Reverse Osmosis Technology Research Articles

An Assessment of Renewable Energies in a Seawater Desalination Plant with Reverse Osmosis Membranes.

The purpose of our study was to reduce the carbon footprint of seawater desalination plants that use reverse osmosis membranes by introducing on-site renewable energy sources. By using new-generation membranes with a low energy consumption and considering wind and photovoltaic energy sources, it is possible to greatly reduce the carbon footprint of reverse osmosis plants. The objective of this study was to add a renewable energy supply to a desalination plant that uses reverse osmosis technology. During the development of this research study, photovoltaic energy was discarded as a possible source of renewable energy due to the wind conditions in the area in which the reverse osmosis plant was located; hence, the installation of a wind turbine was considered to be the best option. As it was a large-capacity reverse osmosis plant, we decided to divide the entire desalination process into several stages for explanation purposes. The desalination process of the facility consists of several phases: First, the seawater capture process was performed by the intake tower. This water was then transported and stored, before going through a physical and chemical pre-treatment process, whereby the highest possible percentage of impurities and organic material was eliminated in order to prevent the plugging of the reverse osmosis modules. After carrying out the appraisals and calculating the amount of energy that the plant consumed, we determined that 15% of the plant’s energy supply should be renewable, corresponding to 1194 MWh/year. As there was already a wind power installation in the area, we decided to use one of the wind turbines that had already been installed—specifically, an Ecotecnia turbine (20–150) that produced an energy of 1920 MWh /year. This meant that only a single wind turbine was required for this project.

Carbon Footprint-Energy Detection for Desalination Small Plant Adaptation Response

The Life Cycle Assessment (LCA) system, which can be used as a decision support tool for managing environmental sustainability, includes carbon footprint assessment as one of the available methodologies. In this study, a carbon footprint assessment was used to investigate seawater production systems of a desalination plant in Senok, Kelantan, Malaysia. Three stages of the desalination plant processing system were investigated and the inventory database was developed using the relevant model framework. Subsequently, measurements and interpretations were performed on several key indicators such as greenhouse gases, energy efficiency, acidic gases, smog, and toxic gases. Overall, the results of the study indicate that the Reverse Osmosis (RO) technology that is used in the desalination plant in the study area is one of the best options to meet the demands of the environmental sustainability agenda (SDGs). This is due to the lower carbon dioxide (CO2) emission, of about 3.5 × 10−2 kg of CO2 eq per m3/year, that was recorded for the entire operation of the system. However, several factors that influence important errors in carbon footprint decisions, such as the lack of EIA reporting data and the literature on carbon footprint in the Malaysian scenario, in addition to direct and indirect carbon input calculations, need to be identified in more detail in future research.

Promising integrated technique for the treatment of highly saline nanofiltration rejected stream of steel industry

This work presents a novel concept for the integration of closed-circuit reverse osmosis (CCRO) technology and solvent-based precipitation as a means of producing an exceptional quality of water by separating the salts especially chlorides and sulphates from highly saline nanofiltration (NF) rejected stream of the steel industry. The NF rejected stream was extremely concentrated with salts like chloride (1560 mg/L), sulphate (4212 mg/L), manganese (28 mg/L), sodium (418 mg/L) and total dissolved solids (TDS), as high as 8100 mg/L, which are well above the permissible limit for surface discharge. The outcome of this work showed that reverse osmosis (RO) with continuous brine recycling achieved excellent desalination performance. Miscible organic solvents such as diisopropylamine (DIIPA), isopropylamine (IPA), and ethylamine (EA) were found to be effective in precipitating chloride and sulphate ions from highly concentrated RO brine. The overall removal efficiency of sulphate and chloride was found to be 99.88% and 91%, respectively. Preliminary treatment cost was estimated and found to be around 7.35 $/m3. The treated water can either be recycled in the system or safely released into the environment. The readers of this research article will be benefitted by gaining a thorough understanding of the treatment of concentrated brine from nanofiltration using an integrated RO-precipitation technique.

