Enhanced phosphorus removal of constructed wetland modified with novel Lanthanum-ammonia-modified hydrothermal biochar: Performance and mechanism

The defective phosphorus (P) removal performance of biochar (BC) inhibited its application in constructed wetland (CW). In this study, a novel Lanthanum-ammonia-modified hydrothermal biochar (La-A-HC) was pre-pared and used as a modified substrate for CW to enhance its P removal. Results showed that La-A-HC had satisfactory P adsorption ability (qm = 43.1 mg P/g) under various pH, ionic strength, and competing ions. TP removal rate of La-A-HC modified CW (i.e., La-CW) was 14.8% higher than CW modified with BC, which was mainly attributed to the formation of La-O-P inner-sphere complexation. Substrate adsorption accounted for 90.9% of P removal in La-CW. Furthermore, the dissolved organic matter (DOM) of La-A-HC promoted the growth of gamma-Proteobacteria and the proliferation of phosphate accumulating organisms (PAOs, 4.02 +/- 0.03 x 10(5) copy numbers g(-1)). The plants in La-CW also showed higher photosynthesize rate since La-A-HC enhanced its tolerance to stronger light.

Automated summary

The use of a novel La-A-HC modified substrate in constructed wetland (CW) can enhance phosphorus (P) removal performance. La-A-HC shows satisfactory P adsorption ability and can form La-O-P inner-sphere complexes, improving P removal efficiency. Additionally, the dissolved organic matter (DOM) in La-A-HC promotes microbial growth and enhances plant's ability to utilize light.