SAS Environmental Services Ltd.

Surface active solutions tank cleaning & crude oil sludge removal


Courtesy of SAS Environmental Services Ltd.

For over ten years Surface Active Solutions has led the way in developing integrated microemulsion solutions for tank cleaning operations, crude oil sludge treatment and slops treatment. The company, with offices in Houston and Grangemouth (Scotland) aims to create real synergy in its approach to tank cleaning by combining its microemulsion chemistries with automated tank cleaning systems.

The cleaning out of oil and fuel storage tanks, supply vessels and tanker trucks is still a time consuming task. All too often tank cleaning results in the generation of large quantities of liquid waste containing wash fluid, oil and solids ranging from clays, sand to carbon and other particles.

The cleaning of tanks from 1,000m3 to 100,000m3 can take anywhere from a few days to a few weeks or even several months depending on the level of contamination, viscosity of the fuel to be removed and the man power employed to carry out the task. The common method of tank cleaning is still one of tank entry by a manual work force that then has to construct scaffolding in order to use scrubbers and sometimes hand held power washers to remove the fuels. In those situations where the fuel is of a relatively high viscosity it is not uncommon that temperatures have to be maintained over 40 – 50oC (100 – 130F) to stop fuel from waxing out past the point where removal is feasible.

In addition the actual cleaning takes a lot of expensive and valuable time. The storage tank is out of service while being cleaned, the supply vessel is not available and the mud pit cleaning could well hold up the drilling process. Surface Active Solutions has developed the philosophy that tank cleaning and the treatment of oily waste could and should be carried out in the most effective way possible, causing the least disruption to operations, and creating from that a minimal volume of waste. In fact, our philosophy was, and is, that any oil trapped in the waste either on the solids or within an emulsion waste represents lost value and lost resource.

Working closely with our partners and clients over the past decade has resulted in the development of some very simple solutions that deliver some remarkable results.

SAS microemulsions chemistries have the ability to reduce the time needed for tank cleaning from several days or weeks to a matter of hours or 1 or 2 days. Looking back over the past ten years we can safely say that in general time requirements for tank cleaning operations are reduced by 50 – 80% when using SAS products compared to water or solvent washes or simple manual cleaning.

The process of using microemulsion products itself is very simple and revolves around two key benefits of the SAS products. The first benefit is the highly efficient cleaning effect of the washing fluid. This very quickly removes any hydrocarbon residues and immediately lowers the viscosity of any sludge or tank bottoms present allowing for easy transportation out of the tank.

The second benefit is the prevention of any emulsion waste forming, which is so often the problem when using standard detergent cleaning products.When using the microemulsion products the waste stream is pumped out of the tank and the solids very quickly settle in a simple settling tank or weir tank allowing the wash fluid to be re-used. Because virtually no solids are carried over in the wash fluid the tank cleaning equipment used does not suffer from blockage or erosion by clay and sand particles.

The automated tank cleaning systems used run on significantly lower pressure than many high pressure systems. In fact the SAS automated tank cleaning systems run on a pressure of 100PSIG or 7 bar. This lower pressure results in less damage to protective coatings on the inside of tanks and is made possible through the use of microemulsion products. Instead of physically moving the waste with the impact force of the jet, the waste is removed through the cleaning effect of the SAS microemulsion products.

SAS products are generally supplied in a highly concentrated format which reduces transport costs. The products can then be diluted to any concentration for use in water and usually a dose of around 5 – 10% is highly effective in most tank cleaning projects. Re-using this wash water 5 – 8 times is custom.

Over the past eight years SAS products have been used to clean out hundreds of tanks, treat thousands of tonnes of oil emulsion waste, tank bottoms and drilling mud slops. Our automated tank cleaning systems are found as mobile CIP systems on the back of trucks and fixed installed on drilling rigs. The philosophy of recovering the resources trapped in waste and doing so efficiently and simply is indeed leading to some remarkable results.

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