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METHANE PHYTOREMEDIATION BY VEGETATIVE LANDFILL COVER SYSTEMS
Rock*, S A. METHANE PHYTOREMEDIATION BY VEGETATIVE LANDFILL COVER SYSTEMS. Presented at International Conference on Contaminated Soils, Sediments and Water, Amherst, MA, 10/22-25/2001.
Landfill gas, consisting of methane and other gases, is produced from organic compounds degrading in landfills, contributes to global climate change, is toxic to various types of vegetation, and may pose a combustion hazard at higher concentrations. New landfills are required to have an impermeable cap that prevents the escape of landfill gas and a system of pipes and pumps to collect the landfill gas. Older landfills may not hve the proper design or necessary equipment to collect the landfill gas. Planting landfills with specific types of trees and grasses has been suggsted as a way to remove the methane from landfill gas by encouraging aerobic degradation of methane in the root zone (rhizosphere) by a process known as phytoremediation. It has been shown that methane levels decrease in the presence of growing plants; however, accurate determinations of the rate and amount of methane consumption have not been established. A 100-gallon stainless steel tank, 35-inch diameter by 34-inch tall, is located in the chamber. A gas distribution diffuser placed within a 4-inch layer of gravel at the bottom of the tank, feeds methane (93% industrial grade) from a cylinder located outside the chamber to the soil via copper tubing. A manual control valve and rotometer, located at the cylinder, are used to control the flow of methane into the tank. Felt is placed above the gravel to prevent soil from entering the gravel layer and to aid in dispersing the gas. Gas samples are collected from 2 slotted PVC pipes positioned vertically at different depths within the soil and from a slotted PVC pipe positioned directly on the soil surface to measure methane leaving the simulated cover. Air samples are collected above the tank. Samples are analyzed by direct injection of GC/FID located in the adjacent control room.