Abstract
This study was conducted to investigate the impact of chemical oxygen demand (COD) and aerobic operational modes on nitrogen and phosphorus removal from a sequencing biofilm batch reactor (SBBR). The anaerobic/oxic/anoxic (A/O/A) SBBR was operated at different influent COD/TN [COD/total nitrogen (TN)] ratios (1–4). The SBBR was operated at different operational modes (A/O/A mode and anaerobic/oxic (A/O) mode). The results showed that, in the A/O/A SBBR, the TN was mainly removed in aerobic process through simultaneous nitrification and denitrification (SND). The maximum SND efficiency of 79% was achieved at COD/TN ratio of 4. The intracellular stored polymers [polyhydroxybutyrate (PHB) and glycogen] were analyzed in the A/O/A SBBR. The advanced nitrogen removal in the A/O/A SBBR was attributed to the PHB and glycogen-driven postdenitrification at COD/TN ratios of 2 and 3. The low phosphorus removal efficiency appeared due to the low phosphorus uptake rate during the aerobic stage at the influent COD/TN ratio of 1–2 and the secondary phosphorus release during the anoxic stage at the influent COD/TN ratio of 4. The advanced phosphorus removal efficiency above 83% ± 2% and TN removal efficiency above 98% ± 2% were obtained when the influent COD/TN ratio was 3 in the A/O/A SBBR system. Compared with the A/O SBBR system, the A/O/A SBBR achieved better nitrogen removal performance due to the anoxic denitrification. In total, the A/O/A SBBR operated at influent COD/TN ratio of 3 was an optimal way to obtain high efficient nitrogen and phosphorus removal simultaneously. Under the conditions of abundant carbon source in influent wastewater, the release of secondary phosphorus in A/O/A SBBR should be avoided by optimizing and controlling the anoxic duration.
Get full access to this article
View all access options for this article.