Improvement of water desalination technologies in reverse osmosis plants

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.

Nitrate removal with reverse osmosis in a rural area in South Africa

Desalination is probably the only means for fresh water supply to countries in decertified climate. The majority of GCC counties rely on desalinated water for fresh water supply to major cities. Over 70% of the desalinated water in the GCC comes from thermal desalination plants including Multi Stage Flash (MSF) and Multi Effect Distillation (MED). The new trend in the desalination plant in the GCC is 30% Reverse Osmosis (RO) and 70% thermal. However, these percentages vary from one to another country depending on feed water quality and expertise. For example, Oman Sea has lower salinity than the Gulf water and hence Oman uses more RO for desalination than MED and MSF. This decision is also driven by economy as RO process less energy intensive and hence the produced water is less expensive as compared to thermal plants. On the contrary, Qatar and Kuwait use more MSF followed by MED due to the high salinity and low quality feed water. This is also because trials of RO in both Qatar and Kuwait were not successful because of the problems of membrane fouling and restrict pre-treatment requirements due to the quality of the water intake.The advantages of RO over thermal technologies are well known in terms of lower energy consumption and the cost of produced water; but are not yet taken advantage of in the GCC zone. One of the reasons is blamed on high feed water salinity and bad water quality; other reasons such as lack of experience, red tides and reliability are contributed to the dominance of thermal plants. However, field experience showed that good pretreatment and optimized RO design may overcome the problems of high feed salinity and bad water quality. Several RO plants, such as Fujairah in UAE, are good examples of a working RO technology in the harsh water environment. Good RO design includes design and optimization of both pretreatment and post-treatment. Field experience showed that most of RO plants failure was due to inefficient pretreatment which resulted in providing low quality water to the RO membrane that caused fouling. Fouling, including biological and scaling, can be handled once an efficient pretreatment process is available. Recent advances in pre-treatment techniques include the combination of Forward Osmosis (FO) with RO among other methods. Recent studies by the authors including commercial implantations have shown that the combination of FO with RO addresses the most technical challenge of RO process and that is fouling, which results in lower energy consumption and less chemical additives. Experience showed fouling in FO process in reversible, i.e. can be removed by backlashing while fouling in conventional RO process is irreversible.In this study, the feasibility of integrating FO with RO process for the desalting of the Gulf water in Qatar is presented. The results are expressed in terms of specific energy consumption, process recovery, produced water quality, chemical additives and overall process cost.The implementation of RO for desalination is not only reducing the cost of desalination but also the environmental impact. More R&D should be done to provide useful data about RO application and suitability for the Gulf water. The R&D should be focused on laboratory to market development of RO technology using rigorous lab scale and pilot plant testing program.

Environmental and economic evaluation of end-of-life reverse osmosis membranes recycling by means of chemical conversion

Reverse osmosis (RO) technology has emerged as a leading desalination and wastewater treatment solution to partially solve this worldwide shortage of fresh water. The present review is a critical appraisal of performance limitations and prospects for improvement in RO plants. The primary factors affecting RO performance include membrane properties, biofouling treatment and prevention, energy recovery devices (ERDs), membrane modifications like surface texturing functionalization and renewable integration. Water permeable and salt rejection properties of membranes are critical to accessing quality water output. Breakthroughs in thin polyamide layers have significantly increased the efficiency of desalination, allowing for greater water flux rates and salt rejection. With the efficiency implications that can result from it, biofouling management is essential in both sustaining and optimizing RO performance. These efforts include the use of pressure exchangers, energy recovery devices and membrane modifications which improve system performance while reducing overall power consumption. Energy Consumption is an Important Indicator of RO Plant Performance, Based on Which Emission Patterns Need to be Reduced Integrating renewables, such as PV-powered systems will help to improve performance and reduce carbon footprints. In addition research to develop pre-treatment technologies and optimize operational conditions has been performed in order to succeed against changes in feed water salinity and prevent membrane fouling. On the other hand, correct comprehension and operation of key performance indicators (KPIs) including permeate flux, salt rejection rate or energy consumption as one superior inter-relating process individual to bypass others that alone are not supportive for each advancements in RO technology. Therefore, this review article provides a comprehensive and synthetic overview of these problems as well as strategies, progress in improving the performance efficiency of RO plants to produce clean water for various end-uses which is intended towards achieving sustainable supply.

