Pre and post-granulation performance of UASB System treating high-strength industrial effluent

摘要

Performance of a high-rate anaerobic treatment system prior to and after the formationof granular sludge was investigated. The 500-L UASB pilot was set up to receiveeffluent from a medium-size traditional slaughterhouse without blood recovery. Thesystem was inoculated with mesophilic municipal anaerobic digested sludge for thestartup and was fed influent with a total chemical oxygen demand (COD) in the rangeof 3000-6000 mg/L. It was operated at 26-29 ℃.After the formation of granules, it was possible to gradually increase the organicloading rate (OLR) up to 11.9 kg COD/m~3.d. At an upflow velocity of 0.8-1 m/hsuperior COD removal efficiencies of up to 85% was achieved with reduced potentialof sludge washout. The granules were dark brownish with a diameter of 1-4 mm and asettling velocity of 20 m/hr. SS and VSS of the granules’ layer were 55-68 and 45-57g/L, respectively with a specific gravity of 1.3. Scanning and transmission electronmicroscopy analyses indicated rod-shaped and filamentous Methanothrix bacteria aswell as Methanosarcina cocci aggregates. Microstructures were an intertwinedsyntropic association between acetogenic and methanogenic microbial populationswith diverse morphologies. X-ray analysis of mineral contents showed a high calciumphosphate apparently related to exracellular polymers of the shell structure.