Enhancing environmental and economic benefits of constructed wetlands through plant recovery: A life cycle perspective.

Plant recovery plays a vital role in reclaiming bioresources from constructed wetland wastewater treatment systems. A comprehensive understanding of the environmental impacts and economic benefits associated with various wetland plant resourcing methods is critical for advancing both plant resource recovery and the application of wetlands in wastewater treatment. In this study, life cycle assessment was employed to evaluate the environmental impacts and costs of seven wetland plant recovery methods. In addition, the potential benefits of extending plant resource recovery within system boundaries were explored to enhance the overall advantages of constructed wetlands for wastewater treatment. The use of wetland plants for biofertilizer production had the lowest environmental impact (-8.52E-03), whereas the use of wetland plants for biochar production was the most cost-effective approach (-0.80€/kg). The introduction of a plant resource recovery component could significantly reduce the environmental impacts of constructed wetland wastewater treatment systems. The environmental impacts and costs of constructed wetland wastewater treatment systems that incorporate plant resource recovery into the system boundary are better than activated sludge methods and highly efficient algal ponds, except for the global warming potential (GWP). The use of plants for biofertilizer production could cut the environmental impacts of constructed wetland wastewater treatment systems by up to 85 % and the costs by 65 %, making it the most suitable method of plant use. Additionally, prioritizing the reduction of greenhouse gas emissions from constructed wetlands should be a primary optimization goal. The findings of this study provide valuable support for the implementation of wetland plant resourcing in constructed wetland wastewater treatment systems.

Successional dynamics of microbial communities in response to concentration perturbation in constructed wetland system.

Constructed wetlands (CWs) are widely considered as resilient systems able to adapt to environmental perturbations. Little attention has been paid, however, to microbial dynamics when CWs withstand and recover from external shock. To understand the resilience of CWs, this study investigated rhizosphere microbial dynamics when CWs were subjected to influent COD perturbation (200 mg/L-1600 mg/L). Results demonstrated that CWs had strong adaptability to different influent perturbations, characterized by transitions from fluctuating to stable pollutant removal. Microbial analysis showed that rhizosphere microorganisms competed for niches in response to increased COD concentrations, and Trichococcus played key roles in resisting concentration perturbations. Structural equation modeling indicated that rhizosphere community succession and microbial energy metabolism were shaped by pH and DO. These findings provide insights into the mechanism for CW stability maintenance when facing concentration perturbations.