Pulp and paper waste treatment

Although UF cannot recover the low MW sugars in waste from the pulp and paper industry, it can remove lignin compounds and most of the color bodies. 

Pulp is made by separating wood into individual fibers. This is done mechanically or chemically. Only 50% of the material in the tree is used as pulp. The remainder is often discarded as waste in the spent pulping liquor. 

In the mechanical process, logs are pressed against a rotating grindstone the resulting fibers are mixed with water and screen filtered. This mechanical pulp contains lignin, gums and mineral salts in addition to the wood fiber. 

Much of the BOD contribution is pulping wastes comes from low MW carbohydrates. RO can often reduce the BOD by 70 to 90% whereas UF effects only a 45 to 55% reduction in BOD.53 However, UF can remove 85 to 98% of the color bodies. 

Ultrafllter tion, mol.wt. Passing Retained Passing Retained 

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Kirkwood, E., Nalewajko, C., and Fulthorpe, R.R., Physiological characteristics of Cyanobacteria in pulp and paper waste treatment systems, J. Appl. Phycol. 15, 324-335, 2003. 

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