The Indicator Microorganisms Diversity Research In Oxygen-enriched Aeration System

The pressure of oxygen enrichment （pure oxygen） is approximately four times thanair. The transfer efficiency and utilization of oxygen are improved greatly, and energyconsumption used for aeration is also decrease with enrichment oxygen replaced air.Meanwhile, water quality of effluent and the removal rate of COD, NH₃-N in pureoxygen aeration system is higher stabilization and better than air aeration system. Asit has so many advantages, more and more attention will be paied to the pure oxygenaeration technology. Pure oxygen aeration will show a good application prospect. Themicroorganism is be closely related to activated sludge character, so we can judge orpredit the stability and the effect of water treatment in pure oxygen aeration systemthrough observing the growth status and diversity of microorganisms. Studied withindicating microbial diversity in pure oxygen aeration system would provide theoryfoundation of biological monitoring and the method of research for variation tendencyof water quality and operational effectiveness about pure oxygen aeration.This study based on the SBR process.Through comparing with air aeration, wecan analyse which different characteristics of indicator microorganism they havebetween pure oxygen and air aeration system during different growth periods ofactivated sludge. We can also analyse the effect of external environment onmicroorganism in pure oxygen aeration system, with changed operating parameter（aeration volume, operating cycle, organic load, etc）. Finally, we use statisticalmethod to annalyse the relevancy between indicator microbial diversity and activatedsludge characteristics with whole process, and such as the effect of water treatment.Concluded that:1) The dominant species in pure oxygen aeration system are opercularia andepistylis, and the dominant species in air aeration system is vorticella. The system ofpure oxygen aeration has higher density of protozoa （with an average of750/ml morethan the air aeration system） and higher proportion （75.2%） of sessile ciliate related tomicroorganism of whole system than air aeration. 2) The aeration volume has big influence on indicator microorganism in pureoxygen aeration system. The richness R of indicator microorganism and sessile ciliateincreased with aeration volume, as well as the diversity index H, but when theaeration volume has passed0.3L/min, the diversity index of indicator microorganismand sessile ciliate is reduced, the amount of suctoria and vorticella is alsodecrease.The results show that the facts of operation cycle, organic loading andtemperature have less influence on the indicator microorganisms.3) The diversity index of sessile ciliate is negatively correlated with SVI in pureoxygen aeration system （the related coefficient of abundance is-0.849, degree ofuniformity is-0.855, diversity index is-0.921）. The dominance has contrary relationto activated sludge settleability, the correlation codfficient is0.899.4) The removal rate of COD is postively correlated with diversity index H andabundance R of sessile ciliate, related coefficient is0.755、0.710respectively, lowcorrelation with uniformity and dominance. The removal rate of NH₃-N is postivelycorrelated with abundance R of indicator microorganism, the related coefficient is0.811. When the species and quantity of ndicator microorganisms （including sessileciliate, swimming ciliate, and other tiny microorganism） is large, the removal rate ofNH₃-N in the system is good.