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Cerium fluoride (CeF3) nanoparticles (NPs) were synthesized and applied in polysulfone (PS) membrane fabricated by phase inversion method. The produced nanocomposite membranes (PS/CeF3) with different contents of CeF3 NPS (0.25%, 0.5%, 0.75% and 1% w/w) were used to treat pharmaceutical wastewaters. The membranes were characterized by FESEM, EDX, XRD, FTIR, porosity, and water contact angle analyses. Evaluation of the characteristics and performance of the nanocomposite membranes confirmed that utilizing photocatalytic CeF3 NPs in membrane structure could effectively decompose organic contaminants in pharmaceutical wastewaters. It also improves the hydrophilicity and antifouling ability of membrane during filtration especially, in the presence of UV irradiation. The permeate flux of the PS membrane increased from 35.1 to 63.77 l/m2h by embedding 0.75% of CeF3 NPs in membrane structure due to the porosity enhancement from 71.36-78.42% and the decrease in contact angle from 62.9º to 53.73º. Moreover, the flux decline of PS/CeF3-0.75% membrane under UV irradiation was from 63.6 to 46.1 l/m2h that considerably lower than that of the neat PS membrane (from 34.7 to 4.9). On the other hand, the degradation efficiency of PS/CeF3-0.75% membrane was more than 97%, and COD removed was more than 65% while they were 75% and 31%, respectively for the nascent PS membrane. Therefore, applying the appropriate amount of CeF3 NPs in PS membranes not only greatly increased the permeate flux but also significantly enhanced the degradation efficiency and COD removal. This indicates that nanocomposite membranes can be confidently applied for pharmaceutical wastewater treatment UV irradiation.

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In the present work, the interaction of dichloromethane (CH2Cl2) and chloroform (CHCl3) on C20 and C19T (T = Cr, Ti, Fe, Ni) has been studied by density functional theory (DFT). The results have been investigated by binding energy, net charge transfer, electrical and thermodynamic properties, and frontier orbitals. Although the complexes of CH2Cl2 and CHCl3 on free C20 nanocages showed slightly binding energy (- 0.029 and - 0.006 eV, respectively), doping of Cr, Ti, Fe, Ni transition metal atoms on C20 nanocage improved the binding energy. The best binding energy was attributed to the adsorption of CH2Cl2 on C19Cr (- 0.755 eV). Based on ESP maps, doping of Cr, Ti, Fe, and Ni is the cause of strong electrophilic region creation which is very useful for adsorption process CH2Cl2 and CHCl3 on nanocages. Also, natural bond orbital (NBO) analysis showed that the best charge transfer was 0.253 eV which was related to the formation of C19Fe-CHCl3 complex. In addition, the least HOMO-LUMO energy gap between free nanocages (C20, C19Cr, C19Ti, C19Fe, and C19Ni) is 4.05 eV (C19Ti). The thermodynamic investigations indicated that due to the negative enthalpy, all of the studied adsorption processes were exothermic.

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In the current work, novel dynamic membranes (DM) were tested and introduced for cheese whey wastewater treatment based on resistant and inexpensive materials, polyesters, and chitosan. For the investigation of dynamic membrane (pre-coated and self-forming) characterizations, polyester as a low-cost and natural material with chitosan were chosen to provide the support of the target membrane. The inherent antifouling character of chitosan accompanied by its high hydrophilicity have made this polymer known as an attractive agent for membrane-based wastewater treatment operations. Zinc oxide (ZnO) and powdered activated carbon (PAC) were employed as the dynamic layer. Neat polyester had a chemical oxygen demand (COD) rejection ratio of about 57.61%, but the flux declined sharply. The higher removal efficiency was for the self-forming type: total phosphate (94%) and citrate (95.5%). Fouled dynamic membranes were backwashed by sodium dodecyl-sulphate (SDS), warm water, and distilled water. Results demonstrated that the pre-coated was reduced and fouling increased the flux recovery rate (FRR) (9.1%) while use of the self-forming DM exhibited an aggravation of fouling by decreasing of support FRR (11.1%). It was found that by substitution of deionized water and hot water with SDS, FRR was enhanced. In the following, the photocatalytic ability of the product was investigated. The UV light source increased the removal ratio and FRR. For example, self-forming COD rejection was enhanced (6.63%).

