A detailed review on solar desalination techniques

Carbon aerogel its fabrication and characterization and its uses in this process were studied for desalinating of saline and brackish water. The carbon aerogel manufacturing process involves the polymerization and pyrolysis of the mixture of resorcinol and formaldehyde. Carbon aerogels were analyzed using BET, BJH, and T-plot after construction. The effect of various parameters (including the influent salt concentration, the intensity of electric current flow, the distance between the electrodes and pH) on salt adsorption were studied. Analysis of BET/BJH shown that the surface of aerogel was 677.8 m2/g. much of porosity in the samples of carbon aerogel were between 1-2 nm, namely micro-pour and a similar level 0f 456 m2/gr is dedicated to micro-pour, with a correlation coefficient (r) equal to 94.5. According to the results, it seems that carbon aerogel electrodes have a good structure in desalination of brackish and saline water.

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.

Climate change, population growth, and increased industrial activities are exacerbating freshwater scarcity and leading to increased interest in desalination of saline water. Brackish water is an attractive alternative to freshwater due to its low salinity and widespread availability in many water-scarce areas. However, partial or total desalination of brackish water is essential to reach the water quality requirements for a variety of applications. Selection of appropriate technology requires knowledge and understanding of the operational principles, capabilities, and limitations of the available desalination processes. Proper combination of feedwater technology improves the energy efficiency of desalination. In this article, we focus on pressure-driven and electro-driven membrane desalination processes. We review the principles, as well as challenges and recent improvements for reverse osmosis (RO), nanofiltration (NF), electrodialysis (ED), and membrane capacitive deionization (MCDI). RO is the dominant membrane process for large-scale desalination of brackish water with higher salinity, while ED and MCDI are energy-efficient for lower salinity ranges. Selective removal of multivalent components makes NF an excellent option for water softening. Brackish water desalination with membrane processes faces a series of challenges. Membrane fouling and scaling are the common issues associated with these processes, resulting in a reduction in their water recovery and energy efficiency. To overcome such adverse effects, many efforts have been dedicated toward development of pre-treatment steps, surface modification of membranes, use of anti-scalant, and modification of operational conditions. However, the effectiveness of these approaches depends on the fouling propensity of the feed water. In addition to the fouling and scaling, each process may face other challenges depending on their state of development and maturity. This review provides recent advances in the material, architecture, and operation of these processes that can assist in the selection and design of technologies for particular applications. The active research directions to improve the performance of these processes are also identified. The review shows that technologies that are tunable and particularly efficient for partial desalination such as ED and MCDI are increasingly competitive with traditional RO processes. Development of cost-effective ion exchange membranes with high chemical and mechanical stability can further improve the economy of desalination with electro-membrane processes and advance their future applications.

Water is important for life and development. About 1.8 billion people will be living in absolute water scarcity by 2025.Non availability of safe drinkable water is the major source of diseases in the different regions of the world especially remote rural and coastal areas. About 97% of water on earth is comprised of seawater. Desalination of saline water is a prominent approach to handle the problem of water scarcity. Conventional desalination technologies cause economic and environmental problems due to their dependency upon fossil fuels. Solar flash desalination is one of the best desalination techniques in the developing stages. Solar energy, passive vacuum and recovery of latent heat of condensation make this system a sustainable option for desalination. In this paper, economic analysis of the solar thermal desalination system of saline water is presented. The unit cost of desalinated water is found to be US$ 0.0147 per litre. The energy and emission payback (EEP) period for vacuum chamber and solar collector has also been presented. The energy payback period of solar collector and vacuum chamber are found to be 1.3 years and 1.5 years respectively. The emission payback period of solar collector and vacuum chamber are found to be 1.8 years and 2.1 years respectively.

Desalination of brackish water by nanofiltration and reverse osmosis

About two-thirds of the world’s population may experience water shortages within several decades. Yet, in many countries, there is still a tendency to solve water scarcity problems by increasing water supply, increasing the storage and distribution of surface and groundwater through the creation of new infrastructure, desalination of saline or brackish water, reuse of wastewater, or recharge of aquifers. This trend should prevail over the focus on reducing water demand, for example, by stopping losses in transport and distribution systems, implementing adequate tariff systems aimed at reducing the level of water demand, changing water use technologies, and, in general, increasing the efficiency of water use in household, industrial trial and irrigation systems; in other words, seeking to improve overall water productivity. However, it is possible to overcome the water shortage through efficient and rational use while using innovative solutions that will significantly modernize the water resources infrastructure. Therefore, using creative principles of freshwater resource management in the context of sustainable development should become a perspective for the next ten years. The article aims to research the current state, regional features, and prospects for developing the innovative potential of freshwater resources in Ukraine. It has been proven that in Ukraine, the share of state budget expenditures for environmental protection of total spending ranges from 0.57 to 1.11%. It was determined that the largest share of state budget expenditures on environmental protection in total spending was observed in 2011 – 1.11%, and the smallest in 2020 was 0.57%. It is noted that in 2020, the volume of expenses for environmental protection was significantly reduced compared to the previous year by UAH 675 million. The analysis showed that during the research period, the largest share of expenses was allocated to preventing and eliminating environmental pollution. Therefore, it was determined that the item of budget expenditures for the prevention and elimination of environmental pollution for 2010-2020 increased from UAH 2,255 million to UAH 6,507 million. However, the structure of total expenses decreased slightly from 78.52% to 71.85%, respectively. Accordingly, in the form of costs, the reduction occurred in the following items of budget expenses: preservation of the nature reserve fund from 7.64% in 2010 to 6.78% in 2020, fundamental and applied research and development in the field of environmental protection from 2.06 % to 1.85%, respectively.

