A flexible inventory model for municipal solid waste recycling

State laws mandate the recycling of municipal solid waste (MSW) across most of the United States. In order to comply, municipalities recycle quotas of materials, generally without regard to fluctuating prices. An inventory system is proposed that allows municipalities to be sensitive to materials prices as they recycle in accordance with state mandates. A dynamic model is developed that uses historical secondary material prices as exogenous inputs to minimize the net present value of MSW recycling system cost. The model provides a cost effective method for municipalities to achieve their MSW recycling targets. The savings is approximately $1.28 per ton of MSW generated as based on total MSWmanagement costs of $13.5 per ton. The model also allows one to investigate the effectiveness of various strategies for increasing the recycling rate, including reducing the transportation cost for recyclables, supporting the market price of selected secondary materials, and landfill bans on selected materials. Our proposed model may also be used to investigate the effect of market price changes on the portfolio of materials held in inventory for recycling. r 2005 Elsevier Ltd. All rights reserved.