Background:  As the largest composter of MSW in North America, the City of Edmonton produces over 50,000 tonnes per year of quality compost which is marketed for agricultural and other uses. One of the challenges is achieving an acceptable level of removal of the miscellaneous glass pieces that accompany typical MSW. While current screening systems are quite effective, the City has a policy of continual improvement and wishes to further improve this characteristic of the compost product.

Objective: To develop a mechanical system that can effectively remove and/or size-reduce glass particles so that any remaining glass is - in quantity, size and characteristic - small and benign.

Status:  Work has been ongoing for about a year. That work has included a broad review of existing technologies and the principles of various materials separation and size-reduction technologies, such as air classification, density separation, screening and pulverization.  In parallel, several hybrid "test-bed" devices have been assembled and tested in the Solid Waste R&D Facility. Two promising technologies are being further developed, with a goal of having a full scale working prototype operating at the R&D facility by the end of March. That device will be evaluated and modified as dictated with an end objective of producing a production unit for installation in the Edmonton Composting Facility by the fall of 2008.  The technologies are based on the principles of "bounce" separation, air classification, and impact size reduction.

Researchers: John Kienholz, Ray Holowach, Bud Latta