Cheffy
Bioengineer
- Oct 10, 2006
- 3
Hello All!
I am working on a multi-phase extraction of a subsurface fuel oil plume under fairly permeable conditions. Vacuum extracted products passes through a 2 tank air stripping system before being moved via a diaphragm pump to an oil water separator. Athough we are currently experiencing some setbacks, my primary issue is the following. While this setup has proven highly effective for removal and recovery of oil, we quickly ran into problems with iron fouling of the oil water separator and sensor columns. The groundwater contains high iron levels (10 - 20 ppm), resulting in the oxidation and precipitation of iron in the oil/water separator. Normally a settling tank would be effective, but the problem is that the oil seems to form a complex with the iron, producing a thick orange scum that floats at the oil/water interface. Tests have confirmed that the bulk of the mass is oil (70%+), about 2.5% solids (only 20-25% of which is iron), and that it is primarily of an inorganic nature (bacteria plate counts = cfu ~ 10^6). Significant scum production occurs only when free product is being extracted, regardless of iron concentrations.
We are currently engaged in a trial use of an organic acid to chelate the iron, and while lab trials seemed effective, only mild to moderate success has been noted in the oil/water sep and due to other complications are difficult to gauge. Lab trials using sodium metabisulphate gave poor results unless very high concentrations were used.
I cannot find any detailed examples of this situation after extensive research, and I'm becoming quite frustrated. Cannot use acid for maintaining solubility due to problems with corrosion in current system.
Any suggestions?
Thanks,
Chef
I am working on a multi-phase extraction of a subsurface fuel oil plume under fairly permeable conditions. Vacuum extracted products passes through a 2 tank air stripping system before being moved via a diaphragm pump to an oil water separator. Athough we are currently experiencing some setbacks, my primary issue is the following. While this setup has proven highly effective for removal and recovery of oil, we quickly ran into problems with iron fouling of the oil water separator and sensor columns. The groundwater contains high iron levels (10 - 20 ppm), resulting in the oxidation and precipitation of iron in the oil/water separator. Normally a settling tank would be effective, but the problem is that the oil seems to form a complex with the iron, producing a thick orange scum that floats at the oil/water interface. Tests have confirmed that the bulk of the mass is oil (70%+), about 2.5% solids (only 20-25% of which is iron), and that it is primarily of an inorganic nature (bacteria plate counts = cfu ~ 10^6). Significant scum production occurs only when free product is being extracted, regardless of iron concentrations.
We are currently engaged in a trial use of an organic acid to chelate the iron, and while lab trials seemed effective, only mild to moderate success has been noted in the oil/water sep and due to other complications are difficult to gauge. Lab trials using sodium metabisulphate gave poor results unless very high concentrations were used.
I cannot find any detailed examples of this situation after extensive research, and I'm becoming quite frustrated. Cannot use acid for maintaining solubility due to problems with corrosion in current system.
Any suggestions?
Thanks,
Chef