Hydrodynamics of hybrid upflow anaerobic sludge blanket reactors using tracer studies

Abstract

The hybrid upflow anaerobic sludge blanket reactor (HUASB) is a modified UASB wherein, inert media variants are used to prevent the biomass washout and its circular shape reduces biological and hydraulic dead zone. The flow pattern is crucial to facilitate hydraulic behavior as it has a direct effect on the microorganism-substrate utilization rate. So present study focuses on hydrodynamics of the HUASB reactors with different inert media viz. seashells (RA) and coconut husk fiber (RB). Tracer studies using a common dye (i.e. congo red) were performed in continuous mode for designed flow ranges from 600 to 1200 ml/hour to determine the hydrodynamic parameters and indices of mixing namely dispersion number (D/uL), peclet number (Pe), no. of reactors in series (N), morril dispersion index (MDI), index of short circuiting (Isc), index of mean retention time (Imean), index of modal retention time (Imodal) and index of average retention time (Iavg). The obtained results for both the reactors indicates the intermediate degree of dispersion seems to be best for max substrate conversion. According to the findings, both HUASB reactors is more closely to the arbitrary flow reactors.