Abstract
Volatile fatty acids can be used as carbon sources for denitrification and are easily supplied as by-products from the anaerobic digestion of waste materials. Nitrification and denitrification processes were carried out in a single reactor feeding volatile fatty acids as electron donors and the changes in microbial communities in the reactor were investigated. The microbial communities in the alternating aerobic and anoxic systems were different, and their structure flexibly changed within one reactor. Bacteroidetes and Firmicutes were highly distributed during denitrification, whereas Proteobacteria was a major phylum during nitrification. In addition, in the denitrification system, the microbial community was substrate dependent. It showed the sequential nitrogen removal in one reactor and the microbial community also followed the change of environmental condition, cyclic nitrification, and denitrification.
Highlights
Volatile fatty acids from anaerobic digester [12], food waste leachate [38], and winery wastewater [39] can be applied as electron donors for denitrification and nitrifying bacteria is able to survive by making low C/N conditions in the cyclic system of nitrification–denitrification
Volatile fatty acid addition induced an increase of hydrolytic bacteria at the start of anaerobic digestion. Both nitrification and denitrification processes were evaluated in a single reactor containing volatile fatty acids; nitrification started with oxygen consumption and denitrification with fatty acid degradation in one reactor
The repeated process did not affect nitrogen removal, and changes in the microbial community were dynamic according to the environment
Summary
Nitrification and denitrification processes were carried out in a single reactor feeding volatile fatty acids as electron donors and the changes in microbial communities in the reactor were investigated. In the denitrification system, the microbial community was substrate dependent. It showed the sequential nitrogen removal in one reactor and the microbial community followed the change of environmental condition, cyclic nitrification, and denitrification. Volatile fatty acids are by-products of anaerobic digestion and they are excellent electron donors for denitrification [12,13,14]. Changes in the structure of a denitrifying microbial community are strongly dependent on the electron donors [15].
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