Performance and mechanism analysis of gel immobilized anammox bacteria in treating different proportions of domestic wastewater: a valid alternative to granular sludge.

The treatment performance of anaerobic ammonia oxidation (anammox) immobilized filler on different proportions of domestic wastewater was evaluated. The results showed that, in comparison to synthetic wastewater, 50% domestic wastewater promoted the anammox reaction of immobilized filler, while 100% domestic wastewater had no significant effect on the anammox activity of immobilized filler but the total nitrogen removal efficiency (TNRE) was improved through enhanced denitrification. The TNRE of the immobilized filler was 82.5%, which was significantly higher than that of AnGS (69.7%), and its average anammox contribution rate was more than 90%. This was because the encapsulated anammox biomass could better maintain competitive advantages and coordinate the symbiotic relationship with denitrifying bacteria. Moreover, lower NH-N concentration resulted in greater influence of C/N ratio on anammox performance than COD concentration, while the opposite was true at high NH-N concentration. This study verified that anammox immobilized filler is effective for mainstream applications.