Aerobic granular sludge to treat paper mill effluent: organic matter removal and sludge filterability

摘要

Recently, researchers working with aerated bioreactors identified a different microbial organization in the form of aerobic granules. In this configuration, bacteria clump together more tightly than conventional floc, which reduces biofilm formation on the membrane surface of membrane bioreactors and allows higher flux for longer time periods during filtration. This study examined the possible formation of aerobic granules treating paper mill effluent and compared the removal efficiency of organic matter from granular with the conventional flocculent sludge. The filterability of both types of sludge was also compared. Two reactors were operated in parallel with aerobic granular and flocculent sludge. Both systems achieved very high Biochemical oxygen demand (BOD5) and chemical oxygen demand (COD)-removal efficiencies. Sludge filtration tests showed a higher critical flux for granular sludge with total suspended solids (TSS) equal to 2,700mgL(-1). However, the opposite behavior was observed when the reactors were operated with a TSS value of 4,400mgL(-1).