Landfarming – using bacteria to clean diesel-polluted soil – is a viable solution for low-income countries

Waste management, even of general household waste, is a challenge in many low-income countries. Hazardous waste management is often aspirational, and treating and disposing of hazardous waste, or requires cross border transportation to a suitable facility, is costly. As a result, hazardous waste may be buried on-site or disposed of in the local waste dump if there is one.

Soil contaminated by hydrocarbons, such as diesel, oil and hydraulic fluids from trucks, generators and mobile plant, is, unfortunately, a common occurrence on construction sites I have visited in low-income countries. There are several reasons, such as lack of training, weak site management, old trucks and equipment, and long timeframes to obtain spares for maintenance or repairs.

One method to treat contaminated soil that has been used successfully at some sites is landfarming. This is a remediation technology that reduces the concentrations of hydrocarbons through biodegradation. It involves spreading the contaminated soils in a thin layer on the surface and using aeration and minerals, nutrients and moisture to stimulate aerobic microbial activity. Shallow soils less than 1 m deep may be treated without removing the soil.

Land farming is generally applied in warmer climates. A recent study in Greenland has successfully bioremediated 82 percent of a total of 5,000 tons of contaminated soil, demonstrating that the technology also works in an arctic climate. In the experiment the contaminated solid was transferred to a landfarm for remediation. Fertiliser was added annually and the soil ploughed and irrigated for five years. Sixty-five percent of the diesel was removed in the first year.

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