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PRO Pretreatment
Published in Chun Feng Wan, Tai-Shung Chung, Membrane Technology for Osmotic Power Generation by Pressure Retarded Osmosis, 2020
Tianshi Yang, Chakravarthy S. Gudipati, Tai-Shung Chung
The concerns of global warming and highly fluctuated oil prices have stimulated the research on alternative renewable and sustainable energies. Among various alternatives, osmotic energy is a promising, green and sustainable one that can be harnessed worldwide. Pressure retarded osmosis (PRO) is one of the technologies to harvest osmotic energy through an osmotically-driven membrane process (Han et al. 2015, Loeb and Norman 1975, Thorsen and Holt 2009). Various solution pairs have been studied and used as feed pairs in PRO processes. The most common one in early PRO studies was the feed pair of seawater and river water (Chu and Majumdar 2012, Chung et al. 2015, Kim et al. 2013b, Loeb 2002, O’Toole et al. 2016, Sharqawy et al. 2011, Thorsen and Holt 2009), but using this pair for PRO was not economically feasible because it produced a low energy density due to its small salinity difference (Bui et al. 2011, Chung et al. 2015, Han et al. 2015, Skilhagen et al. 2008). The feed pair consisting of concentrated seawater brine (denoted as SWBr) from seawater reverse osmosis (SWRO) plants and discharged wastewater retentate (denoted as WWRe) from municipal wastewater plants has drawn global attention (Chung et al. 2012, Kim et al. 2013a, Logan and Elimelech 2012, Saito et al. 2012). In addition to producing a higher energy output, it also lowers the energy consumption for SWRO, mitigates the environmental issues of brine disposal, reduces the water production cost, and produces a greener SWRO process (Chung et al. 2015).
Salinity Gradient
Published in Sergio C. Capareda, Introduction to Renewable Energy Conversions, 2019
A pressure-retarded osmosis (PRO) system uses a membrane to separate a concentrated salt solution (like seawater) from fresh water. The fresh water flows through a semi-permeable membrane toward the sea water, which increases the pressure within the seawater chamber. A turbine is spun as the pressure is compensated, and electricity is generated. The world's first reported PRO plant was built by Statkraft, a Norwegian utility company (Patel, 2014). They estimated that in Norway, up to 2.85 GW [0.09 Quad/yr] of power would be available from this process. The plant, located in Oslo, opened in November 2009. Initial studies were made several years prior to its inauguration. The goal for this facility was to produce enough electrical power to provide light and heat energy to a small town near the Oslo fjord within a few years. The initial output was rather small—a 4 kW [5.36 hp] system (enough to heat a large electric kettle). As currently reported, the plant aims to increase the output to up to 25 MW [0.00075 Quad/yr], enough to equal the power-generating capacity of a small wind farm. The basic principle behind a PRO system is schematically shown in Figure 7.3.
A critical review of fuel cell commercialization and its application in desalination
Published in Hacene Mahmoudi, Noreddine Ghaffour, Mattheus Goosen, Jochen Bundschuh, Renewable Energy Technologies for Water Desalination, 2017
Yousef Alyousef, Mattheus Goosen, Youssef Elakwah
Novel technologies for addressing the problem of high energy consumption in desalination have also recently been reported (Sahin et al., 2016; Wan and Chung, 2016). For example, a potential means of addressing the high energy intensity of traditional desalination plants is the development of pressure-retarded osmosis (PRO) technology. PRO extracts the Gibbs free energy of mixing by allowing water to spontaneously flow through a semi-permeable membrane from a low-salinity feed solution to a high-salinity draw solution against a hydraulic pressure. The Gibbs free energy is converted to the hydraulic pressure of the diluted brine, which can be further converted to mechanical energy by a pressure exchanger (PX) or to electrical energy by a hydro-turbine (Fig. 9.4). While Helfer et al. (2013) concluded that PRO technology is viable, they mentioned that a barrier to its widespread commercial development is the high cost of PRO membranes. The authors claimed that although further investigations are still needed to ensure the viability of PRO technology, this technical advance in desalination technology is promising as a viable alternative for renewable energy production. In a related study, the specific energy consumption of three processes involving seawater reverse osmosis (SWRO) was scrutinized by Wan and Chung (2016), namely, SWRO without a pressure exchanger, SWRO with a pressure exchanger, and SWRO with pressure exchangers and PRO (Fig. 9.4). The results showed that the specific energy consumptions for these three processes were, respectively, 5.51, 1.79 and 1.08 kWh m−3 of desalinated water for a 25% recovery SWRO plant; and 4.13, 2.27 and 1.14 kWh m−3 of desalinated water for a 50% recovery SWRO plant, using either freshwater or wastewater as the feed solution in PRO. Whether these results can be translated into large-scale commercial application remains to be seen. However, it does demonstrate the great potential in energy savings available through combination of conventional with novel systems.
