The application research of rainwater wetland based on the Sponge City

Highlights: • Constructed a variety of wetlands with different plants and substrates • Explored the purification of wetlands on rainwater • The purification efficiency of wetland with Reed and Zeolite • Wetland with Reed and Zeolite can effectively purify initial rainwater. In order to promote the construction of the Sponge City and strengthen the utilization of rainwater resources, this paper attempts to design a wetland that can effectively purify the rainwater. The rainwater quality of Zhengzhou was monitored to provide actual data for follow-up studies. A variety of wetlands with different plants and substrates were constructed to analyze the purification of wetlands on rainwater. The wetland with optimal parameters was selected to ensure the effluent can be reused. The average concentrations of Chemical Oxygen Demand (COD), Total Nitrogen (TN), Nitrate Nitrogen (NO₃⁻-N) and Ammonium Nitrogen(NH₃-N) in the initial rainwater were 140.25 mg/L, 13.31 mg/L, 5.77 mg/L and 6.82 mg/L, respectively. The experimental results show that the efficiency of COD purification in each wetland is great, and the differences between wetland are small. Compared with other substrates (gravel, activated carbon, vermiculite), zeolite effectively enhanced the purification effect of wetland on ammonia nitrogen. The purification efficiency of wetland with reed and zeolite is the best, and the removal efficiency of COD, TN, NO₃⁻-N and NH₃-N is 86.54%, 89.46%, 95.87% and 80.88%, the nitrogen removal efficiency of this wetland is greatly improved. Based on various reuse standards in china, wetland with reed and zeolite can effectively purify initial rainwater, and the effluent can be used to urban miscellaneous water, landscape water and industrial water. This study has important reference significance and practical value for the construction of rainwater wetland in the process promoting the Sponge City.