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21 <br />1. Chemical Cleaning Procedure <br />Chemical cleaning is conducted to restore the membrane to an almost original condition or prepare it for <br />storage. <br /> <br />Cleaning Stages: <br />a. Stop the inlet feed of primary treated influent, RAS, or any other incoming streams into the system. <br />b. Operate the under-tower coarse bubble diffuser mixing system continuously for 10 minutes. <br />c. Shut down the MABR process air blower that feeds the MABR towers. <br />d. Drain the reactor using the reactor's draining flange to remove most MLSS (Mixed Liquor Suspended <br />Solids) that may be accumulated in the Aspiral reactor or detached from the MABR towers during the <br />mixing. <br />e. Refill the reactor with clean water (reused and disinfected water can be used). <br />f. Operate the mixing system (coarse-bubbles diffusers and fine-bubbles diffusers if present) at maximum <br />power (VFD-100%, regulate-valve wide open) for 5 minutes every 10 minutes for 1 hour. <br />g. Drain the reactor. <br />h. If needed repeat steps 5–7 again until the TSS level is below 500 mg/L. <br />i. Fill the reactor with water containing sodium hypochlorite (NaOCl) at a concentration of 0.1% (1000 ppm). <br />j. Operate the mixing system for 1 minute every 6 minutes for at least 4 hours. <br /> <br /> Note: Replenish the hypochlorite concentration to 1000 ppm once every hour. <br /> Note: Foaming during this step is a normal occurrence. To mitigate its impact and protect the <br />surrounding environment, use a water spray hose to manage and contain the foam effectively. <br /> <br />k. Drain the reactor to remove the hypochlorite solution. <br />l. Refill the reactor with clean water and operate the mixing system for 10 minutes to flush out any residual <br />chemicals. <br />m. The system is now ready to be filled and restarted. <br /> <br />Warnings: <br /> Hypochlorite concentration must never exceed 1%. <br /> The process air blower must not be operated unless the membrane towers are fully submerged to avoid <br />irreversible damage. <br /> Handle all chemicals under the product's safety data sheet (MSDS) and safety manual and procedure. <br /> For any uncertainties or additional guidance, consult a Fluence representative. <br />2. Membrane Storage Procedure <br /> <br />Storage Stages: <br />a. Complete the cleaning procedure as described in the above section ('Chemical Cleaning Procedure'). <br />b. Prepare a storage solution of clean water with sodium hypochlorite (NaOCl) at a concentration of 2–5 <br />ppm. <br />c. Fill the tank until membranes are submerged entirely in the prepared storage solution. <br />d. Operate the under-tower mixing system gently for 5 minutes to ensure even distribution of the storage <br />solution. <br />e. Ensure the MABR always remains fully submerged to prevent exposure to air. <br />f. Protect the reactor from direct sunlight or UV exposure by covering the reactor. <br />g. Regularly add water to compensate for evaporation losses and ensure the membrane towers remain <br />submerged entirely.