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Most renewable energy sources are intermittent and seasonal, making energy storage and consumption problematic. Hydrogen gas can save and convey chemical energy, making it a promising sustainable energy source. Electrochemical water electrolysis technology’s sustainable and efficient hydrogen gas production attracts global attention. Higher hydrogen production rates enhance hydrogen volumetric energy capacity by storing intermittent hydrogen gas in high-pressure tanks. Pressurized storage tanks are cost-effective and efficient. Hydrogen gas may be stored economically and efficiently in pressurized tanks, making electrochemical water electrolysis a sustainable energy source. This paper introduced hydrogen as an alternative to natural gas, detailed water electrolysis technologies for hydrogen production, and highlighted how they can manufacture hydrogen efficiently and cost-effectively. The theoretical volume of gaseous hydrogen and oxygen that could be produced by electrolyzing water under typical temperature and pressure (STP) circumstances, assuming a 100% efficiency rate of the process. Since there are always two moles of hydrogen produced by electrolysis and one mole of gas occupies the same volume, the volume of hydrogen developed from water is twice that of oxygen. The volume of liberated oxygen is 0.21 (L/min), and the volume of liberated hydrogen is 0.42 (L/min) with a current density of 30 A, for instance, the tracer’s diffusion coefficient for all conceivable flow rates. A maximum value of 90 liters per hour was determined to be the threshold at which the diffusion coefficient increased with increasing flow rate. It would appear that the diffusion coefficient remains unchanged at flow rates greater than 90 liters per hour.

Abstract This research addresses the scalable and inexpensive synthesis of α-Fe2O3via hydrothermal method without any precipitating agent as well as the enhancement of solar driven photocatalytic and H2 production through doping different chromium proportions. Competency of α-Fe2O3, both pure and doped with chromium, to function as photocatalyst was evaluated by its interaction with multiple dyes, which was real-time monitored utilizing (Internet of Things) IoT technique. By adding chromium, the rate of deterioration increased substantially from 15 to 94% for TB under sunlight in a remarkably brief 20 min by employing a very small amount of Cr0.8Fe1.2O3 (0.3 g/L), as evidenced by high degree of mineralization i.e. 85% and LC-HRMS. Also, the rapid breakdown of Trypan Blue (TB) was indicated by BOD5/COD ratio. Moreover, Cr-doped α-Fe2O3 displays excellent H2 production (~ 132 μmol h−1 g−1) as compared to α-Fe2O3. This work highlights the potential utilization of Cr-doped α-Fe2O3 for the purification of industrial waste water and green energy harvesting.

The present study acknowledges a simple and effective sol–gel: doping method was used for band-gap engineering of titanium dioxide (TiO2) nanoparticles at lowest temperature (40 ℃) to produce doped TiO2 with dopants like N (nitrogen), C (carbon), Ag (silver), and Fe (iron) of different concentrations that decreased band-gap energies (i.e., > 3.2 eV) from UV range to visible range. Structural and functional properties were modulated by controlling the composition of dopants and precursors for better adsorption property and high specific surface area. Tauc-plot with UV–Vis spectrum: N (2.1 eV) > C (2.8 eV) > Ag (2.9 eV) > Fe (3.0 eV) suggested reduced band-gap energies (i.e., ≥ 3.0 eV). The photocatalytic effect was verified with the degradation of methylene blue (MB) and acid pink dye under visible light irradiation. Observation suggested that nitrogen-doped TiO2 (N-TiO2) with 2%wt. concentration has shown a higher degradation rate of 74% with respect to methylene blue in 60 min. A total of 98.4% degradation of acid pink dye (widely used in textile industry) was performed in 60 min by Fe2 (iron-doped TiO2 with 2% wt). The doped-TiO2 nanoparticles were also verified for their antimicrobial activity toward pathogenic strain. XRD (X-ray diffraction) revealed that the doped TiO2 nanoparticles had attained anatase structure at a lower temperature without calcination process as compared to the reported literature. [ABSTRACT FROM AUTHOR]

Graphene (GR) has considered to be a promising material to build proficient graphene-doped composites photocatalyst with superior catalytic activities for wastewater treatment. During the past decade, different graphene-doped composites have been constructed and applied in numerous solar and photocatalyst fields. GR-based composites have a sufficient surface area with numerous photocatalytic sites for wastewater treatment applications. In the present study the effect of hetero-atoms Aluminum, Nitrogen, and Boron on bandgap engineering and tuning of electronic and optical properties of GR-doped-composites by density functional quantum computing calculation. Our computed results demonstrate that hetero-atoms-doped-GR composites having direct energy band (Eg) semiconductor nature with an increment from 0.0 to 1.75 eV by the inclusion of hetero-atoms in GR, maybe some extra strong sites are formed in p state into the lifting of the energy bandgap (Eg). An extensive investigation of optical conductivity illustrates that increment in peaks from 2.5 to 4.0. Due to hetero-atoms dopant the absorbance peaks are increased and moved toward higher energy absorption. Our findings reveal that as compared to pure, Al, N,B hetero-atoms, the B-doped-GR surface has a large surface area with strong active sites for wastewater treatment. These theoretical findings can be useful in practical applications for wastewater remediation through hetero-atom-doped graphene composites. [ABSTRACT FROM AUTHOR]

