Membrane Filtration Patents: Leaders, Trends & White Space 2026
- Filing has cooled sharply since its 2017 peak. 143 filings that year fell to 51 by the midpoint of 2022 and 14 in the most recent (partial) year — a declining trend, not a growing one.
- Separation and water-treatment IPC codes dominate. B01D and C02F together anchor the vast majority of the 2,145 families; food, sugar and fermentation classes appear only as minor overlaps.
- Co-assignment is rare and concentrated. Only 10 co-assignee pairs exist across the whole dataset, and the strongest single pairing accounts for 15 shared filings — most applicants file alone.
Filing growth compares 2021 (106 records) with 2024 (68) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 2,145 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
This dataset tracks patent families combining membrane filtration, reverse osmosis desalination and nanofiltration membrane language with claims tied to fouling resistance, salt rejection, permeate flux, membrane module design or energy recovery. The IPC scope centres on B01D61, B01D71 and C02F1 — separation processes and water treatment — which keeps the corpus focused on the membrane hardware and chemistry itself rather than adjacent downstream uses.
Coverage runs from 2015 through the 2026 data cut-off, drawing on 2,145 published families. Because publication lags filing by roughly 18 months, the most recent year's count is understated and should not be read as a real drop-off on its own.
Filing trend and technology composition
Two views of the same 2,145-family dataset: how filing volume has moved year over year, and which IPC subclasses carry the claim weight.
A peak already behind us
Filings ran at 143 in 2017, roughly a third of that by 2022 at 51, and down to 14 in the most recent partial year. Read against the publication lag, the true recent-year figure is higher than shown, but the multi-year direction from 143 to 51 is a genuine decline, not a data artefact.
Separation and water treatment lead by a wide margin
B01D (1,836 records) and C02F (1,398) dominate the composition, confirming this is fundamentally a separation-process and water-treatment field. B01J, A23L, C13K, C07C, C12P and C13B each appear only in the tens of records, marking narrow overlaps with catalysis, food, sugar and fermentation applications rather than core activity.
Shares are the percentage of the 2,145 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Membrane Filtration and Desalination with Eureka
This page is one run against one query. Ask Eureka your own question about membrane filtration and desalination and every answer comes back with the patent numbers behind it.
Try EurekaKey patents shaping this space
Polyacrylonitrile/chitosan composite nanofiltration membrane containing graphene oxide
Filed by Korea Research Institute of Chemical Technology, this filing describes a polyacrylonitrile support with a chitosan coating layer, either or both modified with graphene oxide, assembled as a nanofiltration membrane. The stated performance profile combines high permeability with a high salt rejection ratio, anti-fouling behaviour and chlorine resistance, and the described format is a spirally wound membrane module.Filed 2016-10-20 — illustrates the material-composite route to combined flux and rejection gains that recurs across the dataset.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US5958243A | Apparatus and method for membrane filtration with enhanced net flux | 182 |
| 2 | US6303035B1 | Immersed membrane filtration process | 148 |
| 3 | US6319411B1 | Method of maintaining clean vertical skeins of hollow fiber membranes and system therefor | 141 |
| 4 | US5762789A | Disposable membrane module with low-dead volume | 138 |
| 5 | US5635071A | Recovery of carboxylic acids from chemical plant effluents | 136 |
| 6 | US5858240A | Nanofiltration of concentrated aqueous salt solutions | 129 |
| 7 | US6755970B1 | Back-flushable spiral wound filter and methods of making and using same | 128 |
| 8 | US4125463A | Reverse osmosis desalination apparatus and method | 121 |
| 9 | US20040232076A1 | Scouring method | 114 |
| 10 | US6893568B1 | Immersed membrane filtration system and overflow process | 111 |
Citation counts favour older filings inside any searched corpus — treat this table as a map of influence, not a ranking of current importance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Three patterns stand out once volume, geography and citation weight are read together.
The claim rush has passed
Filing activity peaked in 2017 and has fallen through the midpoint year to the present, with 2022 sitting at roughly a third of the peak. This does not mean the technology is exhausted — it means the easiest claim territory around fouling resistance, salt rejection and permeate flux was staked out early.
US and China lead filing volume
The United States and China are the two largest receiving offices, followed by Japan, the EPO and the WIPO/PCT route. Australia's presence in the top tier signals desalination-driven filing distinct from the broader industrial water-treatment demand centred in the US, China and Japan.
Most applicants file alone
Only 10 co-assignee pairings exist across 2,145 families, and the strongest of them accounts for just 15 shared filings. This is a field of solo filers, not joint ventures — a contrast with sectors where cross-licensing or JV filing is the norm.
