Study On The Two-phase Anaerobic Process Which Use ABR As Methanogenic Reactor For Organic Wastewater Treatment

At the beginning of the 70th in twenty century, Ghosh and Pohland firstly proposed the concept of two-phase anaerobic digestive systems which overcomes the contradictions of two kinds of microorganismin in single-phase digestive system is a promising wastewater treatment technology. All kinds of new effetive anaerobic reactors which combine the acidogenic reactor and methanogenic reactor in allusion to treat different qualities of wastewater is becoming the hot topic in recent years. Right now, UASB(upflow anaerobic sluge bed) is always used as methanogenic reactor in traditional two-phase technoloy, ABR(anaerobic baffled reactor) used as methanogenic reactor is not been reported in literature.The continuous flows stirred tank reactor and ABR which are designed in our own lab are respectively used as acidogenic reactor and methanogenic reactor in this two-phase anaerobic reactor. In this paper,the start-up and phase-separation of two-phase anaerobic reactor designed for experiment were investigated with synthetic wastewater. The experiment results showed that, when the reactor starts at a constant temperature of 35℃with inoculated mixed aerated sluge in acidogenic reactoand anaerobic granular sludge in methanogenic reactor and simulated synthetic wastewater as substrate,the whole start-up period was 35days. During the whole stage, the acidity-alkalinity is in normal state and methane production shows a rising trend in ABR methanogenic reactor.The running characteristic of two-phase anaerobic reactor is studied in this paper, the results show that, when HRT(hydraulic retention time) was18 hours, the removal rate of COD is the highest, so 18 hours is the best hydraulic retention time. the phase separation strengthening phase, COD removal rate of effluent in acidogenic reactor will decreased from 29% to 34% to 22% ~ 28%, the acidification rate increased to 53%, adding molybdate acid can kill the methanogenic bacteria in acidogenic reactor and has little effect on acidogenic bacteria, it can increase the acidification rate and almost separates the acidogenic phase and methanogenic phase.and , acid production phase achieved almost complete phase separation. COD removal rate in effluent of methanogenic reactor increased to 98% and above. The fermentation products of acidogenic reactor are mainly ethanol and acetic acid-based, it belongs to thanol-type fermentation. Fermentation products are most vulnerable to the No.1 compartment, the conversion speed of all kinds of substrate are as follows: ethanol > acid > acid > acetic acid > propionic acid.Anaerobic sludge in methanogenic reactor is studied in start-up and the stable operation period, the esults show that, the color of the granular sludge in No.1 compartment is gray black, and the sludge in other compartments is black, sewage other Grid mud in black, particle size and settling velocity of sludge increases, methanogenic activity increased in the start-up stage. In operational phase, the color of granular sludge in each compartment are bright black, the sludge concentration gradually become larger, the methanogenic activity also increased. The SEM showed that, in the No.1 compartment the sludge bacteria is very rich, Clostridium, , and long bacillus and short bacillus occupy the superiority, with little amount of filamentous fungus. In the No.2 compartment there are a great many bacillus, little coccus, no filamentous fungus. In the No.3 compartment there are a lot of coccus.