The rapid start-up of CANON process through adding partial nitration sludge to ANAMMOX system

Area of Science:

• Environmental Engineering
• Microbiology

Background:

• The completely autotrophic nitrogen removal over nitrite (CANON) process offers efficient nitrogen removal but faces challenges in rapid start-up and stable operation.
• Partial nitration (PN) sludge has potential for accelerating the initiation of nitrogen removal processes.

Purpose of the Study:

• To develop a rapid and stable start-up strategy for the CANON process by inoculating with PN sludge.
• To optimize conditions for the co-existence and function of nitrifying and denitrifying bacteria in a single reactor.

Main Methods:

• Cultivation of PN sludge with a high nitrite accumulation rate.
• Establishment of an Anammox reactor to enrich specialized microbial communities.
• Integration and start-up of the CANON process with controlled aeration and free ammonia inhibition.

Main Results:

• Successful cultivation of PN sludge within 45 days, achieving a 90% nitrite accumulation rate.
• Enrichment of Anammox bacteria in 70 days, reaching a maximum nitrogen removal rate of 1.74 kg/(m³·d).
• Achieved 95.08% ammonium and 84.51% total nitrogen removal efficiency in the CANON process within 60 days.

Conclusions:

• The addition of PN sludge significantly accelerates the start-up of the CANON process.
• Intermittent aeration and free ammonia effectively inhibit nitrite-oxidizing bacteria, ensuring process stability.
• Key microorganisms like Candidatus Kuenenia, Candidatus Brocadia, and Nitrosomonas play crucial roles in the CANON process.