Enrichment of Anammox bacteria in seed sludges from different wastewater treating processes and start-up of Anammox process

► Three kinds of seed sludges were used to start up the Anammox processes. ► Aboriginal Anammox bacteria were a key factor influencing Anammox start-up. ► The wastewater treating process could influence bacterial ecological niches. ► For rapid start-up, selection of the seed sludge is very important and necessary.