# US 11,298,660 B2 · Electrochemical system with concentration recirculation in cyclic batch mode > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,298,660 B2 - Document ID: US11298660B2 - Status: Granted - Kind: B2 - Application number: 16/098,591 - Filed: 2017-05-04 - Published: 2020-07-09 - Granted: 2022-04-12 - Earliest claimed: 2016-05-06 - Assignees: Evoqua Water Technologies LLC - Applicants: Evoqua Water Technologies, LLC - Inventors: Li-Shiang Liang; Michael J. Shaw; Wenxin Du - Web page: https://patentgrep.com/patent/US11298660B2 ## CPC - B01D 61/44: Ion-selective electrodialysis - C02F 1/469: by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis - B01D 61/46: Apparatus therefor - C02F 1/4693: {electrodialysis} - C02F 1/4695: {electrodeionisation} - C02F 2201/4613: Inversing polarity - C02F 2201/46145: Fluid flow - C02F 2201/4618: Supplying or removing reactants or electrolyte - C02F 2201/46185: Recycling the cathodic or anodic feed - C02F 2209/005: Processes using a programmable logic controller [PLC] - C02F 2209/05: Conductivity or salinity - C02F 2209/06: pH - C02F 2209/40: Liquid flow rate - Y02W 10/37: using solar energy - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes) - Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT ## Abstract A method of operating an electrochemical device includes periodically discharging a volume of concentrate reject in a timed batch cycle and replacing the concentrate reject with feed water. An electrochemical water treatment system includes a recycle line having a valve controlled by a control module. The control module periodically opens the valve to discharge concentrate reject from the recycle line in a batch timed cycle. The recycle line is fed with feed water to replace the discharged concentrate reject. ## Claims ### Claim 1 A method of operating an electrochemical separation device comprising a dilution compartment, a concentration compartment, an ion exchange membrane positioned between the dilution compartment and the concentration compartment, first and second electrodes, a first feed stream fluidly connected to the dilution compartment, a second feed stream fluidly connected to the concentration compartment, and a concentration compartment recycle stream the method comprising: directing the first feed stream to the dilution compartment to produce a product stream; directing the second feed stream to the concentration compartment to produce a reject stream; recycling the reject stream to the concentration compartment; measuring electric current between the first and second electrodes; periodically discharging a volume of the reject stream having a first concentration of ions in a batch cycle; and replacing the discharged volume of the reject stream with an essentially equivalent volume of the second feed stream having a second concentration of ions lower than the first concentration of ions, the batch cycle being determined by the electric current between the first and second electrodes, the method comprising discharging the volume of the reject stream when the electric current decreases to reach a predetermined value. ### Claim 2 (depends on 1) The method of claim 1, further comprising periodically reversing a polarity of the first and second electrodes, and coordinating a timing of the periodic discharge of the reject stream with a timing of the periodic reversal of the polarity. ### Claim 3 (depends on 2) The method of claim 2, further comprising exchanging flow paths of the first feed stream and the second feed stream in coordination with the timing of the periodic reversal of the polarity, such that the first feed stream is directed to the concentration compartment and the second feed stream is directed to the dilution compartment. ### Claim 4 (depends on 1) The method of claim 1, further comprising blending the reject stream with the second feed stream to produce a reject and second feed blend upstream from recycling the reject stream to the concentration compartment, wherein recycling the reject stream to the concentration compartment comprises recycling the reject and second feed blend to the concentration compartment. ### Claim 5 (depends on 4) The method of claim 4, wherein periodically discharging the volume of the reject stream comprises periodically discharging a volume of the reject and second feed blend, and wherein replacing the discharged volume of the reject stream comprises replacing the discharged volume of the reject and second feed blend with an essentially equivalent volume of the second feed stream. ### Claim 6 (depends on 1) The method of claim 1, further comprising blending the reject stream with a third feed stream to produce a reject and third feed blend upstream from recycling the reject stream to the concentration compartment, wherein the reject stream is recycled to the concentration compartment by recycling the reject and third feed blend to the concentration compartment. ### Claim 7 (depends on 6) The method of claim 6, wherein the volume of the reject stream is periodically discharged by periodically discharging a volume of the reject and third feed blend, and wherein the discharged volume of the reject stream is replaced by replacing the discharged volume of the reject and third feed blend with an essentially equivalent volume of the second feed stream. ### Claim 8 (depends on 1) The method of claim 1, further comprising periodically discharging the volume of the reject stream for about 0.5 minutes to about 2.0 minutes in batch cycles of about 15 minutes to about 25 minutes. ### Claim 9 (depends on 1) The method of claim 1, wherein the batch cycle is determined by the ionic concentration of the reject stream, the method comprising periodically discharging the volume of the reject stream when the first concentration of ions reaches a concentration sufficient to form a precipitate. ### Claim 10 (depends on 9) The method of claim 9, comprising periodically discharging the volume of the reject stream when the first concentration of ions is a concentration of greater than about 12,000 ppm total dissolved solids (TDS). ### Claim 11 (depends on 9) The method of claim 9, further comprising measuring the ionic concentration of the reject stream.