Recently, the use of filters has come into light for sanitizing water plants. This study investigated the role of heat-tolerant ultrafilters (UFs) for the remediation of reverse osmosis (RO) plants using periodic thermal disinfection. Two completely identical RO plants (RO plants A and B) were installed in 2006 for surgical hand antisepsis in the operating theater. RO water was stored in the 300 L storage tank and recirculated in the 190 meter-long loop delivering water to 12 faucets in each RO plant. Periodic thermal disinfection came into practice periodically when a UF module was retrofitted to the recirculation loop of each RO plant in 2010. Endotoxin was monitored closely before and after thermal disinfection. Before UF modules were retrofitted, endotoxin increased to a maximum of 0.301 EU/mL in RO plant A and 1.446 EU/mL in RO plant B after thermal disinfection, respectively. Since a UF module was retrofitted to each RO plant in 2010, endotoxin has been continuously below 0.025 EU/mL in RO plant A and exceeded this level five times in RO plant B. On one occasion, endotoxin increased in all samples collected simultaneously after solenoid valves were replaced in the recirculation loop near the air conditioner outlet. At this time, the inside of the pipework was exposed to the ventilation airflow. After the valves were replaced again, this time with the workplace isolated using a curing sheet, endotoxin decreased. On the other occasions, endotoxin increased only in one sample and decreased after thermal disinfection. Annually replaced UF modules were examined twice for estimating the amounts of immobilized endotoxin. The estimated amounts decreased in 2013 by the order of 10-3 in comparison with those in 2011 in both RO plants. The present study suggested that UFs acted synergistically with periodic thermal disinfection for the remediation of RO plants.

Demineralization of brackish surface water by reverse osmosis: The first experience in Morocco

Purpose: review of existing technologies and methods of seawater desalination for drinking water supply. Discussion. Based on modern research methods using statistical data and a review of domestic and foreign literature, a review of methods and technologies for desalination and desaltation of highly mineralized natural waters was carried out. The use of sea water for domestic purposes is impossible due to the high content of minerals, however, after desalination, such water can be used for drinking. The choice of technologies and methods of desalination is primarily determined by the quality of source water, as well as the requirements for the quality of treated water, plant productivity and technical and economic calculations. For the drinking water supply purposes, the most efficient and cost-effective method is desalination using reverse osmosis technology, used for both sea and groundwater with high salinity. Reverse osmosis technology has significant advantages over thermal desalination, especially when applied to small-scale plants of small domestic water supply systems. The use of reverse osmosis plants will significantly increase productivity of drinking water output per watt of electricity consumed. Conclusions. The introduction of modern technologies and careful attention to water consumption play a significant role in maintaining water balance in different countries. The most cost-effective and efficient method is seawater desalination using reverse osmosis plants. Despite the fact that water desalination and desaltion plants are very expensive, the conservation of natural waters is a priority nowadays.

