Advances in Membrane Materials and Processes for Desalination of Brackish Water

Seawater and brackish water desalination has been a practical approach to mitigating the global fresh water scarcity. Current large-scale desalination installations worldwide can complementarily augment the global fresh water supplies, and their capacities are steadily increasing year-on-year. Despite substantial technological advance, desalination processes are deemed energy-intensive and considerable sources of CO2 emission, leading to the urgent need for innovative low carbon desalination platforms. This paper provides a comprehensive review on innovations in membrane processes and membrane materials for low carbon desalination. In this paper, working principles, intrinsic attributes, technical challenges, and recent advances in membrane materials of the membrane-based desalination processes, exclusively including commercialised reverse osmosis (RO) and emerging forward osmosis (FO), membrane distillation (MD), electrodialysis (ED), and capacitive deionisation (CDI), are thoroughly analysed to shed light on the prospect of low carbon desalination.

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.

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

Osmotically and thermally driven membrane processes for enhancement of water recovery in desalination processes

Design and techno-economic evaluation of multi-stage membrane processes for helium recovery from natural gas

As emerging membrane technologies, forward osmosis (FO) and membrane distillation (MD), which work with novel driving forces, show great potential for liquid food concentration, owing to their low fouling propensity and great driving force. In the last decades, they have attracted the attention of food industry scientists in global scope. However, discussions of the FO and MD in liquid food concentration advancement, membrane fouling, and economic assessment have been scant. This review aims to provide an up-to-date knowledge about liquid food concentration by FO and MD. First, we introduce the principle and applications of FO and MD in liquid food concentration, and highlight the effect of process on liquid food composition, membrane fouling mechanism, and strategies for fouling mitigation. Besides, economic assessment of FO and MD processes is reviewed. Moreover, the challenges as well as future prospects of FO and MD applied in liquid food concentration are proposed and discussed. Comparing with conventional membrane-based or thermal-based technologies, FO and MD show outstanding advantages in high concentration rate, good concentrate quality, low fouling propensity, and low cost. Future efforts for liquid food concentration by FO and MD include (1) development of novel FO draw solution (DS); (2) understanding the effects of liquid food complex compositions on membrane fouling in FO and MD concentration process; and (3) fabrication of novel membranes and innovation of membrane module and process configuration for liquid food processing.

Water is the most common substance in the world, however, 97% is seawater and only 3% is fresh water. The availability of water for human consumption is decreasing due to increasing the environmental pollution. According to the World Health Organisation (WHO), about 2.4 billion people do not have access to basic sanitation facilities, and more than one billion people do not have access to safe drinking water (Singh, 2006). Moreover, the world’s population is expected to rise to nine billion from the current six billion in the next 50 years. Chronic water pollution and growing economies are driving municipalities and companies to consider the desalination as a solution to their water supply problems. Generally, desalination processes can be categorized into two major types: 1) phasechange/thermal and 2) membrane process separation. Some of the phase-change processes include multi-stage flash, multiple effect boiling, vapour compression, freezing and solar stills. The pressure driven membrane processes, such as reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF) and microfiltration (MF), have found a wide application in water treatment (Charcosset, 2009). The energy required to run desalination plants remains a drawback. The energy limitations of traditional separation processes provided the impetus for the development and the commercialisation of membrane processes. Membrane technologies (simple, homogenous in their basic concepts, flexible in application), might contribute to the solution of most of the existing separation problems. Nowadays, membranes are used for the desalination of seawater and brackish water, potable water production, and for treating industrial effluents. RO membrane separation has been traditionally used for sweater desalination (Charcosset, 2009; Schafer et al., 2005; Singh, 2006). One of the limitations of membrane processes is severe loss of productivity due to concentration polarisation and fouling or scaling (Baker & Dudley, 1998; Schafer et al., 2005). Membrane pretreatment processes are designed to minimise the potential problems of scaling resulting from the precipitation of the slightly soluble ions. Membrane (MF or UF) pretreatment of RO desalinations plants is now a viable options for removing suspended solids, fine particles, colloids, and organic compounds (Banat & Jwaied, 2008; Singh, 2006). NF pretreatment of sweater is also being used to soften RO feed water instead of traditional softening (Schafer et al., 2005). The industrial development of new membrane processes, such as membrane distillation (MD), is now being observed (Banat & Jwaied, 2008; Gryta, 2007). In MD process feed water is heated to increase its vapour pressure, which generates the difference between the partial

Membrane processes with outstanding advantages have been developed over the past three decades and could be used for oily wastewater treatment applications, effectively. Nowadays, forward osmosis (FO) and membrane distillation (MD) processes, as two essential membrane processes have received considerable attention, for oily wastewater treatment applications. The excellence of MD and FO processes compared to other membrane processes is their cost-effectiveness and capability to remove smaller oil drops with lower energy consumption. Membrane fouling as a challenge with decreasing separation efficiency has hindered the commercialization of FO and MD processes. Therefore, developing new FO and MD membranes with lower fouling tendency is very important for water treatment applications especially for oily wastewater treatment. In this chapter, after bibliographic analysis, the conventional methods developed for treating various types of oily wastewaters are reviewed, in brief. Then, various membrane processes with particular emphasis on their challenges and advances in oily wastewater treatment applications are presented. Afterward, focusing on FO and MD processes, the current materials used to fabricate proper membranes for FO and MD processes are discussed.

