Microorganism Structural Characteristics Research And Cultivation Of Aerobic Granular Sludge Which Is Used For Nitrogen And Phosphorus Removal

With successful cultivation and its significant advantages, aerobic granular sludge quicklybecame a hot research of current water treatment. The particles can form hypoxia area insidethat makes it possible to achieve simultaneous denitrification and phosphorus absorption. Tofurther research the removal efficiency of pollutents, this paper used three sequencing batchreactors (SBR) to cultivate aerobic granular sludge with artificial simulation wastewater. Inthis paper, we focused on using fluorescence in situ hybridization dyeing (FISH) to analyzethe distribution of nitrobacterium and polyphosphate accumulationg bacteria, and utilizingdenaturing gradient gel electrophoresis (DGGE) to study on microbial community structureand function of granular sludge and came to the following conclusions.（1）High load was conducive to the formation of aerobic granular sludge. Comparedwith three reactors which were operating in different cycles (4h,6h,12h), the aerobicgranular sludge cycle was first mature in which run for4h as its operation cycle. Withinfluent COD concentration increased, the biomass enlarged rapidly in three reactors, whenthe sludge particle size increased from0.01mm to1cm as well as the flocculent orangeinoculation sludge gradually changed to spherical or ellipsoidal-shaped black dense sludgewith rules of structure. With the formation of aerobic granular sludge, sludge sedimentationrate gradually increased from0.3cm/s to10cm/s, and sludge concentration was steady atabout7500mg/L after140d, when SVI value was35mL/g.（2）Though running under high load conditions, mature aerobic granular sludge still hadhigh degradation efficiency of COD, TP, TN, and ammonia nitrogen. Influent concentrationsof COD, and TP, TN and NH3-N were controlled at1500mg/L,7.5mg/L,80mg/L and60mg/L, and effluent concentrations of COD was always below100mg/L, when that of TP,TN and NH3-N, can respectively be less than0.8mg/L,30mg/L and8mg/L, as the removalrates of them were89.4%,62.92%and94.5%, respectively.（3）It could be found by Scanning electron microscopic observation that mature granularsludge microbes were mainly made up of cocci, bacilli and filamentous bacteria, and theparticles had many pores inside. External media could be transferred to the particles inside,as well as internal growth and metabolism of microorganisms can escape to the outside,which were all because of the pores provide access. FISH test results showed that, manyphosphorus-accumulating bacteria and nitrifying bacteria are survival inside of the granularsludge. Nitrifying bacteria were distributed both inside and outside surface of the sludge particles, and phosphorus-accumulating bacteria were concentrated on external side ofgranular sludge and in some of the large diameter pores.（4）When using PCR-DGGE technology to analyze changes of the microbial structurefeatures in aerobic granular sludge, the results indicated that, in different periods, microbialcommunity structure of the sludge particles were different. From40d to120d, Nitrosomonasand filamentous bacteria were in a large number, but the number of filamentous bacteria insludge particles reduced when the particles disintegrated (140d). Paracoccus marcusii, asboth aerobic and anaerobic bacteria, assembled when sludge particles began to form (80d).Mature dominant microorganism populations in granular sludge were Paracoccus marcusii,Zoogloea ramigera, Rhodocyclaceae bacterium, Nitrosomonas, Proteobacterium, Thauera,etc.