Feasibility of improving nitrogen removal by integrating the rice straw and zeolite with drainage ditches for farmland runoff control

Abstract Natural zeolite and rice straw have been widely used for removing nitrogen (N) from wastewater due to their different N removal mechanisms. In this study, the N removal performances of three substrate systems composed of zeolite (Z), rice straw (R) and their combination (ZR) were assessed for decontaminating farmland runoff characterized by high loads of ammonium - N or nitrate - N besides of a low carbon content. The N-cycling functional genes were also investigated. The results showed that ZR achieved significantly higher ammonium (48.9%–77.7%) and TN (39.7%–65.9%) removal rates than Z and R (P