Membrane For Oily Wastewater Treatment Research Articles

Preparation and characterization of hydrothermally engineered TiO2-fly ash composite membrane

This work targets the preparation and characterization of an inexpensive TiO2-fly ash composite membrane for oily wastewater treatment. The composite membrane was fabricated by depositing a hydrophilic TiO2 layer on a fly ash membrane via the hydrothermal method, and its structural, morphological and mechanical properties were evaluated. The separation potential of the composite membrane was evaluated for 100–200 mg·L–1 synthetic oily wastewater solutions. The results show that the composite membrane has excellent separation performance and can provide permeate stream with oil concentration of only 0.26–5.83 mg·L–1. Compared with the fly ash membrane in the average permeate flux and performance index (49.97 × 10–4 m3·m–2·s–1 and 0.4620%, respectively), the composite membrane exhibits better performance (51.63 × 10–4 m3·m–2·s–1 and 0.4974%). For the composite ash membrane, the response surface methodology based analysis inferred that the optimum process parameters to achieve maximum membrane flux and rejection are 207 kPa, 200 mg·L–1 and 0.1769 m·s–1 for applied pressure, feed concentration and cross flow velocity, respectively. Under these conditions, predicted responses are 41.33 × 10–4 m3·m–2·s–1 permeate flux and 98.7% rejection, which are in good agreement with the values obtained from experimental investigations (42.84 × 10–4 m3·m–2·s–1 and 98.82%). Therefore, we have demonstrated that the TiO2-fly ash composite membrane as value added product is an efficient way to recycle fly ash and thus mitigate environmental hazards associated with the disposal of oily wastewaters.

Recent developments of carbon based nanomaterials and membranes for oily wastewater treatment

Carbon-based nanocomposite membranes have recently drawn tremendous attentions among membrane scientists due to their excellent chemical, mechanical stability and antifouling properties against oil deposition/adsorption.

Preparation and applications of microfiltration carbon membranes for the purification of oily wastewater

ABSTRACTMicrofiltration carbon membranes for oily wastewater treatment were fabricated from phenolic resin. The effects of oil concentration, running time, additives and regeneration on the removal of oil from wastewater were investigated. The as-obtained microfiltration membranes possess a macroporosity of 39.0% and meso and microporous volumes of 0.134 m3/g, along with two major pore size distributions around 0.1 μm and 20 nm. They are, respectively, attributed to the constituted particles’ stacking and the precursor pyrolysis. The results showed that the microfiltration membranes can efficiently remove the oil in wastewater. In the presence of ethanol as an additive in solution, the oil concentration is dramatically reduced from initial 200 mg/L in feed to below 10 mg/L in permeate, with an oil rejection of 95.3%.

Fabrication of novel superhydrophilic and underwater superoleophobic hierarchically structured ceramic membrane and its separation performance of oily wastewater

Hierarchically engineered asymmetric ceramic membrane is successfully fabricated, and special wettability is endowed to the membrane by introducing superhydrophilic and underwater superoleophobic silica nanoparticles through dip-coating technology onto the active separation layer. Effect of reaction temperature on the wettability of the silica nanoparticles is discussed. It has been found that the hydrophilicity of the silica increases with increasing the temperature and superhydrophilicity can be obtained when the temperature reaches to 60°C. Underwater oil contact measurements are performed using a series of oils and it turns out the as-prepared material bear excellent oil repellency towards various oil droplets. Separation performance of the membrane for oily wastewater treatment was investigated. It has been revealed that the as-prepared membrane can successfully separate the oil contaminated wastewater within one step under a small applied pressure (0.1MPa) with oil rejection coefficient R>99.95%, indicating an extremely high separation efficiency.

Photocatalytic Degradation of Oil using Polyvinylidene Fluoride/Titanium Dioxide Composite Membrane for Oily Wastewater Treatment

