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The core of this study is utilization of the facile one-side self-polymerization of dopamine (DA) on surface of the non-recoverable polyethersulfone (PES) membrane and its antifouling ability assessment during oil-in-water (O/W) emulsion separation. The pristine PES membrane was coated by DA solution for 2 and 4 h. The membranes were characterized using FESEM, AFM, FTIR, water contact angle (WCA) and underwater oil contact angle (UOCA) analysis. The results showed that hydrophilicity and underwater oleophobicity can be achieved successfully. Antifouling properties of the modified membranes were improved so that water flux of the 4 h polydopamine (PDA) coated membrane increased about 793% in comparison to the pristine PES membrane. Also, implementation of classical models showed that PDA coating changes the membrane fouling mechanism from standard blockage model to cake filtration model. The 4 h PDA modified membrane shows antifouling property and easy recovery capability during 30 h of operation. Also, the dependences of steady-state water flux were investigated via changing initial oil concentration, feed salinity, trans -membrane pressure and self-polymerization time of DA. Self-polymerization time of DA was found as the most influential factor on water flux. Also, during O/W emulsion separation, all the membranes exhibited high removal efficiency (above 98%) introducing a promising candidate for practical applications. Image 1 • PDA was coated on PES membrane to improve its antifouling ability. • Membrane fouling mechanism was analyzed by classic fouling models. • Increasing polymerization time led to improved hydrophilicity and underwater oleophobicity. • Influences of self-polymerization time along with operating parameters on water permeability were evaluated. [ABSTRACT FROM AUTHOR]

Polymeric membranes have been commercially used in wastewater treatment and desalination. Polymeric membranes efficiency decreases with time due to fouling, thermal and mechanical instability, chemical degradation and also swelling phenomenon occurrence. Among polymers, sulfone-based polymers have been research interest of membrane manufacturers. However, their intrinsic hydrophobic nature causes fouling under aqueous filtration. Polymer nanocomposite membranes (PNMs) with improved properties and performance than polymeric membranes have attracted much attention all over the world. Size and type of nanofillers, degree of aggregation/dispersion, nanofillers quantity incorporated into the polymeric matrices and compatibility between polymers and nanofillers are the main factors that can considerably affect the PNMs performance and properties. Carbon nanotubes (CNTs) with unique physicochemical properties could be used to improve the PNMs performances in terms of permeability and antifouling properties. Also, it has been reported that by incorporation of CNTs in the polymer matrices, hydrophilicity/hydrophobicity, pore size, porosity, mechanical and thermal stability, surface charge, solute rejection, roughness and other physicochemical properties of the PNMs could be improved, significantly. Effective CNTs functionalization could lead to the improved PNMs characteristics. This article presents an overview of current progresses in fabrication and characterization of CNTs-based PNMs used in various membrane separation processes for water treatment applications with particular emphasis on their challenges and advances. Also, effects of CNTs and their functionalization on structure, performance and properties of the CNTs-based PNMs are deeply investigated. [ABSTRACT FROM AUTHOR]

Positively charged hybrid nanofiltration membrane were prepared by the incorporation of Triethylenetetramine (TETA) functionalized multiwall carbon nanotube (MWCNT) into Polyethersulfone (PES) matrix. In the best nanoparticles loading ratio of 0.4 wt%, the fabricated membrane exhibits a pore diameter of 0.73 nm, a molecular weight cut off (MWCO) of 570 Da and a pure water flux (PWF) of 84.35 L/m 2  h which shows 130% improvement compared to the neat PES. Regarding salts rejection, it follows the order R (MgCl 2 ) > R (MgSO 4 ) > R (Na 2 SO 4 ) > R (NaCl) which confirms positively charge nature of the membranes. Furthermore, the prepared membrane demonstrates effective rejection for two cationic dyes i.e. Rhodamine B (99.23%) and Crystal violet (98.43%) and acceptable rejection for two anionic dyes i.e. Indigo carmine (87.12%) and Orange G (82.13%). In addition of improvements in their mechanical and thermal stabilities, antifouling nature of the hybrid membranes enhances as well due to lower surface roughness and higher hydrophilicity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Antifouling hollow fiber membranes with inner-selective layer were synthesized via facile fabrication method. • High water flux and low reverse salt flux were obtained through OMBR application where wastewater was used as feed flow. • Hollow fiber membranes consisted of antimicrobial outer skin layer and porous medium for enhance wastewater treatment. • Specific performance index (SPI), as a new concept was introduced which is believed to have the potential to be used as a unique FO membrane characteristic. Forward osmosis (FO) hollow-fiber membranes were prepared by in situ thin layer assembly of polyethyleneimine (PEI) on antifouling PES-based porous nanocomposite membranes during membrane formation by spinning and phase inversion, via incorporation of surface-modified silver nanoparticles (NPs) in the dope solution and addition of PEI in the bore liquid; after cross-linking with glutaraldehyde the FO selective layer was obtained at the lumen surface while the shell surface had ultrafilter (UF) properties. This design enabled the utilization of the FO membranes in active layer facing draw solution (DS) orientation to employ maximum effective osmotic pressure, while the UF layer in combination with the antibacterial NPs was supposed to reduce fouling by the wastewater used as feed solution (FS). The quality of the active layer assembly was characterized using atomic force microscopy and scanning electron microscopy analyses, as well as salt rejection, structural parameter (S), and molecular weight cut-off (MWCO) measurements. The separation performance of these membranes was evaluated in an osmotic membrane bioreactor (OMBR) system, showing for the best FO nanocomposite membranes less than 10% fouling and flux reduction over 5 cycles of operation over a total period of 5 days. The best-suited membrane showed promising separation performance in the OMBR system by providing 43.4 LMH water flux and only around 0.2 g/l specific reverse salt flux (SRSF) with 1 M NaCl and DI water serving as DS and feed, respectively. This study focused also on distinctive performance criteria in combined FO and OMBR systems, such as the membrane's potential in a pretreatment step of brine streams (used as DS) to provide proper feed composition for RO units and introduced a new specific performance index (SPI) for better characterization of FO membranes which summarizes all essential characteristics of the membrane application, instead of using existing structural parameter equations for membrane characterization. The best-suited FO membrane offered an SPI of 778.2 gl−1 m−2 h−1, meaning 778.2 g/l reduction of TDS in DS per unit membrane surface area per hour. [ABSTRACT FROM AUTHOR]

