(1) Prepare the cleaning solution, add the agent to clean water, and the preparation water is RO product water or deionized water that removes hardness, does not contain excessive metals and residual chlorine. Ensure that the solution is evenly mixed, and adjust the temperature and pH to the required value.
(2) To input the cleaning solution at a low flow rate, first mix the cleaning solution with the cleaning water pump. The cleaning solution should be preheated at a low flow rate. Then replace the raw water in the element with the lowest possible cleaning fluid pressure, and its pressure only needs to be enough to supplement the pressure loss of the inlet water to the concentrated water, that is, the pressure BX is low enough that no obvious permeation water is produced. The low-pressure displacement operation can minimize the re-precipitation of dirt on the membrane surface. Depending on the situation, part of the concentrated water is discharged to prevent the washing liquid from being diluted.
(3) Circulation When the raw water is replaced, the cleaning fluid should appear in the concentrated water pipeline, allowing the cleaning fluid to circulate back to the cleaning water tank and ensuring a constant temperature of the cleaning fluid.
(4) Soak to stop the operation of the cleaning pump, and let the membrane element soak in the cleaning liquid. Sometimes the component soaking for 1 hour is enough, but for stubborn contaminants, the soaking time needs to be extended, such as soaking for 10-15 hours or soaking overnight. In order to maintain the temperature of the soaking process, a very low circulating flow rate can be used.
(5) High-flow water pump circulation high-flow circulation for 30-60 minutes. The high flow can wash away the contaminants washed down by the cleaning liquid. Under high flow conditions, there will be a problem of excessive pressure drop. The maximum allowable pressure drop for unit element Z is 1 bar (15 psi), and the maximum allowable pressure drop for multi-element pressure vessel Z is 3.5 bar (50 psi). limit.
(6) Rinse with clean water (removal of hardness, RO product water or deionized water without metal ions such as iron and chlorine) for low-pressure flushing. The cleaning fluid in the flushing system can be pretreated qualified product water unless there is corrosion problem. To prevent precipitation, the Z low flushing temperature is 20°C.