Fabrication, testing and evaluation of a dust filtration system for small-scale spice grinding mills

Abstract

The generation of excessive levels of spicy aroma and the airborne dust in spice grinding mills is one of the main ergonomic problems of the workers and sometimes create social problems due to environmental pollution. Although the fine dust as well as the aromatic chemicals has an economic value, collection of them is fairly a difficult task under small-scale processing plants. A technically and economically feasible low-cost dust filtration system was designed to filter and maintain the concentration of airborne dust level below the recommended level of 10 mg/m 3 for 8-hour exposure time, in a spice grinding plant. The dust filtration system was designed based on a similar principle as in the existing spry tower filter. However, the method does not require very high pressure for fluid atomization as in that system and the unit can be fabricated using locally available materials with a very high lifetime. Dust measurements were carried out using a special cloth bag-collecting device with a fixed airflow rate.Dust removal rates were determined with different concentrations of a foaming shampoo (Lifebuoy shampoo) and a non-foaming detergent ('Rinso' automatic washing machine powder). Results showed that the filtration unit is capable of filtering airborne dust with an efficiency of 91% with the foaming detergent while an efficiency of 78% with the non-foaming detergent. An initial dust load of 108-150mg/m 3 in the air was reduced to 9.6mg/m 3 with the foaming detergent and 32mg/m 3 with the non-foaming detergent or tap water without any detergent. Therefore, the dust filtration system is effective only with the foaming detergent.