Secondary treated domestic wastewater in reverse electrodialysis: What is the best pre-treatment?

Abstract

art Highlights  RED-RO is a promising technology for energy-efficient seawater desalination  Secondary-treated wastewater is a potential low salinity source for RED  An efficient pre-treatment of wastewater is needed before use in RED  Rapid sand filtration and 100 µm provide efficient wastewater pre-treatment  River bank filtration does not provide adequate feed water quality AbstractAlthough Reverse Electrodialysis (RED) is most commonly known as a selective separation technology used for the production of sustainable energy, it can also serve as a valuable pre-desalination tool. By coupling RED to Reverse Osmosis (RO) for seawater desalination: (1) sustainable energy is produced in the RED process and (2) seawater is partially desalinated prior to RO thus, decreasing the energy demand. In this study, secondary-treated wastewater is proposed as the low salinity source in RED and suitable pre-treatment techniques for this effluent are investigated. Although it is generally accepted that RED is less prone to fouling than typical pressure driven membrane processes, results showed that pre-treatment is a key to ensure efficient operation of the wastewater-seawater RED. Both 100 µm filtration and rapid sand filtration proved to be suitable, with an increase in pressure drop of only 0.09-0.18 bar and a permselectivity decrease of only approximately 20% during 40 days of continuous operation. Conversely, River bank filtration did not perform better than the non-pretreated sample. As such, 100 µm filtration and rapid sand filtration are considered suitable, robust, and cost efficient pretreatment options for wastewater fed RED, enabling the improvement of the hybrid process of RED-RO seawater desalination.

From non‐renewable energy to renewable by harvesting salinity gradient power by reverse electrodialysis: A review

“…As reported by Vermaas et al, inter‐changing seawater and river water in the RED module feed inlet channels recover the initial power density for a period of operating time, probably due to removal by the reversed electrical current of the multivalent ions and organic foulants in the RED stack 138 . Recent studies on antifouling techniques also include the use of finer prefiltration and the increase of the intermembrane distance, with a major influence of the pretreatment technique used 143,144 . Even though the integration of a pretreatment process might prevent these problems as well, it will require an extra cost that affects the net power density and result in less cost‐effective energy production by RED.…”

“…138 Recent studies on antifouling techniques also include the use of finer prefiltration and the increase of the intermembrane distance, with a major influence of the pretreatment technique used. 143,144 Even though the integration of a pretreatment process might prevent these problems as well, it will require an extra cost that affects the net power density and result in less cost-effective energy production by RED.…”

Electrodialysis Applications in Wastewater Treatment for Environmental Protection and Resources Recovery: A Systematic Review on Progress and Perspectives

“…Filtration pre-treatments of a domestic WWTP effluent (1.13 mS/cm) were compared, i.e., 100 μm filtration, rapid sand filtration or river bank filtration [ 430 ]. Seawater (48.35–58.38 mS/cm) was pre-treated with sand filtration, bead filtration and UV.…”

Life cycle assessment of salinity gradient energy recovery by reverse electrodialysis in a seawater reverse osmosis desalination plant

“…The IEMs robustness against fouling events, which depend on feed water's composition, will determine SGE-RED deployment. [66][67][68] IEMs are the most prone to fouling among RED stack components. 67,69 Hence, to consider the effect of fouled IEMs on RED performance, we assume an annual decline in RED power output of 5%.…”