Determination of Membrane Cleaning Strategy for LP, HP and Ceramic Membranes

Effective Autopsy and Cleaning Approaches for Low Pressure Membranes Mo Malki, American Water Chemicals Fouling Removal – Flow Rate Black fines removed from membrane, Higher Flowrate collected on cartridge (15 gpm per filters during 15 gpm module) clean. Interaction of Cleaning Solution with Foulant Membrane Circulate Soak Surface Membrane Soaking allows time for diffusion of cleaning chemical across the liquid/solid interface into the foulant and facilitates reactions with slower kinetics. Lack of turbulence ensures contact between chemical and foulant across the entire liquid/solid interface, allows for diffusion into foulant layer. Cross-flow creates shear stress on the foulant – removal of “loosened” foulant by scouring, exposing next layer of foulant to chemical. Circulation also constantly replaces cleaning agents consumed locally by the foulant Foulant Removal Cleaning Through the Pores (MF/UF) Cleaning study – Hollow fiber outside-in Water reuse application at a power plant in South Florida Membranes severely fouled, repeated membrane cleaning could not recover performance. Membrane permeability at TMP of 6 psi, 25° C was 0. GFD/PSI. Cleaning Through the Pores (MF/UF) Time 1:35 2:05 nim 03 rof kaoS 2:35 3:05 .nim 03 rof kaoS 3:45 4:00 .mpg5.61 ta retaw etaemrep htiw hsulF .mpg8 ta setunim 2 rof hsawkcaB Solution pH 11.6 11.92 11.67 11.96 11.95 11. Solution Temperature, (°F) 88 93 93 99 99 Cleaning Solution Feed Pressure (PSI) 14 13 11 10 9.5 Return Pressure, (PSI) 1.5 1.5 1 1 1 Transmembrane Pressure (PSI) 12.5 11.5 10 9 8.5 Feed Flow (GPM) 15.3 15.35 15.35 15.4 15.4 15. Cleaning Solution Clear Clear Clear Clear Clear Clear Appearance Comments: High pH cleaning with 2% AWC UF- Lot# 16- Cleaning performed with retained solution from first 2 hours Cleaning performed with reject valve closed. )thgiew noitulos latot fo %1.0~( .HOaN htiw Hp detsujdA .noitulos fo noitalucric detratS .gnikaos rof noitalucric deppotS noitulos latot fo %1.0~( .HOaN htiw Hp detsujdA .noitulos gninaelc fo noitalucric detratseR )thgiew )thgiew noitulos latot fo %1.0~( .HOaN htiw Hp detsujdA .gnikaos rof noitalucric deppotS .noitulos gninaelc fo noitalucric detratseR .gnihsulf rof noitalucric deppotS Permeability increased to 5. GFD/PSI Clean-In-Place (CIP) – Negative Pressure Only soaking is possible in submersible membrane systems. Always check pH and chlorine tolerances of the membrane that you are using (PES, PVDF, PAN). “Ceramic” is a very broad term. Thank You Mo Malki American Water Chemicals, Inc E-mail: momalki@membranechemicals.com www.membranechemicals.com.