AMX TM is a service mark of BKT, and it is a short-cut biological Nitrogen removal process using Nitritation and Denitritation. OBA (Okabe-BBF-Anammox) is a BKT's unique anammox bacteria originally enriched in Japan. AMXTM is a carbon diversion process in which main-stream anammox. AMXTM is used as an effective organic pretreatment (BBF). This process yields a high nitrogen removal efficiency level as well as a high growth rate. The mediums targeted with this technology include municipal wastewater (both main-stream and side-stream), livestock wastewater, A/D effluent, and high-strength nitrogen containing substances.

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After BBF removes more than 95% of solids and soluble organics, AMXTM removes nitrogen wastes at 20 times higher concentration at 2 times faster rate compared to other strains. The AMXTM also exhibits resistance to high salinity (~3%)

Challenges to Anammox Application


  • High organic carbon promotes dominance of fast-growing heterotrophic microorganisms
  • Anammox bacteria’s inability to compete results in system instability


  • Converting half of ammonia content to nitrite is essential to establish anammox activity
  • Stable partial nitritation is a key component of the Anammox process


  • Low growth rate – Doubling time of anammox bacteria is as slow as 10 days
  • Temperature – Mesophilic (30-35°C) is optimal while lower ranges result in activity loss
  • Nitrite concentration – Susceptible to excessive nitrite levels

Overcoming Anammox Challenges

Anammox Challenge BKT AMXTM Solution
Carbon Inhibition Removing organic carbon prior to the Anammox process by BBF
Preventing growth of heterotrophs protects Anammox bacteria.
Partial Nitritation Multiple configuration options ensure stable partial nitritation at various influent characteristics
2-stage & single stage partial Nitritation + Anammox
Biological Sensitivity Strict nitrite monitoring protects Anammox bacteria now
BKT devotes continuous R&D efforts towards technology convergence (i.e. DNA editing technology (CRISPR-cas9))
Seeking to develop advanced Anammox bacteria with greater resistance to low temperature and higher growth rates

The application of AMX BBF at Joint Water Pollution Control Plant (JWPCP, Carson, CA)

for main-stream shortcut nitrogen removal

Anaerobic ammonium-oxidation (anammox) is an energy and cost-effective alternate for main-stream & side-stream treatment compared to a conventional biological nitrogen removal (BNR). Unlike the conventional BNR, which involves a complete ammonia oxidation to nitrate followed by chemoorganoheterotrophic denitrification, anammox involves an autotrophic conversion of a partially nitrified stream containing nearly equimolar mixtures of ammonia and nitrite to dinitrogen gas. Anammox based BNR processes have many advantages including no external organic carbon usage, a 62.5 % less oxygen consumption and a 90% lower biomass yields over conventional BNR processes. Low biomass yield will be highly beneficial to a downstream Advanced Water Treatment (AWT) by reducing the risk of potential membrane biofouling. However, by low temperature, and competitors’ outgrowth (nitrite-oxidizing bacteria (NOB) and Heterotrophs) are often challenges to anammox processes specifically in main-stream treatment.

Figure. Microbial community structure of the AMX BBF at JWPCP. This is based on the amplicon sequencing targeting 16S rRNA genes. 

Figure. Microbial community structure of the AMX BBF at JWPCP. This is based on the amplicon sequencing targeting 16S rRNA genes. 

The link provides Krona chart to demonstrate a progressive increase in Candidatus Brocadia over the pilot operation.

A pilot study of upflow anammox biofiltration system at the Joint Water Pollution Control Plant (JWPCP) of LA County Sanitation Districts has been conducted for over six months to assess the feasibility of an anammox biofiltration at the mainstream condition. Secondary effluent of the JWPCP has average C:N ratio of 1.1 and Nitrite amended secondary effluent was introduced to the anammox biofilter. Within 40 days of operation, the nitrogen removal rate (NRR) and the percentage of the N removal at the anaerobic biofilter have exponentially increased up to 1.5 kg N/m 3 /d, and 90%, respectively. An increased N loading with 20 min. of EBCT has resulted in NRR of 5.5 kg N /m 3 /d. A maximum anammox bacteria growth rate of 0.12 day -1 was determined based on the removal, which corresponded 5.8 days of anammox bacteria doubling time. High-throughput sequencing based on 16S rRNA resulted proportional increase over the operation in anammox bacterial population, genus Candidatus “Brocadia”. The results so far allowed us to provide a significant potential and insight into the feasibility of an energy-efficient anammox biofiltration with non-nitrified secondary effluent as an alternative AWT pretreatment process. The results will be presented in WEF Nutrient Symposium 2017 (Fort Lauderdale, FL).