earticle

영어

Membrane separation has been widely used in many fields because it offers several advantages such as simplicity, continuity of operation, high throughput, and mild operating conditions without addition of chemicals than other conventional methods. In this study, two types of microfiltration membranes (flat-sheet and hollow fiber) were used to separate microalgal biomass from the Chlorella vulgaris culture broth. A flat-sheet membrane, made of a mixed cellulose ester with pore size of 0.45 μm, was used for dead-end filtration. Alternatively, a hollow fiber, a semi-permanent hydrophilic membrane made of polyethylene with pore size of 0.4 μm, was submerged in the microalgal culture. To compare the two membranes, changes of flux and withdrawn permeate were investigated. At the same initial concentration of algal biomass and operating period, a rapid formation of cake layer was observed on the surface of the flat-sheet membrane. The final flux reduction after 140 min of flat-sheet and hollow fiber membrane were observed to be 98.4 and 35.6%, respectively. However, the permeate of the flat-sheet membrane per surface area was five times higher than the hollow fiber. This showed that the hollow fiber maintained much stable flux but the concentration of algal biomass in the retentate was higher in the flat-sheet membrane. To prevent the early fouling of flat-sheet membrane, backwashing or chemical cleaning can be applied. The operating conditions of the hollow fiber membrane can also be optimized by controlling intermittent suction and maintaining critical flux.