One of the cost-effective methods of water purification is reverse osmosis. In the present work, the effect of pressure vessels with different numbers of membranes in two types of reverse osmosis system design is investigated. Simulation results showed that pressure vessels with more membranes have lower energy consumption and higher efficiency in different simple and hybrid designs of reverse osmosis systems. Findings showed that the first design performs better in terms of energy consumption and efficiency than the second design. The study also showed that maximum efficiency was achieved using the first design of the hybrid two-stage brackish water reverse osmosis system. The least efficient system was the hybrid single-stage seawater reverse osmosis system.

Today, water desalination methods are of great importance in solving the freshwater crisis in the world, so that in recent years, the world's water desalination capacity has increased dramatically. Among them, the reverse osmosis membrane technology has been the most popular and the most commonly used. There are problems such as high energy consumption, high operating costs, and fouling in this method. The objective of this paper was to use reverse and forward osmosis membrane methods simultaneously in a hybrid reverse-forward osmosis setting, which enabled us to take advantage of the benefits of forward osmosis such as not being dependent on high hydraulic pressure, lower cost and less membrane fouling compared to reverse osmosis. Another objective of the study was to evaluate the permeate water production efficiency of desalination with this hybrid method. It is expected that using the hybrid method will reduce the required pressure for conducting reverse osmosis process to achieve a specified permeate flux, because it reduces cost and energy. An HRFO laboratory pilot with a capacity of 50 m3/day was designed and set up in the Hydraulic Lab of Shahid Chamran University of Ahvaz for running hybrid experiments. The design of the pilot was such that it could operate in both reverse osmosis and HRFO. HRFO experiments were carried out at pressures of 4.5 to 10.5 bar for Ahvaz urban water as feed solution, as well as NaCl as draw solution with a concentration of 2000 to 10000 mg/L via the experimental HRFO plant. It was found that adding the forward osmosis to reverse osmosis at the best situation (lowest pressure and highest concentration of draw solution) can increase the permeate water production efficiency of desalination by 55.12%. The best hybridization degree of these two methods was determined to be 64.5% for reverse osmosis and 35.5% for forward osmosis.

During patients’ hemodialysis Circle, the amount of heavy metals in feed water to dialysis instrument and the patient’s blood are changed. The present study aims at evaluating the trend of lead, cadmium, chromium and zinc concentration in feed water to reverse osmosis, dialysis instrument and blood of hemodialysis patients in 7 hospitals of Kermanshah. A total of 42 samples of feed water, 42 samples of reverse osmosis systems permeate and 42 samples of hemodialysis instrument permeate were collected from 7 hospitals in Kermanshah. The collected samples were analyzed and the concentration of lead, chromium, cadmium and zinc were determined by using ICP (DV-Optima2100 model) according to a standard method. Furthermore, statistical analysis was carried out by using one-sample t-test to compare mean quality of feed water of dialysis instrument with AAMI and EPH standards. In addition, ANOVA test was used for comparing the results of three sample groups. The obtained results indicated that the mean concentration of lead, cadmium, chromium and zinc in feed water of reverse osmosis system (drinking water), were 18.53± 8.25, 0.706± 0.42, 86.06 ± 5.56, 112.67± 63.56pbb, respectively. Also, quantity of these constituents in the feed and permeate of electrolysis device was 18.81±5.32, 0.719±0.53, 84.25±2.46, 43.39±19.4pbb and 12.5±6.32, 1.39±0.87, 66.15±13.54, 60.38±22.39pbb, respectively. Due to obtained results, the removal efficiency of zinc and chromium by reverse osmosis system in dialysis instrument were 61.5 and 2.1%, respectively, while it was not effective in removing lead and cadmium metals. Discussion & Increasing the level of lead and cadmium in permeate water of the reverse osmosis system rather than the feed water indicated that the reverse osmosis membrane function is out of service; as a result, it is required to be washed or replaced. Decreasing both lead and chromium metals in permeate solution of the dialysis instrument revealed the addition of the amount of those two hazardous metals to the blood of hemodialysis patients, which could be related to reverse osmosis membrane deficiency and high concentration of metals in its water permeate.

According to the present heavy metal pollution is a universal phenomenon, thus concerns about long-term effects of these metals, is increasing. The heavy metal cadmium as a toxic element exposure in humans can cause a variety of symptoms, because of its ability to accumulate in various tissues. The objective of this research was to evaluating the performance of the reverse osmosis system in cadmium removal from drinking water. The standard solution made in laboratory scale, then the removal efficiency of cadmium by semi-permeable membrane for reverse osmosis system (model: FT-30), under the influence of parameters concentration, pH and pressure were investigated. The results of this study showed that in the standard temperature 20 ºC , the concentration 50 ppb, pressure 350 (Kpa) and pH of about 6.8, cadmium removal efficiency by reverse osmosis system was above 98 percent. Thus, can be concluded that reverse osmosis, an ideal method to cadmium removal in areas with contaminated water to this metal.

