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Water Treatment Operations
Published in Frank R. Spellman, Handbook of Water and Wastewater Treatment Plant Operations, 2020
Membranes are a selective barrier, allowing some constituents to pass while blocking the passage of others. The movement of constituents across a membrane requires a driving force (i.e., a potential difference between the two sides of the membrane). Membrane processes are often classified by the type of driving force, including pressure, concentration, electrical potential, and temperature. The processes discussed here include only pressure-driven and electrical potential-driven types. Pressure-driven membrane processes are often classified by pore size into four categories: microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO). High pressure processes (i.e., NF and UF). Typical pressure ranges for these processes are given in Table 15.21. NF and RO primarily remove constituents through chemical diffusion. MF and UF primarily remove constituents through physical sieving. An advantage of high-pressure processes is that they tend to remove a broader range of constituents than low-pressure processes. However, the drawback to broader removal is the increase in energy required for high-pressure processes (Aptel & Buckley, 1996). Electrical potential-driven membrane processes can also be used for arsenic removal. These processes include, for the purposes of this document, only electrodialysis reversal (EDR). In terms of achievable contaminant removal, EDR is comparable to RO. The separation process used in EDR, however, is ion exchange.
Desalination and drying
Published in David Thorpe, Solar Energy Pocket Reference, 2018
Electrodialysis reversal: electricity is applied to electrodes to pull dissolved salts through an ion exchange membrane leaving fresh, low salinity water behind. This and high salinity concentrate are the products. The polarity of the electrodes is switched at fixed intervals to reduce the formation of scale and subsequent fouling and allow the system to achieve higher levels of fresh water recovery. A module contains an electrodialysis stack consisting of alternating layers of cationic and anionic ion exchange membranes. This system is less sensitive than RO to particulates and metal oxides and can remove arsenic, fluoride, radium and nitrates. Units also have a long membrane life (typically 20+ years for potable water installations).
Types of POU/POE Devices
Published in Benjamin W. Lykins, Robert M. Clark, James A. Goodrich, Point-of-use/Point-of-entry for Drinking Water Treatment, 2018
Benjamin W. Lykins, Robert M. Clark, James A. Goodrich
Membrane processes for potable water treatment are divided into two basic categories.(27) One category is that in which the membrane is water permeable. This category includes processes such as reverse osmosis, nanofiltration, ultrafiltration, and microfiltration. The particle size that can be rejected by these typical separation processes is shown in Figure 8. The other category where the membrane is impervious to water includes processes such as electrodialysis and electrodialysis reversal.(27) The two membrane systems generally used in water treatment are reverse osmosis and ultrafiltration.
Decreasing environmental impact of landfill leachate treatment by MBR, RO and EDR hybrid treatment
Published in Environmental Technology, 2021
Judit Ribera-Pi, Marina Badia-Fabregat, Jose Espí, Frederic Clarens, Irene Jubany, Xavier Martínez-Lladó
García-Pacheco et al. [14] used regenerated RO membranes for long-term filtration of brackish water at pilot scale with no performance decline after four months. Coutinho de Paula et al. [15] tested NF regenerated membranes for water river treatment. The authors reported a cost of chemically recycling end-of-line nanofiltration (NF) membranes for a river water treatment of approximately 1.1% of the cost of using a new ultrafiltration (UF) membranes. However, there is no report of RO regenerated membranes being used in landfill leachate treatment. Therefore, the proposed treatment tested in this work is the combination of a membrane bioreactor (MBR) as a pre-treatment of the landfill leachate, followed by an RO step performed using regenerated RO membranes, which will produce the final treated water of the system. Additionally, an electrodialysis reversal (EDR) unit will be used to treat RO brine stream, to further concentrate it and decrease the final volume of waste produced in the process (Figure 1).
Removal of organic matter of electrodialysis reversal brine from a petroleum refinery wastewater reclamation plant by UV and UV/H202 process
Published in Journal of Environmental Science and Health, Part A, 2018
Priscila B. Moser, Bárbara C. Ricci, Clara B. Alvim, Ana C. F. Cerqueira, Míriam C. S. Amaral
A typical refinery effluent treatment plant comprises a primary treatment, in which a combination between physical and physicochemical processes are performed to remove free oil, suspended solids and colloidal substances, followed by a secondary treatment that removes organic matter and nutrients. Although this system could possibly be used to fulfill the discharge requirements, it does not produce a treated effluent that meets the quality for reuse. The reuse requires additional treatment processes and the selection of the method will depend on the characteristics of the wastewater and on the required water quality. The electrodialysis reversal (EDR) is already a reality in Brazilian oil refineries, and aims, among other things, to provide treated water for cooling systems, which can consume up to 90% of the water in this sector.[3] The EDR has shown advantages over similar desalination processes, such as greater robustness, operational reliability and simplicity and less need for wastewater pre-treatment, being used for treating various industrial wastewater.[4]
Treatment options for nanofiltration and reverse osmosis concentrates from municipal wastewater treatment: A review
Published in Critical Reviews in Environmental Science and Technology, 2019
Kimmo Arola, Bart Van der Bruggen, Mika Mänttäri, Mari Kallioinen
It can be concluded that although most studies were conducted with synthetic wastewaters, the traditional electrodialysis could be a promising technology for membrane concentrate treatment for instance as a nutrient concentration technology, especially when concentrate to be treated has a sufficient conductivity (several mS/cm). However, special attention has to be paid to membrane fouling control and potential pretreatment of wastewater when operating ED with real wastewater effluents to minimize fouling of ED membranes. Emerging applications of electrodialysis such as electrodialysis reversal (EDR) and electrodialysis metathesis (EDM) have also been examined as potential technologies for wastewater treatment (Bisselink et al., 2016; Goodman, Taylor, Xie, Gozukara, & Clements, 2013; Jaroszek, Lis, & Dydo, 2016; Yen, You, & Chang, 2017; Yin Yip & Elimelech, 2014; Zhang et al., 2017). The working principle of EDR is similar to traditional electrodialysis; however, in the EDR the polarity of the electrodes is inverted periodically (15–30 min) to control scaling of ionic species such as calcium phosphate or carbonate (Goodman et al., 2013). Goodman et al. (2013) and Bisselink et al. (2016) have studied the utilization of EDR for the desalination of wastewater such as municipal wastewater to provide recycled water for irrigation purposes. Goodman et al. (2013) were able to reduce the total dissolved solids (TDS) of the municipal wastewater effluent from 1104 mg/L to 328 mg/L with the EDR technology, which was below the upper limit of 375 mg/L in the water quality guidelines for horticulture. The conductivity could also be decreased by 72% including the removal of calcium (84%), chloride (76%) and phosphate (60%).