Reduce health damage cost of greenhouse gas and ammonia emissions by assembling plant diversity in floating constructed wetlands treating wastewater

Abstract

Abstract In wastewater treatment, to find a clean approach with low damage cost to human and ecosystem health has received increasing concerns. Constructed wetlands are regarded as a green treatment technology, but they are also important sources of greenhouse gas and ammonia emissions. However, the effects of optimizing plant community on the human and ecosystem health damage costs of multiple gas emissions are poorly understood. In this study, an experiment with 90 hydroponic microcosms that simulated floating constructed wetlands treating wastewater with a high concentration of ammonium was set to manipulate plant diversity to reduce health damage costs, which integrated the emissions of nitrous oxide, methane, and ammonia. Results showed that: (1) increasing plant species richness reduced the human and ecosystem health damage costs of the three gases; (2) the systems with Arundo donax had lower greenhouse gas emissions and ecosystem health damage costs, while the systems with Lythrum salicaria had lower ammonia emissions and human health damage costs than systems without the species; (3) the structural equation model indicated that the plant combinations with high biomass or high nitrate removal ability contributed to reducing health damage costs. This study suggests that manipulating high plant species richness and proper species is a clean approach in floating constructed wetlands for high ammonium wastewater treatment with low environmental costs.