ABSTRACT In this research, polyethersulfone (PES)/polyacrylonitrile (PAN) blend ultrafiltration hollow fiber membranes were prepared via phase inversion induced by a dry-jet wet spinning process. The membranes were characterized by water contact measurements, scanning electron microscopy analysis and permeability measurements, and fouling-resistance measurements. The results show that water contacts of the membranes are enhanced by increasing the PAN content in the spinning dope. The results of an experimental study on separation of oil from oily wastewaters are presented. The results demonstrated that the prepared PES membranes are effective in removing chemical oxygen demand (80.6%), total organic carbon (89.3%), turbidity (99.3%), total suspended solid (100%), and oil and grease content (99.7%), and final permeation flux of about 73.5 L/m2h. Also, it was found that 75/25 wt% of PES/PAN have higher mechanical strength and good separation performance. Hermia's models were used for prediction of the decline in permeation flux. Experimental data and models predictions were compared. The results showed that there is reasonable agreement between experimental data and the cake layer model followed by the intermediate blocking model. [ABSTRACT FROM AUTHOR]

In this work, metal-organic framework derived porous carbon (MOFDPC) nanoparticles (NPs) were synthesized and incorporated into cellulose acetate (CA) polymeric matrix to prepare biodegradable CA/MOFDPC adsorptive membranes via phase inversion method. Polyethylene glycol (PEG) was used as pore former agent. Performance of the prepared membranes was evaluated in methylene blue (MB) removal from aqueous solution via continuous adsorption experiments. The physicochemical properties of the fabricated membranes were characterized by contact angle measurement, SEM, FTIR, AFM, TGA and tensile strength analysis. At first, the effects of PEG concentration and MOFDPC NPs loading were investigated. It was found that the best performance is obtained for the prepared membrane containing 15 wt% PEG and 2 wt% of MOFDPC NPs as the optimal adsorptive membrane. Then, the effects of solution pH, initial MB concentration and operating pressure on the MB removal capability of the prepared optimal adsorptive membrane were investigated. Reusability of the optimal adsorptive membrane was studied via subsequent adsorption/desorption cycles. Its long-term behavior was also studied. The obtained results showed that the prepared biodegradable CA/MOFDPC adsorptive membrane with MB removal percentage of 98.2% and permeate flux of 76.03 LMH and excellent reusability and long-term behavior can be potentially utilized for wastewater treatment applications especially MB removal. [Display omitted] • CA/MOFDPC adsorptive membranes were prepared via phase inversion method. • Membrane performance was evaluated in MB removal from aqueous solution. • Membrane containing 2 wt% of MOFDPC NPs exhibited the best performance. • The MB removal percentage of 98.2% and permeate flux of 76.03 LMH were achieved. • Effects of solution pH, initial MB concentration and pressure were also investigated. [ABSTRACT FROM AUTHOR]

Abstract: Artificial neural network (ANN) was applied to predict separation percent (SP) of lead ions from wastewater using electrodialysis (ED). The aim was to predict SP of Pb2+ as a function of concentration, temperature, flow rate and voltage. Optimum numbers of hidden layers and nodes in each layer were determined. The selected structure (4:6:2:1) was used for prediction of SP of lead ions as well as current efficiency (CE) of ED cell for different inputs in the domain of training data. The modeling results showed that there is an excellent agreement between the experimental data and the predicted values. [Copyright &y& Elsevier]

Abstract: Membranes are widely used in wastewater treatment. In this study, cellulose acetate (CA) (M w =52,000) was mixed with polyethylene glycol (PEG) (M w =400) as an additive in N-methyl-2-pyrrolidone as a solvent. The phase inversion method was used for preparation of flat sheet membranes. Effects of CA and PEG concentrations and also coagulation bath temperature on the membrane morphology were discussed in terms of membrane thickness and cross section structure. Pure water permeation flux of the membranes was also measured. [Copyright &y& Elsevier]

Abstract: This paper presents experimental data, an artificial neural network (ANN) model and a mathematical model (MM) for a laboratory scale electrodialysis (ED) cell. The aim was to predict separation percent (SP) of Pb2+ ions as a function of concentration, temperature, flow rate and voltage. The MM started from a differential equation of steady state mass balance. Neglecting resistances of ion exchange membranes compared with resistances of bulk solutions in dilute and concentrate compartments and deriving a relation for solution resistance as a function of operating parameters, the final one-parameter model was obtained. The applied ANN was a multilayer perceptron (MLP) network with two hidden layers. The fast Levenberg–Marquardt (LM) optimization technique was employed for training the ANN. MM and ANN were able to predict the performance of ED desalination with correlation coefficients of 0.97 and 0.99, respectively. Comparing MM and ANN model results, it was found that ANN model is more capable than MM to predict nonlinear behavior of ED process. However, MM is more efficient at higher feed flow rates and lower voltages, temperatures and feed concentrations. ANN is found out to be an efficient tool to model the complicated ion transfer mechanism in an electrical field. [Copyright &y& Elsevier]

