Constructing effective and low-toxic removal of combined contaminants by intimately coupled Z-scheme heterojunction photocatalysis and biodegradation system

Combined pollution is formed with multiple pollutants in the actual wastewater, including emerging and conventional pollutants, which can be removed by Intimately coupled of photocatalysis and biodegradation (ICPB) systems. However, ICPB systems require abundant photoelectrons for photodegradation and biodegradation, it is hard to meet this requirement because of rapid recombination of photo-induced carriers. Hence, a Z-scheme heterojunction of gCN/TiO₂ (gCNT) was designed to increase the lifetime and transfer of photoelectrons for accelerating the activity of active species and microorganisms. In this ICPB system, 93.55 % of sulfadiazine, 89.91 % of COD, 73.87 % of TN and 70.47 % of TP were simultaneously removed via active species (•OH and •O₂⁻) and microbial metabolism, and maintained the satisfactory removal rates in continuous experiments for 120 h. Then, the photoelectrons could promote the activities of Proteobacteria, Firmicutes and Chloroflexi in biofilm. This ICPB system improves effective and low-toxic removal of combined contaminants.