Resumo

RAMOS, Ana C.T.; RATUSZNEI, Suzana M.; RODRIGUES, José A.D.  e  ZAIAT, Marcelo. Mass transfer improvement of a fixed-bed anaerobic sequencing batch reactor with liquid-phase circulation. INCI [online]. 2003, vol.28, n.4, pp.214-219. ISSN 0378-1844.

An anaerobic sequencing batch reactor (ASBR) containing biomass immobilized in polyurethane foam was used to treat low strength wastewater. The reactor was operated with liquid-phase external circulation in order to minimize the mass transfer limitations, typical of systems containing immobilized biomass. The reactor was operated at 30ºC and an 8-hour cycle was used to treat a synthetic wastewater with chemical oxygen demand (COD) of 500mg/L. The system achieved overall substrate removal efficiency of 72% with no circulation and 87% when circulation was implemented, i.e., the reactor performance increased as mixing was implemented. Furthermore, a first-order kinetic model with residual substrate concentration was fitted to the experimental values to evaluate the influence of liquid circulation on the reactor performance during a cycle time. The apparent first-order parameter was seen to increase (from 1.19 to 2.00h-1) with increasing superficial velocity (from 0.032 to 0.191cm/s) up to a stable value (1.90h-1) for higher values of superficial velocity (from 0.191 to 0.467cm/s).

Palavras-chave : Anaerobic Reactor; Immobilized Biomass; Mass Transfer; Wastewater .