Historical and projected trends of siloxane use in consumer products, associated impacts on municipal solid waste and landfill gas utilization

Abstract

Siloxanes are used in industrial applications including electronics, automotive industry, textiles, construction, medical equipment, food packaging, medicine and cosmetics because of their antimicrobial properties, hydrophobicity and biocompatibility. Presence of siloxanes in landfill gas creates operational challenges at biogas-to-energy facilities due to accumulation of silicon oxides on engine components, increasing the energy recovery costs. In this study, the projected siloxane content in municipal solid waste was estimated based on the trends in patent applications for silicone-based products and siloxanes used in consumer products. Paper/paperboard and construction wood are the two waste categories with the highest silicone use. Based on the analyses of trends in silicone-based patents granted and silicone use in wood and paper, the quantities of siloxanes entering landfills are estimated to increase by approximately 29% in conjunction with a 5% increase in silicone-containing products within the next 10 years and 78% within the next 25 years. These projections take into account the lag time between the use of silicone in consumer products, product use period before being discarded and decomposition times in landfills.