Foundational membrane-module patents still anchor citation graphs
The most-cited records in this corpus concern membrane module construction and hollow-fibre skein maintenance rather than the newer composite-material chemistry. That's a citation-count artefact of age, not evidence that module mechanics matter more than material science today.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to membrane filtration and desalination, with the prior art for and against each one.
Who is active, and where the gaps are
Recent-year momentum across the tracked assignees is flat to negative rather than showing a clear accelerating leader, and collaboration between assignees is rare.
Vito Co., Ltd. holds the only positive recent count
Among the assignees tracked for recent-year momentum, Vito Co., Ltd. is the only one with a filing recorded in the latest year; every other tracked assignee, including Toray Industries, Inc. and Evoqua Water Technologies LLC, shows zero.
A sharp year-over-year drop from a historically active filer
Toray Industries, Inc. recorded a -100% year-over-year change, dropping to zero filings in the latest year after prior activity. That pattern — a historically present assignee going quiet — recurs across several names in the momentum table and matches the field-wide filing decline.
Shuihang Corporation and Nitto Denko Corporation form the densest pairing
This pairing is more than five times stronger than the next-strongest pair (Vito Co., Ltd. and DOYEN WIM at 3), making it the one clear example of sustained joint filing inside an otherwise solo-filer field.
| Assignee | Recent year | YoY |
|---|---|---|
| Vito Co., Ltd. | 1 | — |
| Toray Industries, Inc. | 0 | -100% |
| Evoqua Water Technologies LLC | 0 | — |
| Kobelco Eco-Solutions Co., Ltd. | 0 | — |
| Toshiba Corporation | 0 | — |
| Kurita Water Industries Ltd. | 0 | — |
| Asahi Kasei Chemicals Corporation | 0 | — |
| Shuihang Corporation | 0 | — |
Where to take this research
The filing trend and IPC composition point to a field with settled core claims and narrower openings at the edges.
Map claims against the declining filing curve
With filings down from a 2017 peak, freedom-to-operate work should weight older, still-cited module and rejection-ratio patents alongside newer composite-material filings before assuming a branch is open.
Explore the filing trend in EurekaCheck the material-composite branch specifically
Graphene oxide and chitosan composite coatings appear as a distinct claim style from the older hollow-fibre and module patents that dominate the citation table — worth tracking as a separate design space.
Run a composite-membrane search in EurekaCommon questions on membrane filtration patents
No. Filing peaked in 2017 at 143 records in this dataset and has declined since, falling to roughly a third of that by 2022 and to 14 in the most recent partial year. Publication lag of about 18 months means the very latest year is understated, but the multi-year trend from 2017 through 2022 is a genuine decline rather than a data artefact. This points to a field where core claim territory was staked out earlier in the period.
The dataset tracks recent-year momentum across a set of assignees including Vito Co., Ltd., Toray Industries, Inc., Evoqua Water Technologies LLC and others, and only one of them shows a positive filing count in the latest year. Most tracked assignees, including historically active filers like Toray Industries, Inc., show zero filings in the most recent year — a -100% year-over-year change in that case. This suggests the leadership picture is less about one dominant filer accelerating and more about a field where activity is broadly slowing across established names.
This landscape is scoped to IPC classes B01D61, B01D71 and C02F1, covering separation processes and water/wastewater treatment. In the underlying record set, B01D accounts for 1,836 of 2,145 records and C02F for 1,398, confirming these two subclasses carry almost all of the claim weight. Smaller overlaps appear in catalysis (B01J), food (A23L) and sugar/fermentation classes (C13K, C07C, C12P, C13B), reflecting adjacent industrial uses of membrane separation rather than core desalination activity.
Relative to the dense claim territory around core salt-rejection and membrane-module patents, several adjacent branches show thinner filing density: energy-recovery device integration, anti-fouling surface coatings, graphene oxide composite layers, chlorine resistance in spiral-wound modules, and hollow-fibre skein maintenance systems. These are not unclaimed, but they carry materially fewer filings than the foundational module and rejection-ratio patents that dominate the most-cited table. A first claim in these areas would need to differentiate clearly from the graphene oxide composite work already represented in the corpus.
US20160303524A1, filed by Korea Research Institute of Chemical Technology, covers a polyacrylonitrile support combined with a chitosan coating layer, where either the support or the coating (or both) is modified with graphene oxide, formed into a nanofiltration membrane with stated high permeability, high salt rejection, anti-fouling and chlorine-resistant properties in a spiral-wound module format. It does not block nanofiltration membranes generally — only designs that combine this specific polyacrylonitrile/chitosan/graphene-oxide composite structure. Alternative support materials, different coating chemistries, or graphene oxide applied in a materially different layer arrangement would sit outside its literal claim scope, though a full freedom-to-operate check would need the granted claim language rather than the abstract alone.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.