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The WO3 nanostructures were modified by doping with iron and then the polyethersulfone (PES) ultrafiltration (UF) membrane was developed using prepared Fe0-doped WO3 photocatalytic nanoparticles via layer by layer technology. According to UV-vis diffuse reflectance spectroscopy (UV-vis/DRS) characterization, the photocatalytic activity of WO3 nanoparticles could be improved by doping with Fe impurity. The prepared membranes were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX) and contact angle analyzer. The novel photocatalytic membranes were used in removal of hexavalent chromium (Cr(VI)) ions in batch mode as well as filtration system. The novel photocatalytic membranes have shown significant Cr(VI) ions removal under visible-light illumination. By depositing the (CHI-ALG)3.5 bilayers on the PES/UF membrane surface, the Cr(VI) rejection for 5, 25 and 50 mg/l feed concentration were enhanced from 21%, 17% and 9% for neat PES to 56.3%, 41.6% and 30.1% for PES/ (CHI-ALG)3.5 membrane and 99.2%, 92.1% and 78.1% for PES/ (CHI-ALG)3.5/ Fe0@WO3 membrane, respectively.

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In order to enhance the flux and wetting resistance of PVDF membranes for MD applications, we have developed a novel PVDF blend nanocomposite membrane using a polystyrene/ZnO (PS/ZnO) hybrid nanocomposite. The PS/ZnO nanocomposite was synthesized by free radical polymerization of styrene in the presence of vinyltrimethoxysilane (VTMS) grafted on the surface of ZnO nanoparticles. The blend nanocomposite membrane is fabricated via the phase inversion method and we examined the effects of the PS/ZnO nanocomposite on porosity, mechanical properties, hydrophobicity, LEPw, morphology, surface roughness and MD performance. It was found that the addition of the PS/ZnO hybrid nanocomposite (0.25, 0.5 and 0.75%) resulted in an increase in porosity (>70%), which is attributed to increased pore size and reduction of the spongy layer thickness. Furthermore, the addition of the nanocomposite also improved the surface roughness and contact angle. Comparison between the neat and modified membrane shows that with incorporation of the PS/ZnO nanocomposite, the desalination flux of 30 g L-1 saline aqueous solution significantly increased and rejection reached 99.99%. Meanwhile, during 100 hours continuous desalination process, the membranes composed of 0.75% PS/ZnO hybrid nanocomposite exhibited high performance stability (15.79 kg m-2 h-1) compared with the neat PVDF membrane.

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The purpose of this article is to evaluate the effect of adsorbents and alkali pre-treatment on microorganism activities of activated sludge (AS) for the treatment of landfill leachate (LFL). The chemical oxygen demand (COD) and BOD5/COD ratio of LFL used in this research were 10,500 and 0.68, respectively. In order to survey the role of porous absorbent, perlite was employed as an alternative with low porosity and was compared to powdered activated carbon (PAC), which has been most widely used in the treatment process. As a result, the COD removal efficiency increased from 32% to 47.7% when alkali LFL was loaded to the sequence batch reactors (SBRs) at the optimum conditions of the biological process. Also, at the same condition, both SBRs containing PAC and perlite showed COD removals of over 81% and 72%, respectively. The specific oxygen uptake rate (SOUR) showed that alkali pre-treatment reduces the toxicity effect of heavy metals on microorganism activities. The adsorption capacity (the uptake of COD) was analyzed by Langmuir and Freundlich isotherm models. Further, the kinetic study of COD adsorption during the treatment process demonstrated that the alkali pre-treatment of LFL proceeded faster and was intensified by the presence of adsorbents.

