Microbial degradation of water-borne paint containing high levels of organic solvent

Abstract

A method for degrading, detackifying and reducing solvent in water comprising organic solvent-laden water-borne paint that comprises adding to the water an effective degrading, detackifying and / or solvent-reducing amount of at least one microorganism culture and sufficient micronutrients to sustain the growth of the at least one microorgansim culture and to reduce solvent content of the water. A method of reducing chemical oxygen demand in water comprising organic solvent-laden water-borne paint, wherein the water contains an excess amount of organic solvent from one or both of paint spray operations and paint spray nozzle cleaning operations, the method comprising adding to the water an effective degrading and detackifying amount of at least one microorganism culture and micronutrients to sustain the growth of the at least one microorgansim culture, whereby chemical oxygen demand in the water is reduced by at least 50% relative to the same system without adding the micronutrients.

Description

TECHNICAL FIELD[0001]This invention relates to a method for the degradation of water-borne paint containing high levels of organic solvent. More particularly, the invention relates to a novel biological method for the degradation of water-borne paint, its application for paint detackification, and reduction of chemical oxygen demand, in which the water-borne paint contains high levels of organic solvent.BACKGROUND OF THE INVENTION[0002]The detackification of sticky materials in aqueous systems is a common problem in many industrial operations. Particularly in the automobile industry, the products are coated or painted in enclosed areas referred to as paint spray booths. A significant portion of the paint is oversprayed, that is, not transferred to the object being coated. Such waste paint is generally referred to as oversprayed paint, and is usually collected in water for subsequent waste treatment.[0003]Paint is a tacky material and its tends to coagulate and adhere to the spray bo...

AI Technical Summary

Benefits of technology

[0015]In one embodiment, the present invention relates to a method for degrading, detackifying and reducing solvent in water comprising organic solvent-laden water-borne paint that comprises adding to the water an effective degrading, detackifying and / or COD reducing amount of at least one microorganism culture and sufficient micronutrients to sustain the growth of the at least one microorgansim culture and to reduce solvent content of the water.

[0016]In one embodiment, the present invention relates to a method of reducing chemical oxygen demand in water comprising organic solvent-laden water-borne paint, wherein the water contains an excess amount of organic solvent from one or both of paint spray operations and paint spray nozzle cleaning operations, the method comprising adding to the water an effective degrading, detackifying and / or COD reducing amount of at least one microorganism culture and micronutrients to sustain the growth of the at least one microorgansim culture, whereby chemical oxygen demand in the water is reduced by at least 50% relative to the same system without adding the micronutrients.

[0019]Although it is known to add nutrients to some systems, in the past it has been considered unnecessary to add nutrients to paint detackification operations, since it was known that sufficient micronutrients were provided by the paint itself. However, paint overspray containing high levels of organic solvents both places a higher organic load on the system and thus effectively makes the system deficient in the amounts of nitrogen and phosphorous that are required for sustained balanced growth and COD reduction. Nitrogen is necessary for amino and nucleic acids and phosphorus is necessary for energy compounds such as adenosine triphosphate (ATP). Lack of nitrogen and phosphorous therefore limits the growth of a culture of microorganisms.

Problems solved by technology

The present inventors have discovered that, while prior art microorganism based paint detackification processes have been able to carry out the function of paint detackification and COD reduction in the recirculating Water, in operations in which significantly higher concentrations of organic solvents are used, the microorganisms have been ineffective in reducing the COD.

The present inventors have discovered that, contrary to prior art practices, the nutrients normally present may be insufficient to promote adequate microorganism growth to obtain an acceptable COD reduction.

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