Recycling. Colorado Metropolitan Denver sewage disposal district to complete design of sludge recycling project. Post Je 16, 1976 p.4 Aspen Ribbons Boulder recycling company featured. Post Jy 18, 1976 p.6E U.S. Enviromental Protection Agency demands proof that sludge recycling project will not pollute underground water. Post AS 4, 1976 p.37 Denver firm, Friedman & Son, Inc., to build new paper- recycling plant in Englewood. RMN AS 13, 1976 p.57