Liquid purification or separation – Processes – Making an insoluble substance or accreting suspended...
Patent
1994-03-29
1995-09-26
Hruskoci, Peter A.
Liquid purification or separation
Processes
Making an insoluble substance or accreting suspended...
210710, 210714, 210725, 210727, 210909, 252358, C02F 156
Patent
active
054532051
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the separation of the component of an emulsion.
the term "emulsion" is herein understood to mean a dispersion of a liquid phase in a continuous liquid phase, with either one or both of the liquid phases containing contaminants.
One specific example of a relatively complex emulsion is abattoir waste. Abattoir waste comprises a dispersion of a liquid phase of oils, fats and/or grease (hereinafter referred to as "the oil phase") in an aqueous phase, and further comprises contaminants:
The contaminants include bacteria count, nutrients, BOD, sand, grit and faeces.
Abattoir waste does not satisfy the environmental requirements for disposal into river and stream systems and thus has to be treated to separate the oil phase from the aqueous phase and to remove the contaminants from the aqueous phase before disposal of the aqueous phase is possible. Generally, such treatment includes transferring the abattoir waste through a series of aerobic and anaerobic dams. This is not an altogether satisfactory treatment regime in view of the set-up and on-going costs involved. A further disadvantage is that the treatment is not adapted to recover economically valuable contaminants, such as dissolved protein, in the abattoir waste.
Another specific example of a relatively complex emulsion is mineral oil waste from de-greasing units widely used in industry. Typically, in such units suitable solvents are sprayed onto equipment to dissolve the oil/grease on the equipment, water is then sprayed onto the equipment to remove the dissolved oil/grease and remaining solvent, and the resultant emulsion, which by this stage includes grit and other contaminants, is collected in a sump and pumped to a settling pond.
Mineral oil waste does not satisfy the environmental requirements for disposal into river and stream systems and thus has to be treated to separate the oil/grease phase from the aqueous phase and to remove the solid and liquid contaminants from the aqueous phase before disposal of the aqueous phase is possible. At present there is no altogether satisfactory cost-effective treatment regime for this purpose.
An object of the present invention is to provide a process for separating the components of an emulsion.
A more particular object of the present invention is to provide a process for separating the components of complex emulsions comprising an oil-based liquid phase dispersed in a continuous aqueous phase, such as abattoir waste, mineral oil waste, dairy waste and food waste, to allow the aqueous phase to be released into river and stream systems.
According to the present invention there is provided a process for separating the components of an emulsion, as described herein, comprising the following steps in sequence: in the emulsion; forming the substantially uniform dispersion of inert particulate carrier in the emulsion to form floccs of the inert particulate carrier, the dispersed liquid phase, and the contaminants; settled floccs.
The basis of the present invention is that it has been found unexpectedly that adjustment of the pH of an emulsion, such as abattoir waste, to 4 or less and the addition of a coagulant has the effect of conditioning the emulsion so that inert particulate carrier and flocculent can separate the dispersed liquid phase and the contaminants, including dissolved contaminants, from the continuous liquid phase of the emulsion. The unexpected finding is derived from the combined effect of acid and coagulant being greater than the separate effect of acid and coagulant.
The term "inert" as used herein in relation to "particulate carrier" is understood to mean that the particulate carrier is not substantially attacked by the emulsion. In other words, the term "inert" means that the particulate carrier exhibits both suitable chemical and physical stability in the emulsion.
It is preferred that the flocculent is a polyelectrolyte flocculent. The term "polyelectrolyte flocculent" as used herein is understood to mean any suitable cationic, non-ionic and anionic flocculent.
It
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patent: 4997573 (1991-03-01), Browne
patent: 5133870 (1992-07-01), Heidenreich
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Hruskoci Peter A.
Modern Environmental Service Trust
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