Technical Bulletin No. 0033: Kraft Mill Waste Report – The Use of pH as an Indicator of the Pollutional Potential of Kraft Mill Pulp Wastes

Throughout the aquatic biology work on kraft mill wastes in the course of which, a number of mill surveys were made, it appeared that an index of waste strength representative of the concentration of substances potentially toxic to fish would be desirable. Such a method would be particularly useful if means existed for recording it automatically and continuously in the waste flow and the recorder equipped with signaling devices to warn operators of high strength discharge. During the last year, the Council's project at the Institute of Paper Chemistry under the leadership of Dr. Willis Van Horn undertook this problem. It was concluded from their studies, which are contained in the report enclosed, that pH can be employed as a useful index of waste strength during most periods of mill operation. The pH values can be continuously recorded accurately by several instruments on the market.