Solid waste based manufactured soil – Stabilization of “organics-microorganisms-inorganic skeleton” and performance evaluation

The safe disposal and utilization of bulk solid waste (SW) are critical challenges. Manufactured soil, a soil-like material composed of SW, offers a novel solution for resource recycling. However, the mechanisms underlying SW-based manufactured soil fertility development remain unclear. This study systematically investigated the performance of SW-based manufactured soil using aerobic compost sludge (ACS-soil) and anaerobic digestion sludge (ADS-soil), focusing on the microbial mechanism which driving manufactured soil fertility development. Results showed that the soil nutrient index (SNI) of SW-based manufactured soil was 5 to 8 times higher than that of natural topsoil. These soils significantly promoted wheatgrass growth. However, ACS-soil exhibited superior fertility and plant performance, maintaining stable nutrient levels, whereas the SNI value and soil pH of ADS-soil decreased by 27.13% and 17.68% respectively. Microbial community analysis revealed that homogeneous selection in ACS-soil drove microbial community succession, maintaining stable nutrition content and increasing humification degree. In ADS-soil, the rich in labile compounds (accounting for 41%) led to lower environmental stress, stochastic processes dominated bacterial succession, which driving declined pH and thus negatively impact the soil fertility. Furthermore, based on life cycle analysis results, using SW to prepare manufactured soils had lower carbon emissions than conventional disposal methods (including safe landfill, incineration and direct land use), which demonstrated that SW-based manufactured soil is a promising method for SW disposal. This research underscores the potential of SW-based manufactured soil for waste disposal and enhanced plant growth, emphasizing the importance of selecting appropriate organic components to optimize soil performance.