Effect Of C/P Ratio On The Phosphorus Removal In EBPR Under High Temperature

Phosphorus is an important element for the growth of algae and other photosynthetic microorganisms,excessive phosphorus can cause eutrophication.Therefore,controlling the phosphorus is the basic strategy for preventing the eutrophication in the process of sewage treatment.Enhanced biological phosphorus removal?EBPR?process is widely used in the biological phosphorus removal due to its high efficiency,low cost and sustainability.However,in practical engineering applications,the process stability is difficult to maintain and process efficiency is easy to deteriorate.Therefore,further research on the process and influencing factors in EBPR is of great significance for efficient and stable phosphorus removal performance.In this paper,the different C/P ratios on the phosphorus removal of PAO_HTT in the enhanced biological phosphorus removal?EBPR?reactor which was operated stably at high temperature?30??were studied.The phosphorus removal performance was evaluated by measuring the phosphorus release rate,the phosphorus uptake rate,the acetic uptake rate,and?P/?HAc.The microbial community structure in activated sludge was analyzed by FISH technology,the conclusions as follows:?1?The reactor can operated stably at high temperature?30??,and the phosphorus removal efficiency was up to 99%.The anaerobic phosphorus release rate was 309.69 mgP·gVSS^-1h^-1,the aerobic phosphorus uptake rate was 113.09mgP·gVSS^-1h^-11 and the acetic uptake rate was 549.71 mgHAc·gVSS^-1h^-1,the?P/?HAc was 0.59.The content of Poly-phosphate in the sludge can reached 155.06 mgP·gVSS^-1.The EBPR is efficient and stable.?2?The results of FISH showed that the content of Acc-II-444 probes in PAOmix reached 99%±1%,indicating that the PAO_HTT in the reactor were the“Candidatus Accumulibacter”subspecies PAOII.PAO_HTT in EBPR exists in bisected form.The cell formula of PAO_HTT can be expressed as C₅H₇NO₂P_0.66,according to theoretical calculations and experimental determination.?3?The C/P ratio is the main factor affecting the phosphorus removal of EBPR condition at high temperature.The higher the C/P ratio,the higher the proportion of PAO in the sludge,the higher the maximum phosphorus release rate and phosphorus uptake rate,the greater the?P/?HAc,and the higher the phosphorus removal efficiency.When the C/P ratios were controlled in 20:1,25:1,30:1,the contents of PAOs in the activated sludge were 22.36%,34.53%and 86.01%,the corresponding anaerobic phosphate release rates were 151.86,157.15,193.75 mgP·gVSS^-1h^-1,and the aerobic phosphate uptake rates were 25.15,38.51,39.25 mgP·gVSS^-1h^-1.the acetic uptake rates were 376.41,281.84,279.88 mgHAc·gVSS^-1h^-1,and the phosphorus removal efficiency were 80%,90%,99%.