Denitrification performance and in-situ fermentation mechanism of the wastepaper-flora slow-release carbon source

Using wastepaper as external carbon sources is an optional way to achieve total nitrogen removal faced with low carbon to nitrogen ratio municipal sewage. Most of studies have primarily focused on using cellulose-rich wastes establishing the separate denitrification units to achieve in-situ fermentation, which can cause blockages and prolong the process chain. In response, a novel in-situ fermentation wastepaper-flora slow-release carbon source (IF-WF) was proposed using in the original denitrification unit. IF-WF could be efficiently utilized in situ and the denitrification rate increased with the increase of nitrate nitrogen. The fermentation products were highly available, but internal acidification of IF-WF inhibited fermentation. Moreover, IF-WF limited the growth of polysaccharides in the extracellular polymeric substances of denitrified sludge. IF-WF finally formed the structure dominated by nitrate-reduction bacteria outside and cellulose-degrading bacteria inside. These results provide guidance for understanding the mechanism of IF-WF for in-situ fermentation to promote nitrogen removal.

Automated summary

Using wastepaper as an external carbon source is an alternative method for total nitrogen removal in low carbon to nitrogen ratio municipal sewage. Previous studies focused on separate denitrification units using cellulose-rich wastes for in-situ fermentation, but this approach can lead to blockages and prolonged process chains. In this study, a novel in-situ fermentation wastepaper-flora slow-release carbon source (IF-WF) was proposed and applied in the original denitrification unit. IF-WF was efficiently utilized in situ, with denitrification rate increasing with nitrate nitrogen concentration. However, internal acidification of IF-WF inhibited fermentation, and it also limited the growth of polysaccharides in denitrified sludge. IF-WF ultimately formed a structure dominated by nitrate-reduction bacteria outside and cellulose-degrading bacteria inside. These findings provide insights into the mechanism of IF-WF for in-situ fermentation and nitrogen removal.