Utilization of constructed wetland technology in China's sponge city scheme under carbon neutral vision

Constructed wetlands (CWs) can not only purify water quality, but also store and regulate rainwater in “Sponge City” scheme, which is a national strategy in China. Under carbon neutral vision, how to make reasonable and wiser use of CWs with multiple constrains has become pressing issues in the current sponge city construction. Therefore, this review overviews the role and suggests the wiser use of CWs technology in sponge city scheme under carbon neutral vision. By comparing the “6-character policy” of sponge city technology measures with the basic characteristics of CWs as well as the carbon emission reduction of CWs and sponge city facilities, the different roles of CWs combinations in sponge city construction were given, i.e. using SFCW system in the front-end to control runoff, the multi-level combination of SFCW and SSFCW in the middle-end to balance water volume and enhance water quality, and the hybrid system of HSSFCWs and VSSFCWs in the tail-end to further clean up the contaminants. To realize the ‘double carbon’ target, some strategies and potential technical measures of CWs were proposed and discussed in future sponge city construction mode. It is expected that the review could have great practical significance to the green and low-carbon transformation to help achieving the ‘double carbon’ goal in “Sponge City” construction.