Resiliency of anammox against external stress factors – Effects of temperature and wastewater constituents

Nitrogen r emoval based on anaerobic a mmonium oxidation (anammox) has g ained tremendous popularity as it is energy efficient and environmentally friendly. In this case, anammox is c oupled w ith p artial n itrification (collectively called p artial n itritation-anammox or P N/A systems) t o a ccomplish ne arly 80–90% t otal i norganic ni trogen removal. Despite s ignificant k nowledge gained ab out t he p rocess en gineering an d microbiology related to PN/A systems, very little is known about the effect of external perturbations on P N/A s ystems e specially in a s ystem b iology f ramework. I n this research w e first evaluated t he effects o f m etal an d t oxic l oading o n an en riched anammox community. Thereafter, we operated a single-stage PN/A lab-scale reactor to evaluate the effect of temperature on t he process efficiency and system microbiology. Mercury led to a 50% reduction and lead caused a 20% reduction in specific anammox activity a t 0.8 m g/L concentrations. Cyanide, used as a t oxic ch emical, caused significant anammox activity inhibition at 50 pp b concentration. The results related to temperature changes showed that ammonium oxidizing bacteria (Nitrosomonas sp.) can maintain a relatively stable activity at lower temperatures (13~21°C), while anammox bacteria (Candidatus Brocadia) are more sensitive to temperature reductions.