Every reverse osmosis system is subject to contamination and requires cleaning. Since contamination usually occurs with more than one type of contaminant, the typical cleaning process usually includes two major steps, low pH cleaning and high pH cleaning, as required.
Different contaminants should be cleaned using different cleaning agents, with alkaline cleaning mainly used to remove microbial or organic contaminants and acid cleaning mainly used to remove fouling. Cleaning agents should be selected according to the type of contaminant and membrane type to avoid damage to the membrane.
The order in which the cleaning chemicals are used should be determined according to the actual problem. The usual order of cleaning is to carry out an acid wash first, followed by an alkaline wash.
In some cases, if the contamination is mainly organic or microbial, an alkaline wash can be carried out first, followed by an acid wash and then a final step of alkaline wash.
