Abstract: Gaseous and liquid carbon dioxide (CO2) are applied to a landfill well to penetrate the landfill under rapid pressurization and depressurization repeated in cycles, with or without leachate or fluid in the well. These cycles can be repeated until the CO2 flows more freely down a lower pressure gradient in the well into the landfill surrounding the well screen, creating fissures in the landfill which allow methane and other gases to enter the well, thereby significantly enhancing methane and other landfill gas recovery.

Abstract: Disclosed herein is a method of controlling the landfill gas generation within the landfill in which leachate is recycled to be continuously injected into a deposit of wastes while extracting the landfill gas from a landfill gas extraction pipe inserted into the waste deposit, comprising steps of: (a) maintaining the recycling leachate at the temperature range of 35° C. to 38° C. and/or the pH of 6.5 to 7.5 until the amount of generated landfill gas reaches from the range of 5% to 20% of a capability of the landfill gas generation in the landfill; (b) maintaining the recycling leachate at the temperature range of 30° C. to 35° C. or the range of 60° C. to 65° C. and/or the pH of 6 to 7 until the amount of generated landfill gas reaches from the range of 75% to 90% of a capability of the landfill gas generation in the landfill; and (c) maintaining the recycling leachate at the temperature range of 35° C. to 38° C. or the range of 50° C. to 54° C. and/or the pH of 6.

Abstract: A phosphate mineral based reactive barrier system. Phosphate minerals are known to be sinks for heavy metal contaminants. The reactive barrier prevents the release of contaminants from waste materials, sediments or dredged materials via reaction with the contaminants at the interface between the barrier and the waste material, sediments or dredged material. The barrier is comprised of a phosphate mineral material where the form of the phosphate mineral is variable but primarily insoluble. This barrier is placed below, around, and/or on top of the contaminated materials such that the contaminated materials are completely enveloped, capped, or contained by a grout curtain. The barrier can be in a (i) slurry form, (ii) blended matrix form with other inorganic agents, or (iii) composite form with a geotextile or geofabric. These methods of construction can be used singly or jointly. In some cases, pH control may be used to optimize the chemical reactions within the barrier system.