Electric Resistance Heating (ERH) is an aggressive in-situ remediation method using electric current to heat soil and groundwater and evaporate contaminants. Electrical current is passed through a targeted soil volume between subsurface electrodes. The soil resistivity causes the formation to heat, resulting in increases in temperature and contaminant volatility. After reaching the desired temperature, further energy input causes formation of steam and rapid removal of the volatile contaminants.
Electrode spacing and operating time can be adjusted to balance the overall remediation cost with the programme and desired cleanup levels. Typically, remediation takes a few months, rather than years. Design and costing of an ERH system depends on several factors including; volume of soil/groundwater to be treated, type of contamination, and treatment goals. The physical and chemical reactions of the target compounds, when exposed to heat, give ERH significant advantages over most conventional methods.
At a ‘side-by-side’ technology demonstration, conducted at Launch Complex 34, Cape Canaveral, Florida, Six Phase Heating (ERH) was tested against steam injection and in-situ oxidation (using peroxide and permanganate), by the Interagency DNAPL Consortium, comprising NASA, US Environmental Protection Agency, US Department of Energy, US Department of Defense and US Air Force. ERH was determined ‘best in class’ for cost, effectiveness and speed of remediation of DNAPL.
First developed and used in the US by CES, ERH is now available throughout Europe through several European partners. Duravermeer (Netherlands), Geo (Denmark), Nocon (Netherlands) and Terra Vac (UK) are all represented at Consoil (Stand 2) and would be delighted to discuss and explain the technology further.
Benefits of Electric Resistance Heating:
- Rapid process
- Effective in low permeability soils
- Works at any depth
- No excavation
- High standard of clean-up
- Best in class for DNAPL removal
- Viscosity reduction for heavy oil/tar removal
- Significantly enhances chemical and biological decay
- Effective in both vadose and saturated zone