HSE & Sustainability is being a prime concern across ADNOC Operational footprint. ADNOC onshore Drilling division counts transportation of fresh water into cluster operation as major risk to overall well operation. Cluster is considered as same as offshore in terms of transportation risk, cost of fresh water. Fresh water transported to the well site using local contractor tankers which is posing high road safety risk & affecting budget of the well. Recent advancement of Reverse osmosis technology utilization for island operation, where sea water will be directly routed through reverse osmosis pump in which desalination process is being embedded to demineralizing by flowing under pressure through semi permeable membrane. Filtered water is passed into reverse osmosis system through high pressure pump. Feed Total dissolved solid 2000 PPM is pumped through the fine membranes, where ions present in water gets trapped in membrane surfaces. The membranes used for reverse osmosis have a dense layer in the polymer matrix where the separation occurs & get collected in collection tank. Approximately 940,737 Barrels of freshwater water were consumed for operating artificial island rig operation to meet freshwater requirement for domestic purposes in both rig and camp for last 3 years. Approximately 9400 Haulage trips were depended on to run the rig operation in islands. Haulage transports were generating heavy road safety risk. Cost of the water haulage were same as offshore freshwater contract. Hence cost optimization benefits were not feasible due to contractual obligation. Having implemented Reverse osmosis Haulage traffic risk were eliminated very likely & eventually road traffic accident were reduced drastically due to haulage. Additional high discharge pump to the same system to the sea water resources resolved Nonproductive time caused by waiting for water is being carried through haulage. Approximately 19 M$ expenditure were incurred over last 3 years for well cost to drill wells in island rigs & cost expected to bring down to 4M$ for 5 years eventually it will save about 15 M$ for 5 years due to sea water utilization in Reverse osmosis technology in artificial islands. As Gulf standard no 149/2014 lab report were conducted & its fully meeting the freshwater requirement for domestic purpose at rig & camp. HSE &Cost optimization of drilling the wells are priceless concerns in well drilling operation that needs dynamic solution based on operational geography. Reverse osmosis is trying to support Safety, Sustainability & cost reduction though one technology turning the salt water into usable water that will support rig domestic requirements. This paper illustrates the smart use of resources in supporting the sustainability of water well resources. A great number of incidents associated with tanker rollover in island will be resolved as there would be no water transport required by then the implementation of the RO technology. RO plant is designed in such a way that very minimal people will be operated with least minimum maintenance.

Automation and reliability are the crucial elements of any advance reverse osmosis plant to meet the environmental and economic demands. Early fault indication, diagnosis and regular maintenance are the key challenges with most of the reverse osmosis plants in the Indian scenario. The present work introduces a modern reverse osmosis (RO) plant status monitoring unit to monitor different plant parameters in real time and early prediction for faults and maintenance. Developed RO plant status monitoring unit consists of a touch screen-based embedded monitoring unit, water quality sensors (pH, TDS), sampling chamber for controlled water flow, flow sensors, pressure and level sensors. The present system has been developed in a modular fashion so that it could be integrated with any capacity of RO plant units. Developed embedded system monitors various parameters of the plant such as input power, efficiency of the plant, level of input and output water tank and also guides operator with instructions for plant operation. Other than this, a dedicated smartphone app interface has been developed for the operator to acquire data from status monitoring unit, storage on smartphone, and transfer it to the cloud. The developed smartphone-based app also provides facility to integrate plant data with Google map with location information for easy understanding and quick action. The system has also a backup facility to transfer data to the server using 2G GSM module during the unavailability of the operator. A dedicated centralized Web server has been developed for real-time visualization of all installed RO plant status monitoring units. Different machine learning techniques have been implemented on acquired sensors data to predict early warnings related to power failure, membrane fouling and scaling, input water shortage, pipe, tank leakage, water quality sensors damage, non-operation or wrong operation of the plant along with different maintenance actions such as membrane water and chemical wash. Developed RO status monitoring unit has been tested with various RO plants having capacity from 500 LPH to 2000 LPH and deployed at various nearby villages of Rajasthan.

Design of a small mobile PV-driven RO water desalination plant to be deployed at the northwest coast of Egypt

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.

Detailed analysis of reverse osmosis systems in hot climate conditions

In the past few years, the commercialization of small scale reverse osmosis (RO) plant for low total dissolved solids (TDS) brackish and contaminated groundwater water desalination offered an alternative solution to obtain drinking water with TDS lower than 500 mg/L. Due to rapid development in membrane technology the technical and economical usefulness of RO process has been improved. In the current research work, a prototype Reverse Osmosis (RO) wastewater treatmentplant has been developed and its performance was evaluated to produce the safe and drinkable water at local small community.Salt rejection and ermeatewater flowrate are the key performance parameters. These performance parameters are influenced by other variable parameters such as applied feed pressure, temperature, recovery and feed water salinity.The RO plant performance has been evaluated through testing different water quality parameters; including physical, chemical and biological analysis of the treated sample. The plant was operated by varying feed water pressures and feed water salinity which indicated that the product water has the highest quality and maximum permeateflow rate at 25 bar of applied feed water pressure for feed water salinity upto 4000 mg/L. The water quality results indicate that permeate obtained after treatment has excellent quality free physical and microbial contaminants.

Coupling of a nuclear reactor to hybrid RO-MSF desalination plants