Effect of clinoptilolite on ammonia emissions in integrated vertical-flow constructed wetlands (IVCWs) treating swine wastewater

Constructed wetlands (CWs) is an effective way to removal nitrogen (N) from swine wastewater, which accompanying with the process of ammonia (NH3) volatilization. However, the removal pathway of NH3 volatilization has adverse impacts on the natural biogeochemical cycle of N. Here, this paper presents the first attempt to investigate the potential use of clinoptilolite in reducing NH3 volatilization in integrated vertical-flow constructed wetlands (IVCWs) treating swine wastewater. The NH3 volatilization flux was measured via steady-state chambers. Results showed that the removal rate of TAN (total ammonia nitrogen, NH3 and NH4+-N) in clinoptilolite system was 96.1%, where 93.01% of that was removed by substrate adsorption, it was significantly higher (p < 0.05) than that in quartz sand system (29.6%). Moreover, the microporous structure of zeolite is not conducive for the growth of denitrifying microorganisms. The NH3 volatilization flux covered a range of 0.02-3.00 mg N m−2 h−1, which was lower than the reported date. Furthermore, the proportion of NH3 volatilization in Clite was 0.99%, which was obviously lower (p < 0.05) than that in control (9.01%), and the ammonia volatilization quantities decreased by 180.7% in this study. Results suggest that clinoptilolite plays an important role in reducing NH3 volatilization to the atmosphere.