Abstract: To address the serious pollution of antibiotic-resistant bacteria (ARB) in excess sludge and the low treatment
rate,this study aims to develop an efficient and low-cost technology for inactivating sludge microorganisms based on the photocatalytic
effect of natural pyrite (FeS2),and to evaluate its feasibility for practical sludge treatment. Using methicillin-resistant
Staphylococcus aureus (MRSA) as a typical ARB,the inactivation performance of the FeS2 photocatalytic system and its effect
on the minimum inhibitory concentration (MIC) of MRSA were investigated under different FeS2 dosages and pH conditions.
On this basis,a " CaCO3 +FeS2 +light" composite system was constructed and applied to inactivate microorganisms in actual
sludge thickening tanks. The microbial removal efficiency,sludge settling performance,and underlying mechanisms were analyzed.
The FeS2 photocatalytic system achieved optimal inactivation of MRSA at a dosage of 0. 25 g/ L under acidic conditions,
leading to complete inactivation and a reduction of the MIC value to one-quarter of its initial level. Under neutral conditions
(mediated by CaCO3),the "CaCO3 +FeS2 +light" system achieved over 99% removal of microorganisms from actual sludge,
without negatively affecting sludge thickening performance. Mechanistic analysis revealed that FeS2 photocatalysis accelerated iron
cycling through photoinduced electron transfer,promoting the generation of hydroxyl radicals (·OH) with an accumulated
concentration of 7. 17 μM,which subsequently disrupted the cell membrane structure and metabolic functions of the microorganisms.
The "CaCO3 +FeS2 +light" system based on FeS2 photocatalysis combines high efficiency,low cost,and good compatibility
with practical applications. It represents a promising technology for inactivating sludge microorganisms and provides theo
retical and technical support for controlling ARB in sludge.