Researchers at Sichuan University in China have designed a new system for chemical cleaning and repair of used reverse osmosis membranes (CCR-ROM).
The results indicate that the average salt rejection of the cleaned membranes was increased from 67.5% to 90.6%, while the average water recovery of the cleaned membranes was reduced from 18.8% to 14.6%, and the average difference pressure was reduced from 0.30 MPa to 0.15 MPa.
The treated RO membranes were subsequently tested in an industrial-line water production system for three months, with positive results.
Compared with traditional online chemical cleaning, the CCR-ROM method can prolong the period of water production of the RO membranes by a factor of about four.
In this new method, a single RO membrane consumes only 22.5 L of cleaning solution, i.e. only 37.5% of that used in traditional online chemical cleaning.
The advantages of the new system include reutilisation of the discarded RO membranes, and significant reductions of dosage and waste of the cleaning solutions.
