Environmental implications of Tajoura reverse osmosis desalination plant

Seawater desalination in China: Retrospect and prospect

Change of editorial structure at Social Science & Medicine

Water, otherwise known as the pool of life, is the very essence of all living things and as such is vital for survival, whether for living beings, social, economic development or for environmental sustainability. However, its continuing existence is severely threatened for future as a result of climate change, carbon footprint, population growth, environmental damage, combined with natural disasters like droughts and floods. The prospect of an alternative solution such as desalination of sea or brackish water to counter the limit on conventional water resources such as groundwater, which cannot meet demand, is therefore very promising, particularly in arid and semi-arid regions where water scarcity and impaired quality prevails. Consequently, desalination technology has now become a burgeoning industry in North Africa or southern Mediterranean countries, such as in Libya. However, evidence suggests that as a result of by-products being discharged directly into the sea, particularly from coastal desalination plants, the physico-chemical parameters of the receiving water are changing and posing a threat to marine ecosystems. As a result of studies conducted on these parameters to analyse the brine emitted from the Zwuarah and the West Tripoli distillation plants (ZWDP & WTRIS) on the Libyan coastline, evidence shows there is a significant positive correlation at both sites between the biological data and physico-chemical parameters (rs=0.673; p=0.002) and (rs=0.637; p=0.003), which is a clear indication of the impact of brine disposal from both plants on the marine environment. For most of coastal desalination plants on the Libyan coastline, the most practical and least expensive brine disposal option is to discharge it into the sea. It is necessary therefore, to effectively manage desalination reject brine in order to ensure more efficient disposal and reuse. Therefore, it is suggested that experimental studies are aimed for dual benefit of on-site generation of sodium hypochlorite through brine electrolysis and to recover minerals and NaCl from the brine using evaporation ponds, while protecting the environment. Following the first experiment, the outcome of brine utilisation showed a significant production of NaOCl using graphite electrodes (MCCA 1.82 gr/m3). At interelectrode spacing 2 cm and 4 cm, the power consumption was higher, with a greater concentration of sodium hypochlorite generation varying between 10-25 kw/m3 (573-2140ppm) and 29-24 kwm-3 (572-2600ppm) than at interelectrode spacing 6cm 17-13 kwm-3 (350-1790ppm). Consequently, the selection of an optimum electrical consumption level is key in establishing the best scenario in terms of economy and efficiency. Subsequent to the second experiment of brine evaporation in the ponds, results showed that the evaporation rate in August was lower than in September (9.06 mmday-1, 14.63 mmday-1) respectively. The results of the SEM/EDS test showed that due to elevated surges of Na+ and Cl-, halite (NaCl) was the main mineral evident during crystallisation of the salt samples. Hence, the two experiments reveal that brine can be recycled productively, while protecting the environment.

Both brackish water desalination and seawater desalination processes are well established and in common use around the globe to create new water supply sources. The farther the location of the source water from the ocean or seashore, the lower the salinity (TDS) of the water and the lower the osmotic pressure that needs to be overcome when desalinated water is produced. This is one of the major reasons that brackish desalination is often considered less costly than seawater desalination. A number of project considerations, however, indicate that seawater desalination can be beneficial and more cost-effective than brackish water desalination. To make a fair comparison, we need to properly compare all major aspects of both types of projects to define the best and most appropriate desalination technology. While brackish water has less feed water TDS, it is more challenging to dispose of the produced concentrate. Also, although brackish water desalination needs less energy to overcome osmotic pressure, it usually requires more energy to draw the water from the well than it takes to pump seawater from the open ocean intake. Another factor is that the temperature of the brackish well water may be lower than the temperature of ocean water, giving seawater desalination an advantage in energy demand. In comparing brackish to seawater desalination, these major aspects should be evaluated: (1) Locations of seawater and brackish water plants, relative to the major consumers of the desalinated water, (2) Transportation (pumping and disposal) costs of the feed water and produced water, (3) Potential colocation of a seawater plant with a large industrial user (e.g., power plant) of the seawater for cooling or other purposes, (4) Produced quality of brackish water and seawater desalination in terms of major minerals and emerging contaminants, (5) Sustainability of the water source: capacity and depth of the brackish water wells, as well as the type of soil. (6) Technical and economic aspects of produced concentrate disposal, (7) Permitting process costs for brackish and seawater desalination, and (8) The economics of both brackish and seawater desalination treatment processes: capital costs, operational and maintenance (O&M) costs, lifetime water cost, and total water cost (TWC). This paper discusses the major evaluation criteria and considerations involved in properly comparing the economic and technical aspects of brackish and seawater desalination to determine the more favorable desalination technology for a given desalination project.

The role of desalination in bridging the water gap in Jordan

Optimization of the negative impact of power and desalination plants on the ecosystem

Hybrid membrane system for desalination and wastewater treatment : Integrating forward osmosis and low pressure reverse osmosis

