Zero Liquid Discharge Patents: Who Leads, Where the Gaps Are 2026
- Concentrated at the top. The leading assignee alone accounts for 52 of 275 records, and the top 5 combined hold 50.5% of all filings in scope.
- Filing activity has cooled from its peak. Filings ran from 27 in 2021 to 7 in 2024, a -74% change over that span, after 2026 publication data is still filling in.
- Brine chemistry dominates the claim map. C02F water-treatment classes touch 77.8% of records and B01D separation processes 43.6%, but crystallizer-adjacent classes like C01F and C01B stay under 4%.
Filing growth compares 2021 (27 records) with 2024 (7) — 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 275 records in scope (CR5), not by the ranked leaders only.
What the zero liquid discharge patent record shows
Zero liquid discharge (ZLD) system design sits at the intersection of thermal separation, membrane concentration and crystallization engineering. The 275 records in this dataset span brine concentrators, crystallizer stages, corrosion-resistant materials and energy-intensity claims filed between 2015 and mid-2026. Filing activity peaked in 2021 at 27 records and has since declined, though the two most recent years are still incomplete because publication typically lags filing by around eighteen months.
The assignee ranking is concentrated: a single leader holds 52 records against a field of 79 ranked companies, and the top 10 combined account for 69.8% of all records in scope. That leaves a long tail of single- and low-filing entrants working on narrower slices of the problem, from corrosion materials to niche recovery chemistry.
Filing trends and technology composition
Two views of the same 275-record dataset: how filing volume has moved year over year, and which IPC subclasses carry the claim density.
Filing trend, 2017-2026
Filings rose to a peak of 27 in 2021 before falling to 7 by 2024, a -74% change over that three-year window. 2025 and 2026 figures are still incomplete due to normal publication lag and should not be read as a continued decline.
Technology composition by IPC subclass
C02F (water and wastewater treatment) appears in 77.8% of the 275 records and B01D (separation processes) in 43.6%, confirming that most claims center on core treatment and filtration steps rather than downstream crystallization chemistry, where C01D, C01F and C01B together cover a much smaller share.
Shares are the percentage of the 275 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Zero Liquid Discharge System Design with Eureka
This page is one run against one query. Ask Eureka your own question about zero liquid discharge system design and every answer comes back with the patent numbers behind it.
Try EurekaThe most-cited records in this field
EP3323496B1 — Device and method for reducing acid gas emissions without liquid discharge from wastewater
Filed by General Electric Technology GmbH and granted in 2020, this record couples acid-gas emission reduction with a zero-liquid-discharge wastewater path, tying flue-gas treatment infrastructure to brine handling rather than treating ZLD as a standalone process.Filing and assignee details are drawn directly from the underlying record.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20040055955A1 | Production of purified water and high value chemicals from salt water | 132 |
| 2 | US7083730B2 | Production of purified water and high value chemicals from salt water | 127 |
| 3 | US20060196836A1 | Process and apparatus for the treatment of saline water | 108 |
| 4 | US20090020481A1 | Method and system for treating feedwater | 73 |
| 5 | US7595001B2 | Process for the treatment of saline water | 72 |
| 6 | US20070125719A1 | System and method of reducing organic contaminants in feed water | 67 |
| 7 | US20150315055A1 | Water Treatment Process | 56 |
| 8 | WO2004013048A2 | Production of purified water and high value chemicals from salt water | 53 |
| 9 | US20110180479A1 | Zero liquid discharge water treatment system and method | 50 |
| 10 | WO2014088826A1 | Water treatment process | 39 |
Citation counts reflect influence within the searched corpus and skew toward older filings; they are not a measure of current commercial relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Three patterns stand out once the raw counts are read against their denominators.
The field has a clear center of gravity
With the leader alone holding 52 records and the top 5 combined at 139, new entrants are filing into a space where core brine-concentration and crystallizer claims are already well covered by a small group.
Peak filing has passed, for now
Volume fell from 27 records in 2021 to 7 in 2024. Because publication lags filing by roughly 18 months, 2025-2026 counts are not yet reliable evidence of a continued slowdown.
Claims cluster on treatment, not chemistry
C02F and B01D together dominate the classification mix, while crystallization-adjacent classes such as C01D, C01F and C01B sit in single digits, pointing to lighter claim density downstream of the treatment step.