Rapid industrialization and technological advancement have increased the release of toxic effluents into the water thus decreasing clean water sources day by day. Engineered materials and membrane filtration techniques have emerged as a reliable solution for wastewater treatment. Carbon-based nanomaterials are playing a major role due to their effective adsorbing capacity led by high surface area and porosity. Carbon nanotubes, Graphene and Graphene oxide and natural carbon-based materials were reviewed for the treatment of wastewater. The focused nanomaterials proved the future materials for wastewater treatment in terms of sustainability, availability, high surface area, catalytic activity, environment-friendly, ease of modification, non-toxicity, exceptional structural feature, adsorption selectivity with high strength and many more proves its novelty in the domain of wastewater treatment. This piece of work is a step towards the recent development in greener and sustainable carbon-based nanomaterials with the prospects of technologies that gives enhanced efficiency thus enabling large-scale production for wastewater treatment. [ABSTRACT FROM AUTHOR]

Transition and rare-earth metal oxide-supported nanomaterials have ignited an attraction in many fields such as energy, environment and etc. In this work, transition/rare-earth metal oxide-supported carbon-based nanomaterials (TRM) were prepared by hydrothermal method and it was characterized by UV-DRS, FTIR, XRD, AFM, FE-SEM, HR-TEM, and EDAX techniques. Doping levels of transition/rare-earth metal oxides on the carbon-based material impacts the photocatalytic degradation efficiency. The photocatalytic activity (PCA) of the prepared TRM was examined, and the highest degradation percentage was observed compared to other reported catalysts. TRM 2 exhibits the maximum degradation percentages of azo dye under sunlight (99.8 %) irradiation. The optimization studies were conducted, such as the effect of pH, catalyst dosage, and concentration. The optimum condition for photocatalytic degradation was pH - 6.51, TRM dosage - 10 mg, and dye concentration - 5 ppm. The kinetic studies were conducted for the various concentrations (5–20 ppm), and the rate of reaction was determined; it clearly illustrated that the reaction follows a pseudo-first-order kinetics. The enhanced PCA in the TRM 2 was due to the combination of transition/rare-earth metal oxides on the carbon-based material. This transition/rare-earth metal oxide-supported carbon-based nanomaterials (TRM) is practically helpful in degrading environmental pollutants in real-time wastewater under sunlight irradiation.

A chemostat is a laboratory device (of the bioreactor type) in which organisms (bacteria, phytoplankton) develop in a controlled manner. This paper studies the asymptotic properties of a chemostat model with generalized interference function and Poisson noise. Due to the complexity of abrupt and erratic fluctuations, we consider the effect of the second order Itô-Lévy processes. The dynamics of our perturbed system are determined by the value of the threshold parameter $ \mathfrak{C}^{\star}_0 $. If $ \mathfrak {C}^{\star}_0 $ is strictly positive, the stationarity and ergodicity properties of our model are verified (practical scenario). If $ \mathfrak {C}^{\star}_0 $ is strictly negative, the considered and modeled microorganism will disappear in an exponential manner. This research provides a comprehensive overview of the chemostat interaction under general assumptions that can be applied to various models in biology and ecology. In order to verify the reliability of our results, we probe the case of industrial waste-water treatment. It is concluded that higher order jumps possess a negative influence on the long-term behavior of microorganisms in the sense that they lead to complete extinction.

A chemostat is a laboratory device (of the bioreactor type) in which organisms (bacteria, phytoplankton) develop in a controlled manner. This paper studies the asymptotic properties of a chemostat model with generalized interference function and Poisson noise. Due to the complexity of abrupt and erratic fluctuations, we consider the effect of the second order Itô-Lévy processes. The dynamics of our perturbed system are determined by the value of the threshold parameter C 0 ⋆ . If C 0 ⋆ is strictly positive, the stationarity and ergodicity properties of our model are verified (practical scenario). If C 0 ⋆ is strictly negative, the considered and modeled microorganism will disappear in an exponential manner. This research provides a comprehensive overview of the chemostat interaction under general assumptions that can be applied to various models in biology and ecology. In order to verify the reliability of our results, we probe the case of industrial waste-water treatment. It is concluded that higher order jumps possess a negative influence on the long-term behavior of microorganisms in the sense that they lead to complete extinction. [ABSTRACT FROM AUTHOR]

