A site where all biological remediation work is done directly at the contaminated site. This could be contaminated soil that has been treated without unnecessary and costly removal, or contaminated groundwater that has been remediated at its source. In situ is the preferred bioremediation method because it requires much less manual labor and eliminates the spread of contaminants by transportation or pumping to other processing sites. Bioventing, biosparging and bioaugmentation are the main technology classes. Ex situ means that contaminated material is transported to a remote processing site. This classification is less desirable. Digging up contaminated soil and transporting it by truck is a difficult task. For contaminated water, ex situ use is rare other than pumping groundwater to the surface and biologically treating it in closed reservoirs. Ex situ bioremediation carries the risk of spreading contamination and accidental spills during transport. Three classes of techniques can be used at ex situ processing sites. One of these is land management, where soil is applied and biologically decontaminated. The other is composting, which is an older process. The third class includes biopiles. A mixture that is piled up in silos and composted as a biological treatment. Bioremediation technology courses are prescribed physical activities or strategies used in microbial therapy. The overall process begins by identifying the status of the contaminated site and characterizing the microorganisms present. Scientists observe how these microbes already interact with contaminants and perform laboratory tests to determine colonization requirements. Catabolic activity is studied in the laboratory, from which field plans are developed. Once this is implemented, the bioremediation process will be monitored and adjustments made as necessary. Oil and petroleum waste are a major problem in many places. The same is true for methane outgassing caused by biological effects. Most regulatory agencies are strict about adding other contaminants to the environment, a side issue of the bioremediation process. Oil is lighter than water and floats on surfaces, creating a spill and cross-contamination hazard. Methane gas has an odor and is very unpleasant when released in large quantities. This often occurs when contaminated soil is agitated, but it occurs passively through bioventing and biosparging. Bioremediation has become a leading option for the restoration of contaminated sites in America. It is used in all kinds of situations where sites have been damaged by previous human activity and are rendered unusable without remediation. , is widely used around the world. As the country's population grows, fewer landfill sites are available to relocate contaminated materials. This makes bioremediation very attractive. Thanks to scientific advances, bioremediation is also economical. The greatest advantage of using bioremediation methods is their contribution to the environment. Bioremediation uses nature to repair nature. Appropriately applied by knowledgeable individuals using specialized bioremediation equipment, this is the safest and least invasive soil and groundwater remediation available. Bioremediation works on organic pathogens, arsenic, fluorides, nitrates, volatile organic compounds, metals, and many other contaminants such as ammonia and phosphates. It is effective in cleaning pesticides and herbicides and infiltrating saltwater into aquifers. There are specific devices dedicated to bioremediation. Although some of these require competent operation by trained and experienced individuals, many bioremediation devices are relatively easy to use. Training and maintenance services are readily available from suitable bioremediation equipment suppliers and manufacturers.