Effects of potassium ferrate oxidation on sludge disintegration, dewaterability and anaerobic biodegradation

• Effect of K2FeO4 oxidation on sludge properties was systematically studied.
• K2FeO4 oxidation effectively disintegrated sludge and maximum DDCOD reached 69%.
• More polysaccharides were released from EPS than proteins after K2FeO4 oxidation.
• SRF value reduced by 85% with a K2FeO4 dosage of 500 mg/L.
• Sludge biogas production increased by 44% with a K2FeO4 dosage of 500 mg/L.

Chemical oxidation is a common sludge pretreatment method. This paper studied the effects of potassium ferrate (K2FeO4) oxidation on sludge disintegration, dewaterability and anaerobic biodegradation. Results showed that K2FeO4 oxidation effectively disintegrated sludge, improved sludge dewaterability and enhanced sludge biodegradability. The suitable K2FeO4 dosages for sludge disintegration, dewaterability and anaerobic digestion were all 500 mg/L. The maximum sludge disintegration degree (DDCOD) reached 69% with a K2FeO4 dosage of 500 mg/L. After K2FeO4 oxidation, extracellular polymeric substance (EPS) concentration in the supernatant increased, and the increase of polysaccharides was larger than that of proteins. K2FeO4 oxidation deteriorated the sludge settleability, but significantly improved the sludge dewaterability. Both sludge specific resistance to filtration (SRF) and viscosity decreased after K2FeO4 oxidation especially the sludge SRF reduced by 85% with a K2FeO4 dosage of 500 mg/L. For sludge anaerobic biodegradation, the cumulative biogas production remarkably increased with 500 mg/L K2FeO4 pretreatment, and the final cumulative biogas production increased by approximately 44% compared to control.

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