Water sustenance is the primary exigency for human survival, besides being significant for food, energy generation, ecology, and socio‐economic modernization. The water crisis headed call for wastewater treatment. Owing to positive aspects of Organic Hybrid Hydrogels (OHH) viz. non‐toxicity, multiple‐functionalities, biodegradability, biocompatibility, and high sorption capacities; researchers are exploring their usage in waste‐water treatment for removal of organic (dyes) and inorganic (heavy metals, radionuclides) contaminants. The boon of OHH application is their ease of separation after the adsorption of pollutants by removing and dewatering them. This review corroborates the complete design of the synthesis of hydrogels, and the adsorption of impurities by them followed by their recovery, required for successful application in the removal of organic and inorganic contaminants from wastewater. It was observed hydrogels employed for the removal of metal ions and dyes follow either Langmuir or Freundlich isotherm or both. The usage of bio‐based hydrogels increased the adsorption of contaminants from wastewater. Due to the scarcer exploration of bio/hybrid hydrogels (especially carboxymethyl tamarind kernel gum), this review is expedient for researchers for developing green hydrogels as a water conservation and sustenance technique. [ABSTRACT FROM AUTHOR]

The study investigated the effect of hydrodynamic conditions on the formation of enhanced biological phosphorus removal (EBPR) granular sludge without losing the EBPR capacity, and its structure. The effect of hydrodynamic conditions on the formation of EBPR granular sludge was evaluated by using the minimum settling velocity, (Vs)min, and superficial air velocity. The application of (Vs)min strategy was proved to be beneficial in maintaining granular biomass without losing the EBPR capacity. Microscale structure, the chemical composition and chemically stored phosphorus of the matured EBPR granular sludge were determined by using ESEM‐EDX and cold perchloric acid (PCA) analyses. The results of both the ESEM‐EDX and PCA analyses proved that the poly‐P granules were stored extracellular in EPS structure of EBPR granular sludge. Therefore, the EBPR granular sludge has a high potential for both removal and recovery of phosphorus from wastewater, which needs to be investigated in future studies. [ABSTRACT FROM AUTHOR]

Background and Objectives: Contamination of surface and groundwater sources with aromatic compounds such as phenolic compounds is one of the newest environmental problems that humans encountered it today. One of the ways to remove these pollutants is the use of polymeric adsorbents. In this study, chitosan-bentonite-nano-graphene oxide nanosorbent was synthesized to investigate the phenol adsorption. Material and Methods: In this research, experimental design was performed using Design-Expert 7.0 software to investigate the effect of independent variables including nano graphene oxide, chitosan and bentonite on the dependent variable (phenol removal rate). Moreover, phenol absorption isotherm, kinetics and thermodynamics, were also examined. Results: Eventually, the optimum formulation of nano-adsorbent with specifications of 0.1 g of chitosan, 0.18 g of bentonite and 0.07 g of nano-graphene oxide was investigated. Optimal adsorption conditions were also obtained at a concentration of 100 ppm, pH=5 and 45 minutes of absorption time. Conclusion: Finally, it was found that the synthesized nanosorbent follows the Langmuir isotherm, which represents physical adsorption, and also the kinetics of the adsorption process is the diffusion between particles. As a result, it was found that the optimal application of this nano-adsrbent is in wastewaters with a temperature of less than 400 °C.

Electrocoagulation is one of physical techniques in waste-water treatment that applicable for organic waste from aquaculture. This research aims to determining the effectivity of electro-coagulation technique with different electrical voltages and duration consumed in waste-water treatment. The treatments used two electrical voltage levels (6 dan 12V) and four different durations of time consumed (15, 30, 45, and 60 minutes). The result showed the changes of water quality. Decreasing values shown by Chemical Oxygen Demand (COD) at the voltage of 12V and duration of 60’ (in about 82,89%); orthophosphate at the voltage of 12V and duration of 45’ (67.49%); turbidity at the voltage of 12V and duration of 60’ (69.65%); color at the voltage of 12V and duration of 60’ (70.49%); Total Suspended Solid (TSS) at the voltage of 12V and duration of 15’ (31.90%); and Total Dissolved Solid (TDS) at the voltafe of 12V and duration of 60’ (10.31%). Furthermore, increasing values were found in parameters of free ammonia at the voltage of 12V and duration of 15’ (291.09%); ammonium at the viltyage of 12V and duration of 30’ (8.85%); and pH at the voltage of 6V and duration of 60’ (16%). The best treatment in improving water quality of treated organic waste from aquaculture was the voltage of 12V for 30 minutes.

