PERFORMANCE EVALUATION OF FULL SCALE UASB REACTOR IN TREATING STILLAGE WASTEWATER

Upflow anaerobic sludge blanket (uasb) reactors have been widely used for treatment of industrialwastewater. in this study two full-scale uasb reactors were investigated. volume of each reactor was 420m3. conventional parameters such as ph, temperature and efficiency of cod, bod, toc removal in eachreactor were investigated. also several initial parameters in designing and operating of uasb reactors,such as upflow velocity, organic loading rate (olr) and hydraulic retention time were investigated. aftermodifying in operation conditions in uasb-2 reactor, average cod removal efficiency at olr of 10–11kg cod / m3 day was 55 percent. in order to prevent solids from settling, upflow velocity was increased to0.35 m/h. also to prevent solids from settling, the hydraulic retention time of wastewater in uasb-2reactor was increased from 200 to 20 hours. this was expected that with good operation of uasb-2 reactorand with expanding of granules in the bed of the reactor, cod removal efficiency will be increased to morethan 80 percent. but, because of deficiency on granulation and operation in uasb-2 reactor, this was notachieved. cod removal efficiency in the uasb-1 reactor was little. to enhance cod efficiency ofuasb-1 reactor, several parameters were needed to be changed. these changes included enhancing ofolrs and upflow velocity, decreasing hydraulic retention time and operating with new sludge.