Purification Of Oily Wastewater Research Articles

Robust construction of underwater superoleophobic CNTs/nanoparticles multifunctional hybrid membranes via interception effect for oily wastewater purification

A simple and robust strategy is suggested for fabricating multifunctional hybrid separation membrane loading with catalytic nanoparticles based on the interception effect of porous CNTs network membrane. CNTs functionalized covalently with hydrophilic polyacrylic acid brushes assemble into a superhydrophilic/underwater superoleophobic network structure, which displays thickness dependent porosity. This allows the CNTs membrane capture catalytic nanoparticles by simple filtration process and construct flexibly desired separation membrane. Not only effectively separate oil-in-water emulsion, the prepared CNTs hybrid membranes can also catalytically decompose different organic pollutants in water by conveniently altering catalytic nanoparticles in the membrane. This robust construction provides a convenient means to obtain multifunctional CNTs separation membrane, promoting the practical application of superwettable CNTs membrane in the treatment of complex oily wastewater.

Efficient separation of oily wastewater using polyethersulfone mixed matrix membrane incorporated with halloysite nanotube-hydrous ferric oxide nanoparticle

In this work, self-synthesized halloysite nanotube-hydrous ferric dioxide (HNT-HFO) nanocomposites prepared via chemical precipitation method were incorporated in polyethersulfone (PES) to fabricate novel ultrafiltration (UF) mixed matrix membranes (MMMs) for oil-water separation process. Prior to filtration experiments, the morphologies and physicochemical properties of prepared HNT-HFO nanocomposites and MMMs were characterized using scanning electron microscope with energy-dispersive X-ray, transmission electron microscope, Fourier-transform Infrared spectroscope, atomic force microscope and contact angle goniometer. It was found that the membrane contact angle decreased remarkably from 81.39° to about 50.30° upon addition of 23.08 wt% of HNT-HFO nanocomposite (2.0 loading ratio) in the PES matrix. The improved surface hydrophilicity resulted in the flux enhancement in the MMM, achieving close to 650 L/m2 h bar of pure water flux. This value was about 10 times higher than the flux shown by the pristine PES membrane. In addition to the excellent water flux, the MMM also exhibited almost complete elimination of oil molecules (99.7% rejection) when tested with 1000 ppm oily solution. The findings indicated the potential use of the newly developed MMMs for efficient purification of oily wastewater in the oil field and refinery processes.

Simple yet powerful nanofilters with tunable pore sizes and superhydrophilicity-underwater superoleophobicity for oil spill treatment

Using filtration materials possessing superhydrophilic-underwater superoleophobic property to separate oil/water mixtures has become a research hotspot. However, most of the works are concentrated on building filtration materials with special wettability, ignoring the pore structures. Herein, polydopamine-modified (PDA-modified) nanofibrous mats with tunable pore sizes and special wettability were prepared by combining the electrospinning technique with a very simple modification process for oil/water separation. The results indicated that the pore structure of the PDA-modified nanofibrous mats could be finely modulated by utilizing different kinds of stainless steel wire meshes as collectors, and more interesting was that all the modified nanofibrous mats showed superhydrophilicity-underwater superoleophobicity. For the oil/water separation, the PDA-modified nanofibrous mats displayed high efficiency and high flux in separating oil/water mixtures, and the water flux could be highly improved by controlling the pore size and the optimal flux was high up to 40,405 L m−2 h−1. In addition, the PDA-modified nanofibrous mats exhibited excellent durability and recyclability. Finally, as a proof of concept a novel oil collection device based on the PDA-modified nanofibrous mat was constructed to in situ separate the oil/water mixtures and collect the oil simultaneously. The developed PDA-modified nanofibrous mats would have wide applications in oily wastewater separation and purification.

