OPERATING CHARACTERISTICS OF THE AERATED SUBMERGED FIXED-FILM (ASFF) BIOREACTOR

A multi-stage fixed-film reactor was developed in which a stationary submerged biofilm is attached to ceramic tiles under diffused aeration. Tracer studies revealed that the reactor's hydraulic regime is described by a CSTR-in-series model. Reactor performance at 20 degree C was examined using sucrose wastewaters with organic strength up to 900 mg l** minus **1 COD, at hydraulic loadings up to 0. 1 m**3 m** minus **2 d** minus **1 and organic loadings up to 90 g COD m** minus **2 d** minus **1. The reactor demonstrated the capability of achieving 97% soluble COD removals at low loadings and exhibited efficient and stable performance at high hydraulic and organic loadings. Reactor operation at high loadings appears to be advantageous since organic substrate removal rates and attached biomass per unit surface area increased with the increase in organic loading. This can be attributed to the good oxygen transfer and the considerable quantity and type of attached biomass attained.