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The excessive release of toxic metal ions by the several industrial effluent streams into the environment has imposed a serious threat to the ecological system. Therefore, the removal of these toxic metal ions from the wastewater of various industrial effluent streams has received a considerable amount of interest and also currently becoming an imperative area of research. Since last few decades, ELM based separation processes have been become an attractive and efficient way for the removal of toxic metal ions, organic and inorganic acids, and industrial pollutants of the various aqueous waste effluent streams. ELM is an emerging alternative technique to the conventional solvent extraction processes with an additive advantage of low solvent inventory and energy requirements. Moreover, it also preconcentrates the solute by performing both extraction and stripping operations simultaneously in a single unit. The main aim of this review paper is to elucidate the comprehensive review on the ELM (its pertinent properties/characteristics), its membrane phase compositions, its stability, and its process parameters respectively and also to delineate the applications of this technique for the removal of various low concentrated solutes.

In arid and semi-arid regions of the southwestern United States and other parts of the world, flows of historically ephemeral streams are now perennially dominated by municipal and/or industrial effluent discharges, particularly in urbanized watersheds. Because effluent-dominated and dependent water bodies have previously received limited scientific study, we reviewed select contemporary topics associated with water quality of ephemeral streams receiving effluent flows. Our findings indicate that these ecosystems present numerous challenges to aquatic scientists and water resources managers, including: 1) appropriate ecosystems or upstream conditions used reference sites in biomonitoring are difficult to locate or do not exist; 2) water quality criteria, particularly for metals, are dramatically influenced by unique site-specific stream and land use conditions; 3) effluent-dominated streams represent worse-case scenarios for evaluating and predicting aquatic responses to emerging contaminants (e.g., pharmaceuticals and personal care products); 4) low-flow and drought conditions often preclude effective biomonitoring and water quality interpretation, or skew ambient assessment results; 5) chemical-physical water quality parameters (e.g., dissolved oxygen, conductivity, temperature) are dramatically altered by effluent and stormwater characteristics; and 6) beneficial reuse of reclaimed effluent waters potentially conflict with sustainability of ecological integrity. Subsequently, we recommend several water quality research priorities for effluentdominated water bodies.

Electrochemically converting nitrate ions, a widely distributed nitrogen source in industrial wastewater and polluted groundwater, into ammonia represents a sustainable route for both wastewater treatment and ammonia generation. However, it is currently hindered by low catalytic activities, especially under low nitrate concentrations. Here we report a high-performance Ru-dispersed Cu nanowire catalyst that delivers an industrial-relevant nitrate reduction current of 1 A cm–2 while maintaining a high NH3 Faradaic efficiency of 93%. More importantly, this high nitrate-reduction catalytic activity enables over a 99% nitrate conversion into ammonia, from an industrial wastewater level of 2,000 ppm to a drinkable water level <50 ppm, while still maintaining an over 90% Faradaic efficiency. Coupling the nitrate reduction effluent stream with an air stripping process, we successfully obtained high purity solid NH4Cl and liquid NH3 solution products, which suggests a practical approach to convert wastewater nitrate into valuable ammonia products. Density functional theory calculations reveal that the highly dispersed Ru atoms provide active nitrate reduction sites and the surrounding Cu sites can suppress the main side reaction, the hydrogen evolution reaction.Nitrate, a common pollutant in wastewater and groundwater, has been efficiently converted into valuable ammonia products via an electrochemical method using Ru-dispersed Cu nanowire as the catalyst.

Fluorescence excitation-emission matrix (EEM) spectroscopy combined with principal component analysis (PCA) and parallel factor analysis (PARAFAC) were used to investigate the compositional characteristics of dissolved and particulate/colloidal organic matter and its correlations with nitrogen, phosphorus, and heavy metals in an effluent-dominated stream, Northern China. The results showed that dissolved organic matter (DOM) was comprised of fulvic-like, humic-like, and protein-like components in the water samples, and fulvic-like substances were the main fraction of DOM among them. Particulate/colloidal organic matter (PcOM) consisted of fulvic-like and protein-like matter. Fulvic-like substances existed in the larger molecular form in PcOM, and they comprised a large amount of nitrogen and polar functional groups. On the other hand, protein-like components in PcOM were low in benzene ring and bound to heavy metals. It could be concluded that nitrogen, phosphorus, and heavy metals in effluent had an effect on the compositional characteristics of natural DOM and PcOM, which may deepen our understanding about the environmental behaviors of organic matter in effluent.

