Description
Sludge pits typically contain a semi-emulsified mixture of crude oil, water and miscellaneous solids (together with whatever else has been dumped in them - they are typically used as unofficial and unauthorized waste disposal sites. Cleanup of a sludge pit requires as a minimum efficient separation of oil, water and solids. The oil phase is then recombined with the crude stream, the water should be sufficiently clean (and especially hydrocarbon-free) to dispose of in any available waterway or well (it is EPA-approved for that) and the solids residue, after additional washing with OIL-XORB ERC or any biological treatment that may be necessary (depending on the origin and composition of the solids) should be clean enough to be land-filled.
Addition of OIL-XORB ERC to sludge pits has shown itself in field trials to be extremely effective in achieving all of these objectives although each application may require minimal experimentation on a small scale to define the optimum use conditions. OIL-XORB ERC affords excellent separation of the oil and water components of sludge into two layers that can then be separated by mechanical skimming and promotes settling of solids to the bottom of the pit. From there, the solids can easily be removed after the supernatants liquid have been pumped off and easily stripped of any residual contaminants by re-washing with OIL-XORB ERC. The OIL-XORB ERC solution can be recycled until it is no longer effective (with makeup OIL-XORB ERC, depending on the water level in the untreated sludge, since this acts as a diluent) or it can be disposed of. More OIL-XORB ERC than the usual 10:1 formulation should be used in cases where the sludge has an unusually high water content (say >25%). Even at these higher concentrations, the effluent OIL-XORB ERC solution is not harmful to aquatic species and its use and disposal is approved by the EPA.
Procedure
The best approach is to circulate the sludge (if it will flow - some sludge contains too much solid material that can vary from spent catalyst to sand and scale) using a suitable pump and holding tanks, during which time it is blended with the appropriate amount of OIL-XORB ERC. In most cases, a heater and two tanks are needed - one tank to contained the separated (typically skimmed) oil and one to separate solids from the OIL-XORB ERC solution. A third, smaller tank in which the solids can be washed and, if necessary, treated biologically, is often useful. Even more efficient separation of solids can be achieved by centrifuging, but this type of equipment is seldom readily available.
The contents of the sludge pit are circulated continuously. OIL-XORB ERC is injected into the circulating stream at a rate sufficient to provide a total dosage of 2 bbl (about 110 U.S. gallons) of OIL-XORB ERC to 1,000 bbl (56,000 US Gallons) of sludge. Heating may be desirable to reduce the viscosity of the sludge (which is often high due to suspended solids), especially in cold climates. The receiving tank should be set up to permit continuous skimming of the oil layer, which rises to the top and is transferred to the second receiving tank. The first tank provides both space and time for the solids to settle while the third permits washing of the solids before disposal in a landfill.
Product Recovery
About 90-95% of the oil or crude in the sludge pit will be recovered. Typically, 1,000 bbl of sludge will contain about 50% of crude or crude equivalent. Thus, 450-500 bbl of this should be recoverable. At current world crude prices, this is a substantial saving
Competing Products
OIL-XORB ERC is not aware of any equally effective or equivalent product on the market. Several products from suppliers such as Nalco and Petrolite claim to facilitate sludge pit cleanup but are reportedly much less effective, much more costly and less environmentally friendly. Most allow only minimal recovery of usable hydrocarbons from the sludge.