Trouble shooting - Membrane Cleaning
Once it has been determined that a cleaning is necessary, there are several decisions that need to be made in order to maximize effectiveness. Not all foulant materials can be removed in the same way or with the same chemicals, so the very first task is usually to determine what type of foulant is suspected. The normalized trends are the best place to start as they can tell operators where problems are occurring within the system. If further investigation is warranted at that point it is usually prudent to look at a recent laboratory analysis of the feed water and – if available – the RO concentrate. It is also good practice to review general plant maintenance logs, especially if the normalized or raw data trends show a sudden and unexpected loss of performance. These sudden step changes can often be linked to events outside of the RO array, especially as they pertain to equipment upsets or failures of the upstream pretreatment equipment.
If the exact nature of the problem cannot be determined (or adequately guessed at) from these indirect methods, the operations staff will be faced with a decision; they can either proceed with a “standard” cleaning in the hope that this will do the job, or they can choose to send one or more of their membranes out for destructive autopsy and analysis.