|
|
|||
REMEDIATION TECHNOLOGIES |
|||
In July 2000, a pipeline near a Petrobras refinery in Paraná, Brazil burst, releasing four million litres (one million US gallons) of crude oil into a nearby stream, the Arroio Saldanha, which crosses four wetlands before discharging into the Rio Barigüi. About 30% of the oil reached the waterways, 26% volatilized, and the rest stayed in the terrestrial area. The cleanup of this spill shows the value of using different remediation technologies to meet specific needs. Working under the principle of sustainable development, the decision was made to avoid the ecological damage that would come from large-scale excavations of contaminated soil. Instead, the area was divided into several sectors according to soil type, vegetation cover and other factors. Six distinct treatment methodologies were used. Some sections near the spill site could be treated with injection and recovery trenches to collect “free” or spilled product as it migrated underground. Bioremediation, which involves using micro-organisms to treat contamination, was used to decontaminate soil along the creek and in three of the four wetlands. For the larger wetland, 15 hectares (37 acres), the solution involved building a network of dikes, creating a system of cells connected by simple control structures that allowed water to flow across, with the exception of free-floating oil, which is skimmed off. Visual observations and monitoring of surface water, groundwater and soil show that environ-mental conditions have improved and that the spill no longer contributes to the contamination of the waterways.
|
Matching the cure to the problem – oil spill remediation in Brazil