Abstract: Crude oil often contains water, inorganic salts, suspended solids, and water-soluble trace metals. The first step in the refining processes is to reduce these contaminants by desalting (dehydration) in order to remove corrosion, plugging, and fouling of equipment and also to prevent poisoning the catalysts in the processing units. Sodium, calcium and magnesium chlorides (NaCl, CaCl2 and MgCl2) are frequently found in crude oil. Presence of these compounds in crude oil can cause several problems in the refining processes. At high temperature, water is hydrolyzed, and forms hydrochloric acid (HCl). Also, salts which contain metals can poison the catalysts. Desalting units remove contaminants from crude oil by washing water. After the oil is washed and mixed, demulsifying chemicals are added and then the electrostatic fields are used to break the emulsion. About 2–6% wash water is added to the oil as an extraction agent. Desalter effluent is a combination of many things such as: brine washing water used for removing salt, sand and mud washing water jet used at periodic intervals, connate water produced from the reservoir with crude oil. Desalter’s wastewater contains oil, demulsifier, and oxygen scavenger. Oil contamination is decreased by API separator in Ahwaz, Iran desalting units. The API separator in these units does not meet the standard requirement, because the salinity and organic content of the wastewater is very high. Therefore, the wastewater is injected to dead wells with high pressure. The injecting system has high capital and operational cost. In this research, desalting effluents is treated by using membrane distillation (MD). A polymeric Teflon microfiltration (MF) membrane is employed and the effect of operational conditions is investigated. Very effective separation (high flux and less contaminates in the permeate side) is observed. It is found that this method reduces capital, and operational cost and energy consumption. Besides, water (the permeate) fulfills the watering standards and can be used for agricultural and plant raw water applications. [Copyright &y& Elsevier]

Abstract: In this paper, experimental investigation of wastewater treatment by ultrafiltration (UF) is introduced. In the experiments, a UF membrane (UFPHT20-6338) and samples of Behshahr Ind. Co. wastewater as feed were used. Effect of operating conditions such as pressure difference, cross flow velocity, shear stress, temperature, concentration of organic compounds and pH on permeation flux, flux decline and fouling resistance were studied. Results show that a pressure difference more than 3×105 Pa (3bar), a high cross flow velocity (depending on economic considerations), a temperature of 30°C and a pH of 9 are the best operating conditions. Fouling of the membrane completely follows Hermia''s model (cake filtration mechanism). Analysis of the wastewater treated by UF represents 91, 87, 100, 85 and 40% reduction in COD, TOC, TSS, [PO4 3−] and [Cl−], respectively. Also, treatment of the wastewater by UF-powdered activated carbon (PAC) was studied. According to results, using PAC in feed circulation loop of UF system with a concentration of about 0.1% (W) not only improves water quality but also increases permeation flux. A shear stress induced by PAC on the membrane surface decreases cake layer thickness and as a result increases permeation flux. Analysis of the wastewater treated by UF-PAC represents 94, 93, 100, 99 and 43% reduction in COD, TOC, TSS, [PO4 −3] and [Cl−], respectively. Reduction of the phosphate concentration by UF-PAC is very considerable. A comparison between the results shows that UF is better than conventional biological method and UF-PAC is better than UF. [Copyright &y& Elsevier]

In this paper, electrodialysis (ED) process was modeled based on basic electrochemistry rules and copper ion separation experimental data. Experiments were conducted by Taguchi method as an experimental design. Then the same experiments were performed for zinc, lead and chromium ions. It was found that performance of an ED cell is almost independent on the type of ions and only depends on the operating conditions and the cell structure. With the aid of this valuable result, a model was used for total definite concentration of ion mixtures. The model starts from a differential equation of steady state mass balance. Neglecting resistances of ion exchange membranes compared with resistances of bulk solutions in dilute and concentrate compartments and deriving a relation for solution resistance as a function of concentration and temperature, the final one-parameter model was obtained. The model parameter was determined by experimental data. The approached model gives separation percent for various temperatures, concentrations, flow rates and voltages. In order to assess the reliability of the model, the calculated results were compared with measured experimental data. It was found that there is an acceptable agreement between the calculated results and experimental data. [Copyright &y& Elsevier]

An investigation of wastewater treatment by ultrafiltration (UF) is introduced. In the experiments a OF membrane (UFPHT20-6338) and samples of Behshahr Ind. Co. wastewater as feed were used. The effect of operating conditions such as pressure difference, cross flow velocity, shear stress, temperature, concentration of organic components and pH on permeation flux, flux decline and fouling resistance were studied. The results show that a pressure difference more than 3 bar, high cross flow velocities (depending on economic considerations), a temperature of 30°C and a pH of 9 are the best operating conditions. Analysis of the wastewater treated by OF represents 91%, 87%, 100%, 85% and 40% reduction in COD, TOC, TSS, [P04−3] and [Cl−], respectively. Reduction of the phosphate concentration by UF is very considerable. [Copyright &y& Elsevier]

A new hybrid loose nanofiltration membrane with the positive surface charge was developed by self-assembly of Ethylenediamine (ED) grafted multi-walled carbon nanotube (ED-g-MWCNT) on the top layer of asymmetric Polyethersulfone (PES). The effects of different nanotubes loading on the membrane surface roughness, hydrophilicity, isoelectric point, and thermal and mechanical stabilities were evaluated. Due to the Donnan exclusion, the hybrid membranes exhibited excellent heavy metals rejection rates in the order of Zn (96.7%) > Mg (95.01%) > Cd (92.4%) > Cu (91.9%) > Ca (91.3%) > Ni (90.7%) > Pb (90.5%). Additionally, pure water flux (PWF) of the composite membranes enhanced 122%, compared to the pure PES membrane, and achieved 80.5 L/m2 h. Owing to the high surface hydrophilicity and minor surface roughness, the membranes antifouling properties are significantly enhanced. The overall assessment of the membranes, considering all-important factors was performed by ranking efficiency product (REP). The results indicated that the incorporation of nanotubes with a loading ratio of 0.6 wt% leads to the optimum membrane. Finally, the results of this work introduce an effective solution for water purification from heavy metal ions based on the PES nanofiltration membrane incorporated with the ED-g-MWCNT. Image 1 • A new positively charged loose NF membrane was proposed for heavy metal removal. • Donnan exclusion effect on removal performance of the membranes was evaluated. • The hybrid membranes exhibited superior rejection and permeability values. [ABSTRACT FROM AUTHOR]