The recursive approach for assessing the reliability, availability, maintainability, and dependability (RAMD) of five subsystems in a reverse osmosis (RO) machine was investigated in this study. The components include the raw water tank, precision filter, carbonated filter, reverse osmosis membrane, and water producing tank. Furthermore, the efficacy of a reverse osmosis (RO) unit, mean time to failure (MTTF), mean time to repair (MTTR), and dependability ratio were also assessed. The major aim is to maximize efficiency and identify the critical subsystem or component of the reverse osmosis machine. And finding out how to fix the problem. We utilized data from the RO unit with a repair rate and a failure rate over a 100-day period to validate the technique. There were numerical numbers for each subsystem's dependability, as well as comparisons between subsystem dependability and total system dependability.

Iran is one of the arid and semi-arid countries which face with many problems in water supply. Membrane process such as reverse osmosis (RO) is one of the advanced methods of water treatment which are widely used in arid and semi-arid areas. Reverse osmosis system produces two types of water, one purified water and the other concentrated wastewater. To reuse the concentrated wastewater in reverse osmosis, it is necessary to remove some of the critical elements that cause problems for the membrane. In this research ZLD processes were used for removing the critical elements of reverse osmosis wastewater of Lar city in Fars Province, Iran. The purpose of this study was to evaluate ZLD processes and determine the optimal process for recycling of reverse osmosis wastewater. In this research different scenarios were selected for reverse osmosis wastewater treatment including the processes of absorption, chemical precipitation and combination of these processes. Fluidized bed crystallization (calcium carbonate particles) was used for absorption process and sodium hydroxide, lime, sodium aluminate and aluminum sulfate were used for chemical precipitation processes. These chemicals were combined with wastewater in concentrations of 100, 200, 300, 400, 500 and 600 mg/L and some parameters including calcium, magnesium, chloride, sodium, potassium, pH, salinity, silica and turbidity were measured and optimum chemical concentration was determined. Optimal concentration was chosen based on maximum removal efficiency of harmful elements for reverse osmosis membrane. Optimum removal efficiency of sodium hydroxide, lime, sodium aluminate and aluminum sulfate, were in concentration of 500, 400, 200 and 100 mg.L-1, respectively. To improve removal efficiency, the chemicals were combined together based on the optimal concentration of each chemical which was determined in the previous step. Therefore, aluminum sulfate and sodium hydroxide, aluminum sulfate and lime, sodium aluminate and sodium hydroxide and sodium aluminate and lime were mixed together. At this step the best removal efficiency was obtained in combination of optimal concentration of sodium aluminate and sodium hydroxide. Absorption process in fluidized bed crystallization was investigated for difference fluxes and optimum flux was 1.94 m3.h- 1.m-2. The maximum removal efficiency of harmful elements for reverse osmosis membrane was observed in the combination processes of chemical deposition and absorption which occurred in fluidized bed crystallization with flux of 1.94 m3.h-1.m-2 with adding optimized values of sodium aluminate (200 mg.L-1) and hydroxide sodium (500 mg.L-1).

Background and The chemical quality of feed water to dialysis instrument is very important، especially in terms of heavy metals which could cause serious health problems for dialysis patients. This study aimed to determine the concentration of selected heavy metals (lead، cadmium، chromium and zinc) in feed water to dialysis instrument and compared that with EPH and AAMI standards in hospitals of Kermanshah province in 2014. A total of 42 samples of feed water، and 42 samples of permeate water (feed water to dialysis instrument) of reverse osmosis systems were collected from Kermanshah province hospitals. The collected samples were analyzed and the concentrations of lead، chromium، cadmium and zinc were determined using ICP (DV-Optima2100 model) according to standard methods. Then، the mean concentrations were compared with AAMI and EPH standards. The mean concentration of lead، cadmium، chromium and zinc in permeate water of reverse osmosis system was 18. 81± 14. 32، 0. 719± 0. 53، 84. 25 ± 2. 46 and 43. 39± 19. 1 ppb، respectively. The efficiency of the settled reverse osmosis system before dialysis instrument was 61. 5 and 2. 1%، in removal of zinc and chromium، respectively. But this system was found inefficient in removal of lead and cadmium. The mean concentrations of lead and chromium in the permeate water from the reverse osmosis system was higher than limited standards of AAMI and EPH، but the mean concentrations of chromium and zinc were lower than mentioned standards in all investigated hospitals. Therefore، the reverse osmosis system was able to decrease zinc in moderate and chromium in lower levels، but it was not effective in the removal of other heavy metals. So، periodic washing and cleaning or replacing the membrane of the reverse osmosis system is highly recommended.

