Thus chemical cleaning is thus the most important measure for removing residues that result as undesired substances from the filtration, in other words the elimination of the irreversible fouling.
The variety of cleaning chemicals available offer a kit of almost inexhaustible possibilities for removing fouling, but it is important – as in every good recipe – to know the mode of action of all ingredients and not to ignore any possible interactions. By definition, a membrane is considered to be restored to its original condition, if the molecules being filtered are no longer detectable on or in the membrane.
However, the components and ingredients in the water can drastically alter the efficacy of the cleaning components.
Due to the fact that the channels and pores in the membrane are only a few nanometres in diameter, the minerals in the water (water hardeners) or micro-organisms can block these and thus prevent access to the contaminating molecules that are to be removed by the cleaning chemicals dissolved in water.