Tratamento com lodo aeróbio granular de efluente de fábrica de papel / Aerobic granular sludge treatment of paper mill effluents


IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia




The activated sludge process is widely used for the treatment of industrial effluents, achieving high rates of organic matter removal. Nevertheless, the separation of biological sludge in secondary clarifiers can be a serious problem of this process due to the poor floc formation, causing solids losses and, consequently, deterioration of treated effluent quality. Membrane bioreactors (MBR) emerged as an alternative to solve this problem, since the separation of suspended solids from the treated effluent is not dependent on the sludge settling characteristics. However, it has been observed that malformed flocs foul the pores of the membranes, causing the reduction of flux and consequently an increase in the need for membrane cleaning. Thus, even in MBR, good formation of the biological floc is essential for proper operation of the process. Recently, researchers working with aerated activated sludge reactors found a different organization of the microbiota in the form of aerobic granules. In this configuration, the bacteria clump together more tightly, thus reducing the possibility of biofilm formation on the membrane surface, and allowing the maintenance of a higher flow for longer periods of time during filtration. This study examined the possibility of formation of aerobic granules with paper machine effluent and compared the removal efficiency of COD and BOD of the granular sludge with the conventional flocculent sludge. The filterability of sludge granular and flocculent were also compared. Two reactors were operated in parallel, one with aerobic granular sludge and the other with flocculent sludge. Both systems achieved BOD removal efficiencies of 97% and COD removal of 89% and 91% for granular and flocculent sludge, respectively. In the granular sludge reactor, granules of different sizes with diameters up to about five millimeters, visible to the naked eye were formed. Sludge filtration tests showed a higher critical flow for granular sludge with total suspend solids (TSS) equal to 2700 mg L-1. However, the opposite behavior was observed when the reactors were operated with a TSS of 4400 mg.L-1. A microbiological study to identify bacterial isolates that positively and negatively influence granules formation. Granules were dispersed, pure cultures isolated and a re-aggregation study was carried out indicating that some isolates contribute to the formation of granules and other isolates harm the aggregation process.


biorreator a membranas agregação microbiana biofilme grânulos aeróbios tecnologia e utilizacao de produtos florestais membrane bioreactors microbial aggregation biofilm aerobic granules

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