Effect of Bioenzyme on Deinking Mill Effluent Treatment by Dissolved Air Flotation, 2002 Environmental Conference Proceedings

M. Sain, A. Mehta, Y. Ni and D. Norneau

The Pulp and Paper mills in North America are looking for new efficient technology to clean their process water for value-added recycling. Their ultimate goal is to reduce fresh-water consumption and also to reduce the toxicity load to the surface water, mainly from the local rivers. Currently, Dissolved Air Flotation (DAF) technology is available for reduction of suspended solids up to and above 99%; however, it alone does not reduce the dissolved organic, anionic trash, and color content. A combination of novel-physico-chemical treatment along with existing technology is needed to effectively treat white water to help improve the water recycling efficiency.

For the first stage, DAF technology was used along with a sequence of chemicals to reduce the dissolved volatile organic compounds and anionic trash from deinking mill wastewater. The chemicals investigated consisted of a bioenzyme, colloidal silica particles, cationic polyamine, and an anionic flocculent. It was found that the DAF along with a specific sequence of chemical addition to the wastewater effectively reduced the dissolved organic compounds and color, under temperature and pH control. A longer retention time after DAF process improved water quality significantly. Although several mill trials were taken without bioenzymes, none of them showed effective removal of dissolved solid. A mill trial involving bioenzyme and prolonged retention time after DAF process is under consideration.