Multi-objective optimization of a renewable power supply system with underwater compressed air energy storage for seawater reverse osmosis under two different operation schemes

Water supply in rural islands or coastal areas is a basic task for people's livelihood. The all-pervading reverse osmosis (RO) technology is an energy-intensive process. To achieve sustainability goals, the development of renewable driven power supply system for RO plant is significant. Nowadays, the energy, economic and environmental indicators have rarely simultaneously investigated for the type of renewable power supply system with underwater compressed air energy storage (UW-CAES) for RO plant. In this paper, an energy-economic-environmental trade-off multi-objective optimization for such system is proposed in both grid-connected and off-grid schemes. A bi-level optimization strategy based on MOPSO algorithm and TOPSIS method is adopted to seek the optimal configuration and energy management strategy. A real-world case is implemented to demonstrate this method. The results show that the TPC/COE/EC set in optimal grid-connected scheme system is 3.716 × 106¥/0.814¥kWh−1/795.922 kg with a configuration of 511 PVs, 12 WTs and a 900 m3 bag volume in UW-CAES. Whereas, the TPC/COE/EC in optimal off-grid system is 4.076 × 106¥/2.305 kWh−1/566.254 kg with a 705/8/900 m3 configuration. In energy perspective, both schemes can match the load well. In economic perspective, the grid-connected scheme has a considerable profit, whereas the off-grid has no revenue. In environmental perspective, both schemes can reduce the carbon emission remarkably.

REDUCTION OF CONCENTRATE EFFLUENTS OF REVERSE OSMOSIS UNITS USED FOR TREATMENT OF WASTE WATER CONTAINING ORGANIC POLLUTION

Background Units for electrical desalination of oil, other chemical industries, as well as landfills for the storage of municipal solid waste (MSW) are sources of groundwater and surface water pollution with toxic decomposition products of organic substances. The ability to purify MSW filtrate to the level of modern requirements for purified water supplied to fishery reservoirs is a complex technical problem. The most effective technology for purifying solid waste filtrates is currently recognized as reverse osmosis technology, which allows to effectively remove from water not only contaminants in the ionic form (ammonium), but also dissolved organic compounds determined by the indicator of chemical oxygen consumption. A serious problem when using reverse osmosis technology is the formation of concentrates and their disposal. The consumption of concentrates in the treatment of leachate from MSW landfills by the reverse osmosis method is from 20 % to 30 % of all incoming water for treatment. Aims and Objectives The purpose of this work is to study the issues of processing mineralized wastewater containing oil products and other organic pollution (wastewater from electrical desalting plants, leachate from solid municipal waste storage sites) using reverse osmosis and nanofiltration methods. Results It is noted that a serious environmental problem is posed by reverse osmosis concentrates, which have a high content of salts and organic substances and are difficult to dispose of. It is proposed to use the separation of concentrates into solutions containing their components, depending on the value of the value of their retention using nanofiltration membranes. So, concentrates of reverse osmosis plants can be divided into solutions with a high content of organic substances and saline solutions (containing ammonium salts), the volumes of which are 10-20 times lower than the volumes of concentrates. Using the example of concentrates from reverse osmosis plants, it is shown how multicomponent solutions can be divided into highly concentrated solutions of organic substances and saline solutions of ammonium chloride in order to simplify their further disposal. The technology of separation of solutions is described, using dilution of the concentrate with deionized water, which makes it possible to achieve separation of solutions into components depending on their selectivity - the degree of their retention by nanofiltration membranes.

An IGDT/Scenario based stochastic model for an energy hub considering hydrogen energy and electric vehicles: A case study of Qeshm Island, Iran

