Date of Award
Bachelor of Science
Paper Science and Engineering
Dr. David K. Peterson
A review of flocculation is presented. Included is a discussion concerning the factors controlling pigment and heavy metal removal via flocculation treatment. Also included is a brief background on the regulatory status concerning the heavy metals contained in flexographic inks. A detailed experimental procedure involving the use of jar tests and several industrial polymers is included along with the analyses performed.
It is found that flocculation treatment of flexographic washwaters produces excellent results with respect to clarity and heavy metals removal. In most cases flocculation at an optimum concentration followed by simple gravitational settling resulted in heavy metals removal well within the federal safe drinking water standards. Heavy metal and turbidity removal were proven to have a strict linear relationship to one another with respect to flocculant dosage.
Both the flocculation and settling characteristics of this laboratory study appear to coincide with typical industrial waste treatment practices. The flocculants produced optimum removal of turbidity and heavy metals well within the manufacturers suggested addition range. The gravitational setting of the floc formations was representative of ranges found in common industrial treatment parameters. Overall, this experiment points favorably to the feasibility of polymer treatment of flexographic washwaters followed by gravitational settling as a treatment application in the flexographic and boxboard industry.
Bray, Jack R., "Coagulation and Flocculation of Flexographic Ink Washwaters by Various Organic and Inorganic Polymers" (1981). Paper Engineering Senior Theses. 39.