What is the impact on the permeate water quality if the concentration of the acid cleaner used for RO membrane cleaning is excessively high?

If the concentration of the acid cleaner used for RO membrane cleaning is excessively high, it can damage the membrane material, leading to a decrease in permeate water quality. RO membranes, especially thin-film composite (TFC) membranes, are susceptible to chemical degradation if exposed to strong acids or bases. An excessively high concentration of acid can cause hydrolysis of the polyamide active layer, which is the primary barrier to salt passage. Hydrolysis breaks down the chemical bonds in the polyamide polymer, increasing the membrane's porosity and reducing its salt rejection. This results in a higher salt concentration in the permeate water, decreasing its quality. The damage can also lead to increased permeate flow due to the larger pore size, but this comes at the expense of reduced salt rejection. In severe cases, the acid can completely destroy the active layer, rendering the membrane ineffective. Even if the damage is not immediately apparent, exposure to high acid concentrations can weaken the membrane, making it more susceptible to fouling and scaling in the future. Therefore, it is crucial to use acid cleaners at the recommended concentrations and for the specified duration to avoid damaging the RO membranes and compromising the quality of the permeate water. Thorough rinsing of the membranes after cleaning is also essential to remove any residual acid and prevent further damage.