Production of industrial wastewater is increasing as the oil and gas industry grows rapidly over the years. The constituents in the industrial wastewater such as organic and inorganic matters, dispersed and lubricant oil and metals which have high toxicity become the major concern to the environment and ecosystem. There are many technologies are being used for oil removal from industrial wastewater. However, there are still needs to find an effective technology to treat oily wastewater before in can be discharge safely to the environment. Membrane technology is an attractive separation technology to treat oily wastewater. The aim of this study is to fabricate polyvinylidene/titanium dioxide (PVDF/TiO 2 ) composite membrane with further treatment using hot pressed method to enhance the adhesion between TiO 2 with the membrane surfaces. In this study the structural and physical properties of fabricated membrane were conducted using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) respectively. The photocatalytic degradation of oil was measured using UV-Vis Spectroscopy. The FTIR results confirmed that, hot pressed PVDF/TiO 2 membrane TiO 2 was successfully deposited onto PVDF membranes surface and XRD results shows that the XRD pattern of PVDF//TiO 2 found that the crystalline structure was remained unchanged after hot pressed. Clear water was obtained after synthetic oily wastewater was exposed to visible light for at least 6 hours. In conclusion, PVDF/TiO 2 composite membrane can be a potential candidate to degrade oil in oily wastewater and suggested to possess an excellent performance if perform simultaneously with membrane separation process.

Development of a High Performance PES Ultrafiltration Hollow Fiber Membrane for Oily Wastewater Treatment Using Response Surface Methodology

This study attempts to optimize the spinning process used for fabricating hollow fiber membranes using the response surface methodology (RSM). The spinning factors considered for the experimental design are the dope extrusion rate (DER), air gap length (AGL), coagulation bath temperature (CBT), bore fluid ratio (BFR), and post-treatment time (PT) whilst the response investigated is rejection. The optimal spinning conditions promising the high rejection performance of polyethersulfone (PES) ultrafiltration hollow fiber membranes for oily wastewater treatment are at the dope extrusion rate of 2.13 cm3/min, air gap length of 0 cm, coagulation bath temperature of 30 °C, and bore fluid ratio (NMP/H2O) of 0.01/99.99 wt %. This study will ultimately enable the membrane fabricators to produce high-performance membranes that contribute towards the availability of a more sustainable water supply system.

Processing of alumina-coated clay–diatomite composite membranes for oily wastewater treatment

Crack-free alumina-coated clay–diatomite composite membranes were successfully prepared by a simple pressing and dip-coating route using inexpensive raw materials at a temperature as low as 1000°C in air. The changes of porosity, flexural strength, pore size, flux, and oil rejection rate of the membranes were investigated while changing the diatomite content. A simple burn-out process subjected to the used membranes in air completely recovered the specific surface area, steady state flux, and oil rejection rate of the virgin membranes. The recycled membranes showed an exceptionally high oil rejection rate (99.9%) with a feed oil concentration of 600mg/L at an applied pressure of 101kPa. The typical porosity, pore size, flexural strength, oil rejection rate, and steady state flux of the recycled alumina-coated clay–diatomite composite membrane were 36.5%, 0.12μm, 32MPa, 99.9%, and 6.91×10−6m3m−2s−1, respectively, at an applied pressure of 101kPa.

Engineering design of outer‐selective tribore hollow fiber membranes for forward osmosis and oil‐water separation

Outer‐selective thin‐film composite (TFC) hollow fiber membranes offer advantages like less fiber blockage in the feed stream and high packing density for industrial applications. However, outer‐selective TFC hollow fiber membranes are rarely commercially available due to the lack of effective ways to remove residual reactants from fiber's outer surface during interfacial polymerization and form a defect‐free polyamide film. A new simplified method to fabricate outer‐selective TFC membranes on tribore hollow fiber substrates is reported. Mechanically robust tribore hollow fiber substrates containing three circular‐sector channels were first prepared by spinning a P84/ethylene glycol mixed dope solution with delayed demixing at the fiber lumen. The thin wall tribore hollow fibers have a large pure water permeability up to 300 L m−2 h−1 bar−1. Outer‐selective TFC tribore hollow fiber membranes were then fabricated by interfacial polymerization with the aid of vacuum sucking to ensure the TFC layer well‐attached to the substrate. Under forward osmosis studies, the TFC tribore hollow fiber membrane exhibits a good water flux and a small flux difference between active‐to‐draw (i.e., the active layer facing the draw solution) and active‐to‐feed (i.e., the active layer facing the feed solution) modes due to the small internal concentration polarization. A hyperbranched polyglycerol was further grafted on top of the newly developed TFC tribore hollow fiber membranes for oily wastewater treatment. The membrane displays low fouling propensity and can fully recover its water flux after a simple 20‐min water wash at 0.5 bar from its lumen side, which makes the membrane preferentially suitable for oil‐water separation. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4491–4501, 2015

PES and PES/PAN Blend Ultrafiltration Hollow Fiber Membranes for Oily Wastewater Treatment: Preparation, Experimental Investigation, Fouling, and Modeling

ABSTRACTIn 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.