Wastewaters containing oil-in-water (O/W) emulsions are generated daily in various industrial processes such as petroleum refining, petrochemical and metal finishing. Environmental and economic concerns related to the disposal of oily wastewaters emphasize demands for materials and methods that can effectively separate oil from water. Pressure-driven membrane processes have been employed for oil/water separations. The major challenge that hinders the suitability of membrane technology for industrial oily wastewater treatment is the adsorption of oil and surfactants onto the membrane surface and/or within the pores of the membrane, which severely deteriorates the membrane performance. Materials with both hydrophobic and oleophilic properties have attracted significant attention in recent years for oil removal from water. These oil-removing type of materials can be used for membrane filtration or selective and efficient absorption of oil from water. The application of oil-removing materials can successfully introduce special wettability to the oily wastewater treatment. However, these materials are fouled quickly by oil droplets because of their intrinsic oleophilic properties. The attached oil droplets on the membrane surface severely affect separation efficiency. Besides, the adhered oil droplets are hardly removable from the surface resulting in reduced life-cycle of oleophilic materials, and this thus necessitates the need for costly post-treatment processes. Therefore, it is essential to develop high-performance materials for oil/water separation with elevated separation efficiency and significant antifouling properties. This study aims to review the state-of-the-art superhydrophilic and underwater superoleophobic (SUS) membranes that are being developed to overcome the aforementioned challenges. This allows to probe the maximal potential of developing such materials, and to explore the feasibility of using these novel membranes for de-oiling processes conventionally performed using expensive and low-performance skim tanks and adsorbents. In this review, according to the various materials that have been used for membrane fabrication, development methods for membrane synthesis with SUS properties based on polymeric SUS membranes and organic-inorganic hybrid SUS membranes including grafting, non-solvent phase separation (NIPS) polymeric membrane with hierarchical glue/tape-free surface, surface coating, in situ mineralization combined with polymeric materials and surface coating of polymeric membranes with inorganic nanoparticles, respectively, are assessed, in view of suggesting the success potential of these methods. [ABSTRACT FROM AUTHOR]

Environmental protection and resource recovery require efficient separation of salts and heavy metal ions from wastewater. A new hollow fiber nanofiltration membrane (HFNM) with a highly positive charge was developed via Hyperbranched polyethyleneimine (HPEI) self-assembly and methyl iodide (MeI) quaternization on a polyethersulfone (PES) with carboxylic-PES (CPES) substrate. Effects of different layers on surface charge and roughness, wettability, and mechanical stability were evaluated. MgCl 2 and ZnCl 2 as representative of salts and heavy-metal ions, respectively, were used to investigate separating properties of the membranes in terms of feed temperature and concentrations, operating pressures, antifouling properties, and long-term stability. The relationship between salt/ions rejection and water flux, pore size, and surface positive charge degree was explained by comparing the structures and properties of the membranes. The 1 wt. % HPEI and 0.5 wt. % GA solutions for 30 min crosslinking at pH of 11 and then 5 wt. % MeI solution could lead to the formation of the optimum membrane. Based on high hydrophilicity, low surface roughness, Donnan exclusion, and steric hindrance, the membrane could effectively exhibit superb rejection rates of Zn2+ (99.8 %), and Mg2+ (98.6 %), while showing high flux values (24.47 and 33.54 L m − 2 h − 1). The high flux rate (around 25.41 L m − 2 h − 1) during 4 cycles of regeneration, and high ions rejection (>98 %) were retained even after an 8-hour consistent operation. The prepared membrane, with high durability and structural stability, can introduce an effective solution for water purification from divalent ions. [Display omitted] • An HPEI-assembled PES/CPES hollow fiber membrane was prepared as the first layer. • The second layer of methyl iodide was formed as high positive charge density. • This nano-filter exhibited high ion/salt retention and high permeability performance. • Rejection order of R(Zn2+) > R(Cd2+) > R(Cu2+) and R(Mg2+) > R(Cd2+) was achieved. • This double-positively-charged membrane showed long-term stability and good antifouling performance. [ABSTRACT FROM AUTHOR]

Membrane bioreactors (MBRs) as biotechnology-based wastewater treatment processes have recently attracted lots of attentions. However, membrane fouling/biofouling as a significant obstacle has prevented MBRs from being widely used. The phase inversion method was used to fabricate a novel MIL-101(Cr) (MCPs)/polyethersulfone (PES) composite membrane. Adding MCPs up to 0.4 wt% significantly improved the membrane surface hydrophilicity and increased the membrane porosity, pore size, and fouling/biofouling formation resistance. Pure water flux of the optimal composite membrane increased by about 198.61% compared to the neat one. It also showed the lowest total fouling ratio (Rt: 48.79%) and irreversible fouling ratio (Rir: 10.43%), and the highest flux recovery ratio (FRR: 89.54%) and protein rejection (99%). Its COD removal efficiency for acetate as synthesis wastewater was about 75%. Performance of the optimal composite membrane was also evaluated at varied mixed liquor suspended solids (MLSS) concentrations of 8000, 10,000, and 12,000 mg/L. Increasing MLSS concentration decreased permeation flux due to rising sludge viscosity and fouling/biofouling formation. The results gave useful insights into preparation of hydrophilic composite membranes through blending of MCPs and PES to treat organic wastewaters using the MBR applications. [ABSTRACT FROM AUTHOR]

