Present and Long-Term Composition of MSW Landfill Leachate: A Review

Abstract

ABSTRACT:The major potential environmental impacts related to landfill leachate are pollution of groundwater and surface waters. Landfill leachate contains pollutants that can be categorized into four groups (dissolved organic matter, inorganic macrocomponents, heavy metals, and xenobiotic organic compounds). Existing data show high leachate concentrations of all components in the early acid phase due to strong decomposition and leaching. In the long methanogenic phase a more stable leachate, with lower concentrations and a low BOD/COD-ratio, is observed. Generally, very low concentrations of heavy metals are observed. In contrast, the concentration of ammonia does not decrease, and often constitutes a major long-term pollutant in leachate. A broad range of xenobiotic organic compounds is observed in landfill leachate. The long-term behavior of landfills with respect to changes in oxidation-reduction status is discussed based on theory and model simulations. It seems that the somewhere postulated enhanced release of accumulated heavy metals would not take place within the time frames of thousands of years. This is supported by a few laboratory investigations. The existing data and model evaluations indicate that the xenobiotic organic compounds in most cases do not constitute a major long-term problem. This may suggest that ammonia will be of most concern in the long run.

BOD:COD Ratio as an Indicator for Pollutants Leaching from Landfill

“…Both BOD and COD are commonly used to measure organic matter content in leachate with some reporting BOD and COD values of 20 to 57,000 mg/L and 140 to 15200 mg/L respectively [5]- [8]. It is anticipated that BOD and COD value decrease over time most likely attribute to a combination of reduction of organic pollutants that are leaching in the landfill.…”

Mineral CO2 sequestration by environmental biotechnological processes

“…The anaerobic fermentation and methanogenic phase at landfill treatment sites occur subsequently in different time zones (Kjeldsen et al, 2002), in which silicate mineral dissolution and CO 2 carbonation processes can take place. The stabilization of organic solid wastes in landfill sites is currently slow due to a number of environmental factors such as excessive drop in pH during the fermentation phase (Kjeldsen et al, 2002).…”

“…The stabilization of organic solid wastes in landfill sites is currently slow due to a number of environmental factors such as excessive drop in pH during the fermentation phase (Kjeldsen et al, 2002). Another property of the landfill sites is the longer residence time (20-25 years) compared to the sludge digestion (~ 30 days) (Wouters et al, 2011).…”

Critical Evaluation of Factors Required To Terminate the Postclosure Monitoring Period at Solid Waste Landfills

“…In this phase, the BOD/COD is relatively low because any dissolved organic that is degradable is consumed by the indigenous microbial population. In theory, refuse will continue to decompose until little degradable material remains, at which time the landfill will become aerobic as the rate of O2 infiltration exceeds its rate of depletion (10). However, the authors are not familiar with any landfills that have progressed beyond the fourth phase of decomposition.…”