The development of new materials and prototypes with a sustainable approach to allow an efficient removal from water sources of emergent contaminants, such as drugs and antibiotics, currently represents the next challenging task in the water decontamination field. A modular photoelectrocatalytic reactor composed by single-element devices is here presented. Each single device is a stand-alone system based on a photoelectrochemical cell, which is composed by a WO 3 photoanode integrated in a tandem cell configuration with photovoltaic solar cells. Outstanding abatement results of different emerging contaminants (Atenolol, Carbamazepine, and Levofloxacin) in aqueous solution were obtained through photoelectrochemical degradation tests using the single stand-alone device. In addition, 4-Hydroxybenzaldehyde was selected as representative of natural organic matter, usually present in a real matrix. Herein, it has been proved that the system performance was optimal also for complex mixtures. • Photodegradation of emerging contaminants in wastewater via solar energy. • Nanocrystalline WO 3 active material as electrode for photoelectrocatalysis. • Photoelectrode/photovoltaic tandem cell (PEC/PV TC) configuration. • Environmentally sustainable and stand-alone solar device for wastewater treatment. [ABSTRACT FROM AUTHOR]

This paper presents the estimation of substrate and biomass concentrations inside a Chemostat used for waste-water treatment. These concentrations represent the state variables of the process model. Most research in this field used only deterministic models, not accounting for uncertainties and noises on the states and on the output. Hence, the estimation of these concentrations may not be sufficiently accurate. For a more realistic description, we used here a stochastic formulation. Unlike the other research works, we used a stochastic differential equations (SDE) model which provides a better representation of the system in his natural processing scale. This model also includes the aleatory effects in the process which had been discarded in the other works. We then deal with the state estimation problem using an Extended Kalman filter, which proceeds with a linearization of the model around a deterministic trajectory. The classical prediction and update steps of the filter are then carried-out and led to good results. Notice that the system in study has some interesting properties such as discrete-time observations, high noise intensities and slow-time evolution. Results are presented, discussed and compared with the related state-of-the-art researches.

The textile industry is quickly growing worldwide and has a universally beneficial effect on the economy. The waste-water generated with the growth of the textile industry can cause considerable health and environmental issues if it is not treated properly. Generally, physical, biological, and chemical processes are used independently or in combination to treat textile waste-water. The efficiency of any treatment process depends on the working criteria. In this paper, we implemented a new hybrid methodology based on the fuzzy analytic hierarchy process (FAHP) and fuzzy technique for order preference by similarity to ideal solution (FTOPSIS) to help workers in textile industries select the optimal waste-water treatment process. To illustrate how this hybrid methodology can be used to address the waste-water treatment problem, we conducted a case study involving 11 assessment criteria and four treatment processes used in the textile industry in India. Comparative analysis indicated that the survey overall mean was slightly lower than the overall mean for selected companies in the treatment process. [ABSTRACT FROM AUTHOR]

A microbial fuel cell is an efficient, cost-effective, and green methodology for electricity production and wastewater treatment. A single chambered microbial fuel cell (SCMFC) was designed to generate electric power from potato wastewater and also treated in terms of chemical oxygen demand (COD). A copper anode and zinc cathode were used as electrodes in the current study. Furthermore, best-optimized conditions of room temperature, pH 7, 90 Ω external resistances, and the presence of acetic acid substrate provides the maximum value of 12.45 mA current. The chemical oxygen demand (COD) of potato wastewater was calculated to evaluate the efficiency of SCMFC in treating potato wastewater. The results of optimization showed that maximum voltage obtained from SCMFC was 1.12 V (1120 mV) while COD removal was 40% which indicated that microbial fuel cells are alternative sources of fossil fuels to generate electrical energy from waste along with their treatment. [ABSTRACT FROM AUTHOR]

This paper presents the estimation of substrate and biomass concentrations inside a Chemostat used for waste-water treatment. These concentrations represent the state variables of the process model. Most research in this field used only deterministic models, not accounting for uncertainties and noises on the states and on the output. Hence, the estimation of these concentrations may not be sufficiently accurate. For a more realistic description, we used here a stochastic formulation. Unlike the other research works, we used a stochastic differential equations (SDE) model which provides a better representation of the system in his natural processing scale. This model also includes the aleatory effects in the process which had been discarded in the other works. We then deal with the state estimation problem using an Extended Kalman filter, which proceeds with a linearization of the model around a deterministic trajectory. The classical prediction and update steps of the filter are then carried-out and led to good results. Notice that the system in study has some interesting properties such as discrete-time observations, high noise intensities and slow-time evolution. Results are presented, discussed and compared with the related state-of-the-art researches. [ABSTRACT FROM AUTHOR]

