Study On Degin And Operation Control Technology Of Alcohol Wastewater Treatment

Alcohol wastewater is a kind of high concentration organic wastewater, leading to serious water environment pollution. In this study, the two stages UASB-CASS combination process was used to treat corn alcohol wastewater. The engineering design and operation control techenology were concerned. The quick start-up of the large-scale UASB reactor and rapid anaerobic sludge granular in the UASB reactor were investigated. The purification performance and operating characteristics of the combination process were studied, in order to enhance the operation level of the combination process further.The two UASB reactors were started up separately, at low concentration and high hydraulic loading with intermittent influent. The volumetric loading were controlled as 1.0 kg COD(m3 · d) – 1. After running for 23 d, the COD removal rate of the first stage UASB reactor reached 71.9%, indicating its successful start-up. After that, the influent COD concentration of the first stage UASB reactor increased gradually to increase the treatment loading. After 60 d for increasing loading and 20 d for stable operation, the treatment loading increased to 16.2 kg COD(m3 · d)-1, and the effluent COD concentration ranged from 6587 to 8231 mg · L-1. The average effluent COD concentration was 7274 mg · L-1, and the average COD removal rate was 75.6%. The floc sludge formed when the treatment loading increased to 3.5 kg COD(m3 · d)-1. The granular sludge appeared when the influent COD concentration increased from 3000 mg · L-1 to about 14000 mg · L-1 and the treatment loading increased to 9.5 kg COD(m3 · d)-1. After that, the treatment loading was increased continuously, and a large amount of granular sludge with good sedimentation was generated. This indicated that the sludge granulation was realized.The activated sludge from a municipal wastewater treatment plant was used as inoculation sludge for CASS reactor start-up. After 23 d for increasing treatment loading, the effulent of two stages UASB reactors was used as the influent of the CASS reactor. The stable organic contaminant removal was achieved and the effluent COD concentration was below 100 mg · L-1, meeting the requirements of the wastewater discharge standard. The optimal control conditions of for CASS operation were determined as the ratio of influent to effluent of 1:3, the reculating ratio of 20% and the DO concentration of 2 mg · L-1. The bubble problem occurring during the operation was resolved by adding defoaming agent and increasing the ratio of influent to effluent. The slight sludge disintegration was observed in the CASS reactor during the increase in treatment loading, which could be controlled by increasing treatment loading, reducing aeration time, aerating intermittently and adjusting CASS operation process.The treatment capacity of the wastewater treatment project was 1200 m3·d-1, with a total investment of 3.6712 million yuan. The treatment cost was 2.86 yuan·m-3. The total amounts removed of COD and BOD5 were 9684 t·a-1 and 5929 t·a-1, respectively. Therefore, this project could provide the significant environmental benefits.