Nutrient Remove by Using Nitrite as an Electron Acceptor in Sequencing Batch Biofilm Reactor

Abstract

Simultaneous nitrogen and phosphorus removal by denitrifying polyphosphate accumulatingorganisms (DNPAOs) can take place in the biofilm system. Nitrite was utilized as an electronacceptor in this study. The lab-scale sequencing batch biofilm reactors (SBBRs) were used toinvestigate the performance of the system by control hydraulic and solid retention times of 16 hoursand 12 days, respectively. Two SBBRs were operated under alternating anaerobic-anoxic-aerobiccondition, in which nitrite and mixed nitrate-nitrite were added respectively. The synthetic wastewaterwith acetic acid as a carbon source was supplied at the concentrations of 400 mg COD/l. Thephosphorus and ammonia concentration in the synthetic wastewater were 15 mg P/l and 100 mgN/l, respectively. The results showed that phosphorus could be removed under anoxic condition byDNPAOs utilizing nitrite as an electron acceptor. However nitrate was more favorable than nitrite.The simultaneous nitrogen and phosphorus removal could be also occurred under aerobic condition.Under the condition of nitrite supplying at 60 mg N/l of reactor volume, the ammonia and phosphorusremoval rates were 0.51 g N/m².d and 0.048 g P/m².d, respectively. The high ratio of mole phosphorusuptake to mole electron utilization of nitrite of 0.11 mole P/mole electron in the batch experimentindicated that the major group of denitrifiers which can utilize nitrite was DNPAO.

Keywords : Nitrogen / Phosphorus / Nitrite / Sequencing Batch Biofilm Reactor