Fabrication and characterization of nanoporous anodic alumina membrane using commercial pure aluminium to remove coliform bacteria from wastewater

Nanoporous anodic alumina (NAA) membranes were produced by anodizing process using commercially pure aluminium (1050 alloy). The optimization of processing parameters, such as applied potential, temperature and time in two different electrolyte solutions, has been performed to produce the ordered alumina nano-membrane. Nanoporous anodic alumina membrane (NAAM) was obtained by removing the aluminium substrate and opening the bottom of the pores. The microstructure of samples was studied and analysed by field emission scanning electron microscopy (FESEM). Image processing of FESEM pictures was performed with MATLAB. The results showed that at the optimum conditions of anodizing, the percentage of porosity and ordering of pores in the samples were similar to the productions of the high purity aluminium base. NAA layers that formed in sulphuric acid solution in comparison with oxalic acid had lower pore diameter (20 nm), lower inter-pore distance (45-50 nm) and higher hardness (325HV). The optimized membranes which have been produced with the same thickness were used for separation of Coliform bacteria from the secondary clarified wastewater. The results showed that these membranes can be used as selective filters because of their desirable physical properties.