Start up of anammox process with activated sludge treating high ammonium industrial wastewaters as a favorable seeding sludge source

It is a big challenge to select suitable seeding sludge for the quick startup of anaerobic ammonium oxidation (anammox) systems. Six seeding sludge originating from three municipal wastewater treatment plants (WWTPs) and three industrial WWTPs with high influent ammonium concentrations (landfill, coking and antibiotic production wastewater) were selected to explore suitable seeding sludge for the startup of anammox systems. The abundances of anammox bacteria in the six seeding sludge were characterized by quantitative PCR targeting the hydrazine synthase beta subunit (hzsB) genes, and industrial sludge samples exhibited relatively higher abundances of anammox bacteria than the municipal ones. The logarithm of anammox bacterial abundance in seeding sludge was significantly correlated with the influent ammonium concentration (p < 0.05). Start up performance was evaluated for five (three municipal and two industrial sources) of the six sludge samples in semi-batch mode for 175 d. It took 18-86 d for the five sludge to exhibit detectable anammox activity, with two industrial source sludge (coking wastewater and landfill leachate) exhibiting the shortest start up times (18-33 d). Cloning analysis showed that all of the five final anammox sludge were dominated by Brocadia or Brocadia-like species. This study showed that industrial WWTP sludge treating ammonium rich wastewater might be a good candidate seeding source for the quick startup of anammox process.