In order to ensure long-term sustainability of the reservoir, the gas industry in Qatar is faced with the challenge of reducing the volume of produced and process water (PPW) sent to disposal wells by 50% [1-3]. Recently, Qatargas initiated a project to recycle process water and thus, reduce disposal volumes using commercial advanced water treatment technologies [4]. One emerging technology, “osmotic concentration” (OC) has been identified that offers a low-energy alternative to conventional thermal or membrane volume reduction methods. Osmotic concentration is a membrane filtration process that mimics first step in a forward osmosis (FO) system. It requires a high salinity draw solution (DS) which passes on one side of a semi-permeable FO membrane while the feed passes on the other side. Water from the feed is drawn through the membrane, via natural osmosis, reducing the feed volume and increasing the volume of the draw solution. This paper summarizes the results of bench-scale volume reduction tests wit...

Polyphenols and phenolic acids extracted from plants are natural antioxidants with high market value. However, they are susceptible to thermal processes, and a significant loss throughout food and beverage processing has been widely reported. This work reviews the state-of-the-aft membrane processing of the solution rich in phenolic compounds. Novel membrane processing allows phenolic concentration and water recovery simultaneously without using hazardous chemicals and high temperatures. Comparing pressure-driven membrane filtration processes with the advanced membrane processes at the low pressure in this review allowed the proper process selection to concentration phenolic coumpounds. Pressure-driven membrane filtration processes, namely microfiltration, ultrafiltration, nanofiltration, and reverse osmosis, have been studied. Nanofiltration membranes offer high retention of polyphenols due to their matching molecular weight cut-off. Osmotic distillation, membrane distillation and forward osmosis are membrane processes operated at low pressure. Osmotic distillation and forward osmosis require drawing solutions with osmotic pressure differences to separate water from phenolic compounds. A similar separation is attained in membrane distillation by creating vapour pressure differences. Membrane distillation without drawing solution is recommended since membrane fouling can be mitigated using superhydrophobic membranes with self-cleaning properties.

Chapter 15 - Forward Osmosis, Reverse Electrodialysis and Membrane Distillation: New Integration Options in Pretreatment and Post-treatment Membrane Desalination Process

Water scarcity is an alarming global problem for a growing population with depleting sources of fresh water. Desalination is thus becoming an important solution for water management to address such looming shortage of the municipal water supply. At present, several technologies dominate the desalination industry which can be categorized either as a thermal process such as multi-stage flash distillation or a membrane process such as that of reverse osmosis. New desalination systems are also being developed to make the process more cost-effective and energy efficient. Hence, this work proposes a systematic approach for optimal selection of desalination systems using fuzzy analytic hierarchy process (FAHP) and grey relational analysis (GRA). Fuzzy AHP addresses the vagueness involve in the trade-off of the criteria or attributes used in evaluating the alternatives. On the other hand, the GRA solves the multiple criteria decision problem by aggregating the entire range of performance attribute values for every alternative into a single score in spite of incomplete information. An illustrative case study was presented wherein five desalination systems namely reverse osmosis (RO), combined reverse osmosis and forward osmosis (RO-FO), electrodialysis (ED), multi-stage flash distillation (MSF), and combined forward osmosis and membrane distillation (FO-MD) were evaluated. These desalination systems were compared to each other with respect to energy requirement, land footprint, system efficiency, economic viability, and maturity of technology. Sensitivity analysis was also done to determine the robustness of the modeling results from the variation of weights of the criteria.

Progresses of advanced anti-fouling membrane and membrane processes for high salinity wastewater treatment

Analysis and Design of Membrane Process: A Systems Approach highlights the fundamentals and emerging technology in the field of industrial reverse osmosis desalination and membrane processes. It provides a unique, systems engineering perspective of membrane operation, focusing on analysis, design, and optimization of membrane processes. An explanation of mathematical and optimization knowledge is introduced and then applied throughout the book. Key topics include:Hydrodynamics and mass transfer in reverse osmosis (RO) membranesPredictive models for RO module performanceAnalysis and optimization of brackish and seawater RO desalinationEnergy production using pressure retarded osmosis (PRO)Integration of RO and PRO for energy-efficient desalinationDynamic operation of batch RO and batch PRO This work is essential reading for researchers who are interested in membrane-based processes, and those working within the water industry as well as undergraduate and graduate students.

Today, membrane separation technologies are widely used in many areas of water and wastewater treatment. Membrane processes can be used to produce potable water from surface water, groundwater, brackish water, or seawater, or to treat industrial wastewaters before they are discharged or reused. Membrane separation systems have many advantages over traditional water or wastewater treatment processes, lower operating and maintenance costs in comparison to conventional systems consisting of coagulation, clarification, and aerobic and anaerobic treatments. • Membrane separation systems are easy to operate and the performance is more reliable. • Membrane systems give a compact and modular construction, which occupies less floor space in comparison to the conventional treatment systems. In this review, we will introduce fundamental concepts of the membrane and membrane-separation processes, such as membrane definition, membrane classification, membrane formation, module configuration, transport mechanism, system design. Four widely used membrane separation processes in water and wastewater treatment, namely, microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO), will be discussed in detail. Some basic requirements for membranes are • high flux of the product, good mechanical strength for supporting the physical structure, good selectivity for the desired substances. Generally, high selectivity is related to membrane properties, such as small pores and high hydraulic resistance or low permeability.. The permeability increases with increasing density of pores, and the overall membrane resistance is directly proportional to its thickness. Therefore, a good membrane must have a narrow range of pore sizes, a high porosity, and a thin layer of material. Membranes can be either dense or porous. Separation by dense membranes relies on physicochemical interaction between the permeating components and the membrane material. Porous membranes, on the other hand, achieve separation by size exclusion, where the rejected material may be either dissolved or suspended depending on its size relative to that of the pore. Membranes can be organic (polymeric) or inorganic (ceramic or metallic), according to its composition, and their morphology is dependent on the nature of the material. There is a need for improved membranes that have higher efficiency and are more resistant to the chemical environment, especially chlorine. This article summarizes the art of membrane technology.