A STUDY OF THE MICROFLORA OF SOME RECYCLED FIBER PULPS, BOARDS AND KITCHEN ROLLS

Current methodology used for studying the microflora of pulps and boar ds was assessed and some improvements are recommended. Microbiological quality of 37 samples including recycled fibre pulps, boards, kitchen rolls, virgin fibre sheets and circulating process water were investi gated. The papermaking process had drastically reduced the total micro bial counts. The dominant microflora in all the samples were aerobic b acteria. The amounts in boards were only 10(3)-10(6) cfu g(-1) d.w., w hereas the untreated pulps contained 10(8)-10(10) cfu g(-1) d.w. Aerob ic, anaerobic and facultatively anaerobic spore-forming bacteria forme d a large group in the bacterial flora of pulp samples (10(3)-10(6) an d 10(2)-10(4) cfu g(-1) d.w., respectively). In the boards the maximum numbers of aerobic spore-forming bacteria were about 10(4) cfu g(-1) d.w. and the numbers of anaerobic and facultatively anaerobic spore fo rmers were negligible. Moulds were common in the untreated pulp sample s at 10(2)-10(6) cfu g(-1) d.w., but their occurrence in boards was cl ose to the detection limit. Yeasts were common only in the pulps of on e mill, and were found to be present in the circulating process water. Both mesophilic and thermophilic actinomycetes were detected in pulps at levels up to 10(2)-10(5) cfu g(-1) d.w. However, no mesophilic act inomycetes were detected in boards, although some boards contained up to 10(2) cfu g(-1) d.w. of thermophilic actinomycetes. The virgin fibr e sheets were practically free of microbes. Only a few bacterial colon ies were detected from the kitchen rolls.