Pilot-scale demonstration of one-stage partial nitritation/anammox process to treat wastewater from a coal to ethylene glycol (CtEG) plant

One-stage partial nitritation/anammox (PN/A) process has been recognized as a sustainable technology to treat various domestic and industrial wastewater, due to its low aeration consumption and chemical dosage. However, there is no study to investigate the feasibility of PN/A to treat coal to ethylene glycol (CtEG) wastewater yet, which contains very complex and toxic compounds including ammonium, ethylene glycol, methanol and phenolic. This study for the first time achieved stable one-stage PN/A process in a pilot-scale integrated fixed-film activated sludge (IFAS) reactor treating real wastewater produced from a CtEG plant. An average nitrogen removal efficiency of 79.5% was obtained under average nitrogen loading rate of 0.65 +/- 0.09 kg N.m(-3).d(-1) under steady state. Moreover, the kinetic model can effectively predict the nitrogen removal rate of PN/A process. Microbial community characterization showed that ammonia oxidizing bacteria (AOB) were enriched in the flocculent sludge (12.0 +/- 1.3%), while anammox bacteria (AnAOB) were primarily located in the biofilm (16.1 +/- 5.6%). Meanwhile, the presence of free ammonia (FA) in conjunction with residual ammonium control could efficiently suppress the growth of NOB. Collectively, this study demonstrated the one-stage PN/A process is a promising technology to remove nitrogen from CtEG wastewater.

Automated summary

This study investigated the feasibility of using one-stage partial nitritation/anammox (PN/A) process to treat coal to ethylene glycol (CtEG) wastewater, and achieved a stable nitrogen removal efficiency. The study also successfully predicted the nitrogen removal rate using a kinetic model. Microbial community characterization showed the enrichment of ammonia oxidizing bacteria (AOB) in the flocculent sludge and anammox bacteria (AnAOB) primarily located in the biofilm. Additionally, the presence of free ammonia (FA) and control of residual ammonium were effective in suppressing the growth of nitrite oxidizing bacteria (NOB).