Advanced Powder Technology, Vol.18, No.1, 53-67, 2007
Analysis of enzyme dust formation in detergent manufacturing plants
In the detergent industry, enzymes are used to catalyze the breakdown of tough stains such as oils and fats, which cannot be easily removed with surfactants and bleaches. In the 1960s, a number of plant workers developed respiratory allergies from inhaling enzyme dust over long periods. The response from the enzyme manufacturing companies was to encapsulate the enzymes by granulation, fluid bed coating, extrusion and other techniques. The end users of encapsulated enzymes such as the detergent industry concentrated on the installation of engineering containment and dust extraction systems. These were combined with other safe systems of work, including airborne monitoring and health surveillance. The result was a significant decrease in the concentration of airborne enzyme dust in the working environment and virtually eliminated the incidence of respiratory allergy. However, enzyme dust generation has not been eliminated completely and the integrity of the enzyme encapsulates remains a key control point. In 2000, the Enzyme Dust Consortium was formed with the objective to design a validated test method with a protocol (for granule qualification and quality control) to correlate with dust levels in plant. Current test methods for dust formation do not replicate the mechanical stresses in the detergent plant and limit the enzyme manufacturer's ability to develop better granules. Our efforts are focused on evaluating the prevailing mechanical stresses in detergent manufacturing plants and their effect on enzyme granule attrition. Dust sampling of the factory ventilation ductwork show a large variation in enzyme dust levels. This may be attributed to the presence of some weak granules. Nevertheless, the likely sources and mechanisms of enzyme dust need to be identified. Once a new testing procedure is established, enzyme manufacturers will be able to design and produce improved products that will result in a further reduction of enzyme exposure in detergent manufacturing facilities.