Landfills and Landfill Gas: Land-Filling Is One

Landfills and Landfill Gas:

Land-filling is one of the most popular and widely used method of disposing different types of waste materials, more specifically Municipal Solid Waste (MSW), in many countries. In order to fulfill the federal regulations, the landfills are designed and operated in an efficient way and are located in such areas which are away from the residential areas. It is essential to carefully monitor this whole process, as this method of disposing waste results in the generation of landfill gas (Chalvatzaki & Lazaridis, 2010).

Landfill gas is a mixture of different gases, which include methane, carbon dioxide, nitrogen, ammonia, oxygen, sulfides, carbon monoxide, hydrogen, and many other. In terms of volume, 45% to 60% methane and 40% to 60% carbon dioxide is presented in the landfill gas. Landfill gas is produced as a result of three processes which takes place when the waste material is disposed into landfills. These three processes are (Crawford & Smith, 1985):

1. Bacterial Decomposition

2. Volatilization

3. Chemical Reactions

The landfills are divided into different types on the basis of the waste material and location. Some of the types of landfills are (EPA, 1993):

1. Municipal Solid Waste (MSW) Landfills

2. Open dumps

3. Construction and demolition (C&D) waste Landfills

4. Hazardous waste landfills

5. Vegetation waste disposal areas

6. Animal waste landfills

EMISSION OF METHANE AND CARBON DIOXIDE FROM MATERIAL BEING DUMPED INTO LANDFILL:

The total international emission of methane from landfills located all over the world is reported to be in the range of 30 and 70 million tonnes per year. The amount of methane and carbon dioxide generated from landfill depends on the generation of the landfill gas and overall process of decomposition. The process of decomposition occurs in four different phases, out of which first phase is dependent on the aerobic bacteria which uses all available oxygen and in the remaining three phases the process of decomposition continuous with anaerobic activities without oxygen. Every phase of the decomposition has different composition of gas. Land-filling of one ton waste material results in the generation of around 62 cubic meters methane which is equivalent to the 0.854 ton of carbon dioxide (Themelis, 2003).

It is important to take into consideration different factors which have direct influence on the generation and production of the landfill gas. Apart from amount of oxygen other factors which directly influence the rate and volume of the production of landfill gas include: waste composition, age or refuse, moisture content, and temperature. Methane is generated only when there is no oxygen in the landfill (Crawford & Smith, 1985).