Low Residual Toxicity Microbiological Control, 1997 Engineering & Papermakers Conference Proceedings

To meet ever more stringent discharge levels and future changes preventing the use of enviromnentally harmful biocides, UK Paper trialled a new concept in deposit control fron Nalco. There was a wish in the mill to reduce reliance on conventional organic biocides, which break down slowly into relatively toxic products. A more environmentally friendly programme that would not jeopardise the runnability of the paper machine - PM6 -was required to give the mill a competitive edge.

Extensive evaluation was carried out both on site and at one of Nalco’s customer service laboratories, to determine the effectiveness of peroxyacetic acid / hydrogen peroxide technology prior to the first trial. Initial results showed a major improvement in the programme effectiveness in terms of control of microbiological populations, with the added benefits of a significant reduction in levels of residual toxicity. One of the components of the programme can be demonstrated to break down completely to totally non-toxic end products, namely carbon dioxide and water.

An on-line deposit monitor had been developed for use with this programme and was used on PM6 backwater system to gather background information, prior to and during the...