Integration of Ozone and Membrane Processes for Bleach Plant Effluent Treatment, 2004 Paper Summit, Spring Technical & International Environmental Conference, (including Papermakers; Process Control, Electrical & Information; Product & Product Quality)

The effect of combining ozonation with membrane process on the removal of biologically recalcitrant organic compounds of alkaline bleach plant wastewater was investigated. A ceramic membrane with nominal cut off of 1000 Da was used to separate organics based on their molecular weight. A bubble column reactor was used for ozonation studies. Different chemical and environmental parameters including COD, TC, pH, color, and ozone concentrations in the gas and liquid phases were measured. Preliminary characterization of the alkaline effluent indicated that high molecular weight (HMW) portion of the wastewater consisted mainly of color causing and biorefractory compounds. Ozonation of the alkaline bleach plant wastewater could reduce COD and TC by 20% and 7%, respectively. Pretreatment of the effluent by ultrafiltration, on the other hand, enhanced COD and TC removal by 35% and 25% during ozonation while consuming less amount of ozone. Reaction of ozone with alkaline effluent removed color significantly. Color removal was almost 20% higher for HMW fraction of the wastewater. pH of the solution also decreased significantly during the ozonation process, indicating the production of organic acids. Significant pH and color removal was associated with cleavage of chemical bonds, addition of oxygen to the organic molecules, and production of carboxylic functional groups during ozonation.