A method is used for the chemical disinfection of a reverse osmosis system. The system has a supply tank, a ring line for connecting consumers, at least one membrane module, a feed line to the membrane module, at least one pressure pump for pumping liquid into the membrane module and a disinfectant container. Disinfectant is conveyed from the disinfectant container into the supply tank. The includes comprises the steps of setting a target concentration of the disinfectant, determining the amount of disinfectant required based on the target concentration of the disinfectant, and discharging the amount of disinfectant required for the target concentration from the disinfectant container into the supply tank through a discharge device.

An air filter medium includes a fluororesin porous membrane and a supporting member stacked on top of each other. The air filter medium has a permeability ratio (permeability after disinfection treatment/permeability before disinfection treatment) of 5.0 or less, the permeability ratio being a ratio of permeabilities of the air filter media before and after the disinfection treatment of the fluororesin porous membrane as determined using NaCl particles having a particle size of 0.1 m, and a pressure loss ratio (pressure loss after disinfection treatment/pressure loss before disinfection treatment) of 0.83 or more and 1.15 or less, the pressure loss ratio being a ratio of pressure losses of the air filter media before and after the disinfection treatment of the fluororesin porous membrane.

An air filter medium includes a fluororesin porous membrane and a supporting member stacked on top of each other. The air filter medium has a permeability ratio (permeability after disinfection treatment/permeability before disinfection treatment) of 5.0 or less, the permeability ratio being a ratio of permeabilities of the air filter media before and after the disinfection treatment of the fluororesin porous membrane as determined using NaCl particles having a particle size of 0.1 m, and a pressure loss ratio (pressure loss after disinfection treatment/pressure loss before disinfection treatment) of 0.83 or more and 1.15 or less, the pressure loss ratio being a ratio of pressure losses of the air filter media before and after the disinfection treatment of the fluororesin porous membrane.

Embodiments of the present disclosure generally relate to methods for treating porous membranes. In an embodiment, a method of treating a porous membrane is provided. The method includes flushing the membrane with a first fluid comprising a hydroxide ion and hypochlorite ion, flushing the membrane with water, flushing the membrane with a second fluid comprising an organic peroxide, organic peroxide ion, or both, and flushing the membrane with water.

Embodiments of the present disclosure generally relate to methods for treating porous membranes. In an embodiment, a method of treating a porous membrane is provided. The method includes flushing the membrane with a first fluid comprising a hydroxide ion and hypochlorite ion, flushing the membrane with water, flushing the membrane with a second fluid comprising an organic peroxide, organic peroxide ion, or both, and flushing the membrane with water.