IPC 6 English version  Class C02
SECTION C– CHEMISTRY; METALLURGY

C 02

TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (settling tanks, filtering, e.g. sand filters or screening devices, B 01 D)

C 02 F

TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B 01 D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B 63 J; adding materials to water to prevent corrosion C 23 F; treating radioactively-contaminated liquids G 21 F 9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes) [3]

 ^