Polyethersulfone/HFO Mixed Matrix Membrane for Enhanced Oily Wastewater Rejection

The recent growth of oil and gas industry has led to the increase of oily wastewater release. Membrane technology has been in the spotlight in recent advancement to treat the oily wastewater. Fouling due to surfactant adsorption and/or oil droplets plugging the pore has become one of the major hindrances in most of the research on oily wastewater treatment. In this work, self-synthesized hydrous ferric dioxide nanoparticles (HFO NPs) via chemical precipitation method were incorporated in polyethersulfone (PES) to fabricate a novel nanocomposite mixed matrix membranes (MMMs) for ultrafiltration (UF). The morphologies and physicochemical properties of prepared HFO NPs and MMMs were characterized using Scanning Electron Microscopy (SEM) and Transmission electron microscope (TEM), contact angle goniometer, before further subjected to water permeation test and oil rejection test. It was found that contact angle of membrane decreased remarkably with an increase in HFO nanoparticle loading from 70° to 38° at which proved its improved hydrophilicity which led to a significant rise in permeate flux, achieving 168.06 L/m2h bar in comparison to 63.67 L/m2h bar shown by the plain PES membrane. Total rejection of oil (100% rejection) demonstrated by the MMMs has confirmed the superior potential of PES/HFO UF membrane for total purification of oily wastewater especially to be reused in oilfield and refinery processes as well as to be released to the environment.

A highly efficient, stable, durable, and recyclable filter fabricated by femtosecond laser drilling of a titanium foil for oil-water separation

It has been a long standing challenge to efficiently separate oil and water since prehistoric times, and now it has become even more desirable in oily wastewater purification and oil spill cleanup. Here we introduce a super oil–water separation filter with superhydrophilicity and underwater superoleophobicity, fabricated using femtosecond laser micro-hole drilling of a titanium foil. Such a simply-made filter, without any modification, can achieve a separation efficiency exceeding 99% in eight typical oil–water mixtures. It remains highly efficient after 40 cycles of recycling and after suffering erosion by corrosive media. Furthermore, the used filter, polluted with oil, could be recovered by ultraviolet illumination. The flux of filtered water is tunable by simply selecting the aperture of the microhole or the spacing between adjacent microholes. Such advanced functionality is due to roughness and the TiO2 layers on the ablated surface during fabrication. With superhydrophilic and superoleophobic surfaces, this oil-water filer is also suitable for applications in anti-fouling, anti-smudge, anti-fog, and self-cleaning.

The analysis of emulsion structure changes during flow through porous structure

ABSTRACTThe aspects of emulsion flow through porous media are crucial for many industrial processes, especially in the development of Enhanced Oil Recovery (EOR) techniques and also during oily wastewater purification. In this paper we investigated the hydrodynamics of gravitational flow of emulsions with inner phase of different concentrations. We also tried to determine the quantitative changes in the droplet diameter distribution and concentration of emulsion flowing out of the bed. On the basis of experimental data, it was possible to describe the influence of emulsion concentration on the hydrodynamics process and to characterize the changes of the structure of emulsion.

Analysis of technologies for purification of oily wastewater from airlines using biosorbents

Analysis of technologies for purification of oily wastewater from airlines using biosorbents

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%.

In situ dual-functional water purification with simultaneous oil removal and visible light catalysis.

Dual purification of both oily wastewater and dye-polluted water for enhancing the use of freshwater is an urgent task. We report herein, the facile synthesis of inorganic semiconductor nanomaterials anchored mesh for in situ dual-functional water purification. This resultant mesh combines the excellent capacity of oil removal and the advantage of photocatalytic performance for dye degradation under visible light irradiation at the same time. In addition, the mesh was easily regenerated and remained unaltered in photocatalytic performance over five successive dye degradation cycles. Given the innovative integration of special wettability and photocatalytic activity of such a semiconductor material under visible light for dual elimination of various pollutants from water, we anticipate that this approach will provide a promising pathway for versatile applications in oily wastewater treatment, water purification and so on.

