Optimization of Forward Osmosis for Oil Refinery Effluent Desalination Using Response Surface Methodology.

The Sustainable Development Goal Six (SDG 6) – “ensure availability and sustainable management of water and sanitation for all” places huge responsibilities on stakeholders (industry, domestic and agricultural) to prioritize water saving, water reuse and proper wastewater treatment to make potable water accessible everywhere in the world. With the industrial sector consuming nearly 20% of the fresh water available, there is a corresponding generation of large volumes of effluents. This has been projected to increase, as population is skyrocketing and more economies are becoming more industrialized to accommodate the needs of the ever-increasing population. Over the years, stringent effluent discharge limits have been imposed on the industrial sector to minimize the pollution of the receiving environments, especially the water bodies. In addition, wastewater treatment for reuse is being encouraged, which will ease the stress on freshwater resources. The oil refinery industry is noted for the generation of large volumes of effluents. These effluents are heavy laden with toxic and refractory materials as well as high concentrations of salts which pose huge environmental risks and detrimental ripple effects on humans and animals if these effluents are not properly treated before discharge. Unfortunately, the use of conventional treatment methods to treat downstream oil refinery effluent (ORE) has been unsuccessful in the removal of these materials, especially the salts. This research therefore, aimed at desalinating the effluent from the effluent treatment plant (ETP) of a local South African waste oil refinery to meet discharge limits. The ETP, even though successful in the removal of organics (COD, turbidity and colour), consistently records high levels of sulphates, chlorides and carbonates as a result of the source of their raw material and other in-house processes that take place during the treatment process. The study assessed and compared the feasibility of applying three membrane processes, viz forward osmosis (FO), reverse osmosis (RO) and hybrid FO-RO systems in desalinating the ORE. The FO and RO were first run as standalone processes, where models were generated and used to optimize the important factors using the Box-Benhken design (BBD) of response surface methodology (RSM). Based on the optimized conditions, the hybrid FORO was investigated. The basis of comparison was their permeation fluxes, salt rejection and flux recoverability after membrane cleaning. A total of 45 experimental runs were conducted which catered for pure water flux tests of virgin membranes, optimization studies and confirmatory runs. The factors of interest for FO were feed solution flow rate (FS-FR) (7.5 – 9.4 L/h), draw solution flow rate (DS-FR) (7.5 – 9.4 L/h) and draw solution concentration (DS-C) (20, 35 and 50 g/L NaCl). With RO, focus was placed on operating pressure (14 – 18 bar), feed concentration and operating time (4-6 h). The results showed an average permeation flux of 3.64 ± 0.13 L/m2 h, Clenrichment (reverse solute diffusion (RSD)) of 35.5 ± 5.15%, SO4 2- rejection of 100%, CO3 2- rejection of 94.59 ± 0.32 and flux recovery of 86.01 ± 2.66% for FO. For RO, the average permeation flux achieved was 2.29 ± 0.24 L/m2 h, Clrejection efficiency was 90.54 ± 0.81%, SO4 2- rejection efficiency was 95.1%, CO3 2- rejection efficiency was 97.3 ± 0.4 and flux recovery after membrane cleaning was 62.52 ± 2.62%. The FO-RO hybrid process proved unsuccessful due to constraints from the filtration unit. As an intervention to make the hybrid process work, NF was used as the recovery process. However, results show a low permeation flux of 0.69 ± 0.10 L/m2h on average. From the results obtained, it was concluded that RO presents the best desalination option for treating the ORE using low pressure of between 14 – 18 bar. This will require no post treatment and there will be no contamination of feed due to RSD

Reverse solute flux(RSF) is a big challenge of forward osmosis(FO) technology. This experiment was based on the study of the performance of apple juice concentration by FO technology and the solute diffusion law of functional draw solution(sodium acetate, sodium bicarbonate and sodiumcitrate). Firstly, the basic properties of FO system were studied, including water flux, RSF and rejection rate, by varying the concentration of NaCl draw solution, influent flow rate and membrane operation mode. The concentration ability of deionized water and apple juice and solute diffusion law were analyzed. To achieve the purpose of converting the RSF into advantages, the effect of different functional draw solutions on apple juice concentration and RSF were compared. The results showed that the concentration efficiency and RSF were affected by the concentration of draw solution and membrane operation mode. The membrane mode of pressure retarded osmosis(PRO) led to the higher RSF and the concentration degree of apple juice than the FO mode. In the PRO mode, the RSF reach to 87.34±6.32 g·m−2·h−1 with the NaCl draw solution concentration of 5 mol·L−1. The ability of concentrating apple juice by different concentration of functional draw solution was various. The order of water extraction capacity from high to low was sodium bicarbonate, sodium chloride, sodium acetate, sodium citrate and the order of RSF from high to low was sodium citrate, sodium bicarbonate, sodium chloride, sodium citrate. The RSF was 29.61±2.19 g·m−2·h−1 with 2 mol·L−1 NaCl draw solution, which was only half of the same concentration of NaCl draw solution. Compared with traditional NaCl draw solution, sodium citrate draw solution could effectively control RSF.

