Study On The Performance Of An UASB Reactor Treating Streptomycin Wastewater And The Changes Of Sludge Characteristics

In this study, the start-up and performance of a mesophilic up-flow anaerobic sludgeblanket (UASB) reactor used to treat streptomycin wastewater were investigated and thesludge granulation during start-up and stable operation of the reactor was also explored.The diversity and dynamics of microbial community in anaerobic granular sludgesamples from full-scale UASB bioreactors treating streptomycin wastewater wereinvestigated by PCR-DGGE and FISH. The results were shown as follows:The successful start-up and the stable operation of the UASB reactor could berealized by increasing the ratio and organic loading rate (OLR) of streptomycinwastewater in the influent. The COD removal rate was above80%, and the OLR removedand the methane production reached up to7.2kg/(m3·d) and7.2L/d, respectively. Thestreptomycin wastewater showed the inhibition effect on sludge bioactivity during thereactor start-up, resulting in short-term performance deterioration of the reactor, thenrecovered soon. The decreased methane yield was also observed at high OLR ofstreptomycin wastewater.The sludge characteristics varied greatly during start-up and stable operation of thereactor. The inoculated floicculent sludge transformed to granular sludge gradually. Thesludge diameter, sludge VSS/SS ratio and sludge settleability increased. A large amountof granular sludge with diameter of0.5-1.0mm emerged. The specific methanogenicactivity also increased significantly. These results showed sludge granulation happened.The bacterial species of sludge was scaned with the electron microscope: the inoculatedsludge was made of bacterium and algae, which have some coccus and tyrothricin. InOLR rising stage, some bacilli and coccus appeared. There were large amount offilamentous bacterium on the surface of the granular. They were conjecture methanothrixsoehngenii.The diversity indices of microbial community, including Shannon diversity index,Margalef richness index and Berger-Parker dominance index, were increased obviously.The methanogens and the syntrophic acetogenic bacteria were the dominant species.While the relative abundances of methanogens were from3.5956±8.02%to47.2145±2.19%, and the relative abundances of syntrophic acetogenic bacteria were from1.5956±8.02%to9.2145±2.19%.