The Effluent-Free Mill (EFM) and Salt Recovery Process (SRP) Archive Project

In 1967, Professor Howard Rapson of the Department of Chemical Engineering and Applied Chemistry, University of Toronto, outlined the Effluent-Free Mill (EFM) and Salt Recovery Process (SRP). This technology aimed to facilitate the elimination of effluent from bleached kraft pulp mills by using the wastewater from pulp bleaching in the chemical recovery cycle whereby the organics would be destroyed in the kraft recovery boiler and spent bleaching chemical (sodium chloride) would be removed from the collected recovery boiler flue gas dust.

In recognition of the commercial potential of the EFM and SRP technology, a joint venture company, ERCO Envirotech Ltd., was formed in 1972 between ERCO, a Canadian chemical company supplying chemicals and equipment for pulp bleaching and Envirotech, an American company manufacturing equipment suitable for the SRP. In 1974, ERCO Envirotech Ltd. presented a proposal to Great Lakes Paper Company in Thunder Bay, Ontario. Great Lakes agreed to the proposal and integration of EFM and SRP technology into the design of the mill began.

Professor Douglas W. Reeve of the Department of Chemical Engineering and Applied Chemistry at the University of Toronto collaborated with ERCO Envirotech Ltd. and the Great Lakes Paper Company as the lead process engineer for the EFM and SRP during the process pilot plant development, mill design, mill construction and the extended start up. The mill, also referred to as Closed Cycle Mill, started up in late 1976 and the SRP in March of 1977. The Closed Cycle Mill faced many operational challenges in bleaching, in bleach plant effluent recovery, in salt recovery and in the recovery boiler. Ultimately, owing to poor environmental performance, high costs, and poor reliability, Closed Cycle operation was shutdown.

Added by Nourane Abdelshafy, May 2025