Free-living anammox
Anammox was the most promising low energy consumption wastewater technology because it can save aeration energy consumption and organic carbon source greatly. Long doubling time of anammox extended start-up time of reactors, which is a one of the barriers hindering wide application. Free anammox bacteria was cultured by MBR, low concentration of calcium and magnesium under strict anoxic conditions. After 82 days of culture, the doubling time of anammox was 2.44 d by quantitative PCR, metagenomic analysis revealed that the most abundant genera in free-living was Candidatus Brocadia (7.38%) which played important roles in achieving anammox. The aim of rapid enrichment can be achieved by culturing free anammox bacteria, then the biofilm or particles are formed and put into use to shorten the start-up time.