Pilot Testing of a Zero-Discharge Treatment Processby Pascale Lagacé,
Paul R. Stuart,
Abstract: As environmental regulations become more stringent, pulp and paper mills are investigating alternatives to conventional biological treatment and discharge of effluents into receiving waters. Closed cycle operation, the complete recycle of treated mill effluent, is increasingly being considered as a serious option from environmental, regulatory and economic standpoints. This paper presents the results of pilot scale trials for a zero discharge effluent treatment process at a TMP-newsprint mill. The process consists of aerated basins followed by physical-chemical treatment. The Bio-Lime process is efficient at removing most organic contaminants, maintaining a low hardness of the treated wastewater, and does not require sophisticated and expensive equipment. This makes it a promising zero discharge technology. It was found that a combination of lime and sodium carbonate as the physical-chemical treatment gave the best treatment efficiency when used in combination with the biological treatment process. BOD5 removals of over 99% were achieved, as well as 80% removal of organic carbon and over 90% removal of resin and fatty acids. Resin and fatty acids are known to cause product quality problems in the production of newsprint at concentrations that would be typical with zero-discharge operation. The treatment process also removes over 85% of critical metal contaminants such as aluminum, iron, manganese and zinc.
Subject Headings: Biological processes | Chemical treatment | Effluents | Environmental issues | Industrial wastes | Water discharge | Acids
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