In membrane bioreactor (MBR) application, there are considerably influencing factors on membrane performance over time making serious problems, including reduced permeation flux and rejection percentage as well as formed thick fouling/biofouling layer. This study provided a new preparation strategy to fabricate extraordinary superhydrophilic CuO/PVDF nanocomposite membranes with micro/nano hierarchical structure, using a wet micro-pattern casting knife with simultaneous bombardment of hydrophilic CuO nanoparticles/non-solvent solution via cold spray coating (s-NIPs method). When compared to the neat membrane, the main characteristics of the superhydrophilic membrane enhanced such as surface area (70%) and pure water flux (PWF) (400%). Protein rejection (PR) and chemical oxygen demand (COD) removal were also obtained as about 96.7% and 97.8% at constant mixed liquor suspended solids (MLSS = 6000 mg/l) in a submerged aerobic MBR, fed by the synthesized sodium acetate wastewater (compared to the neat case: 78% and 91%), respectively. Furthermore, its excellent antifouling/biofouling properties were proved via significantly less formation of biofilm and adherence of extracellular polymeric substances (EPSs) and soluble microbial products (SMPs) on the membrane surface. Low variation of sludge flux and COD removal by increasing MLSS from 6000 (348 LMH and 96.7%) to 12000 mg/L (200 LMH and 94.2%) proved the significant impact of the preparation method on the membrane performance. Stability of the F–CuO coated layer caused superhydrophilicity and antibacterial properties to be maintained under long-period. The obtained results demonstrated potential of the fast, facile, simple, and one-step preparation method without compromising the membrane separation ability, while simultaneously providing superhydrophilicity, antibacterial activity, and ultra-low fouling/biofouling formation. [Display omitted] • Superhydrophilic membrane was prepared with micro/nano hierarchical structure. • Stable layer of antibacterial CuO NPs was coated on membrane surface by cold spray deposition. • Implementation of hierarchical structure increased active surface area up to 70%. • Optimal membrane exhibited highest PWF with ultra-low fouling/biofouling formation. • FRR, COD removal, and protein rejection were increased up to 94, 98 and 97%. [ABSTRACT FROM AUTHOR]

Submerged ceramic membrane bioreactors (SCMBRs) are more efficient combinations of traditional activated hazardous sludge and new membrane separation processes in wastewater treatment. Suspended solids are separated from hazardous effluent using microfilter ceramic membranes in SCMBRs. A high loaded wastewater was treated using an SCMBR employing a homemade tubular ceramic membrane in laboratory scale. Hydraulic Retention Time (HRT) was 32 h and COD range was varied from 2000 to 5000 mg/l. COD removal was evaluated to be more than 90% after a week and the lab scale SCMBR showed desired performance for the wastewater treatment. Mixed Liquor Suspended Solid (MLSS) was increased from 2000 to 4000 mg/L during the SCMBR operation time. [ABSTRACT FROM AUTHOR]

The main goal of the present study is synthesis, characterization and performance evaluation of an optimized photocatalytic ceramic membrane for wastewater treatment. It consists of three layers including alumina (Al 2 O 3 ) macroporous support, colloidal titania (TiO 2 ) mesoporous intermediate layer and polymeric TiO 2 mesoporous top layer in order to obtain a pore gradient from the support through the top layer of membrane. The colloidal and polymeric TiO 2 layers were prepared via the sol-gel method and coated using sol dip-coating approach. In order to optimize the membrane, physical separation and photocatalytic degradation capabilities of each colloidal and polymeric layer as a function of time were evaluated using Rhodamine B (RhB) aqueous solution. Thus, optimum coating number of intermediate layer and top layer were determined. Also, the performance of the optimized membrane was investigated via oily wastewater treatment using crude oil and water emulsion. Based on the performance results, two consequence colloidal layers and one polymeric layer were considered as the optimum layer number. Also, RhB photocatalytic degradation was 24.7% and RhB physical separation and permeation flux were 40.4% and 25.7 kg m −2 h −1 , respectively. Furthermore, based on the oily wastewater treatment experiments, permeation flux and chemical oxygen demand (COD) rejection at the best-operating conditions (pressure of 5 bar, the temperature of 30 °C and cross flow of 600 l h −1 ) were 29.1 kg m −2 h −1 and 78.4%, respectively. The prepared membrane was found efficient and exhibited high industrial potential due to its multifunctional capability and thus can be employed as an advanced material for wastewater treatment applications. [ABSTRACT FROM AUTHOR]

Abstract: Hybrid membrane bioreactors have emerged to alleviate membrane fouling, the drawback of conventional membrane. In this study immobilized acclimatized activated sludge on either polypropylene or polyurethane carriers were exploited to run two types of hybrid bioreactors and compare their performances with one conventional MBR in treatment of a synthesized phenolic wastewater at 1000mg/L and a hydraulic retention time of 13h. Immobilization on polyurethane foam resulted in phenol removal of 99% as compared to 72.5% for polypropylene and 70.6% for the conventional MBR. Complete membrane fouling occurring at trans-membrane pressure of 0.6bar was observed after 5, 9 and 21days for conventional MBR, polypropylene and polyurethane hybrid bioreactors, respectively. Additionally, analyses of soluble microbial products showed that proteins positively affect membrane fouling. The performance of hybrid bioreactor containing polyurethane foams under phenol loading shocks was also examined by sudden variations from 1000 to 1250 and 1500mg/L in influent phenol concentration where it was found that although persistent shocks had adverse effect on phenol removal, complete retrieval of phenol removal could be achieved after elimination of shocks. Among bioreactors examined, a hybrid bioreactor using polyurethane foam is therefore proposed as a superior bioreactor considering both performance efficiency and membrane fouling for wastewater treatment. [Copyright &y& Elsevier]

In this paper, the effects of in-line coagulation on permeation fiux (PF), fouling resistance (FR), and total organic compound (TOC) rejection (R) of synthesized mullite ceramic membranes during treatment of oily wastewater in coagulation - MF hybrid process were investigated. Four coagulant ((ferrous chloride (FeCl2.4H2O), ferrous sulphate (FeSO4.7H2O), aluminum chloride (AlCl3.6H2O) and aluminum sulphate (Al2(SO4)3.18H2O)) plus equal concentration of lime in the form of calcium hydroxide (Ca(OH)2) were evaluated in the coagulation - MF hybrid process at different concentrations (Oppm, 25ppm, 50ppm, and lOOppni). The results showed that coagulation can affect the membrane filtration by changing characteristics of the oil droplets. Coagulant agents improve the membrane performance at low dosage (25 ppm) for aluminum chloride and mean dosage (50 ppm) for ferrous chloride, ferrous sulphate, and aluminum sulphate. At the best conditions (50 ppm ferrous sulphate), PF increased from 2.22 × 10-5 to 2.76 × 10-5 (m3/m2s), FR decreased from 4.2 × 1012 to 5.55 × 1011(m-1), and R increased from 93.8% to 97.1%. [ABSTRACT FROM AUTHOR]

