THE EFFECT OF 2,2-DIBROMO-3-NITRILOPROPIONAMIDE, 2-(THIOCYANOMETHYLTHIO) BENZOTHIOAZOLE AND ALKALI DIMETHYL BENZYL AMMONIUM CHLORIDE ON MICROORGANISMS IN A PAPER MACHINE WHITE WATER SYSTEM, ON MACHINE RUNNABILITY AND PAPER QUALITY

An optimum temperature, humidity and ample easily assessable nutrient sources in the paper machine favor the multiplication of bacteria and fungi. As a result, they do not only impair the quality of paper (as per norms for food grade paper), but also reduce the paper production, because of numerous interruptions. The present study aims at determining the various microbes, such as total bacteria, sulphate reducing bacteria, iron bacteria, pseudomonas, yeasts and filamentous fungi present in the white water of the paper machine. The effect of three biocides, namely, 2,2-dibromo-3-nitrilopropionamide, 2-(thiocyanomethylthio) benzothioazole and alkali dimethyl benzyl ammonium chloride on various microbes are studied. It is observed that biocide 2,2-dibromo-3-nitrilopropionamide has a wide spectrum effect on all types of bacteria and fungi, its killing efficiency being, in most cases, of about 100%. A plant trial conducted with 2,2-dibromo-3-nitrilopropionamide indicates that the number of breaks is reduced from 10 to 3 in 24 h, while paper properties get improved.