Carbon release mechanism of synthetic and agricultural solid carbon sources.

Exploring slow‐release carbon source is essential to improve nitrogen removal performance of low C/N wastewater. Synthetic polymers and agricultural products were selected as solid carbon source, the results showed that each solid carbon source followed the first‐order release kinetic equation. The released total organic carbon of polpolycaprolactone, polybutylene succinate, polyvinyl alcohol–sodium alginate, corncob, peanut shell and obsolescent rice were 3.19, 3.49, 5.42, 29.44, 26.95 and 6.53 mg/g, respectively. Acetic was the main released short‐chain fatty acid, whose proportion was higher than 80% for agricultural products and lower than 70% for synthetic polymers. For agricultural carbon source, the porosity and carbon distribution on surface was increased after carbon release, the amount of N–H and benzene rings was increased. While for synthetic carbon source, the carbon distribution on surface was decreased after carbon release. The carbon release mechanism was mainly skeleton dissolution for agricultural solid carbon source, while for synthetic carbon source, Fick diffusion was the dominated function. [ABSTRACT FROM AUTHOR]