In this paper, the effects of in-line coagulation on permeation flux (PF), fouling resistance (FR), and total organic compound (TOC) rejection (R) of synthesized mullite ceramic membranes during treatment of oily wastewater in coagulation – MF hybrid process were investigated. Four coagulant ((ferrous chloride (FeCl2.4H2O), ferrous sulphate (FeSO4.7H2O), aluminum chloride (AlCl3.6H2O) and aluminum sulphate (Al2(SO4)3.18H2O)) plus equal concentration of lime in the form of calcium hydroxide (Ca(OH)2) were evaluated in the coagulation – MF hybrid process at different concentrations (0 ppm, 25 ppm, 50 ppm, and 100 ppm). The results showed that coagulation can affect the membrane filtration by changing characteristics of the oil droplets. Coagulant agents improve the membrane performance at low dosage (25 ppm) for aluminum chloride and mean dosage (50 ppm) for ferrous chloride, ferrous sulphate, and aluminum sulphate. At the best conditions (50 ppm ferrous sulphate), PF increased from 2.22 × 10−5 to 2.76 × 10−5 (m3/m2 s), FR decreased from 4.2 × 1012 to 5.55 × 1011 (m−1), and R increased from 93.8% to 97.1%. [ABSTRACT FROM AUTHOR]

Abstract: In a comparative research, five polymeric membranes were employed to treat the oily wastewater of Tehran refinery using cross-flow membrane filtration. To do these experiments, the outlet wastewater of the API (American Petroleum Institute) unit of Tehran refinery was used as the feed. Five different membranes were used including two microfiltration (MF) PS (0.1μm) and PS (0.2μm) membranes and three ultra-filtration (UF) PAN (20kDa), PS (30kDa) and PAN (100kDa) membranes. The performances of these membranes for treatment of the oily wastewater were evaluated and compared. The final permeation flux of oily wastewater was determined for each membrane (76.0, 73.1, 53.7, 32.1 and 96.2L/m2 h, respectively). The PAN (20kDa), PS (30kDa) and PAN (100kDa) membranes showed higher rejection, lower permeation flux and higher permeation flux, respectively. The PAN (100kDa) UF membrane was effective and suitable for treatment of the oily wastewater to achieve up to 94.1%, 31.6%, 96.4%, and 97.2% removal of TSS, TDS, turbidity and oil-grease content, respectively with a permeation flux of 96.2L/(m2 h). In this work, Hermia''s models were used to investigate the fouling mechanisms of polymeric membranes. The results show that cake filtration model can well predict the initial and final permeation flux of MF and UF membranes. After cake filtration model, the best permeation flux predicted to the experimental data was intermediate pore blocking model and worst predicted permeation flux was for complete pore blocking model. Chemical cleaning of polymeric membranes fouled with oily wastewater was investigated with metal chelating agent (EDTA), surfactant (SDS), and their combination. The results showed that combination of SDS and EDTA are able to clean the fouled polymeric membranes effectively. Mechanisms of the membrane fouling and chemical cleaning of them were also investigated. [Copyright &y& Elsevier]

Abstract: Oily wastewaters in Tehran refinery has become a big issue of water and environment pollution to be solved urgently. The results of an experimental study on separation of oil from oily wastewaters are presented. A polyacrylonitrile (PAN, 20kDa) membrane as the ultrafiltration (UF) membrane and an outlet wastewater of API unit of Tehran refinery were employed and the interaction effects of different operating parameters such as transmembrane pressure (TMP), cross-flow velocity (CFV), temperature and pH on permeate flux and fouling resistance were investigated. In this research, Taguchi method (L9 orthogonal array (OA)) was used initially to plan a minimum number of experiments. In this work, Hermia''s models were used to investigate the fouling mechanisms involved in UF of oily wastewaters. The results showed that the best fit to experimental data corresponds to the cake layer formation model followed by the intermediate blocking model for all the experimental conditions tested. A more detailed analysis of the fouling mechanisms was studied via dividing the filtration curves into different regions corresponding to the different fouling mechanisms. Intermediate blocking and cake layer formation or combinations of them were found to occur during the UF experiments depending on the operating conditions. [Copyright &y& Elsevier]

Abstract: This paper presents experimental data, a fuzzy logic (FL) model, a mathematical model (MM) and a coupled MM–FL model for a laboratory scale electrodialysis (ED) cell. The aim was to predict separation percent (SP) of zinc ions as a function of concentration, temperature, flow rate and voltage. At first, a Sugeno type FL inference system was applied to model zinc ions separation from wastewater using ED. FL modeling results showed that there is an excellent agreement between the experimental data and the predicted values, with mean squared relative error (MSRE) of less than 0.01. Then, the results of a previously developed MM were presented. The MM related SP to hydrodynamic dimension of the ED cell and operation conditions via two distinct parameters. This ability favored the MM for scale-up applications. However, based on MSRE of the MM (about 24), it could not obviously predict the experimental data as well as FL. Hence, as a final step, the MM was coupled with FL to achieve benefits of both. It was found out that the developed coupled model (MM–FL) is able to predict SP of zinc ions at all operating condition and almost every dimension to a high degree of accuracy (MSRE=0.05). [Copyright &y& Elsevier]

