Zero Liquid Discharge Patents: Who Leads, Where Gaps Are 2026
- Filing has cooled, not grown. activity peaked at 7 families in 2021 and has drifted down since, with the 2022 midpoint at just 1 — this is a mature, occupied field rather than a rising one.
- One family of concentrator claims dominates citations. the five most-cited records are all variants of the same "compact wastewater concentrator using waste heat" design, cited between 36 and 69 times.
- Membrane and thermal claims overlap heavily. 54 records sit in C02F (water treatment) and 41 in B01D (separation/filtration), meaning most filings stake claims across both process stages at once.
What the zero liquid discharge patent record shows
Zero liquid discharge (ZLD) patenting concentrates on evaporation, crystallization and membrane concentration steps applied to high-salinity industrial wastewater. The corpus behind this page holds 66 patent families published between 2015 and mid-2026, filed most heavily through the United States, China and India, with a smaller but consistent share routed through WIPO (PCT) and the EPO. The technology composition skews toward two IPC subclasses: C02F for wastewater treatment chemistry and B01D for the separation and filtration hardware that does the physical concentrating.
A secondary cluster in E21B (earth and rock drilling) reflects ZLD's use in oilfield produced-water management, a use case distinct from municipal or general industrial effluent. Filing activity peaked in 2021 and has not recovered since; publication lag means the final one or two years will always look thinner than they eventually turn out to be, but the flat 2022 midpoint suggests this is a plateau, not a reporting artifact.
Filing trend and technology composition
Two views of the same 66-family dataset: how filing volume has moved year over year, and how those filings split across the IPC subclasses that define the technical approach.
Filing trend, 2017–2026
Filings ran at 5 in 2017, rose to a peak of 7 in 2021, then fell back to 1 by the 2022 midpoint. The partial 2026 count reflects publication lag rather than a stop in filing.
IPC subclass composition
C02F (54 records) and B01D (41 records) dominate, confirming that most ZLD claims combine a chemical treatment step with a physical separation step. E21B (12 records) marks the oilfield-water subset; the remaining subclasses each hold one or two records and mark peripheral applications rather than distinct sub-fields.
Shares are the percentage of the 66 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 Wastewater Treatment with Eureka
This page is one run against one query. Ask Eureka your own question about zero liquid discharge wastewater treatment and every answer comes back with the patent numbers behind it.
Try EurekaThe most-cited claims in this field
Zero liquid discharge systems and processes for high-salinity wastewater treatment (WO2021036406A1)
Discloses a ZLD system combining an electrodialysis treatment module, a membrane filtration concentration module and a thermal concentration module in sequence. The electrodialysis stage uses stacked units — each with a diluting chamber, feed chamber and two concentrate chambers separated by exchange membranes — to pre-concentrate the feed before it reaches membrane and thermal stages.Abstract trimmed for length; see the source record for full claim language.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20110174604A1 | Compact wastewater concentrator using waste heat | 69 |
| 2 | US20110100924A1 | Compact Wastewater Concentrator and Contaminant Scrubber | 57 |
| 3 | US20110061816A1 | Compact wastewater concentrator using waste heat | 42 |
| 4 | US8066845B2 | Compact wastewater concentrator using waste heat | 38 |
| 5 | US8679291B2 | Compact wastewater concentrator using waste heat | 36 |
| 6 | US8066844B2 | Compact wastewater concentrator using waste heat | 34 |
| 7 | CN102329036A | 余热利用高效含盐废水零排放回收处理方法 | 27 |
| 8 | US8801897B2 | Compact wastewater concentrator and contaminant scrubber | 24 |
| 9 | CN103253820A | 高效液体零排放废水处理方法及系统 | 22 |
| 10 | US20110174447A1 | Compact wastewater concentrator using waste heat | 15 |
Citation counts inside a searched corpus favor older filings; treat this table as a signal of influence on later filers, not a ranking of current commercial relevance.
Patent titles are shown in the language they were filed in, not translated, so that each record stays verifiable against the original filing — a translated title will not match in Eureka or in any national register. Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the numbers mean for a filing decision
Three findings from the dataset that shape where a new filing is likely to clear prior art and where it is likely to collide with dense claim coverage.
The field has plateaued since 2021
Activity peaked at 7 families in 2021 and dropped sharply by the 2022 midpoint. Combined with a zero count from every top assignee in the latest tracked year, this reads as a settled technology space rather than one still being actively staked out.
One concentrator design anchors the whole field
The five most-cited records are all variants of the same compact wastewater concentrator using waste heat, filed as a continuation family. Any new thermal-concentration filing sits downstream of this prior art and should be checked against it first.
