Design of an Msw·composting Facility

This report provided a good description of a generic large scale composting plant. In this light, it is useful to those who have little knowledge of how such a facility is composed. Of particular interest is the detailed compo­ sition of the Portland waste stream which is presented and which can be compared to other areas. While the flow diagram is complete, generally it would be more illuminating if the mass balance at the various process points were presented. One item not mentioned in the text was whether it was planned to periodically remix and turnover the material during its 21 days on the aeration bed. I believe this is necessary for a good quality product. Since the report was generated in conjunction with the design of a specific plant, a brief summary of con­ struction and operating costs, along with personnel re­ quirements, would be helpful. Construction and op­ erating costs would vary considerably depending on days/year of operation and number of shifts/day. Also, a cash flow analysis would be important to determine the sales price of the compost. A further item of interest would be some indication of how the compost will be utilized in the Portland area and if there is a market to meet the required sales price.