Kidney patients in each dialysis cycle are exposed to extremely large volume of water, which is in direct contact with the patient’s blood . Therefore, water used for this purpose should be treated with advanced methods before use for dialysis. The objective of this study was to assess the efficiency of reverse osmosis systems to improve water quality used for dialysis fluid.
Material & This is a descriptive-analytic study to Evaluation of Reverse Osmosis System of water treatment system for dialysis centers in Imam Ali Bojnurd ciry during 2015on 36 samples of water from the municipal water was reverse osmosis. Post-harvest and transport of samples to the laboratory using the latest according to the standard methods for water and wastewater examination.
The results of this study showed that the reverse osmosis systems significantly reduce the amount of sulfate, nitrate, fluoride, hardness, sodium, potassium. These amounts were lower than AAMI and EPH standards.
Reverse osmosis systems could improve the quality of water used for hemodialysis. Based on the results of this study, it can be concluded that ahh the measured parameters in the hospitals werw below the standard levels. , indicating that removal efficiency reverse osmosis system parameters is desirable.

Among desalination systems, the use of reverse osmosis has become very widespread due to its advantages. One of the challenges in desalination systems especially in the reverse osmosis method is the existence of a control algorithm to overcome the uncertainties and disturbances. Another challenge of such systems is their power supply. A high-pressure pump supplies the pressure behind the membrane in the reverse osmosis system. The use of renewable energy not only does not have any environmental effects but also provides sustainable energy for such systems. In this paper, to answer these two challenges, at first, the integrated model of the reverse osmosis desalination system with the solar photovoltaic system has been examined; then for each part, a control algorithm is designed and simulated. An optimized fuzzy controller has been designed to track the maximum power point at different temperatures and radiation conditions in the photovoltaic solar system. The fuzzy controller has been optimized with the invasive weed optimization algorithm. The electric motor has been controlled using a fuzzy proportional–integral–derivative algorithm. The super-twisting sliding mode control has been used for the reverse osmosis system. The simulation results show that the proposed algorithm for the combined reverse osmosis-photovoltaic system has a good performance in different operating conditions and can remove and eliminate disturbances on the system.

Freshwater is a scarce resource, constituting only 2.5% of Earth's total water. Approximately 90% of freshwater is concentrated near the South Pole of the Antarctic Circle, exacerbating its scarcity for living organisms. Industries such as pharmaceuticals, textiles, food production, and agriculture rely heavily on monthly freshwater supplies for their operations. Proper disposal of wastewater from these sectors is imperative to meet environmental standards. This study aimed to evaluate the effectiveness of reverse osmosis systems in treating well water for human consumption, examine the possibility of reusing reverse osmosis treated wastewater, and assess the feasibility of reducing freshwater consumption and wastewater generation. The study used the qualitative and quantitative data obtained in 2018, 2019, 2022, and 2023 from the manufacturing industry in Guayama, Puerto Rico. Statistical analysis was confidently conducted using the Paired T-Test and Pearson correlation tests, with Minitab Statistical Software (Version 21.1.0) utilized for statistical analysis. The results of this study showed that reverse osmosis is an effective system for treating well water for human use and enabling the reuse of wastewater after treatment. A total of 2,397,000 gallons of wastewater were treated and reused for cooling towers and boilers, representing the same amount of freshwater conserved and wastewater not discharged into the sewer system. The metrics analyzed were total organic carbon, conductivity, nitrate levels, and total aerobic microbial population. Total organic carbon in the samples ranged from 3 to 29 ppb. Conductivity was between 0.3 μS/CM and 1.0 μS/CM. Nitrate levels were all under 0.2 ppm (0.2 mg/l). Total aerobic bacteria counts were 0 cfu per milliliter. Regarding the feasibility of reusing wastewater post-reverse osmosis treatment, the findings showed decreased levels of anions and cations in the treated wastewater. Additionally, all reverse osmosis-treated well water samples tested in 2022 met the quality control laboratory criteria. The study confirms that the reverse osmosis system effectively purifies well water for human use and demonstrates the potential for repurposing treated wastewater. Furthermore, 2,397,000 gallons of treated wastewater were repurposed for cooling towers and boilers, conserving freshwater resources, and preventing the discharge of an equivalent volume of wastewater into the sewer system.