This dataset identifies 69 patent families published between 2015 and mid-2026 that combine anaerobic digestion or biogas digestion terminology with membrane bioreactor or digestate filtration claim language, classified under wastewater treatment and membrane separation codes. That figure reflects a specific search scope rather than every patent that ever touches anaerobic digestion or membranes separately, so a broader search string would return a larger and less precise set. Because publication lags filing by roughly 18 months, the true count for 2025 and 2026 will rise as pending applications publish.

Water-technology majors including Veolia Water Technologies and Evoqua Water Technologies appear repeatedly across the tracked decade, alongside a distinct academic-industry cluster formed by Universitat de Valencia, Universitat Politecnica de Valencia and FCC Aqualia, which share the strongest co-filing relationship in the dataset. None of these assignees, however, show new filings in the most recent tracked year, a pattern consistent with the broader post-2017 slowdown in this niche. Anyone assessing competitive position should track both the corporate filers and this academic cluster together, since their claims interact.

The data shows filings reaching 15 in 2017, the high point of the tracked window, before easing to a midpoint of 8 by 2022 and continuing lower since. This pattern is consistent with a technology whose core process claims filled in during the mid-2010s, after which incremental filings became harder to differentiate against existing prior art. It does not necessarily mean commercial interest has declined — dense claim coverage often precedes, rather than follows, wider deployment.

China's receiving office accounts for 27 of the 69 families in this dataset, more than double the United States' 13 and well ahead of WIPO PCT filings (8), the European Patent Office (6), Japan (4) and Canada (3). That concentration means prior-art and freedom-to-operate searches focused only on US or European filings will miss a large share of the relevant claim base. Teams planning to commercialise in China specifically should treat local prior art as the primary risk, not a secondary check.

Classification data shows every record touches C02F wastewater treatment codes, but only a small minority touch B01D separation-process or B30B press codes, meaning membrane hardware and dewatering equipment claims are comparatively thin relative to process-level digestion claims. Specific under-claimed branches include fouling control tailored to digestate composition, press integration with AnMBR trains, and electrochemical or solar-thermal pre-treatment coupled to digestion. These are narrower, more defensible filing targets than the crowded core process claims.