Treatment of reclaimed municipal solid waste incinerator sands using alkaline treatments with mechanical agitation

Abstract

Solid waste production is rapidly increasing, and municipal solid waste incinerator plants provide a practical and sustainable solution to significantly reduce the volume of waste. Incinerator ash is a byproduct of the combustion process, and lightweight sands can be reclaimed from the ash for use in cementitious materials once treated for hydrogen gas production. This work investigates treatment methods for reclaimed sands for use in concrete. A novel method based on a propriety patent to capture the amount of hydrogen gas production from reclaimed sands is presented using a steel pressure chamber, pressure transducer, and data acquisition system. The setup is maintained under a constant temperature, pressure, and agitation using an environmental incubator. Treatment methods using sodium hydroxide, reused sodium hydroxide, alumina, and alumina + sodium hydroxide are investigated. It is found that sodium hydroxide is an effective treatment solution for reclaimed sands, with the ability to reuse the solution multiple times. Alumina is found not to be an effective treatment method when used alone. Concrete is made using treated reclaimed sands, where it is shown through scanning electron microscopy imaging that large voids in the cement matrix due to hydrogen gas production are significantly reduced in size.