Improved Fluid Distribution System for Bioreactor Landfills
Landfills to treat solid waste are divided into two primary categories, the "dry tomb" and the bioreactor landfill. The key difference between these two types resides in the fact that bioreactor landfills require controlled addition of leachate or moisture to the solid waste in the landfill. These types of landfills are considered to be more environmentally friendly. The effective recirculation of a leachate and other liquids, or fluids (such as septage and gas well condensate) to the solid waste in the landfill is a major component in a bioreactor landfill. The injection of the leachate or moisture into the bioreactor landfill increases the rate of waste decomposition, and thus makes the landfill more efficient and effective.
Description of Technology
This invention utilizes a perforated pipe that is positioned adjacent a permeable layer which has hydraulic conductivity. The permeable layer is arranged on a portion of the solid waste in a bioreactor landfill. A leachate fluid is injected into the perforated pipe under positive pressure so that the fluid exiting the pipe is distributed to the solid waste adjacent to the permeable layer in a uniform manner. Various claims of this invention include methods for collecting and re-circulating waste treatment liquids (leachate recirculation, leachate management), and collecting and removing occurring gases from solid waste in the landfill. The permeable layer may include a layer of reactive material that acts to reduce the reduce the concentration of contaminants in the waste treatment liquid (leachate treatment). A system for injecting fluid into waste in landfill is also claimed as well as a method for determining physical characteristics
- Allows continued use of active landfill: Installation in actively used landfills is possible without interruption.
- Enables uniform distribution of fluid: Uniform distribution of the fluid into the underlying waste or contaminated area, through the permeable layer.
- Avoids Dry Zone Formation: Avoids development of dry zones that can lead to differential settlement of waste that can result in greater landfill cap maintenance costs.
- Allows for improved draining of liquids: Draining of injected and re-circulated fluids avoids potential flooding of the gas collection systems and possible system leakage from the landfill side slopes.
- Enables varying degree of saturation: Saturation of the permeable layer is based upon the rate, duration and frequency of liquid dosing cycle. This allows accelerated decomposition and increased settlement of waste resulting in an improved airspace gain.
- Increased collection of commercially valuable gasses: Allows for acceleration in the generation of landfill gas through improved decomposition, resulting in a potential for higher available gasses for use in gas-to-energy systems.
The technology could be used for uniform injection of waste treatment fluid into a solid waste bioreactor landfill to increase efficiency of operation of the site. The technology could be particularly useful for enhanced collection of landfill gas for use in gas-to-energy systems, for remediation of contaminated landfill sites through more effective removal of contaminants and in addressing problematic landfill situations such as the formation of dry wells and seepage from landfill slopes.
US 7,309,189 B2 (issued Dec 18, 2007)
US 7.628,567 B2 (issued Dec 8, 2009)
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Michigan State University