Abstract: In this paper, effect of influential factors on separation of monovalent (Na+), divalent (Cu2+, Zn2+, Pb2+) and trivalent (Cr3+) ions from wastewater was investigated. Two types of different membranes (AMV and CMV made by Asahi Glass and AR204SXR412 and CR67MK111 made by Ionics) with different ion exchange capacities (IEC) were used. Taguchi experimental design was used to plan a minimum number of experiments. A L9 orthogonal array (OA, four factors in three levels) was employed to evaluate effect of concentration (100, 500, and 1000ppm), temperature (25, 40, and 60°C), flow rate (0.07, 0.7, and 1.2mL/s) and voltage (10, 20, and 30V) on separation percent (SP) of the individual ions in the solution. A L16 OA (five factors in four levels) was applied to enquire the effect of ion valence in a mixture of ions on the response (SP). Statistical analysis, ANOVA, was also employed to determine the relationship between experimental conditions and yield levels. The results show that increasing concentration, voltage and temperature improves cell performance; however, SP decreases with increasing flow rate. At concentrations of more than 500ppm, dependency of SP on concentration diminishes. The optimum levels of influential factors, determined for all ions are: concentration 1000ppm, temperature 60°C, flow rate 0.07mL/s and voltage 30V. According to the results, using a membrane pair with higher IEC improves SP. It was found that performance of an electrodialysis (ED) cell is almost independent on the type of ions and only depends on the operating conditions and the cell structure. This result was confirmed by the experiments conducted on a mixture of ions. It was also found that SP of monovalent ions is larger than divalent and trivalent ions (S Cr < S Cu, S Zn, S Pb < S Na). For ions of similar valence, SP was found to be restricted by molecular weight and electrochemical activation energy of the ions (S Pb < S Cu < S Zn). [Copyright &y& Elsevier]

Abstract: The effect of influential factors on separation of monovalent (Na+), divalent (Cu2+, Zn2+, Pb2+) and trivalent (Cr3+) ions from wastewater was investigated using AMV and CMV ion-exchange membranes. Taguchi experimental design was used to plan a minimum number of experiments. A L9 orthogonal array (four factors in three levels) was employed to evaluate effect of concentration (100, 500, 1000 ppm), temperature (25, 40, 60°C), flow rate (0.07, 0.7, 1.2 mL/s) and voltage (10, 20, 30 V) on separation percent of the individual ions in the solution. The results show that increasing concentration, voltage and temperature improves cell performance; however, the separation percent decreases with increasing flow rate. At concentrations of more than 500 ppm, dependence of separation percent on concentration diminishes. The optimum levels of influential factors, determined for all ions are: concentration 1000 ppm, temperature 60°C, flow rate 0.07 mL/s and voltage 30 V. It was found that performance of an electrodialysis cell is almost independent of the type of ions but strongly depends on the operating conditions and cell structure. It was also found that separation percent of monovalent ions is larger than divalent and trivalent ions (SCr

Performance of inline coagulation-microfiltration (IMF) process for treatment of oily wastewater using a newly developed kaolinitic clay-Based ceramic membrane was investigated. Ceramic microfiltration (MF) membrane was fabricated utilizing kaolinitic clay as starting material and polyvinyl alcohol (PVA) as binder followed by characterizing employing Differential thermal analysis/Thermo-gravimetric (DTA/TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. The efficiency of adding Al 2 (SO 4) 3 as the prime coagulant for IMF of oily wastewater was assessed and modeled utilizing response surface methodology (RSM) based on Box-Behnken design (BBD). Moreover, the performance of long-term process was evaluated through periodic backwashing mode at the optimum condition within 17 cycles (90 min) including 240 s of forward filtration, backwashing for 15 s with 5 s of rest between each cycle. The results exhibited that water flux and rejection can be correlated with the input variables by the models with 2.29% and 1.67% relative deviation, respectively. The analysis of variance (ANOVA) results, which was employed to optimize the experiment input condition were as pH = 7.2, FC = 921 mg. L−1 and CC = 207 mg. L−1 and the corresponded responses after 90 min were water flux = 123.85 L m−2 h−1 (LMH) and rejection = 97.31%. The results of periodic backwashing showed that water flux could be intensified as 1.68 times compared to continuous forward IMF mode, while the oil rejection is equal to 98.06%. The overall results showed that the IMF system could be considered as a promising system for membrane fouling mitigation and filtration performance intensification. [ABSTRACT FROM AUTHOR]

The aim of this study is preparation, characterization and performance evaluation of ceramic monolith as microfiltration (MF) for treating a solid-liquid wastewater. Kaolin as a cheap starting material was used for membrane preparation as an inorganic material. Polyvinyl alcohol (PVA) as binder was also used for membrane preparation and silica (SiO 2 ) powder was used for preparation of synthetic wastewater. The membranes were formed via extrusion method. Response surface methodology (RSM) based on central composite design (CCD) was employed to design the membrane synthesis procedure. The independent variables were PVA concentration, sintering temperature and sintering time. Permation flux, Nephelometric Turbidity Unit (NTU) rejection, mechanical strength, porosity and pore size were considered as the responses. The optimized values of the independent variables were 0.5 wt%, 1150 °C and 5 h of PVA concentration, sintering temperature and sintering time, respectively. Based on the RSM results, the optimized membrane exhibited 80.9 kg m −2  h −1 , 89.8%, 5.8 MPa, 49.3% and 1.2 μm for permeation flux and NTU rejection, mechanical strength, porosity and pore size, respectively. The membranes characterization was carried out using PSD, XRD, DTA/TGA and SEM analysis. The prepared membrane presented high practical separation potential and could be used for treating solid-liquid wastewaters. [ABSTRACT FROM AUTHOR]

