BIOFILMS AND DISPERSANTS - A LESS-TOXIC APPROACH TO DEPOSIT CONTROL

Slime deposits are complex, containing highly diverse microflora along with wood fibers, fines, calcium carbonate, pitch, clay, and additive s. Mills routinely use biocides to control deposition. It may be possi ble to reduce the use of these toxic chemicals by adding appropriate d ispersants to the papermaking system. However, dispersant activity in papermaking systems is poorly understood, partly because of a lack of screening methods for evaluating nontoxic chemicals. This report prese nts the results of laboratory efforts to study the effect of dispersan ts on in vitro cultures of pure biofilms and biofilms containing calci um carbonate. Results from a mill trial of a nonionic polymer dispersa nt showed excellent inhibition of deposition.