This landscape identifies 61 patent families filed between 2015 and the 2026 data cut-off, using a search that combines electrodialysis or electrodialysis-reversal hardware terms with control-specific language such as voltage control, current reversal control, process control and closed-loop control. That is a narrow, control-centric slice of the much larger electrodialysis hardware patent space, not a count of every ED-related filing. Because publication lags filing by roughly 18 months, the true 2025-2026 filing count is understated in current data.

The filing trend is flat rather than growing: activity peaked at 7 filings in 2018, and by the 2022 midpoint had settled to 6, with no acceleration since. This pattern typically indicates that core control claims — voltage setpoints, reversal timing, closed-loop feedback architectures — were staked out in the late 2010s, and later filers are working around an already-defined claim map rather than opening new territory. A flat trend does not mean the technology is dead; it means the claim space is settled.

C02F (water and wastewater treatment) and B01D (separation processes including filtration) dominate, appearing in 59 and 48 of the 61 records respectively — meaning almost every filing frames its control claims as a water-treatment process rather than a generic control-engineering invention. Smaller footholds exist in B01J (catalysis), C25B (electrolytic production of compounds), H01M (batteries and fuel cells), C01B (inorganic compounds), A23C (dairy) and C07C (organic compounds). Those smaller classes mark where ED control logic is being adapted into adjacent industrial processes, and they carry far less filing density than the core water-treatment lane.

The tracked assignee list includes established water-treatment and research names such as Evoqua Water Technologies, MIT, the Institute of Process Engineering at the Chinese Academy of Sciences, Palo Alto Research Center, ELECTROSEP and others. Every one of these shows zero filings in the most recent tracked year, and Evoqua specifically shows a full year-on-year drop to zero. That does not mean their existing claims have lapsed — it means new filing pressure from the historically active names has paused, which is worth confirming against each portfolio's maintenance status before assuming the field is open.

The clearest white space sits outside the crowded C02F/B01D core: electrolytic compound production (C25B) and battery-adjacent current control (H01M) each carry only a handful of records, as do dairy and organic-chemistry crossovers. Within the core lane itself, reversal-timing algorithms tied to fouling mitigation and closed-loop control driven by real-time conductivity or power-differential sensing appear thinly claimed relative to the volume of general voltage-control art. A first filing in these areas should anchor its claims to a specific sensing input and control trigger rather than a general closed-loop architecture, since the general architecture is already densely cited prior art.