Fermentation of human urine with agricultural Jiaosu and molasses: urease-catalyzed hydrolysis inhibition and microbial community enhancement

As a resource-oriented approach to domestic sewage management, the recycling of source-separated urine for agricultural use has garnered significant attention. To mitigate the risks posed by pathogens and elevated ammonia concentrations associated with urine collection and agricultural application, this study proposes and investigates an eco-friendly approach using Agricultural Jiaosu (AJ) and molasses for urine fermentation. Experimental results demonstrated that fermentation dramatically reduced free ammonia concentration and significantly inhibited pathogens in the urine from day 5 onwards. After 10-day fermentation period, the free ammonia was reduced to around 4.8% of the initial value in pure urine, and pathogens in the fermentation broth were reduced to below 7% in relative abundance for the large-scale experiment. The absolute abundances of Lactic Acid Bacteria (LAB) and P ichia spp. yeast both increased by more than an order of magnitude by day 10, with a strong positive correlation between them. These results indicate that the fermented solution is a safer urine-AJ combined blend, which can be beneficial to both crops and soil when diluted properly. To be economical and efficient, a 3% molasses addition and a 10-day fermentation period were recommended. This study provides an eco-friendly method for co-treating kitchen waste and source-separated urine, with potential applications in decentralized rural sanitation and agricultural biofertilizer production.