An electrochemical strategy for dredged sediment resource utilization: Phosphorus forms transformation by a neutral pH electro-Fenton system

Abstract

Dredged sediment has a high-water content and complex contaminant composition, dramatically impacting the environment if not treated and managed correctly. However, at the same time, it is also a valuable phosphorus-rich resource. Treating contaminated dredged sediments for resource recycling is critical to achieving sustainable development goals. In this study, a novelty neutral pH electro-Fenton (EF) experimental device was specifically designed for phosphorus (P) transformation study in dredged sediment. Result showed that the transformation of P forms in dredged sediments due to ·OH generation in this EF system. The decrease rates of organic P (OP) and apatite P (Ca–P) were 21.8 % and 69.6 %, respectively, while, the increase rates inorganic P (IP) and non-apatite inorganic P (Fe–P) were 25.2 % and 250.0 %, respectively, after 6 h of EF reaction. Analysis of the microbial community revealed that the EF reaction did not significantly reduce microbial diversity in the dredged sediment (p > 0.05). Furthermore, the abundance of Massilia and Thiobacillus, which are involved in transforming P form, increased significantly following the EF reaction and was positively correlated with Fe–P and IP (R2 > 0.999) and negatively correlated with OP and Ca–P (R2 > 0.999). This study proves that treating polluted dredged sediment with a neutral pH EF system can transform P into bioavailable forms. This work provides a new and sustainable strategy for recycling P from phosphorus-rich waste streams as a substitute for mining P rock.