This paper examined the feasibility of agricultural wastes used as solid carbon sources and the effect of determined agricultural wastes on improving denitrification. Eight agricultural wastes were evaluated in MBR tests to find out their carbon release capacity, denitrification potential, leaching elements and surface properties. The results showed that retinervus luffae fructus, wheat straw, corncob and rice straw had higher carbon release capacity with COD of 13.17-21.07 mg g(-1) day(-1), BOD5 of 3.33-7.33 mg g(-1) day(-1) and respirable carbon of 8.64-10.71 mg g(-1) day(-1). Correspondingly, they displayed a good denitrification potential of 105.3-140.1 mg NO3--Ng(-1). Rice straw, retinervus luffae fructus and corncob were then applied in MBRs. These three agricultural wastes were found to be effective in enhancing the denitrification process, where the TN removal increased from 43.44% (control MBR) to 82.34, 68.92 and 62.97%, respectively. (C) 2014 Elsevier B.V. All rights reserved.