Phosphorus Accumulation In Denitrifying Gradular Sludge

Discharging wastewater with high levels of phosphorus(P) and nitrogen(N) can result in eutrophication of receiving waters.The biological nutrient removal processes are main methods to remove P and N in wastewater.The process of denitfifying phosphorus accumulation has good properties of low aeration,low C/N,which drawed more and more attentaion by experts;More attention has been payed on its good settling ability.Experiment was carried out to investigate the characteristic of denitfifying phosphate accumulation,the mass relationship among nitrate,PHB and P in anoxic stage,the mass relationship among COD,PHB and P in anaerobic stage cultivated with synthetic wastewater in SBR.The results were showed as follows.(1) In the condition of A/A/O(70min/120min/40min) of SBR,with the HRT was 8h, the SRT was 20d,MLSS between 4000mg/L and 4800mg/L,the concertration of influent of P and COD were 10mg/L and 300mg/L respectively,the phosphorus removal efficiency could reach 93%～97%and the absorptivity of COD could reach 90%～95%.(2) In anaerobic stage,0.78mg PHB was synthesized and 0.24mg P was released when 1mg COD was absorbed,which the SRPR was 54.TmgP/gVSS·h and the SUCODR was 234.7 mgCOD/gVSS.h.(3) In anoxic stage,2.Tmg PHB was used and 1.16mg P was untaken when 1mg nitrate-nitrogen was utilized,which the SUPR was 35.1 mgP/gVSS.h and the SNDR was 36.2 mgNO₃^--N/gVSS·h.(4) Temperture has influence on the SUCODR and the SRPR in anaerobic stage,the SUPR and the SNDR in anoxic stage.In 10℃condition,the SUCODR and the SRPR were 109.8mgCOD/gVSS·h and 23.5mgP/gVSS·h repectively,the SUPR and the SNDR were 29.5mgP/gVSS.h and 23.29mgN/gVSS·h repectively.In 25℃conditions,the SUCODR and the SRPR were 421.4 mgCOD/gVSS·h and 32.5 mgP/gVSS·h repectively,the SUPR and the SNDR were 29.5mgP/gVSS·h and 23.29mgN/gVSS.h repectively.Furthermore,in 10℃the amount of phosphorus uptake per unit mass nitrate-nitrogen was 2.1mg,when it was 1.3 mg in 25℃.