Zero Liquid Discharge Sludge Patents: Who Leads, Filing Trends 2026
- Filing is accelerating, not maturing. activity dipped to zero at the 2022 midpoint before climbing to a peak of 15 families in 2024, a pattern more consistent with a technology re-entering active development than one settling down.
- No single assignee owns the latest year. every assignee tracked for recent-year momentum shows zero filings in the latest year, which points to a fragmented, still-forming competitive set rather than an entrenched leader.
- Claims cluster around water chemistry, not mechanical separation alone. C01F and C07C compound classes each match C02F wastewater-treatment volume, meaning much of the contested claim space is about what the solids and residual chemistry become, not just how the liquid is separated.
What this landscape covers
Zero liquid discharge (ZLD) sludge treatment sits at the intersection of brine minimization and solids handling: systems designed to recover essentially all water from an industrial waste stream while managing what is left behind as a crystallizer solid or dewatered cake. This dataset draws on 70 patent families published between 2015 and mid-2026, filtered to records that combine ZLD or brine-minimization claims with sludge dewatering, solids handling or crystallizer solids management language. Publication lags filing by roughly 18 months, so the 2026 count in particular understates real activity.
The receiving-office spread is dominated by the United States, with Canada, WIPO/PCT and India each carrying a meaningful share — consistent with a technology tied to specific industrial waste streams such as oil and gas produced water and flue-gas desulfurization, rather than a globally uniform consumer product category.
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Filing trend and technology composition
Two views of the same 70-family dataset: how filing volume has moved year over year, and which IPC subclasses carry the claim density.
A restart, not a plateau
Filings measured 5 in 2017, fell to zero at the 2022 midpoint, then rose to a peak of 15 in 2024 before the partial 2026 count of 4. That zero-to-peak swing inside a five-year window is unusual for an established water-treatment category and suggests renewed commercial interest, likely tied to tightening discharge regulation and produced-water reuse economics rather than steady incremental filing.
Chemistry classes rival the separation classes
C02F (water and wastewater treatment) leads with 35 records, but C01F (alkaline-earth, aluminium and rare-earth compounds) and C07C (acyclic and carbocyclic compounds) each carry 19 — matching or exceeding B01D (separation processes, 15) and E21B (well drilling, 15). The practical read: a meaningful share of the claim space is about the chemistry of what precipitates or forms in the crystallizer, not only the membrane or filtration hardware around it.
Shares are the percentage of the 70 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 Sludge Treatment with Eureka
This page is one run against one query. Ask Eureka your own question about zero liquid discharge sludge treatment and every answer comes back with the patent numbers behind it.
Try EurekaThe most-cited records and one recent filing
US20260116790A1 — water purification with zero liquid discharge and resource recovery
The application, assigned to Oxbyel Technologies, Inc. and dated 2026-04-30, describes a water retentate treatment module combining an electrolytic treatment unit with a dissolved solids recovery unit. The retentate stream can undergo electrochemical oxidation and hardness removal, or pass through a dissolved solids removal unit that recovers hydrogen, ammonia or hydrogen peroxide as byproducts.Filed 2026-04-30 · assignee Oxbyel Technologies, Inc.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20190077686A1 | Zero-discharge technique for separating sludge and salt from desulfurization wastewater | 115 |
| 2 | US20140158620A1 | System And Method For Mechanical And Membrane Oil-Water Separation | 88 |
| 3 | US20110077144A1 | Regeneration of ion exchange resin and recovery of regenerant solution | 64 |
| 4 | US5656161A | Salt basket for crystallizer and method of use in zero liquid discharge industrial facilities | 30 |
| 5 | US5472622A | Salt basket for crystallizer and method of use in zero liquid discharge industrial facilities | 29 |
| 6 | US20120087737A1 | Process for Solidifying Organic and Inorganic Provisional Constituents Contained in Produced Water from Heavy… | 19 |
| 7 | US5575923A | Salt basket for crystallizer and method of use in zero liquid discharge industrial facilities | 15 |
| 8 | US9186665B2 | System for ion exchange resin regeneration and regenerant recovery | 14 |
| 9 | US20160244346A1 | Blowdown recycle method and system for increasing recycle and water recovery percentages for steam generation… | 12 |
| 10 | US20140196753A1 | Regeneration of ion exchange resin and recovery of regenerant solution | 11 |
Citation counts inside a searched corpus favour older records; treat this as a signal of influence on later filings, not of current commercial relevance.
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Browse MCP servers →What the numbers mean for a filing decision
Three read-throughs from the trend, the IPC split and the citation table, aimed at someone deciding where to file next or who to watch.
Growth is still accelerating
The swing from zero filings at the 2022 midpoint to a peak of 15 in 2024 is the single clearest signal in this dataset. It is not a mature category cooling off; it reads as a field that stalled and then restarted, likely as regulatory and reuse economics changed.
Chemistry claims are as dense as separation claims
C01F and C07C each match roughly half the volume of the leading C02F wastewater class, and both exceed the dedicated separation-process class B01D. Anyone treating this as a pure filtration-and-membrane space is missing where a large share of the claim density actually sits.