With the development of human societies, new industries and needs are being formed which supplying their power and energy consumption, requires the development of equipment and infrastructure in the field of power generation and transmission. An example of these industries are seawater desalination (SWD) units. In addition, increasing attention to air pollution has led to the proliferation of electric vehicles (EVs) or the use of hydrogen as a zero emission fuel. Energy hubs (EHs) can benefit from advantages such as optimal use of installation capacity and environmental potential by accepting to provide other needs along with common requirements such as electricity, cooling, and heating. In this case, EH is able to increase its flexibility by converting energy into the desired product and storing it in a different form as of electrical or thermal energy. In this paper, EH utilizes a SWD with Reverse Osmosis (RO) technology as a flexible load and an Organic Rankine Cycle (ORC) as a new technology for generating electrical power by means of thermal power. In addition, for better interact with available EVs, one parking lot and a Battery Swapping Station (BSS) are introduced. The Electrolyser uses the electrical power to supply the required amount of hydrogen, and the hydrogen tank in addition to fuel cell (FC) help to balance the production and consumption of hydrogen. In order to model the existing uncertainties, scenario generation method as well as information gap decision theory (IGDT) method have been used. The efficacy of the proposed model is evaluated on a smart commercial building in Qeshm Island, which is located a few kilometers off the southern coast of Iran.

Treatment of Effluent of Upflow Anaerobic Sludge Blanket Bioreactor for Water Reuse

The low-pressure reverse osmosis (LPRO) process is a recent development of reverse osmosis (RO) technology for the reduction in RO energy consumption and operation cost. The goal of this study was to investigate the performance of LPRO processes for the treatment and reuse of effluent discharged from brewery upflow anaerobic sludge blanket bioreactors (UASB). In this study, three different commercially available LPRO membranes were tested to evaluate the water quality that can be achieved under different operational and pretreatment conditions. It was found that the filtration performance and the effluent quality of the LPRO membranes can be considerably affected by the operation conditions and the selection of the pretreatment processes. The ultrafiltration (UF) pretreatment and the control of the operation pressure were found to be essential for mitigating LPRO membrane fouling, which could be caused by Ca2+ associated precipitates and organic gelation, in the treatment of the brewery UASB effluent. Water quality analyses showed that an integrated process of the UASB + UF + LPRO could achieve an effluent quality characterized by concentrations of 10.4–12.5 mg/L of chemical oxygen demand (COD), 1.8–2.1 mg/L of total nitrogen (TN), 1.3–1.8 mg/L of ammonia nitrogen (NH3-N) and 0.8–1.2 mg/L of total phosphorus (TP). The effluent quality and the LPRO performance could be further improved by adding a granular activated carbon (GAC) adsorption process between the UF and LPRO processes, which reduced the concentration of COD to 7–10 mg/L and those of TN, TP, NH3-N to below 1 mg/L. For the treatment of the UASB effluent tested in this study, the UF, UF + GAC (retention time 4 hrs), UF + LPRO, and UF + GAC + LPRO, respectively, achieved overall COD removal efficiencies of 89.6–93.7%, 94.5–96.7%, 99.3–99.1% and 99.3–99.4%; TN removal efficiencies of 73.0–78.2%, 89.2–97.2%, 97.1–98.2% and 94.3–99.7%; and TP removal efficiencies of 29.3–46.2%, 77.0–95.4%, 95.9–97.6z% and 98.0–98.3%. This study showed that both UASB + UF + LPRO and UASB + UF + GAC + LPRO are effective treatment processes for treating brewery wastewater toward reuse water quality standards set by the United States Environmental Protection Agency (US EPA). Therefore, the results of this study would help to answer whether a LPRO can treat the brewery UASB effluent to meet the requirements of wastewater reuse standards.

Optimal operation of the coastal energy hub considering seawater desalination and compressed air energy storage system

An optimal day-ahead operation of a microgrid based on coastal energy hub is presented in this paper. The proposed coastal energy hub includes generation units (wind turbine, photovoltaic cell, and combined cooling, heat and power), energy storage systems (ice storage conditioner, thermal energy storage system, and solar-powered compressed air energy storage), and seawater desalination with reverse osmosis technology as a flexible load. The purpose of the optimization is to minimize the operational and environmental costs subjected to numerous technical constraints. The suggested multi-objective problem considers the stochastic behavior of renewable generations as well as electrical, thermal, cooling, and freshwater demands under various scenarios. This paper uses an augmented epsilon constraint method for solving the proposed multi objective problem and implements a fuzzy based decision maker for choosing the suitable optimal solution amid Pareto front solutions. The proposed model implements the time of use program as a price-based demand response program. Implementation of the proposed framework on the typical coastal energy hub shows that using the solar-powered compressed air energy storage together with ice storage conditioner reduce the total operation cost (cost of purchasing electricity + cost of purchasing natural gas + cost of emissions) by 2.33% compared to the base case.