Permanent magnets with non-uniform magnetic field and an electromagnet with 3–5 mT uniform magnetic field were applied to investigate their effects on both aerobic granulation and COD and ammonium removal in reactors with less than 7% coverage of magnetic field. It was found that both types of magnets had little influence on the granulation speed and the settling ability of granular sludge at the steady state. However, the maximum specific COD degradation rate and the maximum specific NH4+-N removal rate were increased by 45–54% and 30–50%, respectively, in the magnetic fields. Mean effluent COD with the electromagnet and the permanent magnet field, respectively, at the steady state, was 28 mg l−1 and 6 mg l−1, respectively, lower than the control at a statistical significance level of alpha = 0.05. No statistically significant increase in NH4+-N removal was observed at the steady state probably due to almost complete NH4+-N removal before the end of the cycle. In addition, it was found that extracellular polymeric substances in granular sludge with electromagnet were 77% more while soluble microbial products were much less compared with the control, suggesting a positively changed metabolism of granular sludge at steady state. The results in this study indicated that low-intensity magnetic field has a great potential to be applied in granular sludge for an improved wastewater treatment.

Effective methods for graphite felt (GF) treatment based on Fenton's reagent treatment and thermal modification have been used to improve microbial fuel cell (MFC) performance. The effects of the HO content in Fenton's reagent on the performances of MFCs with two different GFs (GFD and ACN-211) have been investigated. For GFD, a maximum performance of 190 mW/m was achieved with HO volume of 100 ml, while for ACN-211, the maximum performance of 450 mW/m is reached with HO volume of 150 ml. MFCs with both treated and untreated ACN-211 consistently showed higher power densities and greater durabilities than those with treated and untreated GFD. The degree of fouling on the surface of ACN-211 was much less than that on the surface of GFD. The higher surface area and better anti-fouling performance of ACN-211 are responsible for its relatively high power density during long-term operation. Thermal modification of ACN-211 was performed at different temperatures and for different durations, and the effects of treatment conditions on the performances of MFCs were studied. Results showed that an MFC fabricated with ACN-211 treated under 400 °C for 2 h exhibited the highest power density, with a maximum value of 470 mW/m, which is higher than that of an MFC fabricated with ACN-211 treated by Fenton's reagent. A Coulombic efficiency of 35% and an energy efficiency of 10% were achieved for an MFC fabricated with ACN-211. [ABSTRACT FROM AUTHOR]

Ion imprinted polymer monoliths (IIMs) for the adsorption of Hg(II) ions in tablet form were prepared by forming a mercury ion (template ion) complex with 2-(methacryloyloxy)ethyl trimethylammonium cysteine (ligand) and thermally copolymerized with a monomer (methacrylic acid), cross-linker (ethylene glycol dimethacrylate), initiator (benzoyl peroxide) and porogen (acetonitrile) in the polyethylene tube (drinking straw) as a mould. The formed composite was thoroughly characterized by means of FTIR, TGA, FESEM and BET, and further tested by applying the changes in solution pH, concentration, contact time, recycle test and selectivity. The analysis revealed that the activity of the materials was maximum at pH 4.7 and adsorption capacity of Hg(II) by IIMs followed the Langmuir isotherm model. The adsorption equilibrium was achieved after 120 min and followed the second-order reversible kinetics. In addition, we found that the IIMs were reusable up to 15 cycles and exhibited good selectivity towards the Hg(II) ions even in the presence of other interference ions such as Pb(II), Cd(II), As(II) and Cr(III). On further testing for the recovery of Hg(II) ions in real-time aqueous samples (contaminated petrochemical and mining industries), the IIM tablets showed higher selectivity and excellent reusability. In summary, we indicate that the IIMs are easy to prepare, possess high levels of permeability, porosity and selectivity, and offer excellent reusability, thereby making them one of the promising candidates for the successful removal of mercury ions from industrial samples. [ABSTRACT FROM AUTHOR]

The influence of the organic loading rate (also known as active anodic chamber volume) on bioelectricity generation in a continuous, two-chamber microbial fuel cell for the treatment of synthetic wastewater, with glucose as the only carbon source, was examined. Ten sets of experiments with different combinations of hydraulic retention times (0.24–1.14 d) and influent chemical oxygen demand concentrations were performed to verify the impact of organic loading rate on the voltage generation capacity of a simple dual-chamber microbial fuel cell working in continuous mode. We found that there is an optimal hydraulic retention time value at which the maximum voltage is generated: 0.41 d. However, there were no similar effects, in terms of voltage generation, when a constant hydraulic retention time with different influent chemical oxygen demand of wastewater was used. The obtained maximal voltage value (600 mV) has also been compared to literature data. Computational fluid dynamics (CFD) was used to calculate the fluid flow and the exit age distribution of fluid elements in the reactor to explain the obtained experimental results and identify the crucial parameters for the design of bioreactors on an industrial scale. [ABSTRACT FROM AUTHOR]

