Simultaneous Nitrogen And Phosphorus Removal By Combined Anammox And Denitrifying Phosphorus Removal Process

The denitrifying phosphorus removal process(DPRP)was utilized to remove the effluent nitrate(NO3-)of single-stage nitrogen removal using anammox and partial nitrification(SNAP)process in this study.Thus,a novel combined(SNAP-DPRP)process was established to achieve carbon,nitrogen and phosphorus removal simultaneously.Firstly,SNAP process and DPRP were established,respectively.The SNAP process was run with continues and intermittent aeration strategies,and the latter strategy could repress the activity of nitrite oxidizing bacteria(NOB)successfully.During 154 days? operation,the SNAP process in this study achieved 95% ammonia removal efficiency.DPRP was enriched with phosphorus accumulation organisms(PAOs)firstly and then enriched with denitrifying polyphosphate accumulation organisms(DPAOs)gradually.During 126 days? operation with three phases,the DPRP in this study achieved 85% phosphorus removal efficiency.Secondly,the SNAP-DPRP was established.The effluent NO3-of SNAP process was introduced to the DPRP at the anoxic period,which was used as the electron accepter for DPAOs to uptake phosphorus.The SNAP-DPRP achieved average 95.7% chemical oxygen demand(COD),98.2% total nitrogen(TN)and 97.8% total phosphorus(TP)removal efficiencies during stable stages.For DPRP,glycogen accumulation organisms(GAOs)who could compete COD with DPAOs were repressed by propionate added in the influent,and the bad performance caused by GAOs also could be recovered.PHV(41.6%)and PH2MV(44.0%)were the main intracellular with mixed carbon sources(1:3 ratio of acetate and propionate)compared with PHB(63.3%)with acetate as the sole carbon source.Compared with acetate as the carbon source,the amount of glycogen degradation and PHA synthesis all decreased for DPAOs with propionate added.Furthermore,Candidatus Kuenenia and Nitrosomonas were identified as the dominant genus for anammox bacteria and ammonia-oxidizing bacteria,respectively.Defluviicoccus was the dominant glycogen accumulation microorganism for DPRP with the acetate as the sole carbon source,while Thiothrix was the dominant organism for DPRP with the mixed carbon source.This combined process could not only resolve the problem of NO3-in the effluent of SNAP process but also simultaneously achieve high removal efficiencies of COD,TN and TP with lower need of carbon sources(C/N/P=25:15:1).