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In this study, a novel photocatalytic thin film nanocomposite (TFC) membrane was prepared for removal of hexavalent chromium (Cr(VI)) from aqueous solution. In this regards, a TFC membrane was modified by a layer of chitosan as an adsorbent and then was coated with a layer of synthesized photocatalytic nanoscale zerovalent iron@titanium dioxide (nZVI@TiO2) nanoparticles via layer-by-layer (LBL) technology. Prepared membranes were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and contact angle analysis. The Cr(VI) removal efficiency of the membranes was evaluated by batch removal and dynamic filtration tests. The water flux was increased from 26.2 to 39.7l/m2h as a consequence of improved hydrophilicity which was approved by contact angle analysis. The modified TFC membrane has shown the significant removal of Cr(VI) in retentate as well as the permeate stream. Further, the Cr(VI) removal of retentate flow decreased with increasing pH and feed concentration whereas the Cr(VI) removal of permeate was enhanced with increasing initial feed concentration. Increasing the flux recovery from 62% (for neat TFC) to 87% (for modified TFC membrane) demonstrated that the modification of membrane improved the anti-fouling property of the modified membrane.

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The co-treatment system of photosynthetic microalgae Chlorella vulgaris and adsorption was investigated as a possible combination of symbiotic mixed culture for the simultaneous removal of nutrients (ammonium and phosphate) and organic contaminants. In this study, response surface methodology for experimental design and optimization was used. For experiment operation, two factorial designs containing five chemical oxygen demand influent (CODin) concentrations (100, 200, 400, 600 and 700 mg l-1) and hydraulic retention times (0.63, 1, 1.75, 2.5 and 2.88 d) were applied. The co-treatment system performed successfully in removing both nutrients (nitrogen and phosphate) and COD, showing around 88%, 75% and 48% removal for the maximum level, respectively. The adsorption-photobioreactor (APBR) displayed superior performance of the microalgae growth rate compared to the photobioreactor. Also, the adsorption capacity (the uptake of COD) has been analysed with the first-order equation. The results showed that the experimental data of the APBR fit well with the model.

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Landfill leachate contains environmental pollutants that are generally resistant to biodegradation. In this study, indigenous and exogenous bacteria in leachate were acclimated in both biofilm and suspension forms to increase the removal of soluble chemical oxygen demand (SCOD). The bacteria from the leachate and sewage were acclimated to gradually increasing leachate concentration prepared using a reverse osmosis membrane over 28 days. The SCOD removal was measured aerobically or nominally anaerobically. Biofilms were prepared using different carrier media (glass, rubber, and plastic). The maximum SCOD removal in suspensions was 32% (anaerobic) and in biofilms was 39% (aerobic). In the suspension form, SCOD removal using acclimated bacteria from leachate and sewage anaerobically increased in comparison with the control (P < .05). In the biofilm form, the aerobic condition and the use of acclimated bacteria from leachate and sewage increased the removal efficiency of SCOD in comparison with other biofilm groups (P < .05). Three species of bacteria, including Bacillus cereus, Bacillus subtilis, and Pseudomonas aeruginosa were identified in the biofilm from leachate and sewage. Bioaugmentation technology using biofilms and acclimations can be an effective, inexpensive, and simple way to decrease SCOD in old landfill leachate.

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Determination of fouling mechanisms and accurate quantitative prediction of nano-porous membrane behavior are of great interest in membrane processes. This work has focused on a comprehensive comparison of two classical and new fouling models. Different operational conditions were tested to analyze the level of agreement of these models with experimental observation. Whey solutions of 8, 0.8 and 0.5 g/L were ultrafiltered in transmembrane pressures (TMPs) of 300 and 500 KPa through a synthesized polyethersulfone/copolymer blend membrane. Fouling mechanisms and the effect of different combinations of TMPs and protein concentrations were determined and analyzed by fitting the experimental data to different models. Based on the results obtained from classical models, it was found that the predictions of the cake layer formation model were quite acceptable, followed by the intermediate blocking model. The new combined pore blockage-cake filtration model, however, was found to be very successful in predicting the flux decline over time for every operational condition tested, with all relative errors of prediction less than 5%. The latter also showed a good performance in the transition from the pore blockage mechanism to cake layer formation.

