Effect of different influent F- concentrations on nitrogen removal efficiency of sulfur-based autotrophic denitrification was researched at room temperature(20-25℃) using domesticated biofilm reactor to explore the feasibility of sulfur-based autotrophic denitrification of photovoltaic wastewater containing high fluorine. The results indicated that when the influent F- concentration was in the range of 0-700 mg·L-1, the nitrogen removal efficiency promoted with rising influent F- concentration. The maximum TN removal rate of 1.0 kg·(m3·d)-1 was attained with the influent F- concentration was 700 mg·L-1. When the influent F- concentration increased to 700-900 mg·L-1, the removal rate of TN reached a stable level at 0.81-0.87 kg·(m3·d)-1 after short-term domestication. When the influent F- concentration was above 900 mg·L-1, the removal efficiency of reactor lowered with rising influent F- concentration. The minimum TN removal rate was 0.4-0.5 kg·(m3·d)-1. Photovoltaic wastewater was used as the influent of the reactor. After 50 d operation, the reactor gained steady denitrification efficiency. With the influent NO3--N concentration of 390-420 mg·L-1, F- concentration of 800 mg·L-1, and HRT of 8.8 h, the maximum TN removal rate of 1.1 kg·(m3·d)-1 was attained. The effluent TN concentration was 15-25 mg·L-1, which met the standard of sewage discharge. Costs of treating photovoltaic wastewater by disposing conventional denitrification and sulfur-based autotrophic denitrification were 2.468 Yuan·t-1 and 2.0728 Yuan·t-1, respectively. Compared with conventional denitrification, the sulfur-based autotrophic denitrification could save more costs.
Keywords: effect of fluoride; element sulfur; nitrogen removal efficiency; photovoltaic wastewater containing high fluorine; sulfur-based autotrophic denitrification.