Short- and Long-Term Performance of the Thin-Film Composite Forward Osmosis (TFC-FO) Hollow Fiber Membranes for Oily Wastewater Purification

Fouling behavior of thin-film composite (TFC) membranes synthesized on sulfonated polyphenylenesulfone (sPPSU) hollow fiber substrates was investigated for separating oil–water emulsions under forward osmosis (FO). The water and salt reverse fluxes of the TFC-FO hollow fiber membranes were found to be stable for a period of 28 days when deionized (DI) water was used as feed. A series of fouling experiments were carried out, and it was observed that water flux decreased faster with increasing oil concentration of the feed solution. In addition, the rate of flux decline was rapid in the initial few hours, because of the cake-enhanced concentration polarization (CECP). Furthermore, we observed that the ratio of salt reverse flux to water flux (Js/Jw) was much lower, compared to that of using DI water as feed. This may indicate that the oil fouling plugs some defects in the selective layer and the oil fouling layer hinders the salt transport, because of the CECP mechanism. Further investigations revealed that...

A Research on Purification of Oily Wastewater with TiO<sub>2</sub> Photocatalysts Supported by Zeolite Particles

It is well-known that TiO2 is an environmental benign photocatalyst which can be used to decompose harmful organic compounds. Recently, many studies are concentrated on the purification of industrial wastewater due to the requirement of environmental protection. In present study, TiO2 nanomaterials supported by fine zeolite particles have been used as the photocatalyst to purify the oily wastewater. It has been found that the oil concentration in the modulated water can be reduced significantly and rapidly under the action of photocatalytic degradation and the ultraviolet light radiation. After 80 minutes, oil concentration in the modulated water can be reduced by more than 80%. The results suggest that TiO2 nanomaterials supported by fine zeolite particles are effective material for purification of oily wastewater. In addition, the present results show that the efficiency of water purification can be significantly increased by use of mechanical stirring during the photocatalytic degradation process.

Straightforward Oxidation of a Copper Substrate Produces an Underwater Superoleophobic Mesh for Oil/Water Separation

A superhydrophilic and underwater superoleophobic Cu(OH)2-covered mesh with micro- and nanoscale hierarchical composite structures is successfully fabricated through a one-step chemical oxidation of a smooth-copper mesh. Such mesh, without any further modification, can selectively separate water from oil/water mixtures with high separation efficiency, and possess excellent stability even after 60 uses. This method provides a simple, low-cost, and scalable strategy for the purification of oily wastewater.

Analysis of Bacterial Communities in A<sup>2</sup>O Membrane Bioreactor Treating Oily Wastewater

To improve the efficiency of oily wastewater purification, a laboratory-scale anaerobic/anoxic/aerobic (A2O) membrane bioreactor was designed to treat the oily wastewater based on the conventional A2O activated sludge process and membrane separation technology, and the variation of bacterial community structure in the activated sludge of key reactors were investigated by PCR-DGGE (denaturing gradient gel electrophoresis). The result of Shannon diversity index comparing indicated that MBR seemed to be more constant than the A/0 system. Four sensitive dominant bacteria were verified in the treatment of oily wastewater. They were Uncultured Comamonadaceae bacterium, Hydrogenophaga sp., uncultured beta proteobacterium, and uncultured Thiobacillus sp. It suggested that PCR-DGGE can be used as an effective supplementary method for verifying cultural dominant microorganisms in activated sludge of oily wastewater.

Purification of biologically treated Tehran refinery oily wastewater using reverse osmosis

Abstract In this paper, results of an experimental study on separation of oil from industrial oily wastewaters with combined biologically method/reverse osmosis (RO) process for purification of Tehran refinery oily wastewater is presented. The effects of different operating parameters on permeation flux and TDS rejection were investigated. Taguchi method (L9 orthogonal array (OA)) was used initially to plan a minimum number of experiments. Analysis of variance (ANOVA) was applied to calculate sum of square, variance, ratio of factor variance to error variance and contribution percentage of each factor on response. The results showed that TMP and temperature have significant effects on the response. Permeation flux was found to increase with increasing transmembrane pressure (TMP), cross flow velocity (CFV) and feed temperature at constant feed concentration but rejection slightly decreases. The pH effects were found to be complex. By increasing acidic and basic nature of the feed, permeation flux was foun...

