Study on H₂SO₄-modified corn straw biochar as substrate material of constructed wetland

The high value resource utilization of corn straw is a long-term problem at present and in the future. Biochar preparation is an important utilization way of corn straw. The research on city tail water treated by constructed wetland (CW) with biochar was carried out to further increase the wastewater treatment capacity of the CW. Surface characterization, structural characteristics, and adsorption of straw biochar modified by different acids were measured. The study found that the ability of H₂SO₄ to remove ash from biochar was stronger than other acids and H₂SO₄-biochar was easy to be cleaned without H₂SO₄ residue. The performance of biochar modified by H₂SO₄ was obviously better than other acids, and the biochar adsorption was enhanced. The modification of biochar substrate modified by H₂SO₄ in CW reduced the change of electrical conductivity (EC) and promoted denitrification. H₂SO₄-modified biochar promoted the absorption of N and P by Iris pseudacorus L. The compound modification effect of straw biochar was obvious. The results revealed the acid modification characteristics of straw biochar, which were beneficial for increasing the wastewater treatment rate by CW. This study will promote the sustainable development of CW.