Effects of low strength ultrasonication on the physico-chemical characteristics of methanogenic granules

The physico-chemical characteristics of methanogenic granules are one of the most important properties for the successful operation of upflow anaerobic sludge blanket, since they could directly affect the substrate and nutrient transportation into granules. In this study, the effect of low strength ultrasonication on the settling velocity, permeability, porosity, and fluid collection efficiency of the methanogenic granule were investigated, and then morphological changes were investigated using scanning electron microscopic technique. The experimental results indicate that low strength ultrasonication increased both permeability (37%) and specific surface area (230%) of the granules through the generation of grater craters and cracks on the granular surface compared to the control granule. As results, the penetration of nutrient and substrate into granules could be enhanced, and then more favorable conditions seemed to be given to the ultrasonicated granules toward to the higher anaerobic performance.