Effectively stimulating partial denitrification to utilize dissolved slowly-biodegradable organic matter by introducing in-situ biosorption and hydrolytic acidification.

In this study, partial denitrification (PD, nitrate → nitrite) using dissolved slowly-biodegradable organic matter (DSBOM) was effectively established by introducing biosorption and hydrolytic acidification (HA) as a pretreatment for carbon capture and conversion. After 119 days of optimized operation, an efficient nitrate to nitrite transformation of 80% was achieved, with an influent nitrate level of 40 mg/L and DSBOM level of 183.8 mg/L. There was a significant shift from exogenous PD to endogenous PD, with energy supplied by HA products of captured DSBOM, i.e., acetate, saccharide and intracellular poly-hydroxyalkanoates (PHAs), jointly facilitating nitrite production. This was well explained by that genera Dechloromonas (26.7%), possibly responsible for carbon HA and nitrite production, were enriched; while abundant enzymes for glycolysis, acetate fermentation and PHAs storage, and 2.6 times more nitrate reductases than nitrite reductases were identified. These results highlight a novel carbon capture reuse and PD-based anammox strategy to cost-effectively treat nitrogen.