Dictyosphaerium sp.-treated aerobic digestate of perishable waste as substitution for vegetable hydroponic nutrient solution

Aerobic bio-digestion is a potential solution for managing perishable waste, but it also produces digestates that contain high salinity and nutrients. These digestates are often treated as wastewater, leading to resource wastage. The main objectives of this study were to investigate and determine the viability of repurposing the aerobic digestate derived from perishable waste as an alternative nutrient solution for vegetable hydroponics. The digestate was rich in carbon sources and other nutrients, indicating its potential for algal culture and crop hydroponic culture. The raw digestate contained various types of suspected pathogens and exhibited high plant phytotoxicity. Dictyosphaerium sp. was isolated to treat digestates due to its high tolerance to the digestate. It efficiently reduced salinity, chemical oxygen demand (COD), and led to enrichment in symbiotic bacteria and fungi and reduction in pathogen abundance. Correspondingly, the digestate treated with algae showed a significant reduction in plant phytotoxicity, and the microalgae provided organic nutrients (e.g. amino acids) beneficial for crops. Metabolomic analysis results indicated that Dictyosphaerium sp. could efficiently utilize the carbon and nitrogen sources in the effluent. The digestate treated with algae could replace 20 % to 60 % of the Hoagland nutrient solution in hydroponic cultivation for radish and Chinese cabbage, thereby enhancing the sustainability of the aerobic bio-digestion solution in perishable waste treatment.