Liquid purification or separation – Processes – Liquid/liquid solvent or colloidal extraction or diffusing...
Patent
1994-01-12
1995-07-18
Spear, Frank
Liquid purification or separation
Processes
Liquid/liquid solvent or colloidal extraction or diffusing...
21050041, B01D 6114
Patent
active
054338603
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a method for the treatment of the effluent from the washing with water of an impregnated object, which method accomplishes the treatment without specially requiring addition of a chemical agent.
BACKGROUND ART
The practice of using a liquid impregnant such as sodium silicate or an unsaturated polyester or an aerophobic liquid impregnant for the purpose of infallibly sealing invisible pinholes in die-cast products and cast products of aluminum, zinc, and other metals; completely filling and sealing pores in sintered metal parts; preventing plated products from blowing by subjecting the parts to the treatment of impregnation before the step of plating; and sealing minute pores in porous non-metallic parts such as wood and ceramics has been in vogue.
For example, the impregnation of a given part is attained by: degreasing and cleaning the part; subjecting the cleaned part to vacuum aspiration in a vacuum tank, thereby removing entrapped air from the minute pores in the part; immersing the part in a bath of an organic liquid impregnant such as an aerophobic resin; maintaining the part in a vacuum; and subsequently exposing the immersed part to the atmospheric pressure, thereby causing the liquid impregnant to permeate the minute pores. In this case, the impregnation can be enhanced by supplying compressed air to the site of impregnation. Then, the liquid impregnant is returned to the reservoir and the part which has undergone the impregnation is centrifuged to expel the liquid impregnant adhering to the surface of the part. Thereafter, the part is cleaned with a detergent to remove the liquid impregnant still remaining on the surface of the part or in the tapped holes. The treatment of impregnation is finished by subjecting the part to a treatment for curing.
In this treatment of impregnation, the effluent to be discharged from the site of treatment is the spent detergent which results when the liquid impregnant, remaining only slightly on the surface of the part which has undergone the treatment of impregnation, is washed off with a detergent. Heretofore, organic solvents such as trichloroethane and fluorinated hydrocarbon have been used as detergents. On account of the anxiety about the environment and the concern about cost, the use of such organic detergents has been giving place to the use of water for the cleaning. In consequence of this trend, there has arisen the necessity for separating and recovering the liquid impregnant contained in the effluent before the effluent is discarded from the plant. This separation of the liquid impregnant from the effluent is a difficult matter.
For the treatment of the effluent of this nature, the following methods have been available to date.
(1) Method of adsorption: The liquid impregnant which is an organic substance is removed by adsorption using an adsorbent such as activated carbon. By this treatment, both the BOD and COD contents in the effluent can be lowered to below several ppm. Thus, this method may well be called a method for final treatment productive of an effluent tolerable for release into rivers. (2) Method of microorganic decomposition: This method, represented by the version resorting to the action of activated sludge, allows the same degree of treatment as the method of adsorption by the decomposition of organic matter with aerobic bacteria. (3) Method of combustion: The effluent is dispersed in heavy oil and the resultant mixture is burnt by spraying into a flame. Since this combustion produces carbon dioxide gas and water, this method effects perfect detoxification of the effluent. (4) Method of thermal polymerization: This method utilizes the phenomenon that an impregnant polymerized in water is insoluble in water. Generally, the water containing the impregnant is heated for the purpose of promoting the reaction. The treated effluent is subjected to solid-liquid separation by filtration or settling (difference in specific gravity). The treated effluent has a COD content of from some thousand to some t
REFERENCES:
patent: 4865742 (1989-12-01), Falletti
patent: 5273662 (1993-12-01), Muiseher et al.
Loctite Corporation
Miller Eugene F.
Spear Frank
Welch II Edward K.
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