An Alternating, Current-Induced Electromagnetic Field for Membrane Fouling and Scaling Control during Desalination of Secondary Effluent from Municipal Wastewater

Abstract

Membrane treatment of secondary effluent for reuse applications is a promising approach to expand water supplies and provide flexibility to water resources management. However, effective control of membrane fouling and scaling is crucial for cost-effective treatment and system resilience. This study compared the performance of antiscalants to an alternating, current-induced electromagnetic field (EMF) as an alternative pretreatment method to reverse osmosis. Compared to the no-EMF control experiments, the EMF device resulted in 13% higher water recovery and 366% lower flux decline at 60% of water recovery, along with 2–8 times lower precipitation of fouling and scaling, as evidenced by scanning electron microscope, energy dispersive X-ray spectroscopy, and chemical extraction analysis. The combination of the EMF with antiscalant was more effective for reducing membrane fouling and scaling, increasing water recoveries up to 89.3%, as compared to the EMF (67.5%) and antiscalant-only (73.6%) configurations. This is the first study to demonstrate synergistic effects of using an EMF in combination with antiscalants and could lead to lower pretreatment costs. Additional research is required to quantify the economics of this approach and to fully understand the fundamental mechanisms governing fouling and scaling control by an EMF.

Reverse Osmosis with Intermediate Chemical Demineralization: Scale Inhibitor Selection, Degradation, and Seeded Precipitation

“…For concentrates containing high CaSO 4 , suitable scale inhibitors were selected from the following three aspects: Ca 2+ concentration in the concentrate, macroscopic scaling amount, and microscopic CaSO 4 precipitation morphology. RO-400, being the preferred scale inhibitor, shows an effective inhibition effect across a wide range of SIg (2.3-6) and pH (5)(6)(7)(8)(9)(10)(11) values. In the UVD process, a 40 W UV light with 70 mg/L H 2 O 2 can degrade RO-400 completely in 15 min.…”

“…Secondary reverse osmosis (SRO) can further treat the salt-containing concentrate to reduce the amount of high-concentration brine. The two-stage RO process integrating RO desalination with intermediate concentrate demineralization (ICD) is one of the promising strategies to overcome the recovery limitation caused by mineral scaling during RO desalination [6][7][8][9][10][11]. ICD can reduce the concentration of calcium sulfate in the RO concentrate, allowing it to be further desalted in a subsequent SRO process [6,12].…”

Effect of Electric Field on Membrane Fouling and Membrane Performance in Reverse Osmosis Treatment of Brackish Water

“…Cao [31] used a variable-frequency electric field as a pretreatment process for seawater treatment by RO, and the solute rejection and permeate flux were increased by 15-35%, respectively, and the pollutants adhering to the membrane surface were also relatively reduced. Similarly, Penteado de Almeida [32] applied an AC-induced electromagnetic field (EMF) to RO wastewater treatment. The system achieved a 13% increase in the recovery rate, along with a 2-8 times reduction in the scaling rate.…”

Electromagnetic Water Treatment and Soil Compost Incorporation to Alleviate the Impact of Soil Salinization

“…Previous studies demonstrated that EMF is an environmentally friendly, non-chemical treatment that minimizes chemical usage, reduces cost (saving time, money, and manpower), and is easy to install with no maintenance and low or no energy consumption [31,32]. It is anticipated that EMF could improve nutrient uptake, plant yield, water efficiency, and soil desalination [31][32][33][34][35]. Studies showed positive effects of EMF-treated synthetic saline irrigation water on plant yield [28,29] and seed germination [36] when different types of EMF devices were used.…”