Abstract: There are few organic carbon sources in micro-polluted water with excessive total nitrogen. Adding an external carbon source can promote denitrification to remove nitrogen. Solid carbon sources have attracted attention because they overcome the shortcomings of the traditional carbon source. In this study, two solid carbon sources, PSPC-Ⅰ and PSPC-Ⅱ, were prepared by cross-linking, using agricultural waste corncob and polymer materials as carbon sources and polyvinyl alcohol and sodium alginate as skeleton carriers. The carbon release characteristics of the two solid carbon sources and their enhanced denitrification effect were studied. The results showed that the two solid carbon sources released carbon continuously and did not reach carbon release equilibrium within 28 days. The maximum carbon release values of PSPC-Ⅰ and PSPC-Ⅱ were 6.3 and 8.7 mg/g (calculated via the dissolved organic carbon (DOC)), respectively. Three-dimensional fluorescence results showed that the released carbon sources were mainly soluble microbial metabolites and aromatic proteins that were easily degraded by microorganisms. In comparison with the biological rope without an added carbon source (6 200 ng/g, calculated via the adenosine triphosphate (ATP)), both solid carbon sources significantly increased the biomass of biological rope biofilm (PSPC-Ⅰ: 400∼600 ng/g, PSPC-Ⅱ: 300∼500 ng/g). Additionally, both solid carbon sources significantly enhanced denitrification. The control group did not produce denitrification, but the denitrification rates of the two solid carbon sources were as high as 80.4% and 75.0%, respectively.

Key words: solid carbon source, corn cob, biological denitrification, denitrification, biological medium