In this paper, we report a unique type of core-shell crystalline material that combines an inorganic zeolitic cage structure with a macrocyclic host arrangement and that can remove trace levels of iodine from water effectively. These unique assemblies are made up of an inorganic Archimedean truncatedhexahedron ( tcu ) polyhedron in the kernel which possesses six calixarene-like shell cavities. The cages have good adaptability to guests and can be assembled into a series of supramolecular structures in the crystalline state with different lattice pore shapes. Due to the unique core-shell porous structures, the compounds are not only stable in organic solvents but also in water. The characteristics of the cages enable rapid iodine capture from low concentration aqueous I 2 /KI solutions (down to 4 ppm concentration). We have studied the detailed process and mechanism of iodine capture and aggregation at the molecular level. The facile synthesis, considerable adsorption capacity, recyclability, and β- and γ-radiation resistance of the cages should make these materials suitable for the extraction of iodine from aqueous effluent streams (most obviously, radioactive iodide produced by atomic power generation). The removal of radioactive elements is important to human health and sustainable development. Here, the authors reveal the synthesis of water-stable Archimedean solids based on the earth-abundant element for the fast removal of trace iodine.

The process of carbon capture and sequestration has been proposed as a method of mitigating the build-up of greenhouse gases in the atmosphere. If implemented, the cost of electricity generated by a fossil fuel-burning power plant would rise substantially, owing to the expense of removing CO 2 from the effluent stream. There is therefore an urgent need for more efficient gas separation technologies, such as those potentially offered by advanced solid adsorbents. Here we show that diamine-appended metal-organic frameworks can behave as ‘phase-change’ adsorbents, with unusual step-shaped CO 2 adsorption isotherms that shift markedly with temperature. Results from spectroscopic, diffraction and computational studies show that the origin of the sharp adsorption step is an unprecedented cooperative process in which, above a metal-dependent threshold pressure, CO 2 molecules insert into metal-amine bonds, inducing a reorganization of the amines into well-ordered chains of ammonium carbamate. As a consequence, large CO 2 separation capacities can be achieved with small temperature swings, and regeneration energies appreciably lower than achievable with state-of-the-art aqueous amine solutions become feasible. The results provide a mechanistic framework for designing highly efficient adsorbents for removing CO 2 from various gas mixtures, and yield insights into the conservation of Mg 2+ within the ribulose-1,5-bisphosphate carboxylase/oxygenase family of enzymes. A cooperative insertion mechanism for CO 2 adsorption is shown to generate highly efficient adsorbents for carbon capture applications. Efficient CO 2 absorption in a metal-organic framework Advanced solid adsorbents are being investigated as potential agents for efficient gas separation technologies that could help make carbon capture technologies more economical. This paper probes the mechanism of carbon dioxide adsorption of a previously reported diamine-appended metal-organic framework. This material demonstrates unusual and potentially practically useful adsorption properties. The authors find that CO 2 adsorbs through insertion into the highly stable metal-amine bonds of the metal-organic framework. As a consequence of the homogenous and perfect spacing of amines, as dictated by the framework's topology, the insertion of a single CO 2 molecule induces neighbouring sites to also adsorb CO 2 in an unprecedented chain reaction process.