Adsorption of oil from waste water by coal: characteristics and mechanism

The work described here was focused on exploring the potential application of coal to purification of oily waste water. Coal was added to oily waste water as an adsorbent and then removed through a flotation process. This allowed economical and highly efficient separation of oil from the waste water. The absorption time, coal type, coal particle size distribution, pH value and oil concentration were investigated. The results indicate that oil absorption by a coal increases for a period of 1.5 h and then gradually tends toward an equilibrium value. It appears that the absorption capacity of anthracite is more than that of lean coal or lignite, given the same coal particle size distribution. The absorption capacity of a coarse coal fraction is less than that of finer coal, given the same of coal type. The absorption capacity of anthracite decreases slightly as the pH increases from 4 to 9. The adsorption of oil on anthracite follows the Freundlich isothermal adsorption law: given initial oil concentrations of 160.5 or 1023.6 mg/L the absorption capacity was 23.8 or 840.0 mg/g. The absorption mechanism consists of two kinds of absorption, a physical process assisted by a chemical one.

Experimental investigation of oily wastewater treatment using combined membrane systems

Investigations were carried out for purification of oily wastewater by a combined of ultrafiltration/reverse osmosis (UF/RO) processes. Laboratory-scale UF using polysulfone (PS) and polyacrylonitrile (PAN) membranes were employed with typical oily wastewater collected from API unit of Tehran refinery. The PAN membrane showed higher rejection, more permeation flux and less fouling resistance than the PS membrane. Both membranes produced permeate with oil and grease contents generally less than 5 ppm. Rejection of chemical oxygen demand (COD) and biological oxygen demand (BOD5) were found to be 65% for UF treatment. In this work, Hermia's models were used to investigate the fouling mechanism involved in UF of the oily wastewater. The results showed that the best fit to experimental data corresponds to the cake layer formation model followed by the intermediate blocking model for both the UF membranes. For further treatment of the UF permeates, RO was applied using a thin film composite polyamide membrane. The rejection of COD, BOD5 and total dissolved solid (TDS) after UF/RO treatment increased up to 98%, 98% and 95%, respectively. The results showed that the final permeate has very high quality and even better than that is currently introduced to the cooling towers in Tehran refinery.

Purification of oily wastewater by hybrid UF/MD

Investigations on the treatment of oily wastewater by a combination of ultrafiltration (UF) and membrane distillation (MD) as a final purification method have been performed. A tubular UF module equipped with polyvinylidene fluoride (PVDF) membranes and a capillary MD module with polypropylene membranes were tested using a typical bilge water collected from a harbour without pretreatment. The permeate obtained from the UF process generally contains less than 5 ppm of oil. A further purification of the UF permeate by membrane distillation results in a complete removal of oil from wastewater and a very high reduction of the total organic carbon (99.5%) and total dissolved solids (99.9%).

Purification of oily wastewater by ultrafiltration

Investigations have been carried out for purification of oily wastewater by a combination of ultrafiltration/reverse osmosis processes. A tubular ultrafiltration system using cellulosic and non-cellulosic membranes was tested with typical oily wastewater collected from harbour and simulated emulsion without any pretreatment. Both membrane types produced a permeate with an oil content generally less than 10 mg/dm 3. Rejection of chemical oxygen demand (COD) is 80% for ultrafiltration treatment. The permeate is generally of acceptable quality for direct sewer discharge. For further treatment of UF permeate, reverse osmosis was applied with tubular B1 PCI modules using cellulose acetate membranes. The rejection of COD after ultrafiltration/reverse osmosis treatment increased up to 98.5% and total dissolved solids (TDS) to 95.7%. Reverse osmosis treatment will permit reuse of the treated water as process water.