| Compared with the conventional denitrification process, the new concepts ofmicrobial treatment processes for the nitrogen removal in wastewater which based onshortcut nitrification has the advantages of saving energy and shorting the reaction time,but the ammonia oxidizing bacteria (AOB), generation time is long, slow growth of thenitrite,that become a rate-limiting steps of the new denitrification process. Therefore,efficient and stable nitrosation reaction is the key factor to the new denitrification process.Aerobic granular sludge is a kind of special microorganism organization structure form,has lots of advantages, such as compact structure, good settling performance, highconcentration of biological, organic load resistance is strong, etc. The shortcut nitrificationtechnology coupled with aerobic granular sludge technology, rich in ammonia oxidizingbacteria (AOB) in granular sludge with good settling performance characteristics andshortcut nitrification, laid the technical foundation of development and application of highefficient bioreactor.In the study of the past, the most cultivation of aerobic granular sludge are in SBR,the SBR has a larger height-diameter ratio and sequencing batch running, but today, mostsewage treatment for the pollution sources is continuous flow. By using SBR to treat thewastewater, it need to provide a buffer pool or adjust pool, and can not form a steady stateflow running on time reaction process, what worse, the large height-diameter ratio cannotbe used in practical engineering modification or upgrade existing. We adopt theself-designed ABR-CSTR one-piece reactor for the cultivation of aerobic granular,preliminary exploration the possibility of cultivating aerobic granular sludge in continuousflow and in a reactor with low height-diameter ratio is low. The Anaerobic baffle reactor(ABR) is the third generation of highly efficient anaerobic reactor, and has the advantagesof simple structure, low sludge production rate and resistance to water and organic shockloading, low investment cost. The combining of ABR process and CSTR process can beused to remove high carbon and high nitrogen wastewater. The matured granules,withgold yellow color and settling velocity of20.8m·h-1, with MLSS of6600mg·L-1and SVIof50mL·g-1in114days. The amount of granules with diameter larger than0.58mm isabout99%of the total. Strong hydraulic selection pressure (gas velocity on the surface of> 2.6mm·s-1, settling basin rise velocity> to60cm·h-1) and with the constant elutriation ofsludge, the sludge load constantly improved (from0.5kgCOD/MLSS·d up to1.6kgCOD/MLSS·d) is the main reason for the formation of aerobic granular sludge.In this study, to form the nitrosation granules, inoculated the aerobic granular sludgeafter5months cultivation in ABR-CSTR, gradually increasing influent NH4+-Nconcentration (65-165mg·L-1), adjust the pH at8.1-8.4, control the temperature of30℃-35℃. System running75days, the influent loading rate of NH4+-N reached5.4kg·m-3·d-1and the average ammonia removal efficiency was above95%, the nitriteaccumulation rate reached5.0kg·m-3·d-1, the nitrite accumulation rate is more than90%.The edge of nitrosation is more smooth, structure of the nitrosation is more compact, thesettling velocity is30m·h-1, the MLSS is8800mg·L-1, the SVI is30mL·g-1, and the colorof the granular sludge by the inoculation of golden gradually into orange. Highconcentrations of FA in the CSTR is the main factor to achieve and maintain the stabilityof nitrosation. |
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