What process is primarily responsible for the breakdown of organic materials in a landfill?

The breakdown of organic materials in a landfill is primarily driven by anaerobic digestion. This process occurs in environments where oxygen is limited or absent, which is typical in landfills. During anaerobic digestion, microorganisms, such as bacteria, decompose organic materials, converting them into biogas (which is primarily composed of methane) and other substances. This bioconversion process is crucial for reducing the volume of waste and producing energy in the form of biogas that can be captured and utilized.

While thermal oxidation involves the burning of organic waste at high temperatures, and incineration is a method of waste disposal that reduces the solid mass of materials through combustion, these processes are not the primary means of organic material breakdown in landfills. Thermophilic biodegradation refers to the breakdown of organic materials at elevated temperatures, often in controlled composting environments, but this is not the typical condition found in landfills. Thus, anaerobic digestion stands out as the process most pertinent to organic material degradation in a landfill setting.