| The Internal Circulation Reactor (IC reactor), which was developed by Paques BV based on UASB reactors, can be operated at high reactor volume lading rates and high liquid up-flow velocity with low investment cost and space occupation.This full-scale study on alcohol production wastewater is a cooperative project with the alcohol factory of Huixian City. Because the factory is small and its production wastewater is characterized by the high COD, SS, low pH value etc, IC reactor was selected as the anaerobic reactor. In this study, two round steel-made IC reactors were designed which were called 1# reactor and 2# reactor. The single reactor is 18m high and its volume is 692.37 cubic meters. And the gas-liquid separator located at the top of the IC reactor is 4m high. The first and second start-up of the full-scale IC reactor in treating the alcohol production wastewater and the characteristics of granular sludge during start-up were studied.The influent model on organic loads was Mn=350 X (1 +0.03)n-1 in the first start-up of IC reactor. Inoculation sludge had three sources which were domesticated anaerobic sludge cultivated by the alcohol factory of Huixian city itself, anaerobic dehydration sludge of domestic wastewater treatment plant of Zhengzhou city and anaerobic granular sludge of the Mengzhou alcohol factory. At the beginning of the first start-up, the sludge concentration of 1# and 2# reactor were 13.40g/L and 10.85g/L respectively.The results showed that the first start-up of IC reactor could be finished in 55 days with COD loading rate 1800kgCOD/d. After adjustment, the COD concentration of corn alcohol production wastewater was about 15000mg/L and the pH value was 6.0 or so, then fed the wastewater to the IC reactor intermittently. And the reaction temperature was 30~40C. During start-up, the COD concentration of 18m was about 500mg/L and its COD removal was more than 95%, while the 9m COD concentration was 700mg/L and its COD removal could reach 90%. The pH value of reactors rose from 6.0 to 6.8. Meanwhile, VFA fell sharply to 300mg/L which was 1400mg/L initially. The results showed there was little VFA accumulation in IC reactors. A lot of granular sludge appeared in l~3m of reactors, and a little in 9m. The granular diameter was 0.5-3.5mm and its appearance changed into gray sphericity or ellipse gradually.The secondary start-up of IC reactor could be finished in 36 days with COD loading rate 4000kgCOD/d and COD removal more than 92%. The influent water was changed from corn alcohol production wastewater to potato production wastewater on the 29th of Feb. in 2004. Although its COD concentration, SS, pH and temperature fluctuated largely, the bioactivityof anaerobic microorganism could not be influenced badly. During start-up, the characteristics of granular sludge changed greatly. The granular sludge of 2mm diameter was increased a lot and the largest diameter could reach 4.5mm. Moreover, the number of granular sludge was more than that of the first start-up. And the sludge concentration of 1# and 2# reactor increased to 13.40g/L and 10.85g/L respectively. Through microscope, several types of microorganisms were observed in the granular sludge, such as Methaothrix, Methanococcus, Mthanobacterium and some protozoa fungi. And Methaothrix was the main bacteria.The Application of IC reactors not only solved the pollution of the alcohol production wastewater efficiently, improved local environment but also brought economic benefits to the alcohol factory.
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