A review of emerged constructed wetlands based on biochar filler: Wastewater purification and carbon sequestration/greenhouse gas reduction

Abstract

Constructed wetlands (CWs) are a promising ecological wastewater treatment technology. The method of biochar (BC) filler to enhance CWs has been widely researched in the past decade. This article summarizes the applications of BC-added CWs technology and consolidates the various impacts of BC filler on the operation of CWs, which can be divided into two aspects. One is to enhance the wastewater purification performance of CWs ecosystems, and the other is to improve the abilities of CWs to sequester carbon and reduce greenhouse gas (GHG) emissions. These two aspects are precisely among the environmental challenges facing humanity globally. The BC prepared from CWs plants used as CWs filler can solve excess biomass in CWs. Moreover, the large specific surface area of BC, excellent adsorption performance, and good biocompatibility improve the sewage treatment effect of CWs. The BC has a high potential for stimulating the growth of CWs plants, biomass carbon sequestration, inhibition of organic carbon mineralization in CWs substrates, and reducing GHG emissions, which mitigates global climate change. In short, the BC-added CWs is a technology that combines wastewater purification and carbon sequestration/GHG reduction. This study provides solid references for the engineering promotion of CWs based on BC filler.