ANAEROBIC FLUIDIZED-BED PRETREATMENT OF HOG WASTE-WATER

The anaerobic fluidized bed (AFB) reactor, using spherical granular ac tivated carbon (GAC) particles as the media, is evaluated for the pret reatment of hog wastewater. A laboratory investigation is performed to assess the effects of organic loading-rate on organic removal and met hane production. The experimental evidence indicates that good removal of five-day biochemical oxygen demand (BOD5) (filtered and unfiltered ) and filtered chemical oxygen demand (GOD) (i.e., >60%) can be achiev ed at loadings as high as 10.4 g unfiltered COD L/d. On the other hand , the removal of unfiltered COD was unsatisfactory because of the pres ence of high volatile suspended solids (VSS) concentrations in AFB eff luents. The observed specific methane yield decreases with increasing loadings; however, the biogas produced is rich in methane, especially at low loadings. Attached biomass densities ranging from 0.01 to 0.024 g volatile solids (VS)/g carbon are attainable, which accounts for >9 9% of total reactor VS. Therefore, the GAC particles used are conduciv e for buildup of attached biomass in AFB reactors.