly to meet the goals set by many countries to reduce greenhouse gas emissions. A deep and wide investigation of the environmental impact of solar and wind energy is important before any solar or wind plants' construction is made. In this study, the literature is reviewed to summarize the environmental impact of solar and wind energy systems in terms of the following factors; land use, water consumption, impact on biodiversity, visual and noise effects, health issues, and impact on micro climate. Although the benefits of solar and wind energy are obvious and great, negative perception of these technologies can inhibit their wide penetration in some regions. This review paper includes a critical and an inclusive analysis of solar and wind energy’s environmental impact and may serve as an important tool to conduct a proper environmental impact assessment. This critical analysis may serve also as a tool for developers, policy, and decision-when planning future solar and wind farms.

Abstract The mean squared slowing-down distance (Flux Age) and relaxation length have been measured in water using AmBe neutron source. With BF 3 -proportional detector the mean squared slowing-down distance was determined at cadmium resonance of 0.6 eV. The epithermal and thermal fluxes as a function of distance from source dipped in water were measured. The relaxation length for AmBe source is 10.8 ± 1.0 cm in water. The relaxation length was employed to extrapolate the observed data. The flux age comes to 58.5 ± 4.1 cm 2 . The effect of extrapolation of fast flux beyond measured values on flux age was also determined.

End-of-life tires are an increasingly important environmental burden. Since retreading is only partly possible, safe and economic methods of disposal need to be developed. Pyrolysis of ELTs, and subsequent upgrading/application of the produced energy carriers, is considered a valuable treatment method. In order to design the process, numerous operation units have to be taken into account. Char, vapour and gas are formed in the reactor. The char is purified from ZnO with a leaching process. The pyrolysis vapour is separated into a condensable fraction (oil) and a non-condensable fraction (gas) thanks to a cross-flow condenser with air as indirect cooling medium. The remaining gas is compressed to 6 bar: a part of it is continuously converted in electricity for process use, while another part is stored for power generation at peak demand time. A flowsheet of the process is established and environmental and assessment of investments and production are discussed. For the pyrolytic treatment of 3 ton/hr of ELTs, the required heat for the reactor is 271 kW at 380 °C, provided by electrical heating elements. A reactor volume is determined for a residence time of about 6 h. For the cross-flow condenser, indirectly air-cooled, a heat-transfer area of about 13.2 m2 is required. The compression of the gas the pressurized pyrolytic gas storage tank depends upon the excess pyrolytic gas produced during operation. The char cooler requires a heat-transfer area of 10.2 m2, when indirectly cooled by water. Operating parameters of the leaching and subsequent recovery of Zn2+ complete the design. The product added-value and the large-scale capacity make the process economically viable, although the ROI is between 2 and 3 years.

CSP plant are facing the new challenge of being water thrifty because of their desert, hot and arid usual location. Actually, the water consumption of a CSP plant can reach around 2500 m3/GWh. Solutions have to be found to face the constraint of a reducing water availability in the concerned areas. Regarding the different water use items (power block's cooling : 90% of the total water use, solar field cleaning, up to 5% and steam generation), the WASCOP project is aiming at proposing different kind of solution in a holistic approach that will support the reduction of the water used by the whole plant without affecting its profitability. Regarding cooling, dry cooling is turning to zero the water use but the plant efficiency and profitability is significantly affected due to capacity limitations under high ambience and additional utilities costs. The solutions proposed in WASCOP are turned to increase the efficiency of the cooling systems under high ambience, through the addition of heat storage for delayed heat exhaust, the addition of water spray for enthalpic air refreshment of dry cooling systems and their increased efficiency and the optimized management of hybrized cooling system (wet/dry). For the cleaning needs of the plant, WASCOP proposes to develop different cleaning strategies. Firstly, limitation of the dust settlement on the optical surfaces is done through dust barriers and antisoiling coatings (both for reflectors and absorber's glasses). Secondly detection of the soiling level, for adapted cleaning frequencies at different locations within the solar field, is proposed thanks to different kind of soiling sensors : at low cost for a wide distribution, or with a capacity to discriminate soiling to mirror permanent degradation, or for specifically absorbers glasses. Thirdly, innovative cleaning devices using very few water, are proposed such as an ultrasonic cleaner, removing settled dust with a thin water layer thanks to cavitation properties, and a heliostat cleaner using the optical surface condensed water, and the rotating properties of the heliostat to remove dust with an adapted rotating cleaning lip. All the solutions developed in WASCOP are supported by numerical modelling as to be able to propose them within a single toolbox, selecting the most adapted solutions, depending on the plant technologies (type of solar field : PTC, LFR or ST and type of current cooling : WCC,ACC, Hybridized…) and locations (DNI, soiling rate…). Current results show that the proposed solutions are able to reduce the water use significantly both for cooling and cleaning purposes without affecting the plant global efficiency. Additional works have whatever to be done to better quantify the associated water reduction of individual solution and their synergy potentials.