Large amounts of produced water are generated during oil and gas production. Produced water, as it is known in the oil industry, is briny fluid trapped in the rock of oil reservoirs. The objective of this study was to test produced waters from a Montana USA oilfield using a mobile station to design a plant to cost efficiently treat the produced water for agricultural irrigation. We used combined physical and chemical treatment of produced water in order to comply with reuse and discharge limits. This mobile station consists of three stages: pretreatments, membrane filtration and post treatment. Two spiral-wound membrane units were employed and the rejections of various constituents were examined. The performance of two membranes, 20 kDa weight cut-off (MWCO) ultrafiltration and a polyamide-composite reverse osmosis membrane was investigated. The mobile station effectively decreased conductivity by 98%, COD by 100% and the SAR by 2.15 mgeqv(0.5) in the produced water tested in this study. Cost analysis showed that the treatment cost of produced water is less expensive than to dispose of it by injection and this treated water may be of great value in water-poor regions. We can conclude that the mobile station provided a viable and cost-effective result to beneficial use of produced water.

The importance of the treatment of water and wastewater has been steadily increasing because of the ever greater demands to eliminate environmental pollution. Pressure-driven membrane separation processes, including ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO), have been widely used in water and wastewater treatment and are applied on an industrial scale worldwide. The aim of our paper is to introduce the results of our research team on this field. The main research area within the membrane separation was the reduction of resistances. The effect of ozonation, vibration and application of dolly particles were examined in our scientific works.

After their use for heating, e.g. in greenhouses, waste thermal waters may cause environmental problems due to their high contents of ions, and in some cases organic matter (associated with an oxygen demand) or toxic compounds. The aims of this work were to decrease the high organic content of waste thermal water by a combination of ozone treatment and membrane separation, and to investigate the accompanying membrane fouling. The results demonstrated that the chemical oxygen demand and the total organic content can be effectively decreased by a combination of ozone pretreatment and membrane filtration. Ozone treatment is more effective for phenol elimination than nanofiltration alone: with a combination of the two processes, 100% elimination efficiency can be achieved. The fouling index b proved to correlate well with the fouling and polarization layer resistances.

A B S T R A C TThe membrane technique of microfiltration (MF) was used to investigate the degree of reduction of the membrane resistance. The application of dolly-particles seems very beneficial for some MF processes with conventional equipment. A pile of bakelite enhanced the local shear near the membrane surface. This phenomenon depends greatly on the components and properties of the feed suspension; the shear force is dependent on the radius and the amount of the particles. This approach has been successful in increasing fluxes of MF. The larger particles induce a much higher shear-induced diffusion and therefore dramatically improve mass transfer. Increasing size of the bakelite particles could be associated with increasing flux.To prevent the fouling of MF membranes during the processing of chalk-dust solutions, a high degree of turbulence should be introduced in the membrane surface. The application of microparticles (bakelite) as dolly-particles was investigated for this purpose. The experiments were carried out in MF/K1 equipment. The influence of the microparticles on the flux was investigated with a 0.45 mm tubular ceramic membrane.The size of the bakelite particles used was 90-125 mm, 125-160 mm, 160-200 mm or 200-400 mm. It was concluded that in all cases the applied bakelite increased the permeate flux. Increasing size of the bakelite particles was associated with an increasing flux. The largest Bakelite particles (200-400 mm) caused the highest fluxes and the smallest cake resistance (R Cake ) and total (R T ) resistance. This work has yielded new experimental results in an alternative approach for the reduction of fouling.

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