Filing is spread across three distinct regimes
No single office holds a majority share. The US leads narrowly, but China and India each carry a meaningful share, and Australia and PCT filings show ZLD's relevance to water-stressed, mining- and industry-heavy jurisdictions beyond the usual US/EU/China triad.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to zero liquid discharge wastewater treatment, with the prior art for and against each one.
Who holds the claims, and where the gate sits
Filing here is fragmented rather than dominated by a single corporate portfolio; the strongest links in the dataset are between individual named inventors and one recurring corporate assignee, not between large competing firms.
An inventor pair, not a corporate rivalry, anchors the citation leaders
The most-cited concentrator patents trace to the same two named inventors working together, with a Chinese assignee appearing as a secondary partner across several of those same filings. This is a smaller, tighter cluster than the raw citation counts might suggest.
No assignee is currently active in the most recent tracked year
Every major assignee in the ranking, including Nanjing-based and Japanese filers, shows zero filings in the latest year. That is consistent with the overall plateau in the trend data rather than any one company exiting the space.
Assignee base is international, weighted toward Asia
Named corporate assignees include Chinese engineering firms, Japanese industrial groups and an India-based membrane separation specialist, alongside US-based individual inventors. No single geography or company holds a controlling share of the 66 families.
| Assignee | Recent year | YoY |
|---|---|---|
| Heartland Technology, Inc. | 0 | — |
| Rochem Separation Systems (India) Pvt. Ltd. | 0 | — |
| RUTSCH MICHAEL J | 0 | — |
| CLERKIN CRAIG | 0 | — |
| Jiangsu Zhongsheng High-Tech Industry Co., Ltd. | 0 | — |
| Organo Corporation | 0 | — |
| DUESEL BERNARD F JR | 0 | — |
| Ruiying Environmental Protection Technology (Yangzhou) Co., Ltd. | 0 | — |
Where to take this analysis
The dataset points to a mature, geographically spread field with one dominant citation cluster and several thinly claimed branches. The next steps depend on whether you are filing, licensing or tracking competitors.
Check freedom-to-operate against the concentrator family
Any thermal or waste-heat concentration filing should be checked against the compact wastewater concentrator claims first, since they anchor citations across the entire corpus.
Run a freedom-to-operate check in EurekaMap the under-claimed branches in detail
Electrodialysis pre-concentration and hybrid membrane-thermal sequencing show thin coverage relative to core C02F/B01D claims; a targeted search would confirm how open they really are.
Explore white space in EurekaTrack assignee activity past the data cut-off
Every tracked assignee shows zero filings in the latest year, which publication lag can partly explain; monitoring new publications will show whether the plateau is real or temporary.
Set up assignee tracking in EurekaCommon questions on ZLD patents
A single family of concentrator patents dominates by citation count: the "compact wastewater concentrator using waste heat" design and its close variants, cited between 36 and 69 times each, far ahead of anything else in the corpus. These patents cover thermal concentration equipment that uses waste heat to reduce energy costs in evaporating high-salinity wastewater. Any new filing in thermal concentration should be checked against this family specifically, since later filers in the dataset consistently cite it.
No. Filing activity in this dataset peaked at 7 families in 2021 and had fallen to just 1 family by the 2022 midpoint, with every major assignee showing zero filings in the most recent tracked year. Some of that recent drop is publication lag, since patent publication typically trails filing by around 18 months, but the flat multi-year trend before that suggests the field has genuinely plateaued rather than accelerated. New entrants are filing into a mature, well-mapped claim space rather than a fast-growing one.
The United States leads with 17 filings in this dataset, followed by China at 13 and India at 9. Australia and WIPO (PCT) each account for 8, and Europe via the EPO adds 4 more. The spread across water-stressed and industrial economies, rather than concentration in a single bloc, reflects ZLD's relevance to mining, power generation and heavy industry wastewater management in multiple regions at once.
Most filings sit in C02F, the water and wastewater treatment subclass, with 54 of 66 records, and B01D, separation and filtration processes, with 41 records; many records fall in both, indicating combined chemical-and-physical-stage claims. A smaller cluster of 12 records sits in E21B, earth and rock drilling, reflecting ZLD's application to oilfield produced-water treatment. The remaining IPC subclasses each hold only one or two records and represent peripheral applications like alkali-metal compound recovery rather than distinct technical sub-fields.
The thinnest coverage relative to the core C02F/B01D claim density sits in electrodialysis pre-concentration staging, waste-heat integration specifically for crystallizer trains, and hybrid control schemes that sequence membrane and thermal stages together. The E21B overlap for produced-water ZLD in drilling applications is also comparatively under-claimed given how few records combine it with the core water-treatment subclasses. None of these are unclaimed, but each shows narrower prior art than the dominant thermal-concentrator cluster, making them worth a focused search before drafting new claims.
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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.