Experimental Investigation of Recycling of MLP and LDPE Plastic Waste into Cofiring Fuel and Sustainable Materials

Global waste is a major issue in day-to-day life, which affects human health and environmental conditions. This includes all types of waste yielded by human activities. This research focuses on plastic waste only. The consumption and production of plastic waste are directly proportional to the world population. Recycling of these plastic wastes is of the utmost importance. In this study, a thermomechanical recycling technique is utilized, which overcomes the plastic waste production and its accumulation. This is the most suitable method with minimal adverse environmental effects due to different grades of waste plastic. The potential of this method is to produce value-added products, such as plastic fuels for cofiring in cement and steel industries and plastic bricks used in sustainable housing, building materials, water resistance, etc. The production and utilization of these products are discussed with respect to the performance, environmental, and economic benefits. Analysis of calorific values is conducted by using an automatic bomb calorimeter at room temperature, which operates according to the ASTM E711 standard test for LDPE and MLP plastic waste samples. It is found that low-density polyethylene (LDPE) has a higher calorific value (40.1 MJ/kg) as compared to multilayered plastic (MLP) waste (28 MJ/kg). The compressive strength is tested using a universal testing machine (UTM) by utilizing ASTM D638 standard procedures. It is found that the LDPE and MLP plastic bricks give compressive strengths of 36.53 N/mm² and 24.53 N/mm², respectively, which is mainly dependent on the crack length propagation. These bricks have better compressive strengths as compared to conventional bricks. The fume production in this process is reduced to less than 10% in complete operation due to high-pressure and low-temperature conditions as compared to the conventional melting and reshaping processes. This research highlights that the products formed from plastic waste represent a promising technology toward sustainable waste management.