Desalination of Complex Multi-Ionic Solutions by Reverse Osmosis at Different pH Values, Temperatures, and Compositions.

For a thorough mechanistic understanding of reverse osmosis (RO), data on ion retention obtained by desalination of multi-ionic solutions are needed. In this paper, we show how to obtain such data under controlled laboratory conditions at any nonextreme pH. For that, we propose a simple method where we use N2 and CO2 gas control to set the composition of a gas phase in equilibrium with the feedwater solution. By increasing the CO2 partial pressure, the pH of the solution will decrease and vice versa. We applied this method of CO2 gas control to extend and validate an existing data set on ion retention of multi-ionic brackish water with 10 different ionic species, whereas conditions in the prior data set were slightly uncontrolled; in our new analysis, we performed experiments at precisely controlled pH and temperature. We run experiments at pH 6.73 and pH 7.11 and in a temperature range of T = 15–31 °C. Our results show that when pH is decreased, or temperature increased, the ion retention of most ions decreases. We also tested the influence of the Na+ to Ca2+ concentration ratio in this multi-ionic solution on ion retention at pH 6.73 and T ∼ 31 °C. We noticed that this ratio has a larger effect on ion retention for cations than for anions. We compare our data with the earlier reported data and describe similarities and differences. The improved data set will be an important tool for future development of accurate and validated RO ion transport models. Such RO models that describe desalination performance in detail are important for successful commercial application of the RO technology. We also discuss a relevant preparation method for water slightly oversaturated with barely soluble CaCO3 by solution preparation at high CO2 pressure, after which the solution is brought to the required pH by the N2 and CO2 gas control method.

A rigid-flexible interpenetrating polyamide reverse osmosis membrane with improved antifouling property fabricated via two step modifications

Polyamide thin-film composite reverse osmosis (RO) membranes usually suffer from fouling problem, which greatly limits the wide application of RO technology. In this study, a novel rigid-flexible interpenetrating polyamide RO membrane was fabricated via two step modifications to alleviate the membrane fouling during the RO process. The first step modification was carried out by incorporation a new aliphatic diamine of 1,3-diamino-2-propanol (DAPL) into the aromatic m-phenylenediamine (MPD) aqueous solution to react with trimesoyl chloride (TMC) to form a rigid-flexible interpenetration polyamide (PA) separation layer for enhancing its permeability. Then, the second modification was performed by grafting PVA on the top surface of the DAPL-based PA layer to tailor more hydrophilic, smoother and less negatively charged surface and endowed the modified membrane favorable antifouling property. Under the optimized condition, the permeability flux of the modified RO membrane reached 58.6 L/m2h with an about 58.8% increase than the pristine RO membrane (about 36.9 L/m2h), and the salt rejection was also maintained about 99.6% without any loss. At the same time, the modified RO membrane presented a favorable resistance to the dye foulants of methylene blue (MB) and crystal violet (CV) with flux recovery rate of 76.8% and 84.2% respectively. This study provides a facile and effective way to fabricate a novel antifouling reverse osmosis composite membrane with favorable comprehensive separation performance.

Cost analysis and scheduling of the desalination vessel using reverse osmosis technology

Water scarcity issue becomes severe due to climate change and increase of water needs, globally. In order to provide fresh water in islands, small-scale desalination plants (< 100 m3/day) had been installed using reverse osmosis technology. To decrease high desalination cost of small-scale SWRO plants in islands in Republic of Korea, the desalination vessel having RO system (300 m3/day) was recently suggested. The desalination costs of the small-scale SWRO plants in islands and desalination vessel which can provide desalinated water to several islands were analyzed and were compared. The operational schedule of the desalination vessel in Shinan-gun, Republic of Korea was suggested considering the water demands, velocity and water storage of the desalination vessel, and distances between target islands. It was found that the water production cost could be saved when the desalination vessel was applied in Shinan-gun, Republic of Korea.

