Enhancing Simultaneous Carbon and Nitrogen Removal by HN-AD Bacteria in Low-Carbon Wastewater With Solid Carbon...

Heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria require a high C/N ratio and exhibit a certain carbon dependency, limiting their practical application. In the study, the properties of the four solid materials and the performance in enhancing low C/N wastewater treatment via the HN-AD consortium T-1 were investigated. The results of leaching experiments showed that polybutylene succinate (PBS) was not a good candidate carbon source among the four carbon materials. Corncob (CC) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) as sole carbon sources achieved higher NH₄ ⁺-N removal efficiency than peanut shell (PS) and PBS. Although PS supported the growth of T-1, its NH₄ ⁺-N removal performance was poor. In low C/N wastewater batch tests, PHBV and CC achieved NH₄ ⁺-N removal efficiency of 99.55% ± 0.07% and 89.76% ± 1.09% at 48 h, respectively. Continuous experiments indicated that CC and PHBV had stable carbon release ability and similar pollutant removal performance in low C/N wastewater treatment. The microorganisms in the biofilm on the carbon materials mainly included hydrolytic bacteria and HN-AD bacteria. KEGG annotation showed that a complete denitrification pathway existed in the biofilm; however, AMO and HAO genes were not mapped. The findings demonstrate that CC, a cost-effective and readily available material, can be used not only as a carbon source but also as a carrier to quickly start the heterotrophic nitrifying reactor, so it is more competitive in practice.