Dissolved and Colloidal Substances (Dcs) and the Charge Demand of Papermaking Process Waters and Suspensions: A Review

Abstract

Dissolved and colloidal substances (DCS) in the process waters of paper machine systems can interfere with the retention of fine particles, retard the drainage of water from the wet web, and generally hurt the intended functions of various polyelectrolytes that are added to the process. This review considers publications that have attempted to characterize the nature and effects of different DCS fractions, in addition to some of the ways that paper technologists have attempted to overcome related problems. The consequences of DCS in a paper machine system can be traced to their ability to form complexes with various polyelectrolytes. Such tendencies can be understood based on a relatively strong complexing ability of multivalent materials, depending on the macromolecular size and charge density. Continuing research is needed to more fully understand the different contributions to cationic demand in various paper machine systems and to find more efficient means of dealing with DCS.

Wastewater Treatment and Reclamation: A Review of Pulp and Paper Industry Practices and Opportunities

“…The situation just described can be addressed by use of a charge demand titration (Hubbe et al 2012b). The charge demand corresponds to the amount of a strongly charged polyelectrolyte that needs to be added to reach a charge-neutral condition of the surfaces (Rasteiro et al 2008; Blanco et al 2002a,b).…”

“…The heating is probably responsible for increased release of material into the water phase (Rintala and Puhakka 1994;Stephenson and Duff 1996;Kortekaas et al 1998;Willfor et al 2003), though the literature search did not reveal data to support such an expectation. The peroxide-bleaching of thermomechanical pulp (BCTMP) is known to convert hemicellulose components of TMP into negatively charged carboxylate species, which readily enter into solution and can contribute to the pollutant load (Sundberg et al 2000;Puro et al 2010;Hubbe et al 2012b;Miao et al 2013). In general, however, high-yield pulps contribute relatively low levels of COD to the effluent.…”

“…zero zeta potential) is to allow for the efficient action of another charged additive, the flocculant, which is called a "retention aid" by papermakers. By leaving a small proportion of the original negative charge at the surfaces of the fibers, a cationic acrylamide copolymer of very high molecular mass is able to find suitable points of adsorption in order to be effective (Hubbe et al 2012b). Retention aids have been shown to function by a bridging mechanism, such that the polyelectrolyte is able to join the solids together efficiently, especially in the presence of agitation (Gregory 1973;Hubbe et al 2009).…”

“…Follow-up tests might be done if the best treatment level appeared to be outside of the tested range. A further challenge faced by operators of wastewater treatment plants is that the coagulant by itself sometimes is insufficient to bring about a distinct change in the appearance of the mixture; rather, the desired rapid settling and large flocs might occur only upon addition of the flocculant, and then only if the coagulant had been added within a narrow optimum window of treatment level.The situation just described can be addressed by use of a charge demand titration (Hubbe et al 2012b). The charge demand corresponds to the amount of a strongly charged polyelectrolyte that needs to be added to reach a charge-neutral condition of the surfaces (Rasteiro et al 2008; Blanco et al 2002a,b).…”

Polyethyleneimine Addition for Control of Dissolved and Colloidal Substances: Effects on Wet-End Chemistry

“…In the papermaking process it is difficult to solve problems related to dissolved and colloidal substances (DCS) (Holmbom and Sundberg 2003;Zhang et al 2007;Hubbe et al 2012). The DCS can interact with inorganic electrolytes such as Ca 2+ and soluble aluminum compounds in the wet-end system, leading to the formation of deposit-prone substances.…”