The spatial distribution of nitrogen removal functional genes in multimedia biofilters for sewage treatment

Abstract: Real-time PCR was fist used to quantitatively study the spatial distribution of the absolute abundance, relative abundance, and relative richness of amoA, nxrA, narG, napA, nirK, qnorB, nosZ, nas, and nifH genes and anaerobic ammonium oxidation (anammox, or ANO) bacteria in four multimedia biofilters. The results showed that these multimedia biofilters could provide NH4 + and total nitrogen (TN) average removal efficiencies of 88%. Except for nifH, ANO and the other nitrogen removal functional genes all were dominantly enriched in different zones. In fact, ANO, napA, qnorB, nosZ, and nxrA were enriched by 5.6–330.1 times; and nirK, narG, amoA, and nas were enriched by 1.4–2.1 times. In addition, ANO, napA, qnorB, and nosZ showed partially or mutually beneficial cooperation. The nxrA and nirK genes showed protocooperation, and the amoA and narG genes showed partially beneficial cooperation. [Copyright &y& Elsevier]