Enhanced Biological Phosphorus Removal Performance And PAOs Polymer Dynamics At Low Organic Loading Rates

Phosphorus is a kind of nutricnt elements which will cause eutrophication. As we know enhanced biological phosphorus removal (EBPR) has become an important means of the phosphorus removal from wastewater. After periods of low organic loading EBPR are disturbed and sometimes even failure. The dynamic of PAOs in the short time or long time low nutrition loading is unclear. This study selects a appropriate extracellular polymeric substances separation methods.And then,the activity characteristics and dynamic parameters of PAOs are get from experiment.The results showed that Organic loading in EBPR has a great influence on PAOs. In this study, under different organic loading, polymer dynamics study will be carried out.At different organic loading rates, the PAOs strains production in SBR-H reactor was being formed at23.6mg SS/g COD、17.5mg VSS/g COD,and26.5mg SS/g COD、18.6mg VSS/g COD in SBR-L reactor. After long-term domestication, it can be found that organic loading does not affect the yield of PAOs or biological activity, and low organic loading (COD is100mg/L)is advantageous to PAOs to become more competitive.The kinetic parameters in different organic loading of PAOs have been get from anaerobic tests:rPHB/NaAc is1.08mol-C/mol-C (0-50min) and0.66mol-C/mol-C(50-110h)、 rinGLU/NaAc is1.10mol-C/mol-C (0-50min) and0.28mol-C/mol-C (50-110h).On low carbon source loading (COD100mg/L) we find more extracellular polysaccharide of PAOs(about128.09±29.77mg-C/mg VSS). The extracellular polysaccharide of PAOs at high organic loading rate (COD200mg/L) is comparat-ively lower(82.84±2.20mg-C/mg VSS).During starvation in activated sludge performing, the intracellular glycogen of PAOs is rapidly consumed but extracellular polysaccharide quantity increasing.For this, the decrease in the number of total carbohydrate is not obvious.The conclusions indicate PAOs will consume intracellular glycogen rapid on low carbon source loading if we exclude the influence of extracellular polysaccharide.Except this,in this study we find that PAOs will consume intracellular glycogen for maintain cell function unless it less than80±10mg-C/g VSS.So the number of glycogen is an effective measure of PAOs endogenous respiration process.Under anaerobic starvation conditions we observed the decay rate of PAOs,on low carbon source loading(COD100mg/L), is0.038d-1.And the decay rate under aerobic starvation conditions is0.058d-1.In this experiment, PAOs which was acclimated under both high and low organic loading had been studied and investigated during low or high organic carbon loading break. Afterwards, dynamic variation of PAOs polymers would be taken.In addition, it found that after carbon loading impact, PAOs maintain the quantity of glycogen in priority.And a low influent organic loading impact induced PAOs endogenous respirations during aerobic period. No matter high nor low influent organic loading impact has happened, EBPR could not recover its phosphorus removal ability in a short period.