Dry Mills Research Articles

Effects of Personal Exposures on Pulmonary Function and Work-related Symptoms among Sawmill Workers

Three green mills and two dry mills were studied for personal exposure to wood dust and biohazards associated with wood dust and their correlation to lung function and work-related symptoms among sawmill workers. The levels of exposure to endotoxin, (1-->3)-beta-D-glucan, bacteria and fungi were high in green mills compared with dry mills. Compared with dry mill workers, green mill workers had significantly high prevalence of regular cough, chronic bronchitis, regular blocked nose, regular sneezing, sinus problems, flu-like symptoms, and eye and throat irritation. Significant positive correlations were found among endotoxin and Gram (-)ve bacteria, (1-->3)-beta-D-glucan and fungi, and endotoxin and (1-->3)-beta-D-glucan exposure levels. Significant dose-response relationships were found for personal exposures and lung function, and lung function and work-related respiratory symptoms. The significant correlations found for respirable fractions show that not only inhalable but also respirable fractions are important in determining potential health effects of exposure to wood dust. The management and employees of the sawmilling industry should be educated on the potential health effects of wood dust. Wood dust should be controlled at the source.

Effects of Personal Exposures on Pulmonary Function and Work-related Symptoms among Sawmill Workers

Three green mills and two dry mills were studied for personal exposure to wood dust and biohazards associated with wood dust and their correlation to lung function and work-related symptoms among sawmill workers. The levels of exposure to endotoxin, (1→3)-β-D-glucan, bacteria and fungi were high in green mills compared with dry mills. Compared with dry mill workers, green mill workers had significantly high prevalence of regular cough, chronic bronchitis, regular blocked nose, regular sneezing, sinus problems, flu-like symptoms, and eye and throat irritation. Significant positive correlations were found among endotoxin and Gram (−)ve bacteria, (1→3)-β-D-glucan and fungi, and endotoxin and (1→3)-β-D-glucan exposure levels. Significant dose–response relationships were found for personal exposures and lung function, and lung function and work-related respiratory symptoms. The significant correlations found for respirable fractions show that not only inhalable but also respirable fractions are important in determining potential health effects of exposure to wood dust. The management and employees of the sawmilling industry should be educated on the potential health effects of wood dust. Wood dust should be controlled at the source.

Control of the mill charge behavior in dry tumbling mills

Powder filling of a dry mill has a large influence on grinding capacity and wear rate of grinding media and liners. In particular low powder filling levels can cause extensive wear rates. This paper discusses the influence of some operating parameters of the mill circuit on powder filling, when airflow through the mill is applied. An method of warning against low powder filling levels inside the mill is shown, a piezoelectric strain transducer installed on the mill shell accomplishing this task.

Conversion of corn milling fibrous co-products into ethanol by recombinant Escherichia coli strains K011 and SL40

Corn hulls and corn germ meal were both evaluated as feedstocks for production of ethanol for biofuel. Currently, these fibrous co-products are combined with corn steep liquor and the fermentation bottoms (if available) and marketed as cattle feed. Samples were obtained from wet and dry corn mills. The corn hulls and germ meal were evaluated for starch and hemicellulose compositions. Starch contents were 12 to 32% wlw and hemicellulose (arabinoxylans) contents were 23 to 64% w/w. Corn fibrous samples were hydrolysed, using dilute sulphuric acid, into mixed sugar streams containing arabinose, glucose and xylose. Total sugar concentrations in the hydrolysate varied from 8.4 to 10.8% w/v. The hydrolysates were fermented to ethanol using recombinant E. coli strains KOll and SL40. Ethanol yields were 0.38 to 0.41 g ethanol producedlg total sugars consumed and fermentations were completed in 60 h or less. However, residual xylose was detected for each hydrolysate fermentation and was especially significant for fermentations using strain SL40. Strain KOll was a superior ethanologenic strain com­ pared with strain SL40 in terms of both ethanol yield and maximum productivity.