A pilot-scale nonwoven roll goods manufacturing process reduces microbial burden to pharmacopeia acceptance levels for non-sterile hygiene applications

A total of seven source fiber types were selected for use in the manufacturing of nonwoven roll goods: polyester; polypropylene; rayon; greige cotton from two sources; mechanically cleaned greige cotton; and scoured and bleached cotton. The microbial burden of each source fiber was measured as a preliminary assessment of microbial contamination using heterotrophic spread plate counts. Greige cotton fibers exhibited the highest levels of total microbial contamination, which were reduced by both storage time and trash removal in the form of mechanical cleaning. Changes in microbial burden levels were measured at each step in the nonwoven manufacturing process. The hydroentanglement process resulted in the greatest overall reduction in microbial burden with no detectable levels of aerobic microbial contamination present on any of the final hydroentangled roll goods regardless of the source fiber. No detectable levels of aerobic microbial regrowth were observed on any fabrics despite storage time or ambient storage conditions. Analysis of suspended solids present in hydroentanglement effluents collected during fabric production revealed significantly less suspended solids from synthetic fibers compared to all cotton fiber types. The study provided insight and potential guidelines that could be incorporated into a nonwoven processing line to ensure specific sterility requirements are met for various converters in end-uses such as hygiene and medical applications.