Unprecedented development of anammox in presence of organic carbon using seed biomass from a tannery Common Effluent Treatment Plant (CETP)

•Anammox enriched using seed biomass from a tannery CETP in simple SBR operation.•Nitrogen removal performance of anammox increased with enrichment.•Anammox tolerated organic carbon available by cell lyses.•Competing co-existence of anammox and denitrification.•Anaerobic ammonia removal in presence of organic carbon by an unknown mechanism. This work describes development of a microbial consortium dominant in anammox in presence of organic carbon (available through cell lyses) by employing simple sequencing batch operation in 23 cycles exceeding 400days. Seed biomass from a tannery Common Effluent Treatment Plant (CETP) was enriched for anammox and attained maximum removals of NH4-N (95%) and NO2-N (98%). The anammox was confirmed by nitrogen mass balance in a controlled batch experiment and by DNA extraction-PCR-agarose gel electrophoresis. The effective anammox followed first order reaction kinetics with rate constant of 0.0141/h and half-saturation constant of 10.6mg/L. Evidence for coexistence of denitrification (99% NO2-N removal) and anammox (57.8% NH4-N removal) was demonstrated. This study opens-up possible application of microbial consortium dominant in anammox for simultaneous removal of ammonia and organic carbon from wastewaters.