Impacts of aeration and biochar on physiological characteristics of plants and microbial communities and metabolites in constructed wetland microcosms for treating swine wastewater

Constructed wetlands (CWs) by modifying operation strategies or substrates have grown in popularity in recent years for improving the treatment capacity. However, few studies focused on the responses of wetland vegetation and associated microorganisms in CWs for treating high-strength wastewaters. This study evaluated the long-term responses of plants and microbes in CWs with biochar and intermittent aeration for treating real swine wastewater. The results showed that intermittent aeration or combined with biochar could decrease the stress response of wetland plants against the swine wastewater. Biochar addition promoted the production of extracellular polymeric substances (EPS, total 516.27 mg L−1) mainly including protein-like, humic-like and tryptophan-like components. However, intermittent aeration resulted in the EPS reduction (99.24 mg L−1). As for microbial communities, biochar addition supported rich and diverse microbial communities (652 OTUs), while the combination with biochar and aeration could not improve diversity of microbes (597 OTUs). Additionally, the combination altered the microbial community structures and changed microbial composition correlated with environmental factors.