Effects of using biochar in performance of nitrate removal bioreactors of underground drainage water

Biochar is a coal produced from plants biomass and agricultural waste in limited Oxygen condition. In the process of producing Biochar no Carbon Dioxide is released into atmosphere, so Biochar is fully carbonated. Many studies have been conducted on the ability of Biochar in improving soil condition and maintaining soil nutrients; however limited studies have been conducted on effect of Biochar on nitrate removal from drainage waters. In this paper, it has been assumed that because of high amount of Carbon in Biochar, using Biochar instead of raw Carbon materials in nitrate removal bioreactors can effectively eliminate the nitrate from subsoil drainage. In order to evaluate the effect of different mixtures of Biochar (0, 10, 15, 20and 30 percent) and effect of different inlet nitrate concentration (40, 160 mg/liter) on bioreactor performance regarding nitrate removal, bioreactors with 125cm poly-ethylene pipes were stimulated. The experiment was performed in factorial method in a random scheme with three repetitions. Results showed that nitrate removal is strongly affected by Biochar percentage used in them. The maximum nitrate removal was reported in pipes with 30% Biochar (96.4%) and the minimum was reported in replication pipes with no Biochar (80.7%). Also, nitrate removal is also affected by concentration of inlet nitrate solution. Nitrate removal percentage in C2 treatment (160 gr/liter) was lower than C1 treatment (40 mg/liter), the results were 89.9% and 91.4% respectively.