US and PCT routes lead filing strategy
The United States receives the most filings at 79, followed by WIPO PCT applications at 38, with Australia, Europe, India and Canada each holding a meaningful but smaller share.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to zero liquid discharge system design, with the prior art for and against each one.
Who holds the ground, and where it opens up
The ranked leaderboard covers 79 assignees across 275 records. Coverage above the leader is concentrated, but the classification data shows several branches with comparatively thin claim density.
A single assignee sets the pace
The leading company's 52 records place it well ahead of fifth place at 15 and tenth place at 7, meaning any freedom-to-operate review in core brine-concentration claims should start with this portfolio.
A long tail beyond the leaders
With 79 companies ranked in total and the top 10 already covering 69.8% of all records, most of the remaining assignees hold only a handful of filings each, often in adjacent materials or niche recovery methods.
Co-assignee activity is limited but pointed
Only 10 co-assignee pairs appear across the dataset. The strongest pair shares 6 co-filed records, suggesting most development in this field happens inside single-assignee programs rather than joint ventures.
| Assignee | Recent year | YoY |
|---|---|---|
| Aquafortus Technologies Ltd | 0 | — |
| General Electric Co | 0 | — |
| Aquatech International LLC | 0 | — |
| The Trustees of Columbia University in the City of New York | 0 | — |
| Saline Water Conversion Corp | 0 | — |
| Oasys Water Inc | 0 | — |
| University of South Carolina | 0 | — |
| BL Technology Inc | 0 | — |
Where to take this analysis
The dataset points to a concentrated leaderboard and specific under-claimed branches. The next steps depend on whether you are clearing a filing or scouting for it.
Run a freedom-to-operate check against the leader's portfolio
With one assignee holding 52 of 275 records, any new brine-concentrator or crystallizer-stage filing should be checked against that portfolio before drafting claims.
Explore assignee portfolios in EurekaTrack the corrosion-material and energy-recovery branches
Classes tied to corrosion-resistant materials and energy-recovery motors show comparatively low claim density inside this dataset, which may leave room for narrower, defensible filings.
Search white space in EurekaWatch for the 2025-2026 filing correction
Because publication lags filing by around 18 months, the apparent drop after 2024 will likely revise upward as more records publish; revisit the trend before concluding the field has cooled.
Set a filing alert in EurekaCommon questions on zero liquid discharge patents
The ranking covers 79 assignees across 275 records, and it is concentrated rather than evenly spread: the top-ranked company alone holds 52 records, with fifth place at 15 and tenth place at 7. The top 5 assignees combined account for 50.5% of all 275 records in scope, and the top 10 combined reach 69.8%. This means a small group of companies controls most of the documented claim space, while the remaining assignees each hold only a few filings.
Filing volume peaked in 2021 at 27 records and had fallen to 7 by 2024, a -74% change over that three-year span. However, patent publication typically lags filing by roughly 18 months, so the lower counts shown for 2025 and 2026 in this dataset are incomplete rather than evidence of a real slowdown. A fair read of momentum should focus on the 2021-2024 window, where the decline is measured against complete data.
Water and wastewater treatment (IPC class C02F) appears in 77.8% of the 275 records, and separation processes such as filtration (B01D) appear in 43.6%. Alkali-metal compound chemistry (C01D) covers 20.0% of records. Because a single patent can carry multiple IPC classes, these shares add up to more than 100%, but the pattern is clear: most claims center on the core treatment and separation steps rather than downstream crystallization or corrosion-material chemistry.
Several IPC subclasses appear in less than 10% of the 275 records, including C01F alkaline-earth and rare-earth compounds at 3.6%, C01B non-metallic elements at 3.3%, E21B well-drilling applications at 4.7%, and F03G motor-related mechanisms at 5.8%. These lower-density branches, particularly corrosion-resistant materials and energy-recovery integration, suggest narrower but still-open claim opportunities compared with the heavily filed core treatment classes.
EP3323496B1, assigned to General Electric Technology GmbH and granted in 2020, covers a device and method for reducing acid gas emissions without liquid discharge from wastewater, linking flue-gas emission control to a zero-liquid-discharge wastewater path. It is a useful representative record because it shows claims that combine ZLD with an adjacent process (gas emission control) rather than covering brine concentration in isolation. Anyone filing in a similar combined-process space should review its specific claim scope directly, since combination claims like this can create narrower but still real barriers around linked process steps.
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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.