| EGSB is a novel anaerobic reactor, which is reformed from UASB reactor, andhas been widely used in the degradation of high concentration organic wastewater.Inoculation with anaerobic granular sludge reactors can accelerate degradation oforganic matter. Thus, cultivating good properties of granular sludge in EGSB reactorplays an important role in engineering application. Numerous scholars haveinvestigated the factors and mechanisms in the formation of the granular sludge.However, the start-up period of anaerobic reactor would take two or three mouths, andeven more than one year. Therefore, accelerating the formation process of granularsludge, shortening the start-up time of the reactor and cultivating granular sludge withgood properties is becoming a hot spot at home and abroad.In this paper, the effect of the presence of the filamentous cells ofMethanosaeta harundinacea6Ac in the EGSB reactor on granular sludge formationunder the medium temperature was studied, as well as the properties of the granularsludge and the operation of the reactor, in order to provide the references forcultivating granular sludge in actual production.Methanosaeta harundinacea which was the Laboratory of Microbial Resources,Institute of Microbiology isolated from an anaerobic sludge reactor treating beerwastewater and analysed its gene organization and structure.6Ac is a kind ofmethanogens used acetic acid as the matrix and has two types of strains: short stemcells (3~5um) and filamentous cells (>200um). It has been confirmed that the celldensity influenced the morphological changes. Methane bacteria, as a kind of methanebacteria group used acetic acid as the matrix, are the principal methane bacteria inanaerobic digestion and the important function bacteria in sewage treatment reactor.The long filaments of methane bacteria contribute to the formation and duration ofgranular sludge in sewage treatment and natural environment.Two laboratory-scale reactors were conducted to cultivate granular sludge in theconstant temperature conditions (35±1)°C, which a reactor (R2) was inoculatedanaerobic flocculent sludge while adding the filamentous cells of Methanosaeta harundinacea6Ac, another reactor (R1) as the control group was only inoculated withthe anaerobic flocculent sludge. R1and R2ran for142d and167d respectively. Theseexperiments showed that when the organic load gradually increased to11.1kgCOD/(m3d), the COD removal rate of R2reached85.9%, higher than R1(75.0%).Granular sludge was founded in both reactors after46days, and the percentage ofsludge particle greater than0.1mm has reached62.3%in R2. During28~46days, thepercentage of sludge particle between0.1~0.3mm in R2increased from10.0%to49.8%, whereas it increased only from10%to33.3%in the control group R1, whichwere still mainly detected as flocculent sludge. At the end of the reaction, the surfaceof granular sludge in R1, which was loose structure, was mainly made up offilamentous fungi and a small amount of methanococcus by testing the appearanceshape of granular sludge in R1. The surface of granular sludge in R2, mainlycomposed of Methanosaeta harundinacea and minority of methanococcus.The filaentous cells of Methanosaeta harundinacea6Ac are more easilyattached on solid substrates due to its special long chains, leading to strengthen theadsorption between cells and bacteria, which has an influence on the formationmechanism of granular sludge to an extent. This study showed that addingMethanosaeta could promote the formation of granular sludge, enhance itsproliferation and stability, improve its precipitation and the removal of organic matter,and accelerate the start-up of EGSB. |
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