Stainless steel membranes for harvesting cyanobacteria: Performance, fouling and cleaning

Stainless steel membranes with 0.45, 1 and 2 μm pore sizes were applied to harvest cyanobacteria. Their critical fluxes were determined and continuous filtration tests were conducted. Two novel transition-combined models for constant flux filtration were developed and applied to describe observed variations in fouling. A pyrolysis cleaning method was proposed and tested. The results showed that the 2 μm membrane was preferable for practical applications as it could process more than twice the filtrate volume before clogging than the other two membranes, with an 8% reduction in rejection rate. The transition-cake-intermediate model predicted fouling better than the combined models, and the fouling mainly resulted from cake formation. Pyrolysis cleaning removed the foulants more effectively and quicker while converting the foulants into desirable products, making it a promising cleaning method for heat-resisting membranes fouled by algae. But both cleaning methods could lead to the enlargement of pore sizes and porosity.