MBBR using Arundo donax

In this study, raw Arundo donax (A. donax) pieces were applied as carbon source and biofilm carriers for denitrification in a lab-scale moving bed biofilm reactor (MBBR) for the treatment of reverse osmosis concentrate gathered from local wastewater reuse plant. At stable phase (about 60 days), efficient denitrification performance was obtained with 73.2% ± 19.5% NO3--N average removal and 8.10 ± 3.45 g•N m-3•d-1 NO3--N average volumetric removal rate. Mass balance analysis showed that 4.84g A. donax was required to remove 1g TN. Quantitative real-time PCR method was used for gene analysis, relatively higher copy numbers of nirS and nirK genes with lower abundance of narG and nosZ genes were observed in both carrier biofilm (BF) and suspended activated sludge (AS) in MBBR, and all the copy numbers of detected denitrification genes in BF were higher than those in AS. High-throughput sequencing analysis demonstrated that similar dominant phyla and classes with different abundance were obtained for BF and AS. The class Gammaproteobacteria affiliated with phylum Proteobacteria was the most dominant microbial community in both BF (52.6%) and AS (41.7%). However, denitrifying bacteria Acinetobacter (10.9%) was the most predominant genus in BF, while Lactobacillus (4.4%) was most abundant in AS. It was experimentally verified that A. donax could be used as cost-effective carbon source and biofilm carriers for denitrification MBBR, and high denitrification capacity could be achieved. Further studies should be carried out for its engineering application in the future.