Highly efficient and synchronous nitrogen removal from ammonia-rich wastewater and domestic wastewater via a novel anammox coupled with double-nitrite-shunt process at low temperature

Anaerobic ammonium oxidation (anammox) has been widely accepted as an energy-efficient approach for nitrogen removal from high-strength sidestreams. However, insufficient nitrogen removal due to the excessive NO3--N residue represents the major challenge, especially at low temperature. In this study, highly efficient and synchronous nitrogen removal from ammonia-rich wastewater and real domestic wastewater was achieved via a novel anammox-mediated treatment by coupling with double-nitrite-shunt process in two-stage sequencing batch reactors. Stable partial nitrification/anammox (PNA) was successfully developed, while the total nitrogen (TN) removal efficiency was limited to 86.9 % due to excessive NO3--N accumulation. Significantly, integration with partial denitrification (NO3--N. NO2--N) coupling anammox (PDA) process offered an efficient solution, which transformed the overproduced NO3--N of PNA to NO2--N and subsequently completely removed with NH4+-N via anammox pathway by mixing with real domestic wastewater (NH4+-N of 69.0 mg/L, COD of 203.6 mg/L). Excellent nitrogen removal performance with average TN removal efficiency of 98.4 % and high-quality effluent with average TN of 4.9 mg/L was maintained despite the temperature dropping to 13.0 degrees C. S-16 rRNA gene sequencing unveiled the different community of anammox bacteria cooperating stably with AOB and denitrifiers in the two systems. Compared with conventional nitrification/denitrification methods, the novel PNA-PDA process not only enabled 60% saving in aeration energy and 95.5% saving in organic carbon for ammonia-rich wastewater treatment, but also required no aeration energy for domestic wastewater treatment. Overall, this study provides a promising application with simple-control strategy for cost-effective and synchronous nitrogen removal from sidestreams and mainstreams.