Triangle of Environment, Water and Energy: A Sociological Appraisal

طی دوره‌ی 2010 تا 2016 بازار نمک‌زدایی آب با رشد سالانه‌ی 9 درصد و مجموع سرمایه‌گذاری 88 میلیارد دلار، یکی از پررونق‌ترین بازارهای جهان بوده است. رشد شتابان بیش از 60 درصد ظرفیت جهانی نمک‌زدایی، نه تنها حکایت از سهیم شدن دریاها در تأمین آب شرب کانون‌های جمعیتی سواحل دارد، بلکه گویای زوال تدریجی کیفیت آب‌های داخلی نیز می‌باشد. پیش‌بینی افزایش دما و تقلیل بارندگی در افق 2050 در بیست کشور واقع در شمال آفریقا و غرب آسیا (منطقه‌ی منا) منابع جدید آب را در این منطقه‌ی حساس جهان، کمیاب‌تر و دسترسی به آن‌ها را پرهزینه‌تر کرده و دولت‌ها را به ناچار به سمت گزینه نمک‌زدایی آب پیش می‌برد. در مقیاس جهانی، 38 درصد از حجم روزانه‌ی تولید جهانی آب نمک‌زدایی شده (2/65 میلیون متر مکعب) متعلق به کشورهای منطقه‌ی منا است و در محدوده‌ی جنوبی خلیج فارس، ظرفیت نصب شده نمک‌زدایی آب از 10 میلیون متر مکعب در روز فراتر است. پایه و اساس فرآیندهای گوناگون نمک‌زدایی آب، بر بهره‌گیری از انرژی استوار است و هر گونه تحلیل، سیاستگزاری و آینده‌نگری در موضوع نمک‌زدایی آب، بدون لحاظ سیاست‌های انرژی، ناقص خواهد بود. مهم‌ترین مسئله‌ی زیست محیطی این تأسیسات، شورابه‌های آن‌ها است که در گروه پساب‌های صنعتی قرار داشته و تخلیه‌ی گسترده‌ی آن‌ها به خلیج‌ها و سواحل مرجانی، سبب تغییر گونه‌ها و تهدید حیات آبزیان می‌شود. در سال‌های اخیر با توسعه و بهینه‌سازی فرآیندها، هزینه‌ی نمک‌زدایی هر متر مکعب آب، به حدود نیم دلار تقلیل یافته است، اما قیمت بازار آن هم‌ چنان در محدوده‌ی یک تا دو دلار باقی مانده است. ظرفیت نمک‌زدایی آب در ایران افزون بر 450 هزار متر مکعب در روز است که 65 درصد آن مربوط به آب شرب است. این مقدار کم‌تر از 2 درصد ظرفیت جهانی نمک‌زدایی آب است.

In recent years, numerous large-scale seawater desalination plants have been built in water-stressed countries to augment available water resources, and construction of new desalination plants is expected to increase in the near future. Despite major advancements in desalination technologies, seawater desalination is still more energy intensive compared to conventional technologies for the treatment of fresh water. There are also concerns about the potential environmental impacts of large-scale seawater desalination plants. Here, we review the possible reductions in energy demand by state-of-the-art seawater desalination technologies, the potential role of advanced materials and innovative technologies in improving performance, and the sustainability of desalination as a technological solution to global water shortages.

The integration of desalination plants and mineral production

Impact of chemical composition of reject brine from inland desalination plants on soil and groundwater, UAE

Due to unstainable use of natural water resources, alternative water resources such as brackish water and seawater desalination have been an emerging solution. However, development of desalination capacity is limited due to the high energy requirements for removing salt ions from water. Currently, capacitive deionization technology (CDI), following the working principle of supercapacitors, has attracted considerable attention from academia, industry, and government agency. As compared to conventional desalination technologies, CDI has several advantages including low energy consumption, easy regeneration, high water recovery, and no secondary waste. In CDI, by applying an external electric filed between two parallel of nanoporous carbon electrodes (i.e., carbon aerogel, activated carbons, carbon nanotubes, and graphene), ions can be stored at the electrode/solution interface via electrical double layer (EDL) formation. Additionally, microbial desalination cell (MDC) is a new bioelectrochemical technology for seawater desalination with simultaneous electricity generation and wastewater treatment. Basically, a MDC reactor contains an anode chamber, a desalination chamber, and a cathode chamber. In MDC, microorganisms can oxidize organic waters in wastewater to harvest electric energy, and meanwhile, salt ions can be removed during the electricity generating process. In this study, we propose a hybrid electrochemical desalination system for seawater desalination by coupling CDI device with a MDC reactor. As a result, MDC produced electricity with open circuit voltage of 0.8 V and a current of 3 mA by using bacteria to degrade organic contaminants through anode bacterial oxidation and cathode reduction. In MDC, 91% removal of chemical oxygen demand (COD) in synthetic wastewater can be achieved, and the solution conductivity can be reduced from 17,000 µS/cm to about 200 µS/cm. More importantly, CDI device can be driven by electricity harvesting from the two MDCs in parallel, and as the downstream desalination process to further desalinate salt water. The results of this study can demonstrate the feasibility of the integrated electrochemical MDC-CDI system for simultaneous wastewater treatment, power production, and water desalination. .

Water desalination in Egypt; literature review and assessment

the large-scale application of non-grid-connected wind power in sea water desalination industry has not only solved the difficulty in grid connection of wind power, but also can be an inexhaustible clean energy supply for the sea water desalination. Such application, breaking through the traditional sea water desalination technology and wind power development ideas and realizing the 100% local use of renewable energies, is a perfect combination of the new energy industry and the power consumption industry. The large-scale industrialization application of non-grid-connected wind power sea water desalination can not only maximize the efficiency of wind power and realize the unification of social benefit, environmental benefit and economic benefit, but also is of great strategic significance in accelerating the transformation of the economic development mode of China, and meanwhile, plays a leading role in the diversified development of the world wind power industry. 1. High-energy consumption factors restrict the development of sea water desalination Sea water desalination is a source-opening incremental technology for realizing the utilization of water resources, which can increase the total amount of fresh water and is not limited by time, space and climate with good water quality, and can guarantee the stable water supply of drinking water for coastal residents and industrial water supplementation. Since sea water desalination is the substitutional and incremental technology of fresh water resources, many countries are attaching more and more importance on it. With the rapid development of the economy and society of China, especially with the acceleration of urbanization, some coastal developed areas and large cities near the sea are having a greater and greater demand on water resources. In this condition, the development of sea water desalination has a great strategic significance in the supplementation of water resources in the sustainable development process of these areas[1,2].