In the realm of wastewater treatment, constructed wetlands (CWs) stand as efficient tools for nitrate removal. However, a recent study delves into a nuanced approach, exploring the interplay between plant litter and biochar in CW environments. The research examines the effects of adding common reed litter and reed biochar at different pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More temperatures (300°C and 500°C) on nitrogen removal, greenhouse gas emissions, dissolved organic matter (DOM) dynamics, and microbial activity.

The results highlight that the combined addition of reed litter and biochar significantly enhances nitrate and total nitrogen removal compared to biochar alone. Reed litter addition alters DOM characteristics, favoring the enrichment of denitrification-associated bacteria. Notably, the study identifies a climate-friendly aspect, showcasing that the combination of reed litter and 300°C-heated biochar reduces nitrous oxide and methane emissions significantly.

Constructed wetlands often require external carbon sources for denitrification, and the study underscores the potential of biochar, with its large surface area and porous structure, as an environmentally friendly alternative. The research also emphasizes the need to consider the interactions between plant litter and biochar, presenting an unexplored avenue for optimizing carbon substrates in CWs.

Furthermore, the study sheds light on the temporal variations in DOM characteristics and composition, revealing gaps in current understanding. The addition of carbon sources influences greenhouse gas emissions and microbial dynamics within CWs, with biochar demonstrating potential in curbing emissions. This comprehensive study contributes valuable insights into improving both nitrogen removal performance and greenhouse gas reduction in CWs, paving the way for more sustainable wastewater treatment practices.