A simulated column packed with soil-activated carbon for organic matter removal

A sustainable sorption process was developed for environmental protection of an area around a landfill without control. Different columns, acting as a simulated permeable barrier, packed with semi-wasted activated carbon (AC) and soil samples, were studied to remove natural organic matter (NOM). The AC was supplied from a deionized equipment; meanwhile, the soil was taken from a landfill, without any contamination control, located in Mexicaltzingo, Mexico. These samples were taken at 3 and 12 m depth. NOM was represented by leachate samples (LS) taken from a landfill site, and laboratory prepared samples (LPS). NOM measured, like chemical oxygen demand, biochemical oxygen demand, nitrites and nitrates, was removed through packed columns. Two different packed columns were tested; in the first one, the AC was placed as upper support for the soil; meanwhile, in the second one, a homogeneous mixed AC-soil was used. It was demonstrated that there was an influence in the way the column was packed: a homogeneous mixture in the second column was more efficient than in the first column. Moreover, experiments showed that 60 min is an optimal time for a fast NOM removal in LPS, and the four indicated parameters decreased almost at 100% in the second column. In addition, it has been evidenced that there is no influence in soil depth for NOM removal, but actually, there is an influence for leachate since all columns were more efficient for LPS. In this work, NOM removal through packed columns was proposed, and it showed to be viable applying AC in a permeable barrier, in order to reduce the contamination risk due to leachate produced in the landfill area. Finally, the AC has been revalorized as waste, since it is possible to use it in a second process.