Older desulfurization and crystallizer patents anchor the field
The most-cited record addresses sludge and salt separation from desulfurization wastewater; the next tier covers oil-water separation, ion-exchange regeneration and crystallizer salt baskets. These older records shaped the vocabulary later filings had to work around, but citation counts inside a searched corpus structurally favour age over current relevance.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to zero liquid discharge sludge treatment, with the prior art for and against each one.
| Assignee | Co-assignee | Shared families |
|---|---|---|
| State Industries Canada Ltd. | HPD LLC | 4 |
| State Industries Canada Ltd. | Veolia Water Technologies North America | 2 |
| State Industries Canada Ltd. | MINNICH KEITH | 2 |
| State Industries Canada Ltd. | KUS JOHN | 2 |
| State Industries Canada Ltd. | GAMACHE DAVID | 2 |
| HPD LLC | MINNICH KEITH | 2 |
| HPD LLC | KUS JOHN | 2 |
| HPD LLC | GAMACHE DAVID | 2 |
Only 8 co-assignee pairs appear in this dataset; the strongest pairing recurs 4 times, the next tier twice. That is a low co-filing density for a field with this much chemistry-plus-hardware overlap, suggesting most assignees are still developing ZLD sludge capability in-house rather than through joint filings.
Who is filing, and where the gaps sit
Recent-year momentum data shows every tracked assignee at zero filings in the latest year — a fragmented field where no single company has pulled ahead in the current cycle, even though several hold multi-family positions built earlier.
No dominant current filer
The recent-year momentum table lists assignees including Innovative Energy LLC, State Industries Canada, Albemarle, Husky Oil Operations, Rayne Dealership Corp and HPD LLC, all showing zero filings in the latest tracked year. That flat recent picture sits alongside a real historical filing base, meaning positions were built earlier and are not currently being defended with new filings.
A small, concentrated collaboration core
The strongest co-assignee pairing repeats 4 times and links a Canadian industrial-solutions entity with HPD LLC, a crystallizer and evaporator specialist; a second pairing with a North American water-treatment technology group repeats twice. Beyond that core, collaboration thins out quickly.
US and Canada dominate the receiving-office spread
The United States and Canada together account for the majority of receiving-office activity, with WIPO/PCT, India, Australia and the EPO trailing well behind. That pattern tracks industrial waste streams — produced water, oil sands, flue-gas desulfurization — concentrated in North America.
| Assignee | Recent year | YoY |
|---|---|---|
| Innovative Energy LLC | 0 | — |
| State Industries Canada Ltd. | 0 | — |
| Albemarle Corporation | 0 | — |
| Husky Oil Operations Limited | 0 | — |
| RAYNE DEALERSHIP CORP | 0 | — |
| HPD LLC | 0 | — |
| Ionics, Incorporated | 0 | — |
| WorleyParsons Canada Services Ltd. | 0 | — |
Where to take this
The trend and assignee data point to a field re-accelerating after a quiet 2022, with claim density concentrated in specific chemistry and separation subclasses rather than spread evenly.
Map the crystallizer-chemistry claims in detail
C01F and C07C carry as much volume as core wastewater treatment claims; a subclass-level read of exactly what compounds and reactions are claimed will show how much of that space is genuinely occupied versus loosely adjacent.
Explore the IPC breakdown in EurekaTrack the assignees with historical but no recent filings
Several assignees hold multi-family positions built before the latest tracked year but show zero recent activity — worth watching for renewed filing or for acquisition of dormant portfolios.
Set up assignee monitoring in EurekaCheck the white-space branches against your own claims
Electrochemical resource recovery and crystallizer solids valorization show thinner density than the core separation classes; a freedom-to-operate check here is cheaper before a claim is drafted than after.
Run a white-space search in EurekaCommon questions on ZLD sludge treatment patents
In this dataset it means patent families that combine zero liquid discharge or brine-minimization claim language with sludge dewatering, solids handling, or crystallizer solids management. That combination matters because ZLD as a broader term covers many process steps, but the sludge and solids side specifically concerns what happens to the concentrated waste left after water recovery. Filters built this way pull in crystallizer salt-basket patents, desulfurization sludge separation, and produced-water solids handling, rather than general brine treatment.
The recent-year momentum data shows a fragmented picture: assignees such as HPD LLC, Albemarle, Husky Oil Operations, and a Canadian industrial-solutions entity all appear in the historical filing base but show zero filings in the latest tracked year. There is no single assignee currently pulling ahead; positions built earlier are not being actively defended with new filings right now. That makes this a field where historical portfolio strength and current filing momentum diverge.
The dataset shows filings at zero in the 2022 midpoint year before climbing to a peak of 15 families in 2024. This pattern is more consistent with a pause driven by external factors, such as commodity price cycles in the oil and gas sector or a lag in regulatory enforcement, followed by renewed investment, than with steady organic growth. Because publication lags filing by roughly 18 months, the true 2024-2026 filing rate is likely higher than the published record currently shows.
C02F, covering water and wastewater treatment, leads with the largest share of records, but C01F and C07C, covering alkaline-earth/aluminium compounds and acyclic/carbocyclic compounds respectively, each carry nearly as much volume. B01D separation processes and E21B well-drilling classes are also well represented, reflecting the produced-water and oil-field origin of many filings. A search strategy limited to separation-process classes alone would miss a substantial share of the relevant chemistry claims.
Branches showing thinner overlap with the dense core classes include crystallizer solids valorization, electrochemical resource recovery from retentate streams, and integration of hardness removal with produced-water reuse. These areas appear in the newest representative filing in this dataset but are not yet heavily claimed across the broader corpus. A first claim in these areas would likely need to specify the exact recovered byproduct stream and integration point with the dewatering or crystallization step to differentiate from the existing core.
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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.