Changes of effective phosphorus content and its simple microbiological mechanism during electric field-assisted aerobic fermentation of municipal sludge

Phosphorus bioavailability proved a critical indicator for assessing compost product quality, yet the efficiency of phosphorus activation in traditional sludge composting processes is unfavorable. This study investigated the effects of the presence and absence of an external electric field on the transformation of phosphorus fractions during the composting process, and analyzed the roles of phosphorus-solubilizing bacteria communities such as such as Proteobacteria and Bacteroidetes. Results demonstrated that the electric field-assisted aerobic composting (EAC) facilitated the conversion of more organic phosphorus (OP) to inorganic phosphorus (IP), leading to a 23.76% increase in available phosphorus (AP) compared to the conventional aerobic composting (CAC). Applying an electric field induced alterations in the composition and structure of the phosphorus-solubilizing bacteria community during composting, and significantly enhanced the phosphatase activity. Furthermore, the variance partitioning analyses (VPA) indicated phosphatase was the primary factor in phosphorus activation during electric field-driven composting, accounting for 46.82% of the contribution. In summary, the EAC can significantly enhance the compost, boost the activities of phosphorus-solubilizing bacteria, and augment the biotransformation of phosphorus in compost products.