Advanced oxidation processes generate highly reactive hydroxyl radicals, typically through combinations of UV light, ozone, hydrogen peroxide, electrochemical cells or catalytic surfaces, to break down organic contaminants and inactivate pathogens. In a disinfection context this overlaps with sterilisation classifications like A61L 2/08 as well as water-treatment classifications like C02F 1/32 and C02F 1/78. The patent literature treats it as a chemistry-and-apparatus combination rather than a single mechanism, which is why filings span filtration, catalysis and sterilisation classes at once.

There is no single dominant corporate assignee in this dataset; the strongest filing relationship is a cluster of individual co-inventors (Visnja Orescanin, Nenad Mikulic and Denis) who appear together across multiple shared families. Named corporate assignees such as De Nora Water Technologies and Siemens hold representative filings but not concentrated portfolios. This is consistent with a technology area where the founding patents were filed some years ago and current activity is thin across many small filers rather than a race between a few large ones.

Filing activity peaked at 5 records in 2018 and had fallen to just 1 by the 2022 midpoint, with no recovery evident heading toward 2026. Because publication lags filing by roughly 18 months, the very last year or two in any such trend is always understated, but the multi-year decline from the 2018 peak is a real pattern, not a data artefact. Overall this points to a mature, low-growth filing area rather than one still attracting fresh investment.

Thin coverage shows up in photocatalytic disinfection applied outside core water treatment (food-contact and packaging uses), combined microflotation-plus-AOP staging, and electrochemical AOP specifically targeted at drinking water distribution mains. These branches have single-digit or single-record representation in the underlying IPC classes despite the core water-treatment classification carrying the bulk of filings. A first claim in one of these areas would need to tie the oxidation chemistry to the specific application context (e.g., a packaging line or a distribution main) to distinguish from the broad prior art anchors.

US20040120844A1, titled Advanced oxidation of dangerous chemical and biological sources, is the most-cited record in this dataset at 151 citations and represents broad early claim scope over using advanced oxidation against combined chemical and biological threats. New filings on pathogen inactivation methods that rely on similarly broad hydroxyl-radical generation and exposure steps should be checked against its claims and its related family WO2002045756A2. Because citation counts favour older records, its high citation count reflects long-standing influence on the field rather than current commercial dominance.