The AEV Sand Cleaning System

The OPS AEV sand cleaning system was developed in response to a request from the Swedish Government in 2003 for assistance to clean up contaminated sand following a large oil spill in Southern Sweden. Since that time the system has been further developed and international patents applied for. Many other projects to remove crude oil and other oil based contaminants from sand have subsequently been undertaken around the world and AEV technology has now been used to clean more than a million tonnes of contaminated products in the last 5 years.

Complete plants incorporating AEV technology are offered for sale or rental to contractors and end users wishing to undertake such projects themselves, and experienced advice is available to ensure project success.

OPS’s standard size AEV plant processes 35 - 40 tonnes per hour of contaminated sand, although larger capacity units are available. In a single pass the AEV can reduce the oil concentration of the solids fraction to less than 0.1 % by weight (1000 mg/kg). Oily sludges with up to 30% oil by weight may be treated by the AEV system.

The process utilises high pressure water to blast the sand particles clean. Some additional heat may be required, but the use of chemical additives is rarely necessary unless contaminants are chemically bound with the solids.

The sand or sludge is fed into a slurry tank by conveyor where it is mixed with water and heated if necessary. The slurry is then pumped through the AEV unit where shear is used to separate the oil from the sand and silt. The cleaned sand and silt then pass to a spiral classifier for separation. Free waste oil is recovered via a hydrocyclone. Approximately 98% of the water is cleaned up using desilters and a media bed if necessary. It is then ready to be re-used in the wash cycle. Plants may be either diesel or electric powered.

The oil is collected in a waste oil tank. If required, this waste oil can be further processed in an optional treatment system to produce oil of less than 1% BS&W (base solids and water).

Further options include a water treatment skid that can treat any excess water such as rainwater run-off to a discharge standard whereby all solids above 25 micron particle size have been removed, and the oil-in-water content is less than 5 ppm. Optional filtration and softener units or Reverse Osmosis systems permit the plant to run on either seawater or oil formation water if sufficient fresh water is not available locally.

The system is mobile, and can be assembled and disassembled in 2 days, allowing for flexibility of operation. The plant requires two to three operators, including the shovel driver.

Partial List of Projects on which AEV technology has been used:

Ystad, Sweden, 4000 tonnes of fuel oil contaminated sand
New Jersey, USA. 90,000 tonnes of sand /soil contaminated with PCB and Phthalates
Oil refinery, Sweden. Treatment of 4000 tonnes of Tank Bottoms
Tar pits, Layette, USA, 35,000 tonnes of oil contaminated tailings

Other contaminants that have been treated using the AEV system:

Contaminant	Type of soil	Tonnes
Cr (VI), CN, PAH	Clay	7,500	MPG plant
Pb, TPH	Sand, clay	5,000	Police shooting range
PAH, Ni, Cu	Soil	7,800	Non-ferrous strip mill
Dioxins, PCB	Soil	12,400	Former paper-mill
Cu, Ni, TPH	Soil	7,800	Scrap yard