Water Desalination & RO

Clean water is critical to ensure good health, strong communities, vibrant ecosystems, and a functional economy for manufacturing, farming, tourism, recreation, energy production, and other sectors’ needs. Research to improve desalination technologies can make nontraditional sources of water (i.e., brackish water; seawater; produced and extracted water; and power sector, industrial, municipal, and agricultural wastewaters) a cost-effective alternative. These nontraditional sources can then be applied to a variety of beneficial end uses, such as drinking water, industrial process water, and irrigation, expanding the circular water economy by reusing water supplies and valorizing constituents we currently consider to be waste. As an added benefit, these water supplies could contain valuable constituents that could be reclaimed to further a circular economy.

Abstract: While over 70 per cent of the Earth’s surface is covered by water, most of it is unusable for human consumption. Freshwater lakes, rivers and underground aquifers represent only 2.5 per cent of the world’s total freshwater supply. Unfortunately, in addition to being scarce, freshwater is also very unevenly distributed. The United Nations has compared water consumption with its availability and has predicted that by the middle of this century between 2 billion and 7 billion people will be faced with water scarcity. Increased demand for water is a global problem. In many parts of the world local demand is exceeding conventional resources. More economical use of water, reducing distribution losses and increased use of recycled water can help alleviate this problem but if there is still a shortfall then desalination of seawater or brackish water is a must. Many areas suffering from water shortages are also short of conventional energy resources and cannot afford expensive fossil fuels. More recently, there is remarkable awareness that even if fossil fuels were much cheaper, the burning of these fuels will contribute to climate change and global warming. For these reasons, the use of renewable energy for desalination has to be encouraged. Renewable energy is not a firm source of power and energy is expensive to store in large quantities. Water on the other hand is easily and cheaply stored. Thus, there is compatibility between renewable energy and desalination. This study aims to provide a review of the state of the art technologies of water desalination and discuss the benefits, disadvantage and economic impact of each. The key conclusion of this review is that desalination alone cannot deliver the promise of improved water supply unless that the desalination technology itself has evolved substantially. It has to be significantly cheaper, more reliable, less energy-intensive and more environmentally friendly. Nanotechnolgy would bring desalination technology to meet these requirements in the near future. Recently, new methodologies have been developed recently based on using nanotechnology for water desalination such as Reverse osmosis, Ultra- and Nano-filtration. Also, new technologies based on using solar concentrators for solar desalination have been developed. This report will highlight all of these new methodologies in details. New methodology which combines solar desalination and nanotechnology based on producing low cost nanocomposite to enhance the rate of solar thermal water desalination has been developed in our laboratory (patent pending). These new nanomaterials absorb light so strongly and convert it efficiently into heat energy.

Introduction: Once the desalination plant service area, location, site, source water quality, product water quality and concentrate water quality are determined, and the intake and discharge type and configuration are selected, the next step of the desalination project planning process is to complete conceptual plant design. The conceptual design includes the type and sequence of the treatment processes and equipment, facility and equipment design criteria and incorporates preliminary plant site layout and hydraulic profile. It also includes project capital and O&M cost estimates and the project implementation schedule. Furthermore, the conceptual design addresses the type of technology and equipment for energy recovery from the plant concentrate, post-treatment of the plant RO permeate, handling and disposal of the solid and liquid waste streams generated during source water pretreatment and membrane cleaning and finally, plant product water storage and delivery systems. The conceptual plant design process takes under consideration the physical, operational and environmental constraints imposed on the project, and usually involves initial development of several project alternatives, followed by selection of the most viable alternative based on a set of criteria. This includes capital and O&M costs, size of the overall plant site footprint, environmental impacts, carbon footprint of plant, ease of plant operation and maintenance, overall plant performance in terms of energy and chemical use, plant fresh water production reliability, redundancy and spare capacity, plant expansion and phasing flexibility and ability of the proposed plant design and facility configuration to accommodate future technologies and equipment.