Ex-Situ methods require excavation of contaminated soil or pumping of groundwater before they can be treated. Ex-situ treatment requires shorter time periods than in-situ treatment, and there a greater uniformity of treatment because of the ability to homogenize, screen, and continuously mix the soil.

Land Farming

Land farming is an ex-situ method in which contaminated soils, sediments, or sludges are turned over and allowed to interact with the soil and climate at the site. Soil conditions, such as moisture, aeration, and pH are controlled to optimize the rate of contaminant degradation. Ex-situ land farming is most successful in treating petroleum hydrocarbons.

Slurry Phased Biological Treatment

Slurry phased biological treatment, or slurry biodegradation, is the controlled treatment of excavated soil in a bioreactor. After stones and rubble have been removed, an aqueous slurry is created by combining soil, sediment, or sludge with water and other additives. The slurry is mixed to keep solids suspended and microorganisms in contact with the soil contaminants. Upon completion of the process, the slurry is dewatered and the treated soil is disposed of. Matter contaminated with explosives, petroleum hydrocarbons, petrochemicals, solvents, pesticides, wood preservatives, and other organic chemicals have been successfully treated with this method.

Sequential/Fluidized Biological Reactor Treatment

Contaminants in extracted ground water are put into contact with microorganisms in attached or suspended growth biological reactors. In suspended systems, such as activated sludge, contaminated groundwater circulated in an aeration basin. In attached systems, such as rotating biological contractors and trickling filters, microorganisms are established in an inert support matrix. Semi-volatile organics, fuel hydrocarbons, and any biodegradable organic material are the main contaminates treated with this method.