Performance of spiral wound ultrafiltration membrane module for with and without permeate recycle: Experimental and theoretical consideration

• Volume reduction factor (VRF) characterised for with and without permeate recycle.
• Maximum fouling resistance was observed for without permeate recycle.
• Brownian diffusion model calculated permeate flux was best fitted with experiment.
• Permeate quality was superior for with permeate recycle compared to without recycle.
• Fouled UF membrane was cleaned with three different cleaning agents.

A synthetic fruit juice was clarified by a spiral wound ultrafiltration membrane module at two different operating conditions, namely, with and without permeate recycle. The juice was prepared by mixing a known composition of sucrose and pectin in deionised water. Membrane performance was studied in terms of volume reduction factor (VRF) and transient flux decline. For without permeate recycle, rate of pectin particle adsorption on the membrane surface was higher and pectin concentration in the permeate was found to increase compared to with permeate recycle. As a result, viscosity, turbidity, total dissolved solids (TDS) and electrical conductivity reduction and clarity in permeate were superior for with permeate recycle compared to without permeate recycle. Maximum membrane fouling was observed for without permeate recycle at low operating time. Permeate flux values were calculated on the basis of Brownian diffusion, shear induced and combined diffusion models. It was observed that Brownian diffusion model estimated flux values were best fitted with the experimental flux values within the range of ± 9%. Fouled ultrafiltration membrane modules were cleaned with different cleaning agents, such as, deionised water, sodium dodecyl sulphate (SDS) and ethylenediaminetetraacetic acid (EDTA). Maximum cleaning efficiency in terms of membrane permeability recovery was achieved with EDTA solution.