Speciation transformation and bioavailability of heavy metals during biogas production from coal slime

Abstract

In order to increase the utilization of coal slime, achieve efficient utilization of resources and protect the environment, the changes in speciation transformation and bioavailability of heavy metals during the biomethane conversion process from coal slime were explored. The transformation of heavy metal speciation and bioavailability in different coal slimes during biomethane conversion were analyzed using biogas production simulations; fluorescence spectroscopy; determination and speciation of heavy metals; and inductively coupled plasma mass spectrometry. The results show that the organic matter in various coal slimes could be converted to biomethane. After biodegradation, the dissolved organic matter content dropped significantly. In addition, the concentrations of heavy metals in different coal slimes were significantly different. Among them, Zn, Ni, Cd and As were mainly found in the reducible fraction (F2); Cu was mainly found in the oxidizable fraction (F3); and Pb occurred predominantly in the residual fraction (F4). The biogas production process in coal slime had a great influence on the speciation of heavy metals. This research deepens the understanding of heavy metal migration in coal slime during biogas production, and provides a reference for clean utilization of coal slime and environmental protection.