A combined system for asbestos-cement waste degradation by dark fermentation and resulting supernatant valorization in anaerobic digestion

The use of biological processes for the treatment of asbestos cement waste (ACW) has gained interest in recent years. Nevertheless, this methodology is not yet consolidated because of the incomplete ACW conversion during the biological treatment and the consequent need for further treatments that generally require a high amount of energy and chemicals. In this study, the efficiency of both mesophilic and thermophilic dark fermentation (DF) fed with glucose in fed-batch conditions was assessed for ACW biological treatment. Both thermophilic and mesophilic DF of glucose resulted in a partial conversion of glucose into organic acids that successfully degraded all the asbestos fibers contained in an ACW sample. A hydrogen-rich biogas was produced as well: at the end of the mesophilic DF treatment 0.14 L-H2 g(glucose)(-1) were obtained. In addition, the anaerobic digestion (AD) of the DF supernatants led to the production of 0.38 L-CH4 g(COD)(-1).

Automated summary

This study evaluates the efficiency of mesophilic and thermophilic dark fermentation (DF) using glucose as the substrate for the biological treatment of asbestos cement waste (ACW). The results show that both types of fermentation partially convert glucose into organic acids, successfully degrading asbestos fibers and producing hydrogen-rich biogas.