Removal of Heavy Metal from Wastewater using Water Chestnut Shell as an Adsorbent

The contamination of water resources as a result of industrial activity is on the rise and is a global concern. The heavy metals found in wastewater are long lasting and non-biodegradable. Contamination with heavy metals over acceptable limits could result in major health problems. Chemical precipitation, chemical oxidation, ion exchange, membrane separation, reverse osmosis, electrodialysis, adsorption, and other technologies are used to lessen the influence of heavy metals on water bodies. Some procedures are extremely costly, energy-intensive, and frequently result in the production of harmful by-products. The use of adsorption as a cost-effective approach for removing heavy metals from industrial wastewater has been examined. The usage of Trapa bispinosa peels/shell as a low-cost adsorbent for wastewater treatment is discussed in this paper. Chemical activation was used to make activated carbons from Trapa bispinosa peels and shells. Activated carbons made from a combination of Trapa bispinosa peels/shells and Phosphoric acid with varying impregnation ratios. The results revealed that the activating temperature for the production of Trapa bispinosa-derived activated carbon is 500℃ (AC). CHNS, X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy were used to analyze the activated carbons.

Cellulose-derived polyols as high-capacity adsorbents for rapid boron and organic pollutants removal from water

Excess boron in water could result in a critical hazard to plants and humans. Traditional treatment approaches cannot efficiently remove boron from water, especially during seawater desalination using reverse osmosis technology. Achieving satisfactory adsorption capacity and rate for boron remains an unmet goal for decades. Herein, we report cellulose-derived polyols as high-performance adsorbents that can rapidly remove boron and organic pollutants from water. Cellulose-derived polyols were synthesized from saccharides and cellulose via controlled radical polymerization and click reaction. Remarkably, CA@NMDG can adsorb boron with an astonishing capacity of ~34 mg g-1 in 10 min, which surpasses all those cellulose-based materials reported thus far, meanwhile, much faster than those of commercial adsorption resin. Moreover, cellulose-derived polyols also showed high removal efficiencies (70–98% in several minutes) toward certain organic pollutants, including Congo red and Reactive Blue 19. The water-insoluble characteristic of cellulose-derived polyols is advantageous to be separated from the treated sewage after adsorption for reuse. This work provides a novel insight into the fabrication of safe, fast, and high-capacity cellulose adsorbents for water purification.

Energy, exergy and exergoeconomic (3E) analysis and multi-objective optimization of a closed-circuit desalination system with side-conduit

Membrane desalination technologies such as reverse osmosis (RO) are being widely used around the world to deal with the growing freshwater shortage. In addition, the use of new reverse osmosis technologies that improve the performance of traditional ones, has received more attention. The main problem in desalination plants is the high total specific energy consumption as well as high capital investment, maintenance and repair costs. In this study, the performance of a new closed-circuit reverse osmosis (CCRO) desalination system with side-conduit as a replacement for energy recovery device, is investigated based on energy, exergy and exergoeconomic (3E) analysis. 3E analysis is performed based on four important factors including 1) concentration of inlet feed water 2) number of cycles 3) osmotic pressure 4) mass flow rate of feed water. Then, using the output data obtained from 3E analysis, the optimal points for six key parameters of exergy efficiency, net driving pressure (NDP), total unit cost product (SUCP), mass flow rate of permeate, recovery ratio and specific energy are determined through multi-objective optimization. The simulation results show that in the proposed system, by increasing the number of cycles, the recovery ratio increases while the system costs also increase due to increase in pressure and concentration of inlet feed. It is found that the optimal recovery ratio of 64.29% is obtained for 9th cycle and inlet feed concentration of 6.95% and the optimal specific energy consumption of 2.5 kWh/m3 is obtained for 7th cycle and inlet feed concentration of 6.07%.

