Effect of Wheat-Straw Biochar on Nitrate Removal in Laboratory Denitrifying Bioreactors.

Denitrifying bioreactors are an innovative nitrate-reduction strategy that reduces NO₃-N with carbon substrate. In this study, application of biochar as a carbon substrate in DNBRs and the effect of biochar application rate and bioreactor heights on nitrate and ammonium concentration in the laboratory were investigated. Four mixtures of soil–biochar–wheat straw content of B₀ = 0 (control treatment), B₁ = 10, B₂ = 20, and B₃ = 30 percent of biochar were used. Also, to evaluate the effect of bioreactors heights, four heights 30, 60, 90, and 120 cm were used. The results showed that the nitrate concentration removal for control, B₁, B₂, and B₃ treatment was 74.5, 81, 86.4, and 90.6% and biochar application rate, and bioreactor height have a significant effect on NO₃-N removal and ammonium concentration. The results also showed that NO₃-N removal and ammonium concentration increased with time. The effluent pH value of bioreactors does not have any particular trend during the experiment. Article Highlights: Effects of biochar in DNBRs on nitrate and ammonium removal was investigated. Biochar rate and bioreactor thickness affects nitrate and ammonium removal. Biochar rate and bioreactor height have effects on NO₃−N and ammonium removal. NO₃−N removal and ammonium concentration increased with time. The effluent pH value does not have any particular trend during the experiment. [ABSTRACT FROM AUTHOR]