Heterogeneous catalytic system enhances water purification and phosphorus recovery potential in constructed wetlands

In many low- and middle-income countries, there are limited or unsatisfactory techniques for sustainable water purification and phosphorus (P) resource recovery. Constructed wetlands (CWs) are highly desirable as an economical and safe solution. Here we used a cost-effective heterogeneous catalytic system (HCS) to enhance sustainable pollution control and P recovery potential in CWs through a unique HCS-microorganism-plant synergistic framework. HCS-enhanced CW overcome the instability of contaminants removal under fluctuating high pollution load conditions, achieving efficient sulfamethazine, ammonia nitrogen and P co-removal efficiencies of 98.2 %, 86.0 % (after day 60) and 95.3 %, respectively. The mechanistic analyses indicated that HCS promotes synergistic effect of plant and microorganism through three pathways, including antibiotic removal, oxygen supplement and non-inhibitory dynamic P starvation regulation. Through HCS-induced P precipitation and non-inhibitory dynamic P starvation regulation, HCS-enhanced CWs addressed two limiting challenges of P recovery pathways, including antibiotic residue for P-precipitated fertilizers and low P acquisition efficiency for plant as biomass products, reaching high P recovery potential (over 90 %) during long-term operation (240 days). Furthermore, a simple and scalable floating HCS-CW device has been designed for large-scale engineering implementation, offering an estimated annual benefit of USD 4.4 to 26.1 billion through simulating the upgrade of 1161 existing field-scale CWs across China. This work provides a novel solution to the long-term challenge of integrating water purification and P recovery, contributing to a sustainable circular water economy. • HCS-enhanced CWs achieved stable co-removal of SMZ, P and NH 4 + -N during 240 days. • HCS promoted microbially driven nitrification-denitrification processes in CWs. • P recovery potential exceeded 90 % in HCS-enhanced CWs. • Dynamic P starvation regulation improved P-cycling functional gene profiles. • HCS-induced degradation process reduced the residual risk of SMZ.