How environmental policy impacts technology adoption: A case of landfill leachate

The leachate from the landfill is a kind of organic wastewater that highly pollutes the water environment. Water polluted by landfill leachate has been found globally. Therefore, it is necessary to properly treat the leachate before the final discharge. Environmental policy, among other factors such as cost, often has critical impact on water and wastewater treatment technology adoption. In the present study, a comprehensive database of leachate treatment projects is compiled based on literature review and a survey of manager of leachate treatment companies, aimed to explore the impact of national policies on the adoption of treatment technologies. Results show that although China produces a large amount of leachate (0.53–0.75 million tons/day) and the operating cost is high (US$5.60 ± 2.05), the new standard issued in 2008 has higher requirements on wastewater discharge standard, which makes membrane technology, especially membrane bioreactor (MBR) + nanofiltration (NF)/reverse osmosis (RO) technology, widely used in China. This increasing employment of membrane technology to treat leachate in China is a direct result of the new leachate standard, which demonstrates that new environmental policy prevail the concern of treatment cost and advances the adoption of environment friendly technology.

Extended exergy analysis of a solar driven water production plant via reverse osmosis

• Novel small scale solar desalination plant provides a solution for water scarcity. • Proposed desalination plant using solar energy studied via extended exergy analysis. • Extended exergy analysis evaluates solar plant performance and sustainability. • Labor and capital exergy equivalents are 42.68 MJ/workhour and 12.09 MJ/Euro. • Products having much higher specific exergy content could be produced. Water scarcity and contamination of available water are becoming one of the most complex problems worldwide and they compromise economic development, global sustainability, and human supply, among others. Water is required in almost all human activities and also for planet equilibrium in terms of biodiversity. In this research a new home scaled water desalination plant, using a reverse osmosis technology and driven with solar energy is analyzed via extended exergy analysis, which is one of the most accurate methods for evaluating both energy performance and sustainability. The proposed system, that is presented and analyzed, consists of a solar concentrator having 1000 concentrating rate, a Photon Enhanced Thermionic Emitter, a Dye-Sensitized Solar Cell for the electricity generation and a Reverse Osmosis Desalination Plant (RODP) for water purification using the produced electricity. This system allows water desalination in small scale plants requiring low density energy sources and can produce sustainable water for multiples uses, such as domestic use or agricultural, among others. The most important results are labor and capital exergy equivalents, 42.68 MJ/workhour and 12.09 MJ/Euro , respectively, and an exergy destruction of 389.700 GJ for all the system annually. The proposed technology can be extended and used in different locations and the Extended Exergy Analysis can be used as a powerful tool for both design and optimization.

A two-stage IGDT/TPEM model for optimal operation of a smart building: A case study of Gheshm Island, Iran

Using poly-generation schemes based on energy hub (EH) concepts is one of the new ways to efficiently supply energy (electrical/thermal/cooling/water) demanded by smart buildings equipped with building energy management system (BEMS). Regarding severe uncertainties pertaining to renewable generation and demands, BEMS is faced with challenges to optimally operate EH during day-ahead. The present study proposes a stochastic day-ahead optimization model for BEMS to minimize the operation costs and emissions under a number of techno-economic constraints considering extreme uncertainties related to generations, demands, and prices. The proposed grid-connected EH includes combined cooling, heat, power (CCHP) system as dispatchable generation, and wind turbine (WT) and photovoltaic (PV) as non-dispatchable generations. To enhance the reliability of energy and water supply, two energy storage systems (ESSs), namely battery energy storage (BESS) and thermal energy storage systems (TESS) and one water storage tank (WST) have been installed in EH. Moreover, to improve flexibility of the proposed EH, it utilizes a seawater desalination (SWD) with reverse osmosis (RO) technology as an active load and an organic Rankine cycle (ORC) as a new technology for generating electrical power by means of thermal power. Also, it considers a demand response program as time of use (TOU) to enhance the flexibility of the operation. The proposed stochastic model is solved by a two-stage algorithm. The first stage formulates the uncertainties of the demands and renewable generations by two-point estimate method (TPEM) while the second stage models the extreme uncertainty of the gas price by information gap decision theory (IGDT) method as well as economically dispatching the generations and storages with risk-averse and risk-seeker strategies. The efficacy of the proposed model is evaluated on a smart commercial building in Gheshm located not far away from the southern coast of Iran in Persian Gulf. It is seen that the total cost of the EH equipped with a WST reduced by 16.55% compared to the one without a WST.