Moving bed biofilm reactor (MBBR) incorporates benefits provided by both attached and suspended growth systems. It is an advanced high rate wastewater treatment technology with high treatment efficiency; low capital, operational, maintenance and replacement cost; single reliable and robust operation procedure. Moreover, this technology is applicable to wide range of wastewater flows ranging from 10,000 to 150,000 m³ day⁻¹. The MBBR has proved to be effective in removing up to 90 % chemical oxygen demand and 95 % biochemical oxygen demand with nutrients from the effluent stream at optimum condition, provided there is sufficient retention time. It is a cost-effective way of upgrading existing wastewater treatment system as it is efficient, compact and easy to operate. This process can be provided for new sewage treatment works or for retrofitting existing wastewater treatment plants where a higher treated effluent standard is required without any running and capital cost. The performance of MBBR depends on the percent of media provided in the reactor, surface area of the biocarrier, dissolved oxygen and the organic loading. Various mathematical models are also described in this review paper which is generally used to calculate the reactor volume, effluent organic concentration and substrate removal rate.

Electrocatalysis offers a promising route to convert CO 2 into alcohols, which is most efficient in a two-step cascade reaction with CO 2 -to-CO followed by CO-to-alcohol. However, current alcohol-producing CO 2 /CO electrolyzers suffer from low selectivity or alcohol crossover, resulting in alcohol concentrations of less than 1%, which are further diluted in downstream cold-traps. As a result, electrocatalytic alcohol production has yet to be scaled beyond the lab (1-10 cm 2 ). Here, we reverse the electroosmotic drag of water using a cation exchange membrane assembly, enabling the recovery of over 85% of alcohol products at a concentration of 6 wt.%. We develop a multi-step condenser strategy to separate the produced alcohols from the effluent gas stream without dilution. Scaling up this approach to an 800 cm 2 cell resulted in an output of 200 mL alcohol/day. The electrocatalytic upgrading of CO 2 /CO provides a promising route to produce carbon-neutral alcohols but suffers from product loss to crossover and dilution. Here, the authors report on a CO reduction electrolyzer that recovers over 85% of alcohol without dilution, which is then scaled to 800 cm 2 .

Advanced oxidation process, via photo-catalytic oxidation process was demonstrated in this study as one of the promising techniques of simulated oily wastewater treatment. Several effective factors such as initial oil concentration, catalyst dose, stirring speed (rpm), pH value and hydrogen peroxide (H 2 O 2 ) dose influencing on the photo-catalytic degradation rate of oily wastewater were investigated. The catalyst used in this work was titanium dioxide (TiO 2 ). The solubility of oil in water was increased using emulsifier. Results indicated that the photo-catalytic oxidation process has a good removal percentage of oil from oily wastewater reached to 98.43% at optimum operating parameters of 1 g/L initial oil concentration, 850 rpm, 8 pH, 3 mL H 2 O 2 and 1.5 g/L of TiO 2 after 40 min of irradiation time. The degradation reaction follows a first order kinetics with a correlation coefficient (R 2 ) of 93.7%. Ultimately, the application of photo-catalytic oxidation processes at these optimum operating parameters on an industrial oily wastewater collected from an effluent stream of Ras Shukair at Red See supplied by Asuit Petrochemical Company was done in Egypt. The results showed that the best oil removal (99%) was achieved after adding 3 mL of H 2 O 2 in a reaction time of 40 min compared to without adding H 2 O 2 .

Acetic acid can be generated through syngas fermentation, lignocellulosic biomass degradation, and organic waste anaerobic digestion. Microbial conversion of acetate into triacylglycerols for biofuel production has many advantages, including low-cost or even negative-cost feedstock and environmental benefits. The main issue stems from the dilute nature of acetate produced in such systems, which is costly to be processed on an industrial scale. To tackle this problem, we established an efficient bioprocess for converting dilute acetate into lipids, using the oleaginous yeast Yarrowia lipolytica in a semicontinuous system. The implemented design used low-strength acetic acid in both salt and acid forms as carbon substrate and a cross-filtration module for cell recycling. Feed controls for acetic acid and nitrogen based on metabolic models and online measurement of the respiratory quotient were used. The optimized process was able to sustain high-density cell culture using acetic acid of only 3% and achieved a lipid titer, yield, and productivity of 115 g/L, 0.16 g/g, and 0.8 g·L−1·h−1, respectively. No carbon substrate was detected in the effluent stream, indicating complete utilization of acetate. These results represent a more than twofold increase in lipid production metrics compared with the current best-performing results using concentrated acetic acid as carbon feed.