Hypochlorite oxidation coupled with FeCl3 flocculation to improve sludge dewatering
In this experiment,hypochlorite coupled with FeCl3 flocculation was used to study the dewatering performance of sludge.The optimal pretreatment conditions were determined by single factor experiment.The mechanism of the pretreatment promoting the sludge dewatering performance was analyzed and clarified by using characterization methods such as zeta potential,protein polysaccharide,DNA content,magnetic field nuclear resonance,three-dimensional fluorescence and cell visualization.Pearson correlation analysis was used to further analyze the reasons for the improvement of sludge dewatering performance.The results showed that the sludge dewatering efficiency reached the highest when the dosage of NaClO was 50mg/g TS and FeCl3 was 100mg/g TS.The specific resistance and CST of the original sludge decreased from 2.45×1012m/kg and 119.7s to 9.3×1011m/kg and 27.9s,respectively.Sludge lost the most water and dehydrates the fastest.Under the combined action of oxidation and flocculation,the EPS structure of the sludge was destroyed,the sludge particles were loose,and the internal bound water was released.The increase of DNA content in sludge and the visualization analysis of sludge showed that the cell membrane of microorganism in the floc was destroyed,resulting in the release of intracellular water,thus improving the dehydration efficiency of activated sludge.
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