Study On Treatments Of The Stickies In Wastewater Of Pulping From Waste Paper With Enzymes

With the increases of regenerated fiber using, the impurities problem from the waste paper has become more serious, especially in which the pitch trouble causing by stickies received. The stickies are found mainly in waste paper stock and follow-up white water system As the stickies rise to a certain level, drainage in the wet-end of the paper machine becomes uneven, resulting in paper flaws such as paper hole and stain. In addition, a series of corrosion problems were emerged from the synergistic effect between the stickies and other pollutants, which would cause the stickies barriers and affecting the production.There fore, the study on the stickies is very important in the recycle of waste paper.Treatments of the stickies in homemade wastewater of pulping from waste paper with two kinds of lipase were investigated. The FTIR and GC-MS were used to investigate the compositions of the stickies and characterize the pulping wastewater of the recycled fibers. The processes of the enzymatic treatments were optimized through the study of the factors that affect the processes, and FTIR and GC-MS were used to characterize the change between the treated wastewater under the optimal conditions and untreated wastewater. The simulative wastewater constitutes of model substance were treated with two kinds of lipase in order to furtherly understand the mechanism of enzymes controlling sticky. Results confirmed that the lipases are able to break the ester bonds of sticky, which is instrumental in the removing of sticky from the wastewater.The character of the wastewater were studied and the turbidity, conductivity, and average particle sizing were76.0NTU,1.05ms·cm-1and10243nm, respectively. And the CODcr was3650mg/L, pH was9.The CD of the wastewater was as high as0.725meq·L-1. IR spectrum shown that a very strong broad band near1300-1000cm-1which was due to the interactions of water with CO-O-C and C-O-C stretching of the ester and ether bonds, and the weak absorption band observed around3600cm-1due to the groups of O-H stretching of alcohols and phenols shown there were few hydroxyl groups of alcohols and phenols in the wastewater. Over20substances were detected by the GC-MS and the most of them were p-hydroxybenzoic acid dodecanoic acid tetradecanoic acid hexadecanoic acid dehydroabitetic acid and icosanoic acid.The optimal conditions for treatment of wastewater with lipases of R were revealed as enzyme dosage of20u/100mL, temperature of50℃, pH value of7.5and enzymatic contact time of2h; while the optimal conditions for lipase S treatment of wastewater were revealed as enzyme dosage of15u/100mL, temperature of50℃, pH value of7.0and enzymatic contact time of2h. Under these optimal conditions of each lipase, both of the two lipases show the excellent performance in the treatment of the stickies in the wastewater.Under the optimal conditions,simulative wastewater mainly consitsting the simulation model of stickies was treated and analyzed by the GC-MS. Results suggested that over40substances were detected from the extraction of the wastewater and the organic substance account99.66%of the extractive components. These organic substances include organic acid, alcohols, benzene, alkane and ether. The organic acids that relative amount account over5%include hexadecanoic acid, cis-octadecenoic acid, Octadecadienoic acid, Sandaracopimaric acid, dehydroabietic acid, abietic acid and Cholesterol. Though the species and quantity of the organic substance didn’t show apparent change before and after the enzymatic treating the wastewater, the relative amount of each organic substance species changed significantly. For example, the relative amount of Octadecadienoic acid, Sandaracopimaric acid, dehydroabietic acid, abietic acid, oleyl alcohol. Linoleic Acid, pimaric acid, isopimaric acid and glycerol monooleate in the wastewater decreased apparently after the treatment with lipases, indicating that lipase has a strong ability of degrading the resin acid, these results underlined that effective control of the pitch trouble can be reached by the treatment with the lipase.