Metal-free catalysis for organic micropollutant degradation in waste activated sludge via poly(3-hydroxybutyrate) biopolymers using Cupriavidus sp. L7L coupled with peroxymonosulfate

This study employed a novel and environment-friendly biopolymer/oxidant catalytic system, viz., poly(3-hydroxybutyrate)/peroxymonosulfate (PHB/PMS), for pretreating wastewater sludge for the first time. Under optimal conditions, i.e., 3.1 x 10(-4) M of PMS and 3.3 g/L of PHB at pH = 6.0, the PAHs in the sludge matrix was decreased by 79 % in 12 h. Increase in salinity (75 % synthetic seawater) achieved 83 % of PAHs degradation. Functional groups (C=O) of the biopolymer matrix were active centers for biopolymer-mediated electron transfer that produced reactive oxygen species (SO4 center dot-, HO center dot, and O-1(2)) for adsorption and catalytic oxidation of PAHs in the sludge. Functional metagenomic analysis revealed the main genus, Conexibacter (phylum, Actino-bacteria) exhibited PAH-degrading function with high efficiency in the biodegradation of PAHs from sludge pretreated with PHB/PMS. Coupling chemical oxidation and biostimulation using bacterial polymer-based bio-materials is effective and beneficial for pretreating wastewater sludge toward circular bioeconomy.

Automated summary

This study employed a novel and environment-friendly biopolymer/oxidant catalytic system, poly(3-hydroxybutyrate)/peroxymonosulfate (PHB/PMS), for the first time to pretreat wastewater sludge. The results showed that under optimal conditions, the PAHs in the sludge matrix were significantly decreased, and increasing salinity further improved the degradation. Functional metagenomic analysis revealed the efficient PAH-degrading function of the Conexibacter genus in the system.