Conversion of solid waste from electricity cogeneration into slow-release fertilizer

Abstract

Sugarcane bagasse from the sugar and ethanol industry is generated in large quantities in Brazil and is typically burned in plant boilers to produce electricity in the so-called cogeneration process. After combustion, the remaining solid waste, known as sugarcane bagasse ash (SCA), does not have many applications and is usually discarded around the industries. SCA can be converted into zeolites, which can be applied as support for the slow-release fertilizers, treatment of industrial effluents, carbon sequestration and capture, among others. Therefore, the present study aimed to obtain high-purity type A zeolite from SCA with NH4+ incorporated into its structure and evaluate its application in agriculture. An SCA sample generated in a power cogeneration plant located in São Paulo, Brazil, was used to synthesize zeolite type A (ZASC), which was characterized in terms of chemical composition (XRF), mineralogical composition (XRD), and morphology (SEM). Ammonium ion was incorporated into ZASC by ion exchange. The presence of NH4+ in the zeolite structure was confirmed by using the Fourier Transform Infrared Spectroscopy (FTIR) technique. The NH4+ modified zeolite was labelled as ‘ZASCN1’. The amount of NH4+ released from ammonium-modified zeolite (ZASCN1) over time was evaluated through contact with water and saline solution in a static system and the concentration was measured by ion chromatography. Results showed that ZASCN1 can release a greater amount of nutrients in saline solutions when compared to water. In addition, both curves showed that the release of NH4+ occurred slowly and steadily for more than 1 month. Therefore, it can be concluded that the sugarcane industry has many possibilities for research, as well as the development and generation of products with market competitiveness, as the slow-release fertilizers, following the principles of the circular economy.