Performance enhancement of H2S-based autotrophic denitrification with bio-gaseous CO2 as sole carbon source through new pH adjustment materials.

H2S-based denitrification could achieve synchronous removal of nitrate and H2S and had been regarded as an efficient way for biogas desulfurization and wastewater denitrification. Using CO2 in biogas as carbon source had a potential of saving cost further, but the performance deteriorated due to the drop in pH. Two kinds of nature ore, medical stone and phosphate ore, were added as new pH adjustment materials in this study, and feasibility of using CO2 as sole carbon source for H2S-based denitrification was investigated. As a result, both materials could increase the pH from 4.5 to above 6.0. Compared with medical stone, higher level of pH (up to 6.39) and nitrate removal efficiency (99.1%) were obtained with phosphate ore. In addition, ATP increased more rapidly than the control, reflecting improvement on microbial activities. Therefore, phosphate ore as the pH adjustment material could improve H2S-based denitrification performance obviously.