HIGH UPFLOW VELOCITY AND ORGANIC LOADING RATE IMPROVE GRANULATION IN UPFLOW ANAEROBIC SLUDGE BLANKET REACTORS

Five laboratory scale upflow anaerobic sludge blanket (UASB) reactors were seeded with nongranular sewage sludge. Granulation was obtained a fter 15-35 days when between 0.5 and 2.0 m/h upflow liquid velocity wa s applied, with an organic loading rate (OLR) of 8 g COD/l.d (COD is t he chemical oxygen demand). Granules had different physical characteri stics and specific activity (g CODREMOVED/g volatile suspended solids) depending on the upflow liquid velocity applied. Granules were obtain ed in short startup periods (5 and 14 days) when a pilot-scale (180 I) UASB reactor with a height of 4.7 m was used to study hydraulic effec ts on the granulation process.