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A bench-scale integrated process based on submerged aerobic powdered activated carbon-membrane bioreactor (PAC-MBR) has been utilized and established for the treatment of landfill leachate. The results showed that the submerged PAC-MBR system effectively removed biodegradable trace organic compounds by the average removal rate about 71 % at optimum food to microorganism (F/M) ratio of 0.4 gCOD/g day under a HRT of 24 h. Adding nanofiltration (NF) process increased the treatment efficiency up to 99 %. Further, adding powdered activated carbon to activated sludge (AS) resulted in a higher adsorption capacity in comparison with AS. Adsorption isotherms were investigated and fitted by the Langmuir and Freundlich isotherm models in which the Langmuir model performed better. The specific oxygen uptake rate (SOUR) showed that adding PAC reduces the effects of COD on microorganism activities. NH3-N, TKN and Heavy metals removal efficiency amounted to 97 ± 2, 96 ± 2, and 99 ± 2 %, respectively.

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This paper is focused on the fouling behaviour of the ultrafiltration membrane for landfill leachate treatment. Natural organic matter fouling is considered a critical factor controlling the membrane performance. In this regard, the polyethersulphone nanoporous membrane was fabricated by phase inversion. In order to investigate the effects of operating conditions on fouling, landfilled leachate treatment was done at different transmembrane pressure and feed concentration. At high concentration of landfill leachate, the effect of operating pressure can be negligible. The maximum amount of RFR was 0.961 for raw landfill leachate. Flux decline data were also obtained for the filtration of landfill leachate. The rates of flux decline drastically dropped to about 46-48% of the initial values in the first 30 minutes of the experiment at all the examined pressures. The data were also analyzed using a model in order to provide explanations for simultaneous pore blockage and cake formation. The model showed very good agreement with the data for all transmembrane pressures and feed concentrations. The initial fouling due to pore blockage is related to the feed concentration at constant pressure, so by diluting the feed concentration, the effect of pore blocking was increased.

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The treatment of the yeast industry wastewater was investigated by nanofiltration (NF) membrane process on a pilot scale. Two wastewaters were used as feed: (i) dilute wastewater with COD 2000 mg/L and (ii) concentrate wastewater with COD 8000 mg/L. The permeate flux, COD retention, color and electrical conductivity (EC) removal were evaluated in relation to trans-membrane pressure and long-term filtration. A linear growth in permeate flux was found with increasing in trans-membrane pressure for wastewaters. In addition, the COD retention, color and EC removal increased with trans-membrane pressure enhancement. The results obtained from the long-term nanofiltration of dilute wastewater indicated that the permeate flux decreased from 2300 L/day to 1250 L/day and COD retention increased from 86% to 92%. The quality of the permeate in term of COD is lower than the discharge standard in river (200 mg/L). Thus, this process is useful for treatment of wastewaters produced by yeast industry.

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Olive oil mill wastewater (OMW) is a concentrated effluent with a high organic load. It has high levels of organic chemical oxygen demand (COD) and phenolic compounds. This study presents a unique process to treat OMW. The process uses ultrafiltration (UF) membranes modified by a functionalized multi wall carbon nano-tube (F-MWCNT). The modified tube has an inner diameter of 15-30 nm and is added to the OMW treatment process to improve performance of the membrane. Tests were done to evaluate the following operating parameters of the UF system; pressure, pH and temperature; also evaluated parameters of permeate flux, flux decline, COD removal and total phenol rejection. The Taguchi robust design method was applied for an optimization evaluation of the experiments. Variance (ANOVA) analysis was used to determine the most significant parameters affecting permeate flux, flux decline, COD removal and total phenols rejection. Results demonstrated coagulation and pH as the most important factors affecting permeate flux of the UF. Moreover, pH and F-MWCNT UF had significant positive effects on flux decline, COD removal and total phenols rejection. Based on the optimum conditions determined by the Taguchi method, evaluations for permeate flux tests; flux decline, COD removal and total phenols rejection were about 21.2 (kg/m(2) h), 12.6%, 72.6% and 89.5%, respectively. These results were in good agreement with those predicted by the Taguchi method (i.e.; 22.8 (kg/m(2) h), 11.9%, 75.8 and 94.7%, respectively). Mechanical performance of the membrane and its application for high organic wastewater treatment were determined as strong.

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