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.

Because of their superior environmental performance, mycelium-based composites (MBCs) offer a promising sustainable lightweight alternative material. MBCs are frequently prepared using agricultural by-products as substrates. However, because agricultural by-products are seasonal, their output is limited by a constant need for substrates. In order to examine the feasibility of creating MBCs using sewage sludge (SS) in place of bagasse, 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 analysis were tested and analyzed. The results showed that the bagasse MBCs’ colonization appearance took precedernce over that of the SS MBCs at early stagy. However, both the bagasse and SS promoted fungal growth to create a dense mycelial network on day 10. The bagasse-based MBCs were the lightest and adding SS increased the density and compressive strength of the MBCs. The volume shrinkage first decreased and then increased. The optimal ratio of mycelium to sewage sludge was 2:1, which produced an outstanding compressive strength of 690.20 KPa. The thermal conductivity of bagasse-based and SS-based MBCs were 0.12 Wm-1K-1 and 0.13 Wm-1K-1. The physico-mechanical characteristics satisfiy the requirements of lightweight backfill materials in highway. Additionally, SS improved the hyphae of MBCs, giving them a denser and stronger structure. In comparison to bagasse, it also showed better thermal stability and a higher residual mass. It is feasible to produce MBCs with SS in place of bagasse, and the biocomposite proposed in this study could be used as lightweight backfill materials that are widely needed in highway.

Sewage sludge is an inevitable solid waste of wastewater treatment. Its low-carbon treatment and resource utilization is becoming an urgent and inevitable issue. In this paper, the production status of sewage sludge in Sichuan Province was investigated, the current treatment process and disposal status of sludge projects were summarized. Additionally, the new approaches of resource utilization were reviewed with a view to providing reference for the optimization of sewage sludge treatment and disposal processes for other cities and the industry.