The research aims to use a new technology for industrial water concentrating that contains poisonous metals and recovery quantities from pure water. Therefore, the technology investigated is the forward osmosis process (FO). It is a new process that use membranes available commercial and this process distinguishes by its low cost compared to other process. Sodium chloride (NaCl) was used as draw solution to extract water from poisonous metals solution. The driving force in the FO process is provided by a different in osmotic pressure (concentration) across the membrane between the draw and poisonous metals solution sides. Experimental work was divided into three parts. The first part includes operating the forward osmosis process using TFC membrane as flat sheet for NaCl. The operating parameters studied were: draw solutions concentration (10 – 95 g/l), draw solution flow rate (12-36 I/h), temperature of draw solution (30 and 40°C), feed solution concentration (10 -210 mg/l), feed solution flow rate (10 -50 l/h), temperature of feed solution (30 and 40°C) and Pressure (0.4 bar). The second part includes operating the forward osmosis process using CTA membrane as flat sheet for NaCl. The operating parameters studied were: draw solution concentration (15 – 95 g/l), feed solution concentration (10-210 mg/l). Constant temperature was maintained at 30°C. The last part includes operating the reverse osmosis process using TFC membrane as spiral wound module in order to separate NaCl salt from draw solution and obtain on pure water so as to usefully in different uses and also obtain on solution of NaCl concentrate which was recirculated to forward osmosis process. It is then used as draw solution. The operating parameter studied was: feed solution flow rate (15-55 l/h). The experimental results show that the water flux increases with increasing draw solution concentration, feed solution flow rate, temperature of draw solution and decreases with increasing feed solution concentration, draw solution flow rate and temperature of feed solution. The experiments also show that CTA membrane gives higher water flux than TFC membrane for forward osmosis operation.

In this study, we propose a novel module design to integrate forward osmosis (FO) and membrane distillation (MD). The two processes are sealed in one module and operated simultaneously, making the system compact and suitable for a wide range of applications. To evaluate the system under large-scale module operating conditions, FO and MD experiments were performed separately. The effect of draw solution (DS) temperature on the FO performance was first assessed in terms of flux, reverse salt flux (RSF), and specific RSF (SRSF). While a higher DS temperature resulted in an increased RSF, a higher FO flux was achieved, with a lower SRSF. The influence of DS concentration on the MD performance was then investigated in terms of flux and salt rejection. High DS concentration had a slightly negative impact on MD water vapor flux, but the MD membrane was a complete barrier for DS salts. The FO-MD integrated module was simulated based on mass balance equations. Results indicated that initial DS (MD feed) flow rate and concentration are the most important factors for stable operation of the integrated module. Higher initial DS flow rate and lower initial DS concentration can achieve a higher permeate rate of the FO-MD module.

In order to ensure long-term sustainability of the reservoir, the gas industry in Qatar is faced with the challenge of reducing the volume of produced and process water (PPW) sent to disposal wells by 50% [1-3]. Recently, Qatargas initiated a project to recycle process water and thus, reduce disposal volumes using commercial advanced water treatment technologies [4]. One emerging technology, “osmotic concentration” (OC) has been identified that offers a low-energy alternative to conventional thermal or membrane volume reduction methods. Osmotic concentration is a membrane filtration process that mimics first step in a forward osmosis (FO) system. It requires a high salinity draw solution (DS) which passes on one side of a semi-permeable FO membrane while the feed passes on the other side. Water from the feed is drawn through the membrane, via natural osmosis, reducing the feed volume and increasing the volume of the draw solution. This paper summarizes the results of bench-scale volume reduction tests wit...

