Bio-dispersants on short loop treatment of paper machines

3 Bio-dispersants on short loop treatment of paper machines 

Conventional wisdom has held that dispersants act as biopenetrants to open the biofilms and allow penetration of the exopolysaccharides by biocides. Claims have been made that the dispersants act to allow penetration of the biocides into the cell or that the dispersants trigger biofilm sloughing. At best the mode of action of these dispersants is poorly understood. Among the difficulties of work with non-toxic agents is the lack of measurement systems. Evaluation of biocides is done by measuring kill or inhibition. With non-toxic materials, alternative methods of assessing chemical efficacy must be developed. 

Experimental methods that have been developed to evaluate bacterial biofilms and biofilms containing particulate calcium carbonates. These include environmental scanning electron microscopy (ESEM), Confocal Laser Scanning Microscopy (CLSM), and light microscopy in addition to gross diameter measurements. Chemical agents evaluated include various lignosulfonates and non-ionic dispersants. 

In parallel to lab experiences, optical fouling monitors and coupons (removed at 14 days intervals and analysed for colony forming units of aerobic bacteria and sulphate-reducing anaerobic bacteria) have been used to monitor and measure biofilm formation on machines. 

In lab studies, lignosulfonates did not appear to inhibit the formation of bacterial biofilms and even lignosul-fonate fractions containing sugars appeared to increase biofilm formation. 

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