Polyethylene glycol and membrane processes applied to suction control in geotechnical osmotic testing
Published in International Journal of Geotechnical Engineering, 2022
Rick Vandoorne, Petrus J. Gräbe, Gerhard Heymann
Different osmosis modes may be defined with regard to the forces driving the osmosis process (Roest 2018). These driving forces are transmembrane osmotic pressure (), transmembrane hydrostatic pressure () and the matric suction () of the soil sample. Figure 4(a) illustrates and defines the four osmosis modes in the context of geotechnical osmotic testing, namely: forward osmosis (FO), reverse osmosis (RO), pressure-assisted osmosis (PAO) and pressure-retarded osmosis (PRO). In the absence of a transmembrane pressure difference ( = 0), FO occurs and is governed by matric suction and osmotic pressure. FO between two liquid bulk phases is equivalent to dialysis where the osmotic pressure difference () is the sole driving force (Baker 2004).
Dye synthetic solution treatment by direct contact membrane distillation using commercial membranes
Published in Environmental Technology, 2020
Heloisa Ramlow, Ricardo Antonio Francisco Machado, Andrea Cristiane Krause Bierhalz, Cintia Marangoni
The technology of membrane distillation can reduce the worldwide water-energy stress in a sustainable way [6,7]. Direct contact membrane distillation (DCMD) is an attractive technology to treat dyeing wastewater since a recovery of heat is possible directly near to the fabric dyeing machine. Dyeing baths are usually discharged at 80–100°C and, therefore, there is no need of thermal energy for heating them before DCMD [8,9]. In addition to the possibility of water reclamation, the dye can potentially be recovered from the concentrated solution [10]. DCMD is a separation process in which a temperature difference across membrane surfaces induces the vapour pressure difference on both sides of the membrane, resulting in a permeate composed theoretically by volatile compounds. Dyes are non-volatile substances at mild temperatures and are theoretically separated from aqueous solutions in DCMD. In order to enhance the water recovery and improve energy efficiency, MD can be integrated with other processes such as reverse osmosis (RO), freeze desalination (FD), forward osmosis (FO), and pressure retarded osmosis (PRO) [11–13].
Altering substrate properties of thin film nanocomposite membrane by Al2O3 nanoparticles for engineered osmosis process
Published in Environmental Technology, 2022
Zhen-Shen Liew, Yeek-Chia Ho, Woei Jye Lau, Nik Abdul Hadi Md Nordin, Soon-Onn Lai, Jun Ma
Water and energy are two main resources that are needed by human. As the demands on water and energy continue to grow, researchers are looking for sustainable technologies to minimise environmental impact. Engineered osmosis (EO) is an emerging technology that can harvest osmotic power for electricity generation via pressure retarded osmosis (PRO) and convert saline water to fresh water via forward osmosis (FO) [1]. There is immense interest in EO due to its potential to enable a wide range of new, sustainable processes through a single platform technology. Confronted with stringent environmental regulation and high energy cost, the potential of EO as an effective renewable energy source and water source worth to be considered [2].