Effect of draw solution concentration and operating conditions on forward osmosis and pressure retarded osmosis performance in a spiral wound module

Combination and performance of forward osmosis and membrane distillation (FO-MD) for treatment of high salinity landfill leachate

The present work aims to study forward osmosis process using different kinds of draw solutions and membranes. Three types of draw solutions (sodium chloride, sodium formate, and sodium acetate) were used in forward osmosis process to evaluate their effectiveness with respect to water flux and reverse salt flux. Experiments conducted in a laboratory-scale forward osmosis (FO) unit in cross flow flat sheet membrane cell. Three types of membranes (Thin film composite (TFC), Cellulose acetate (CA), and Cellulose triacetate (CTA)) were used to determine the water flux under osmotic pressure as a driving force. The effect of temperature, draw solution concentration, feed and draw solution flow rate, and membrane types, were studied with respect to water flux. The results showed an increase in water flux with increasing feed temperature and draw solution concentrations In addition, the flux increased with increasing feed flow rate while the flux was inversely proportional with the draw solution flow rate. The results showed that reverse osmosis membranes (TFC and CA) are not suitable for using in FO process due to the relatively obtained low water flux when compared with the flux obtained by forward osmosis membrane (CTA). NaCl draw solution gave higher water flux than other draw solutions and at the same time, revealed higher reverse salt flux.

In this study, the feasibility of Forward–Reverse osmosis processes was investigated for treating the oily wastewater. The first stage was applied forward osmosis process to recover pure water from oily wastewater. Sodium chloride (NaCl) and magnesium chloride (MgCl2) salts were used as draw solutions and the membrane that was used in forward osmosis (FO) process was cellulose triacetate (CTA) membrane. The operating parameters studied were: draw solution concentrations (0.25 – 0.75 M), oil concentration in feed solution (FS) (100-1000 ppm), the temperature of FS and draw solution (DS) (30 - 45 °C), pH of FS (4-10) and the flow rate of both DS and FS (20 - 60 l/h). It was found that the water flux and oil concentration in FS increase by increasing the concentration of draw solutions, the flow rate of FS and the temperature for a limit (40oC), then, the water flux and oil concentration decrease with increasing the temperature because of happening the internal concentration polarization phenomenon. By increasing the oil concentration in FS and the flow rate of the DS, the water flux and oil concentration in FS decreased, while it had a fluctuated behavior with increasing pHof oily wastewater. It was found also that MgCl2 gives water flux higher than NaCl. So the values of resistance to solute diffusion within the membrane porous support layer were 55.93 h/m and 26.21 h/m for NaCl and MgCl2 respectively. The second stage was applied reverse osmosis process using polyamide (thin film composite (TFC)) membrane for separating the fresh water from a diluted (NaCl) solution using different parameters such as draw solution concentration (0.08–0.16 M), feed flow rate (20–40 l/h).

This paper was aimed to study the efficiency of forward osmosis (FO) process as a new application for the treatment of wastewater from textile effluent and the factors affecting the performance of forward osmosis process.The draw solutions used were magnesium chloride (MgCl2), and aluminum sulphate (Al2 ( SO4)3 .18 H2O), and the feed solutions used were reactive red, and disperse blue dyes.Experimental work were includes operating the forward osmosis process using thin film composite (TFC) membrane as flat sheet for different draw solutions and feed solutions. The operating parameters studied were : draw solutions concentration (10 – 90 g/l), feed solutions concentration (5 – 30 mg/l), draw solutions flow rate (10 – 50 l/hr), feed solutions flow rate (20-60 l/hr), constant pressure and temperature were maintained at 0.5 bar and 30ºC respectively. And includes operating the forward osmosis process using cellulose triacetate (CTA) membrane as flat sheet for different draw solutions and feed solutions. The operating parameters studied were : draw solutions concentration (10 – 90 g/l), and feed solutions concentration (5 – 30 mg/l), constant temperature at 30ºC. It was found that water flux increases with increasing draw solution concentration, and feed solution flow rate and decreases with increasing draw solution flow rate and feed solution concentration for TFC and CTA. It was found MgCl2 given water flux larger than Alum. And also found that reactive red given water flux larger than disperse blue.The experiments also show that CTA membrane gives higher water flux than TFC membrane for forward osmosis operation. The increase in water flux for CTA is about 12.85% than TFC.

Mathematical approach for improved performance of flat-sheet forward osmosis membrane

Experimental investigation of forward osmosis process for boron removal from water

Desalination by ammonia–carbon dioxide forward osmosis: Influence of draw and feed solution concentrations on process performance

Thermodynamic optimization of Multistage Pressure Retarded Osmosis (MPRO) with variable feed pressures for hypersaline solutions

Modeling and measurement of temperature and draw solution concentration induced water flux increment efficiencies in the forward osmosis membrane process