Simultaneous enhanced biological high-strength phosphorus removal and nitrite accumulation in a lab-scale sequencing batch reactor
The enhanced biological phosphorus removal (EBPR) has been widely applied in treating domestic wastewater, while the performance on high-strength P wastewater is less investigated and the feasibility of coupling with short-cut nitrogen removal process remains unknown. This study first achieved the simultaneous high-efficient P removal and stable nitrite accumulation in one sequencing batch reactor for treating the synthetic digested manure wastewater. The average effluent P could be down to 0.8 ± 1.0 mg P/L and the P removal efficiency was 99.5 ± 0.8%. Candidatus Accumulibacter was the dominant polyphosphate accumulating organism with the relative abundance of 14.2-33.1%, while the presence of glycogen accumulating organisms (Defluviicoccus and Candidatus Competibacter) with relatively higher abundance (15.6-40.3%) did not deteriorate the EBPR performance. Moreover, nitrite accumulation happened in the system with the effluent nitrite up to 20.4 ± 6.4 mg N/L and the nitrite accumulation ratio was nearly 100% for 140 days (420 cycles). Nitrosomonas was the dominant ammonia-oxidizing bacteria with relative abundance of 0.3-2.4% while nitrite-oxidizing bacteria were almost undetected (<0.1%). The introduction of extended anaerobic phase and high volatile fatty acid concentrations were assumed as the potential selectors to promote partial nitrification. This study provided a new sight to combine the EBPR and short-cut nitrogen removal via nitrite to achieve simultaneous nitrogen and phosphorus removal.