Functionally specialized microbial community driving carbon and nitrogen removal in two-stage aerobic process for...

This study developed a two-stage aerobic process using sequential batch bioreactors (Stage I and II) to remove carbon and nitrogen from dimethylacetamide (DMAc) wastewater. Among, Stage I used DMAc (1,000 mg/L) as substrate, yielding NH₄⁺ as residue. Stage II further removed residual TN with an external carbon source. Results showed Stage I achieved 99 % DMAc and 95 % COD removal, but TN removal was only 28 %. After Stage II, TN removal improved to 81 %. DMAc was hydrolyzed and oxidized into alkylamines and NH₄⁺, with CO₂ released in Stage I. The resultant NH₄⁺ was converted into N₂ via heterotrophic nitrification and aerobic denitrification in Stage II. It was attributed to the difference in the microbial communities. Stage I enriched carbon removal bacteria, Stage II featured nitrogen removal bacteria. Notably, the high efficiency of the two-stage aerobic process was mainly due to increased functional enzymes and the metabolic division of C/N pathways.