Submerged membrane bioreactors (sMBRs) are a promising technology for nitrogen removal in recirculating aquaculture systems (RASs). However, there are still relatively few reports on the experimental application of this strategy. In this study, a laboratory-scale system, mimicking a RAS fitted with a sMBR, was designed and automated, and a simple dynamic sMBR model including biological and physical phenomena was validated. The system was analyzed based on measurements collected by a data logging structure involving a programmable logic controller (PLC), an industrial network protocol and a LabView application software. This study confirms the suitability of sMBR systems within aquaculture applications. The dynamic model has good predictive capabilities and could be used for the design of advanced control structures, such as model predictive control. [ABSTRACT FROM AUTHOR]

The overall influence of dissolved oxygen (DO) concentrations and biofilm thicknesses on single stage anammox process performance has been evaluated in this study. Results indicated the biofilm displayed a rapid initial increase and followed by a relatively slower formation rate during the operational period. The optimal DO concentration could be determined from a variety of biofilm thicknesses and as well the best biofilm thickness was required among different DO levels. In our lab-scale single stage anammox reactor with a constant hydraulic retention time of 1.0 h and influent ammonium of 400 mg L −1 , an optimal nitrogen removal capacity was acquired (TN removal loading of 2.18 kg-N m −3 d −1 ) at the DO level of 0.6 mg L −1 and biofilm thickness of 700 μm. Species identification showed that Nitrosomonas related aerobic ammonium-oxidizing bacteria (AerAOB) and Candidatus Brocadia fulgida -like anaerobic ammonium-oxidizing bacteria (AnAOB) were the predominant functional bacteria mixed together with each other and exhibited no distinct niche. However, AerAOB exhibited higher biodiversity at the thinner biofilm while AnAOB showed a stable but lower biodiversity. Moreover, the population of AnAOB was smaller along with more scattered cells at the thinner biofilm while they trended to form specific irregular cauliflower-like zooglea as biofilm thickness increased. [ABSTRACT FROM AUTHOR]

The Orange County Sanitation District (OCSD) diverted wastewater discharge (5.3 × 10 8 l d −1 ) from its primary deep (56 m) outfall 8 km offshore, to a secondary shallower (16 m) outfall 1.6 km offshore for a period of three weeks. It was anticipated that the low salinity and density of the effluent would cause it to rise to the surface with limited dilution, elevating nutrient concentrations in near-surface waters and stimulating phytoplankton blooms in the region. Three Teledyne Webb Slocum gliders and a Liquid Robotics surface wave glider were deployed on transects near the outfalls to acquire high spatial and temporal coverage of physical and chemical parameters before, during, and after the wastewater diversion. Combined autonomous underwater vehicle (AUV) and MODIS-Aqua satellite ocean color data indicated that phytoplankton biomass increased in the upper water column in response to the diversion, but that the magnitude of the response was spatially patchy and significantly less than expected. Little evidence of the plume or its effects was detectable 72 h following the diversion. The effluent plume exhibited high rates of dilution and mixed throughout the upper 20 m and occasionally throughout the upper 40 m during the diversion. Rapid plume advection and dilution appeared to contribute to the muted impact of the nutrient-rich effluent on the phytoplankton community in this coastal ecosystem. [ABSTRACT FROM AUTHOR]

The influence of g-C 3 N 4 in TiO 2 photocatalyst on photodegradation of organic pollutant in aqueous solution has been investigated in the present study. The g-C 3 N 4 was synthesized from low cost urea and used as precursor to synthesize g-C 3 N 4 /TiO 2 composite by wet impregnation method. The synthesized g-C 3 N 4 and g-C 3 N 4 /TiO 2 composite photocatalysts were thoroughly characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and UV–vis diffuse reflectance spectroscopy. The photocatalytic performance of pure g-C 3 N 4 , pure TiO 2 and g-C 3 N 4 /TiO 2 composite photocatalysts were evaluated for the photodegradation of acid orange 7 (AO7) under visible light irradiation. The photocatalytic experiments demonstrated that the g-C 3 N 4 /TiO 2 composite photocatalyst showed much better photocatalytic degradability of AO7 than the pure TiO 2 and g-C 3 N 4 . This may be due to the increased absorption of light in the visible region and also by a lower recombination of charge-carriers. Further, the photoelectrochemical measurements of g-C 3 N 4 /TiO 2 revealed the faster migration of photo-induced charge-carriers. This study demonstrates that g-C 3 N 4 /TiO 2 composite can be a good candidate for environmental remediation of polluted waters. [ABSTRACT FROM AUTHOR]

