Study on Cultivation and Morphology of Granular Sludge in Improved Methanogenic UASB

Based on the mesophilic two-phase anaerobic reactor for maize ethanol wastewater treatment, the start-up, cultivation and the morphology of mature granular sludge in improved methanogenic UASB were studied. The reactor was initiated at a low loading rate. By means of increasing volume loading rate gradually and regulating internal circulation, the improved methanogenic UASB was operated under an optimal condition. After more than two months of operation, the size for the 63% of total granular sludge was more than 1.3mm, the biogas production rate and COD removal rate achieved 539L/d and 90%, respectively. Start-up of improved methanogenic UASB was accomplished successfully. Improved UASB, served as methanogenic phase of two phase anaerobic process, can adjust pH value of influent automatically. The manual regulation of pH value during start-up could be stopped when the granular sludge in improved methanogenic UASB went into maturity stage. The microfloras of mature methanogenic granular sludge are mainly brevibacterium and filamentous bacteria. Methanothrix soehngenii is the dominant consortium after the long-term operation under low-strength.