Purification mechanism of sewage from constructed wetlands with zeolite substrates: A review

Constructed wetlands (CWs) have good purification effect and low cost for sewage, and its application scale is increasing. There are many factors affecting the purification effect of CW. In this paper, zeolite materials with better denitrification effect were selected to carry out research. On the basis of literature research methods, the material properties of zeolite, isothermal adsorption simulation, adsorption kinetics simulation, and purification effect of pollutants were studied. The results show that the zeolite has a high static adsorption capacity for NH4+-N, and the adsorption effect is better than that of total phosphorus (TP). Langmuir equation and Freundlich equation were used to fit the isothermal adsorption of NH4+-N and TP, and the correlation coefficient was higher after fitting the Langmuir equation. Adsorption kinetics simulation showed that the correlation coefficient R2 of the two-constant equation was the highest. Zeolite as the substrate of CW has a good purification effect on NH4+-N in sewage, while the combined substrates of zeolite and ceramsite has a relatively better purification effect on CW. The adsorption capacity of zeolite to pollutants can be significantly improved by modification. The research is of great significance to promote the progress of CW technology.