A tubular Microbial Fuel Cell (MFC) reactor consisting of four modules (total reactor volume of 1 l) was fed with food processing washdown water as a chemical oxygen demand (COD) removal process to decrease effluent pollution levels and discharge costs. Two different operational modes were tested: (A) Under static electrical loads with substrate circulated to and from different storage vessels and (B) employing maximum peak power point tracking (MPPT) whilst re-circulating substrate through a single storage vessel. After 7 cycles through the reactor, notionally equivalent to 28 concatenated tubular MFC modules, 84% of the soluble COD (960 mg l −1 ) was removed from the effluent in Mode A and 70% (800 mg l −1 ) in Mode B with MPPT. In the study, acetic acid was consumed first and propionic acid increased initially before depletion after 7 cycles, showing that higher carbohydrates were degraded during the effluent polishing process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ru 0.9 Eu 0.1 O x @TP enhances catalytic selectivity and stability towards chlorine evolution reaction. • Doping rare earth metal Eu into RuO 2 causes a strong charge redistribution between Eu and Ru. • The DFT calculations prove that the doped Eu could improve the adsorption ability with OCl and suppress OOH intermediates. The chlorine evolution reaction (CER) plays a significant role in the generation of Cl 2 and active chlorine during chlor-alkali electrolysis. However, CER competing with oxygen evolution reaction (OER) on the anode side always suffers from low selectivity due to the adsorption of OCl and OOH intermediates on active sites. Herein, Eu-doped RuO 2 catalysts on Ti plate (TP) with excellent CER performance is reported by the rational design of doping rare earth metal Eu into RuO 2 , which induces a strong charge redistribution between Eu and Ru and tunes the adsorption ability. The representative Ru 0.9 Eu 0.1 O x @TP reveals a yield of active chlorine of 12.8 mg h−1 with a high selectivity of 96.5% toward CER at 20 mA cm−2, and a mass activity of about 2.94 times higher than that on Ru-based DSA in 0.5 M chloride-containing solution. Additionally, Ru 0.9 Eu 0.1 O x @TP shows a robust stability of over 225 h at 1000 mA cm−2 in 0.5 M of H 2 SO 4. The microstructural characterizations and density functional theory (DFT) reveal that doping Eu into RuO 2 decreases the charge on Ru sites, thus enhancing the adsorption ability with OCl and supressing OOH. In addition, Ru 0.9 Eu 0.1 O x @TP exhibits the activity toward NH 4 +-N removal rate with a degradation rate of 95% in 1 h at 20 mA cm−2, suggesting its potential application for waste-water treatment. Moreover, the expected service life of the electrode is estimated to exceed 13.4 years. [ABSTRACT FROM AUTHOR]

The industrial production of chitin generates large volumes of protein effluents that need to be handled and depurated before discharge. The current study highlights the suitability of four effluents, derived from the chemical and enzymatic hydrolysis of Illex argentinus pen to produce β-chitin, as peptones for the growth and metabolite production of six bacteria with different nutrient requirements. Batch cultures were carried out determining the growths by dry weight and viable cell counts and modelling kinetics using the logistic equation. Two lactic acid bacteria were perfectly supported by alternative media formulated with chitin effluents and the results were better than those found in commercial ones. For the other four bacteria, the biomasses in chitin peptones were lower but the number of produced cells was similar to those defined using Marine medium (MM) and tryptone-soy broth (TSB). An economic assessment demonstrated the profitability achieved when commercial peptones are replaced by those generated from squid pen: reduction of costs by 6 times for lactic acid bacteria, 50-100 times for marine bacteria and 6–17 times for Gram (+) bacteria. [ABSTRACT FROM AUTHOR]

High strength wastewaters (HSWW) are energy-rich biogenic waste streams. Their properties make them promising substrates for Microbial Fuel Cells (MFC). Three HSWW, as substitutes for human Blackwater (BW) were investigated in 12 single chamber MFCs in batch and continuous operation over 80 and 67 days, respectively: an idealized HSWW, a synthetic human BW, and pig manure. Polarization curves (IV-curves) and cyclic voltammetry were used to characterize MFC performance and the substrates with respect to limiting factors in MFC operation. Power densities are provided as IV-maxima (up to 969 ± 131 mWm −2 anode surface area) and steady state outputs across a fixed external resistance (up to 586 ± 21 mWm −2 ). TOC-removal, coulomb efficiency, and energy recovery rates (up to 0.79 kWh kg −1 TOC removed or 0.49 kWhkg −1 COD removed) were compared with respect to the properties (e.g. bioavailability) of the investigated substrates. Aspects of MFC decentralization for BW treatment are addressed and discussed. [ABSTRACT FROM AUTHOR]

