Economic aspects of critical flux operability in star shaped microfiltration membranes: Influence of some operating conditions

The economic feasibility of operating at the achievable critical flux under different operating parameters (feed concentration, crossflow velocities and pH) using non-circular channelled membranes has been investigated. The increase in critical fluxes with increasing crossflow velocities is accompanied by increasing axial pressure loss. This leads to substantial increase in the specific energy consumption, reducing the energy-saving potential. Minimum specific energy consumption occurs at the crossflow velocity of 0.9 m s⁻¹ where the trade-off between axial pressure loss and the achievable critical flux occurs. Increasing the feed concentrations and pH led to declining and increasing critical fluxes, respectively. Axial pressure loss remains consistent at feed concentrations <10 g l⁻¹ and increases at feed concentrations >10 g l⁻¹. This is attributed to the change in the viscosity of the suspension which affects the specific energy consumption. The influence of pH on critical flux is attributed to the changes in the titanium dioxide particle charges and coincides with the changes in the viscosity of the suspension. The optimum energy-saving potential was found at pH 9.0. Solution chemistry (particle charges and rheology) and hydrodynamics influence the achievable critical flux and axial pressure loss within these channels which ultimately determine the economics of operation.