Asymmetric polyethersulfone ultrafiltration membranes for oily wastewater treatment: Synthesis, characterization, ANFIS modeling, and performance

Oily wastewater in Tehran Oil Refining Company has become a big issue of water and environment pollution to be solved urgently. In this research, polyethersulfone ultrafiltration hollow fiber membranes were prepared via phase inversion induced by dry-jet wet spinning process. The membranes were characterized by water contact measurements, SEM analysis, filtration measurements (flux and fouling). In this work, the results of an experimental study on separation of oil from oily wastewaters are presented. To do these experiments, the outlet wastewater of the API unit of Tehran Refining was used as the feed. The results demonstrated that the prepared polyethersulfone hollow fiber membranes are effective in removing chemical oxygen demand (COD), total organic carbon (TOC), turbidity, total suspended solids (TSS), and oil and grease content (OGC). The results showed that the prepared polyethersulfone hollow fiber membranes exhibit COD, TOC, and OGC removals of about 83.1%, 96.3%, and 99.7%, and final flux and fouling of about 84.1L/(m2h) and 63.0%, respectively. Comparison of results of this method showed that quality of the finally treated outlet water is high and even better than standard water that are currently introduced to cooling towers. Moreover, this paper explores the application of the ANFIS as a model to predict permeation flux in UF process. 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.

Oily wastewater treatment using membrane bioreactor

A novel implementation of a membrane bioreactor (MBR) has been studied in this paper. It is utilised as combination of rotating biological contractor (RBC) and an external membrane for oily wastewater treatment. The performance of MBR was compared with the standalone RBC. The RBC used in this investigation is the same one combined with the membrane to form the MBR. Wastewater biodegradability has been evaluated by two factors: chemical oxygen demand (COD) and total petroleum hydrocarbon (TPH). They are both compared together for different hydraulic retention times (HRTs) and petroleum pollution concentrations in RBC and MBR. The ratio of TPH to COD of molasses has been varied between 0.2 to 0.8 at two HRTs of 18 and 24 h while the temperature, pH and dissolved oxygen were kept in the range of 20–25°C, 6.5–7.5, and 2–3.5 mg/L, respectively. Optimal TPH removal efficiency (99%) observed at TPH/COD = 0.6 and HRT = 24 h in MBR. The experimental results showed that MBR had higher treatment efficiency than RBC at all ratios and HRTs.

Low-cost clay-based membranes for oily wastewater treatment

Low-cost clay-based membranes for oily wastewater treatment

Preparation and characterization of PVDF–PVP–TiO2 composite hollow fiber membranes for oily wastewater treatment using submerged membrane system

A series of polyvinylidene fluoride (PVDF) hollow fiber ultrafiltration membranes made of different titanium dioxide (TiO2) concentrations with the presence of polyvinylpyrrolidone as additive was prepared. The membrane performances were characterized in terms of pure water flux, permeate flux, and oil rejection, while the membrane morphologies were analyzed using scanning electron microscope and atomic force microscope. The experimental results showed that when 2 wt.% TiO2 was incorporated into PVDF membranes, optimized permeate flux and oil rejection of 70.48 L/m2 h (±1.41) and 99.7% (±0.3), respectively, could be obtained when tested using 250 ppm synthesized oily solution under vacuum condition. Compared to the PVDF membrane without TiO2 addition, all the composite membranes showed relatively higher permeate flux and oil rejection. Based on the results obtained, it is reported that the composite PVDF membrane incorporated with 2 wt.% TiO2 exhibited the best separation performance in which complete removal of oil was able to achieve regardless of the feed oil concentration. However, decrease in permeate flux was observed when the feed oil concentration increased from 250 to 1,000 ppm. The results concluded that the composite PVDF membrane showed better performance in treating oily solution compared to that of without TiO2.