Biological phosphorus removal (BPR) has been demonstrated to be successfully achieved in the aerobic/extended-idle (AEI) wastewater treatment regime in previous bench-scale studies. To date, however, its feasibility has never been evaluated by any full-scale investigation. Here we report a first full-scale (180 m 3 /day) evaluation of the AEI process and its integration with intermittent sand filter to treat highway rest area sewage that is often neglected but actually brings significant impacts on receiving water bodies in China. The results showed that 70–99% of influent phosphate was removed in the AEI zone, although the sewage contained 23–37% of carbohydrate that is usually considered to be detrimental for BPR. Batch experimental investigation revealed that the presence of glucose (model compound of carbohydrate) promoted the AEI-inducing BPR efficiency, as opposed to deteriorating the conventional anaerobic/oxic regime-inducing BPR performance. Although the performance of AEI zone was affected by seasonal variation, the efficiencies of contaminant removal were stable and excellent (total nitrogen > 86%, others > 92%) in the integrated system. This study offers an attractive option for BPR from carbohydrate-rich wastewaters and also provides a prototype for wastewater treatment in remote areas. [ABSTRACT FROM AUTHOR]

Nowadays, there are plenty of models of the anaerobic digestion process, however the impact of this odor emission on these models has received very little attention. Hydrogen sulfide (H 2 S) has been used as odor trace marker for odor dispersion studies which is formed by microbial action of sulfate reducing bacteria under anaerobic conditions. A mathematical model with focus on the H 2 S generation with a reduce number of parameters of five stages was developed. The model and parameters were calibrated and validated with experimental data from two pilot scale anaerobic reactors treating sewage sludge. The developed model is able to describe properly the dynamic behavior of this system, particularly, its gas phase composition with an accuracy of 90%, for hydrogen sulfide and carbon dioxide, and 60% for methane, within 99% of confidence. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate microbial communities in a continuous anaerobic phenol-degrading system using a next generation sequencing tool. The anaerobic granules adapted to phenol were first obtained by repeated-batch operation, which were then inoculated in an up-flow anaerobic sludge blanket reactor (UASB) operated at various organic loading rates (OLRs). Lag periods for both phenol degradation and CH 4 production decreased as batch fermentation was repeated, indicating a progressive adaptation of the granules to phenol. In the UASB operation, the highest OLR handled was 6 kg COD/m 3 /d, in which the attained biogas production rate, phenol degradation, and CH 4 contents were 2.1 m 3 /m 3 /d, 79.0%, and 75.3%, respectively. Syntrophorhabdus and Clostridium were found to be the dominant bacteria, whose sum occupied around 60% of total bacterial sequences. In particular, there was a significant increase in Syntrophorhabdus (39.2% of total bacterial sequences), known to degrade phenol to benzoate and subsequently to acetate and hydrogen in syntrophic association with a hydrogenotrophic methanogen. In terms of archaea, Methanosaeta (42.1% of total archaeal sequences), and Methanobacterium (24.5% of total archaeal sequences) became dominant as operation continued, which were negligible in the inoculum. [ABSTRACT FROM AUTHOR]

In present study, different blend compositions of polybenzimidazole (PBI) and polyvinylpyrrolidone (PVP) have been analyzed as polymer electrolyte membrane in single chambered MFCs. Four membranes namely, pure PBI, PBI/PVP 70:30, 50:50, and 30:70 blend ratios with increasing PVP content were casted, where the hygroscopic properties of the membranes were found enhanced with increasing PVP content. The membranes were characterized at room temperature (22 + 2 °C) with different ion exchange (IEC) and proton conductive capacities, where an IEC of 0.06 meq g −1 , 0.15 meq g −1 , 0.24 meq g −1 and 0.36 meq g −1 and proton conductivity of 2.5 × 10 −4 , 4.8 × 10 −4 , 9.36 × 10 −4 and 1.2 × 10 −3 S cm −1 were observed from pure PBI, PBI/PVP 70:30, 50:50, and 30:70 membranes respectively. As membrane electrode assemblies (MEA), the casted membranes were sandwiched in-between carbon cloths, where a maximum power and current density of 231.38 ± 12 mW m −2 and 1242 ± 62 mA m −2 were observed from 30:70 PBI/PVP fitted MFC, using mixed firmicutes as biocatalysts. A gross 84.36% COD removal from 30:70 PBI/PVP membrane indicated the added effect of PVP in blend composition with approximately 81% higher power over pure PBI membrane. The results indicate the potential efficacy of PBI/PVP blends as seperators in microbial fuel cell, for bio-energy conversion over pure PBI membrane. [ABSTRACT FROM AUTHOR]