Pathways for minimal and zero liquid discharge with enhanced reverse osmosis technologies: Module-scale modeling and techno-economic assessment

While mechanical vapor compression is typically applied for the concentration of brine, new approaches that are less costly and less energy intensive are needed to facilitate minimal and zero liquid discharge. Several variations of reverse osmosis for high-salinity desalination and increasing recovery rates beyond the pressure limitation of conventional RO have been proposed in the literature. The promise of these enhanced RO approaches entails a reduction in energy consumption when compared with thermal desalination methods. In this paper, low-salt rejection reverse osmosis (LSRRO), cascading osmotically mediated reverse osmosis (COMRO), and osmotically assisted reverse osmosis (OARO) were comparatively assessed via module-scale, cost optimization models to gain an accurate perspective of the performance differences between each of these configurations. We quantified the optimal levelized cost of water (LCOW) of each technology for the case of desalinating feedwater at 70 g/L at 75% recovery, which would result in a brine concentration near 250 g/L, a level that allows further treatment with crystallizers. For baseline scenarios, LCOW results for LSRRO, COMRO, and OARO were 6.63, 7.90, and 5.14 $/m3 of product water, respectively, while the corresponding specific energy consumption (SEC) values were 28.9, 12.8, and 10.3 kWh/m3. A sensitivity analysis is also presented.

The potential recovery energy of SWD (sea water desalination) by SGP (salinity gradient power)

Fresh water is needed in industrial activities. For these needs sea water is usually used as raw material if the plant is near the sea and far from the river. SWD (sea water desalination) is used to process sea water to fresh water, that is by reducing levels of salinity or reducing levels of total dissolved solid (TDS). There are two technologies in SWD, namely thermal distillation and reverse osmosis (RO) membrane technology. Residual SWD process or also called blowdown water has high salinity levels can be converted into electrical energy through SGP (salinity gradient power). There are two technologies to capture energy from salinity differences, namely PRO (Pressure Retarded Osmosis) and RED (Reverse Electrodialysis). PRO and RED are renewable energy technology, there are no emision, no moving part, abundant availability in nature and can be recycled. In this article, an analysis for SWD of oil refinery is carried out. From the analysis results it is known that the plant uses thermal distillation technology, requires power as 64.25 MW and 3,403 m3/h seawater to produce 242 m3/h freshwater. With SGP, the potential recovery of power gained is 0.786 MW. This recovery potential is still too small when compared to energy requirements of SWD with thermal distillation technology, but if it use RO technology that only requires 3.6-5.7 kWh/m3 or 0.87 - 1.40 MW to produce 242 m3/h, a significant impack to saving energy will be obtained.

Optimization of combined Reverse Osmosis: thermal Zero Liquid Discharge system parameters for an Ammonia and Urea production complex

Zero liquid discharge (ZLD) has shown to be a promising technology to recycle water with good quality. The ZLD objective is to purify the water from all the liquid waste. The ZLD approach is concentrated on reducing wastewater for possible reuse. In conventional ZLD systems, thermal processes are fundamental. The biggest challenge to implement thermal ZLD systems widely is its intensive energy consumption. As a solution, thermal ZLD systems are integrated with membrane-based reverse osmosis (RO) technology to reduce both capital and operational costs. This study, therefore, focuses on the optimizing a RO/thermal ZLD system based on one of the most important parameters of design—the salinity of the reject brine of evaporator. To give more practical aspect to the results, solution is based realistic design data of a petrochemical complex as the producer of ammonia (2050 ton day−1) and urea (3250 ton day−1). Results show that increasing the salinity of brine stream in evaporator reduces the total required heating surface area of the ZLD plant as well as its required power. This decrease is evident at lower amounts of Xb, but the rate is lowered with increasing of this parameter. So, further increase in Xb does not have much effect on reducing the total heating surface area and power consumption. It means that there is an optimum amount of Xb which can be selected for different applications.