LAUSR

Denitrifying bioreactors are an innovative nitrate-reduction strategy that reduces NO 3 -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 B 0  = 0 (control treatment), B 1  = 10, B 2  = 20, and B 3  = 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, B 1 , B 2 , and B 3 treatment was 74.5, 81, 86.4, and 90.6% and biochar application rate, and bioreactor height have a significant effect on NO 3 -N removal and ammonium concentration. The results also showed that NO 3 -N removal and ammonium concentration increased with time. The effluent pH value of bioreactors does not have any particular trend during the experiment. 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 NO 3 −N and ammonium removal. NO 3 −N removal and ammonium concentration increased with time. The effluent pH value does not have any particular trend during the experiment.