The report gives an overview of equipment used for municipal solid waste (MSW) size reduction and discusses its performance and cost. Of the 11 basic equipment types used for shredding MSW, only hammermills and grinders find wide application. An evaluation of available hammermill and grinder performance data indicates that: their specific energy consumption is independent of throughput for the same product size distributions and feed characteristics (power, however, is a function of throughput). Higher shaft speeds produce finer size distributions and require more energy for the same throughputs; smaller grate spacings (exit clearances) produce finer particles; and for constant feed and shredder operating conditions, specific energy consumption is a minimum at 30-40% refuse moisture content. On the basis of available cost estimates, the initial cost for shredders ranges from $3528 to $6174 per Mg/hr. Fine shredding performance or cost benefits information is not available. The need for fine shredding in most material/energy recovery systems is currently dictated by process constraints and the benefits may be system specific.

Issued July 1976. Includes bibliographical references (pages 56-58).