Anja Maul

Central sorting and recovery of MSW recyclable materials: A review of technological state-of-the-art, cases, practice and implications for materials recycling

Todays waste regulation in the EU comprises stringent material recovery targets and calls for comprehensive programs in order to achieve them. A similar movement is seen in the US where more and more states and communities commit to high diversion rates from landfills. The present paper reviews scientific literature, case studies and results from pilot projects, on the topic of central sorting of recyclable materials commonly found in waste from households. The study contributes, inter alia, with background understanding on the development of materials recovery, both in a historical and geographical perspective. Physical processing and sorting technology has reached a high level of maturity, and many quality issues linked to cross-contamination by commingling have been successfully addressed to date. New sorting plants tend to benefit from economies of scale, and innovations in automation and process control, which are targeted at curtailing process inefficiencies shown by operational practice. Technology developed for the sorting of commingled recyclables from separate collection is also being successfully used to upgrade residual MSW processing plants. The strongest motivation for central sorting of residual MSW is found for areas where source separation and separate collection is difficult, such as urban agglomerations, and can in such areas contribute to increasing recycling rates, either complementary to- or as a substitute for source separation of certain materials, such as plastics and metals.

Insight into economies of scale for waste packaging sorting plants

This contribution presents the results of a techno-economic analysis performed for German Materials Recovery Facilities (MRFs) which sort commingled lightweight packaging waste (consisting of plastics, metals, beverage caitons and other composite packaging). The study addressed the impo1tance of economies of scale and discussed complementary relations occurring between capacity size, technology level and operational practice. Processing costs (capital and operational expenditure) per unit waste input were found to decrease from above 100 € for small plants with a basic technology level to 60-70 € for large plants employing advanced process flows. Typical operational practice, often riddled with inadequate process parameters was compared with planned or designed operation. The former was found to significantly influence plant efficiency and therefore possible revenue streams from the sale of output material streams.