탈질 환경에서 투과매질 내 생물벽체 형성

초록

Recently, a subsurface biobarrier formation which has potential applications as both cutoff walls for the containment of groundwater flow and reactive barrier for the degradation of contaminants was conducted under an aerobic condition. But there were several limitations to make an aerobic condition that needs special oxygen delivery technique in subsurface soil. Thus, in this study, we examined biobarrier formation under a denitrifying condition using nitrate as an electron acceptor. Experiments were performed with a sand column inoculated with activated sludge acquired from a wastewater treatment plant. The substrate medium including acetate and nitrate was pumped into the sand column at different substrate loadings. During the experimental period, we examined microbial activity and the permeability reduction trend in a sand column. The effulent showed characteristics of denitrification and proper microbial activity at high substrate loading rate. During the low substrate loading period, the hydraulic conductivity reduction rate was similar throughout column. During high substrate loading period, the hydraulic conductivity reduction occurred in gradient through the column, with the greatest reduction in column inlet. These results are likely due to biomass increase and higher nutrient consumption rate at the column inlet and delivery limited substrate to latter part. The hydraulic conductivity had correlationship to the biomass attached in the column, But there was limitation of hydraulic conductivity reduction over some biomass concentration level. As a result, we found potential to formation biobarrier under denitrifying condition using nitrate instead of oxygen injection. And thickness and hydraulic conductivity reduction rate of biobarrier could be controlled by adjusting the medium conditions of microbial growth.