Phenolic wastewater was treated using anaerobic submerged membrane bioreactor (ASMBR). Effect of different solids retention times on MBR performance was studied. Various ratios of carbon to nitrogen were used in the synthetic wastewaters. During the operation, phenol concentration of feed was changed from 100 to 1000 mg L−1. Phenol concentration was increased stepwise over the first 30 days and kept constant at 1000 mg L−1, thereafter. For the first 100 days, a chemical oxygen demand (COD) to N ratio of 100:5.0 was used and this resulted in phenol and COD removal more than 99 and 95%, respectively. However, the ammonium removal decreased from 95 to 40% by increasing the phenol concentration of feed, from 100 to 1000 mg L−1. For the last 25 days, a COD to N ratio of 100:2.1 was used due to the ammonium accumulation in the ASMBR. This led to the complete ammonium removal and no ammonium was detected in the ASMBR permeate. These results suggest that in the ASMBR at high phenol loading of 1000 mg L−1, COD to N ratio of the phenolic wastewater must be 100:2.1 for ammonium removal, while at low phenol loading, COD to N ratio of 100:5.0 can be used. [ABSTRACT FROM AUTHOR]

Transport of phenol through a flat sheet supported liquid membrane (SLM) containing cooking oil as liquid membrane (LM) was investigated. Factors affecting permeation of phenol such as membrane phase, support material, feed phase pH, stripping phase concentration, stirring speed, and initial concentration of phenol were studied. It was found that these parameters strongly influence phenol removal efficiency; PTFE membrane as support material, grape seed oil as liquid membrane, feed pH of 2.0, initial phenol concentration of 100 mg/L, stirring speed of 350 rpm, and 0.2 M sodium hydroxide as effective stripping agent were found as the best conditions for greater phenol transport. Under these conditions, permeability was found to be 7.46 × 10−6 m/s. After 10.5 h, phenol was completely removed from the feed phase to strip phase. According to stability experiments, it was observed that the SLM is stable after 22 h. Thus, the use of cheap, nontoxic, and naturally oil as a novel and green membrane for recovery of phenol from wastewater was demonstrated. [ABSTRACT FROM AUTHOR]

Phenols pose a risk to the environment and to human health. Phenol and its derivatives are toxic pollutants, frequently found in surface and tap waters, and in aqueous effluents from various manufacturing processes. In this paper, an experimental study regarding transport of phenol through a supported liquid membrane (SLM) using tributyl phosphate (TBP) and sesame oil as liquid membrane (LM) was performed. Factors affecting permeation of phenol such as initial phenol concentration, carrier concentration, feed phase pH and stripping phase concentration were analyzed using Taguchi method. Optimal experimental condition of phenol transport was obtained using analysis of variance (ANOVA) after 7 h extraction (feed concentration: 200 mg/L; carrier concentration (%TBP): 40%; feed pH: 2; strip phase concentration: 1.1 M). Mass transfer coefficient for this system was evaluated, and compared with similar works, and it was shown that it has the highest mass transfer rate. In addition to transport study, stability of the membrane was investigated by examination of stripping phase concentration, carrier concentration and salt concentration effects. [ABSTRACT FROM AUTHOR]

ABSTRACT This work presents an experimental investigation and modeling of fouling mechanisms involved in ultrafiltration of oily wastewater streams. Hermia's models were used to investigate the fouling mechanisms. The experimental results performed at different cross flow velocity (CFV) (0.5, 1, and 1.5 m/s) and transemembrane pressure (TMP) (1.5, 3, and 4.5 bar) showed that the best fit to the experimental data corresponds to the cake layer formation model followed by the intermediate blocking model for all the experimental conditions tested. Furthermore, this work explores the application of the ANFIS as a model to predict permeation in ultrafiltration (UF) system. The selected experimental data were trained by a hybrid learning algorithm combining the forward pass and the backward pass. The good agreement of the model with experimental data underscores the ease and accuracy of the ANFIS in modeling such a complex systems. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: A large amount of oily wastewaters is generated by industrial sources. Oil-in-water emulsions are the most serious pollutants for which current treatment technologies are often costly and ineffective. In recent years, membrane processes have been applied for oily wastewater treatment. Microfiltration (MF) was successfully used in oil-in-water separations. In this research, investigations were carried out for treatment of an oily wastewater. A tubular ceramic MF (α-Al2O3) system was employed for treatment of a typical oily wastewater comes from API effluent of Tehran refinery. This system could produce a permeate with oil and grease content of 4mg/L that meets the National Discharge Standard and exhibited TOC removal efficiency higher than 95%. Also, effects of operating parameters such as transmembrane (TMP), cross flow velocity (CFV) and temperature on permeate flux, TOC removal efficiency and fouling resistance (FR) were investigated. The recommended operating conditions are TMP of 1.25bar, CFV of 2.25m/s and temperature of 32.5°C. In this system, backwashing was used to remove oil droplets and particulates that block the membrane pores, and the results showed that backwashing could prevent permeate flux decline significantly. Based on the results, this system was proposed to be replaced with the conventional wastewater treatment method. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, results of an experimental study on separation of oil from actual and synthetic oily wastewaters with mullite and mullite–alumina tubular ceramic membranes are presented. Mullite and mullite–alumina microfiltration (MF) symmetric membranes were synthesized from kaolin clay and α-alumina powder. The effects of different operating parameters such as pressure (0.5–4bar), cross flow velocity (0–2m/s), temperature (15–55°C), oil concentration (250–3000ppm) and salt concentration (0–200g/L) on permeation flux (PF), fouling resistance (FR), fouling and rejection (R) of mullite and mullite–alumina membranes for treatment of synthetic wastewaters were investigated. In order to determine the best operating conditions, 250–3000ppm condensate gas in water emulsions was employed as synthetic oily wastewaters using mullite membrane. At the best operating conditions (3bar pressure, 1.5m/s cross flow velocity and 35°C temperature), performance of mullite and mullite–alumina membranes for treatment of real and synthetic wastewaters were also compared. The results for treatment of emulsions showed that the mullite ceramic membrane has the highest R (93.8%) and the lowest FR (28.97%). Also, the mullite–alumina ceramic membrane with 75% alumina performs high PF (244L/m2 h) and low R (81.3%). Also for all the membranes, R for the real wastewater is lower than that for the synthetic wastewaters. [Copyright &y& Elsevier]