Analysis of desalination alternates for phosphoric acid plant in Tunisia

The demand of fresh water is continuously increasing due to frequent rainfalls, shortage of ground water and pollution of natural resources via industrialization. Therefore, solar desalination of available saline and brackish water using solar still is gaining importance among the scientific community for domestic, irrigation and drinking purposes owing to be an economical and sustainable approach of producing fresh water with a simple working principle. Currently, continuous efforts have been made to improve the productivity of solar still by various techniques and configurations. A critical review of solar stills with phase change material (PCM) is presented. This paper highlights the impacts of design specifications along with an economic analysis and the type of PCM material used in recent past. Furthermore, a detailed discussion has been provided on future scope with recommendations to improve the productivity of fresh water for sustainability.

Desalination and disinfection of inland brackish ground water in a capacitive deionization cell using nanoporous activated carbon cloth electrodes

Brackish water desalination using reverse osmosis and capacitive deionization at the water-energy nexus

Purpose: The invention relates to the oil industry, inorganic chemistry, in particular, to the methods of complex processing of formation water, using flare gas of oil and gas field as fuel for producing enriched concentrates of iodine, bromine, magnesium and valuable trace elements, as well as desalinated water (technical and drinking water). The technology includes pre-cleaning of formation water from mechanical impurities and oil using adsorbents, followed by evaporation of water under vacuum, condensing water vapor in the barometric condenser, using of condensed water vapor as the coolant, using of saline water as a coolant of hot water coming out of the barometric condenser to 15–20 °C. The novelty of the design?: The novelty of the design is to get a comprehensive treatment of formation water, using flare gas of oil and gas field as fuel for obtaining enriched concentrates of iodine, bromine, magnesium and valuable trace elements, as well as desalinated water (technical and drinking water)....

برای بررسی اثر سطوح شوری آب آبیاری و زمان شروع آبیاری با آب شور و لب‌شور بر خصوصیات کمی خربزه دیررس، آزمایشی با 7 تیمار و 3 تکرار در قالب بلوک‌های کامل تصادفی با استفاده از روش آبیاری قطره‌ای نواری، در مرکز تحقیقات کشاورزی و منابع طبیعی خراسان رضوی انجام شد. تیمارهای آبیاری عبارت بودند از: 1- آبیاری با آب شیرین (6/0 دسی‌زیمنس بر متر) از ابتدای کاشت تا انتهای فصل برداشت، 2- آبیاری با آب با شوری 3 دسی‌زیمنس برمتر از ابتدا تا انتهای فصل داشت، 3-آبیاری با آب با شوری 6 دسی‌زیمنس بر متر از ابتدا تا انتهای فصل، 4- آبیاری با آب با شوری 6 دسی‌زیمنس بر متر از 20 روز بعد از جوانه‌زنی تا انتها، 5- آبیاری با آب با شوری 3 دسی‌زیمنس بر متر از 20 روز بعد از جوانه‌زنی تا انتها، 6- آبیاری با آب با شوری 6 دسی‌زیمنس بر متر از 40 روز بعد از جوانه‌زنی تا انتها و 7- آبیاری با آب با شوری 3 دسی زیمنس بر متر از 40 روز بعد از جوانه‌زنی تا انتهای فصل داشت. نتایج نشان داد که، شوری آب بر عملکرد کل، عملکرد اقتصادی و کارآیی مصرف آب آبیاری تاثیر معنی‌داری داشت. بالاترین عملکرد کل و عملکرد اقتصادی و کارآیی مصرف آب آبیاری از تیمار شاهد بدست آمد که تفاوت آن‌ها با تیمارهای آب شور و لب‌شور معنی‌دار بود. در ضمن تفاوت بین عملکردهای تیمارهای شور و لب‌شور معنی‌دار نبودند. آبیاری با آب شیرین در اوایل دوره رشد باعث افزایش محصول نشده بلکه، باعث وارد شدن تنش بیشتر به گیاه می‌شود.

Desalination of high salinity brackish water by an NF-RO hybrid system

Research progress of sodium super ionic conductor electrode materials for capacitive deionization

The brackish water is an important potential water source and has frequently been utilized to drip-irrigate cotton due to the water shortage in the arid region of Xinjiang, northwestern of China. The brackish water is usually saline water with salinity ranging from 1 g/L to 5 g/L, which is widely distributed in this area, so the reasonable use of that brackish water may not only play a vital role in the local agricultural production, but also save plenty of freshwater. However, irrigation with brackish water usually causes the reduction of crop yield and soil salinization which can negatively impact plants through three major components: osmotic, nutritious and toxic stresses. Therefore, a field experiment, with eight different time-series irrigation modes using brackish water (3.5±0.2) g/L and freshwater, less than 1 g/L, beneath a combined film and drip-irrigation system was carried out to study the changes of soil salt content and cotton yield aiming to search for a balanced method during the 2 cotton growing seasons in 2012 and 2013. The results indicated that the time-series irrigation modes determined the soil salinity and moisture distribution based on observed spatio-temporal distribution of water content and electric conductivity, and soil salinity generally gathered at the depth of 0-10 cm and 60 cm of soil with the increase of irrigation quota. Moreover, the results demonstrated that the yields of cotton which was grown using brackish water and freshwater were better than those only using freshwater and the soil salinity with reasonable irrigation timing was not accumulated obviously. Keywords: brackish water, mulch drip irrigation, timing and duration for irrigation, irrigation scheduling, cotton DOI: 10.25165/j.ijabe.20171006.3108 Citation: Wang C X, Yang G, Li J F, He X L, Xue L Q, Long A H. Effects of timing and duration under brackish water mulch drip irrigation on cotton yield in northern Xinjiang, China. Int J Agric & Biol Eng, 2017; 10(6): 115–122.