Experimental Assessment of Multiple Properties of Mycelium-Based Composites with Sewage Sludge and Bagasse

Mycelium-based composites (MBCs) have a lot of potential as an alternative lightweight material due to their small environmental footprint and their biodegradability. The unique properties of cellulose-rich sewage sludge (SS) allow it to be used as a substrate for manufacturing MBCs. In order to examine the feasibility of creating MBCs using SS, this study used SS and bagasse as nutrient substrates and cultivated MBCs on ready-made mycelium (Pleurotus ostreatus). The physico-mechanical properties, morphological properties, and thermal stability of MBCs were tested and analyzed. The results show that both the bagasse and SS promoted fungal growth to create a dense mycelial network on day 10. Adding SS increased the density and compressive strength. The volume shrinkage of the MBCs first decreased and then increased. The optimal ratio of ready-made mycelium-sewage sludge was 2:1. The thermal conductivity of the bagasse-based MBCs was 0.12 Wm^-1K^-1 and that of the SS-based MBCs was 0.13 Wm^-1K^-1. These physico-mechanical characteristics satisfy the requirements of lightweight backfill materials for use in highways. Additionally, the SS supported more robust growth of hyphae and resulted in stronger MBCs. In comparison to bagasse, it also showed better thermal stability and a higher residual mass. It is feasible to produce MBCs with SS, and the biocomposite proposed in this study could be used as a lightweight backfill material of the type that is widely needed for use in highway construction and maintenance.