Industrial-scale composting of swine manure with a novel additive-yellow phosphorus slag: Variation in maturity indicators, compost quality and phosphorus speciation

Composting experiment of swine manure, adding with yellow phosphorus slag(YPS) at 5% (w/w), was conducted in an industrial-scale reactor covered with semi-permeable membrane. During 27 days of composting, the changes in temperature, compost quality and phosphorus(P) speciation of products were monitored. Results indicated that the temperature of compost pile was sharply increased on day 2, and the thermophilic period lasted for 15 days. The dynamics in germination index(GI), pH, nutrient contents, etc. of products were in line with conventional composting process. For P distribution, the contents of total-P and citric acid extracted-P(CAP) of products were increased during composting, while that of Olsen-P was decreased. HCl extracted inorganic P(HCl-Pi), a slowly release fraction of P, was dominated in the product, which showed an increasing trend during the composting. These results suggest that the industrial-scale composting with novel YPS additive can be accomplished, and its product contains abundant slowly released P.