Development of a new composite ceramic membrane from mullite, silicon carbide and activated carbon for treating greywater

In this experimental research, it is aimed at evaluating a novel composite ceramic membrane for treating and recycling on-site greywater. Therefore, three types of tubular microfiltration ceramic membrane including Mullite, Mullite/SiC and Mulite/SiC/AC composite were fabricated and sintered at a relatively low temperature (1250 °C) under N2 atmosphere. Field Emission Scanning Electron Microscopy (FE-SEM) and Atomic Force Microscopy (AFM) analyses showed that the presence of silicon carbide and activated carbon can improve the surface roughness. Besides, the changes in open porosity, radial and longitudinal shrinkage, mean pore size and mechanical strength were measured and compared for the pure Mullite and composite membranes to determine the most appropriate membrane for the treatment of greywater. The highest pure-water permeability of 3954 kg/m2h.br was associated with the Mullite/SiC/AC membrane with the highest porosity of 64.7% and an acceptable appropriate mechanical strength (17.2 MPa approx.). Furthermore, the highest removal efficiency was related to Mullite/SiC/AC in comparison with Mullite and Mullite/SiC membranes. It was observed that using the Mullite/SiC/AC membrane, the removal efficiencies for chemical oxygen demand (COD), biochemical oxygen demand (BOD), total sulfate, total nitrate, phosphate, and detergent (ABS) were 88.0%, 87.0%, 71.5%, 86.5%, 94.3%, and 40.4%, respectively.