Novel Functionalized Nano-TiO2 Loading Electrocatalytic Membrane for Oily Wastewater Treatment

Membrane fouling is a critical problem in membrane filtration processes for water purification. Electrocatalytic membrane reactor (ECMR) was an effective method to avoid membrane fouling and improve water quality. This study focuses on the preparation and characterization of a novel functionalized nano-TiO(2) loading electrocatalytic membrane for oily wastewater treatment. A TiO(2)/carbon membrane used in the reactor is prepared by coating TiO(2) as an electrocatalyst via a sol-gel process on a conductive microporous carbon membrane. In order to immobilize TiO(2) on the carbon membrane, the carbon membrane is first pretreated with HNO(3) to generate the oxygen-containing functional groups on its surface. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS) analyses are used to evaluate the morphology and microstructure of the membranes. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements are employed to illustrate the eletrochemical activity of the TiO(2)/carbon membrane. The membrane performance is investigated by treating oily wastewater. The oil removal rate increases with a decrease in the liquid hourly space velocity (LHSV) through the ECMR. The COD removal rate was 100% with a LHSV of 7.2 h(-1) and 87.4% with a LHSV of 21.6 h(-1) during the treatment of 200 mg/L oily water. It suggests that the synergistic effect of electrocatalytic oxidation and membrane separation in the ECMR plays a key role.

Formation and performance of Kaolin/MnO 2 bi-layer composite dynamic membrane for oily wastewater treatment: Effect of solution conditions

To develop an efficient dynamic membrane for application in oily wastewater treatment, there is a need to explore an appropriate coating technique and to advance its separation performance. The formation and separation performance of the dynamic membrane from Kaolin and MnO 2 were investigated with particular objectives on the choice of an appropriate membrane-coating technique and the discussion of the effect of solution conditions. The microstructures of the dynamic membrane were examined using the scanning electron microscope. The results showed that the deposition of MnO 2 particles onto the surface of Kaolin dynamic layer forming a Kaolin/MnO 2 bi-layer composite dynamic membrane is an effective coating technique. The optimum concentrations of the Kaolin solution and KMnO 4 solution should be 0.4 g L −1 and 0.1 g L −1 respectively. With the rise of oil concentration, the steady permeate flux decreased and oil retention ratio increased. In the low oil concentration range from 0.1 g L −1 to 1.0 g L −1, the variation characteristics were more obvious. In neutral or alkaline environments, the dynamic membrane was stable with high permeate flux and oil retention ratio of over 99%. As the temperature rose from 283 K to 313 K, the steady retention ratio decreased from 99.9% to 98.2% and the steady permeate fluxes increased from 120.1 L m −2 h −1 to 153.2 L m − 2 h −1.

Application of the Al 2O 3–PVDF nanocomposite tubular ultrafiltration (UF) membrane for oily wastewater treatment and its antifouling research

Nanocomposite tubular ultrafiltration (UF) membrane Al 2O 3–PVDF was prepared by the phase-inversion method. Oily wastewater of Daqing oilfield was treated by PVDF and Al 2O 3–PVDF tubular ultrafiltration membranes, respectively. The membrane water permeations of the UF process were analyzed. Retentions of chemical oxygen demand (COD) and total organic carbon (TOC) were more than 90% and 98%, respectively. The results indicate that after UF treatment, oil content was below 1 mg/L, suspended solids content was below 1 mg/L, and solid particle median diameters were less than 2 μm. The quality of the permeation water met the requirement by oilfield injection or drainage. Fouled membranes and washed membranes were analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM), and fouled membranes were backwashed with different solutions. Results show that the addition of nano-sized alumina particles improved membrane antifouling performance, and the flux recovery ratio of modified membranes reached 100% washing with 1 wt% of OP-10 surfactant solution (pH 10).

Performance study of ceramic microfiltration membrane for oily wastewater treatment

Abstract Cross-flow microfiltration (MF) processes were studied with oily wastewater using a ceramic (α-Al2O3) membrane with 50 nm pore size. The influence of parameters such as transmembrane pressure (TMP), cross-flow velocity (CFV), oil concentration in feed, pH and salt concentration on the separation behaviors were investigated by the measurements of permeate flux, total organic carbon (TOC) removal efficiency, and size and zeta potential of the emulsion droplets. The results showed that there were different degrees of effect on the permeate flux by these parameters. The TOC removal efficiencies higher than 92.4% were achieved under all experimental conditions. A non-steady model of the accumulation volume of permeation was developed. It was found that the predicted values from the model were in good agreement with the experimental results. A sensitivity analysis (SA) of the model was also conducted to identify the degree of influence of the parameters on the accumulation volume of permeation. The results showed that the accumulation volume of permeation was significantly affected by the transmembrane pressure, indicating the model was reliable.