MICROORGANISM PROLIFERATION

The large amount of nutrients inside the organic matters, the availability of water and humidity,

and a temperature between 5°C and 45°C, make the waste bin

AN IDEAL ENVIRONMENT

FOR THE

PROLIFERATION OF MICROORGANISMS

to be spread far away by INSECTS AND RATS

BACTERIA PROLIFERATION SPEED SAMPLE

(typical 20 minutes bacteria proliferation rate)

NOW: 1 bacterium

after 6 hours: 260'000 bacteria

after 12 hours: 68'000'000'000 bacteria

after 24 hours: 4'000'000'000'000'000'000'000 bacteria

after 2 days: 22'000'000'000'000'000'000'000'000'000'000'000'000'000'000 bacteria

after 3 days: 105'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000'000 bacteria

LANDFILL GAS METHANATION

Landfill gas (LFG) is a natural byproduct of the decomposition of organic material in landfills. LFG is composed of roughly 50 percent methane (the primary component of natural gas), 50 percent carbon dioxide (CO2) and a small amount of non-methane organic compounds. 

Methane is a potent greenhouse gas 28 to 36 times more effective than CO2 at trapping heat in the atmosphere over a 100-year period, per the latest Intergovernmental Panel on Climate Change (IPCC) assessment report (AR5).

Municipal solid waste (MSW) landfills are the third-largest source of human-related methane emissions in the United States, accounting for approximately 15.1 percent of these emissions in 2019. The methane emissions from MSW landfills in 2019 were approximately equivalent to the greenhouse gas (GHG) emissions from more than 21.6 million passenger vehicles driven for one year or the CO2 emissions from nearly 12.0 million homes’ energy use for one year.

When MSW is first deposited in a landfill, it undergoes an aerobic (with oxygen) decomposition stage when little methane is generated. Then, typically within less than 1 year, anaerobic conditions are established and methane-producing bacteria begin to decompose the waste and generate methane.

The following diagram illustrates the changes in typical LFG composition after waste placement. Bacteria decompose landfill waste in four phases. Gas composition changes with each phase and waste in a landfill may be undergoing several phases of decomposition at once. The time after placement scale (total time and phase duration) varies with landfill conditions.

The quantity of methane that can be emitted by a landfill depends from different factors (type of waste, humidity, temperature...) , nevertheless the US-EPA has calculated that the amount of methane that can be emitted by 1 metric ton of MSW is between 56.6 to 198.2 cubic meters over a period of about 15 years.

LEACHING 

Landfill leachate forms via decomposition of putrescible and organic fractions of landfill material transported by water percolating through the soil profile.

The composition of leachate is site specific and can vary significantly due to the different waste sources and stages of waste decomposition.

Leachate is normally a potentially highly polluting liquid because it contains high concentrations of dissolved and suspended organic matter, inorganic chemicals, and heavy metals as well as having both a high chemical oxygen demand (COD) and a high biological oxygen demand (BOD).

The significant impacts of landfill leachate could be eutrophication of aquatic systems and toxic effects on fauna which are caused by a variety of contaminants.

Due to its high toxicity, landfill leachate is a major threat for aquifer and surface water health status.