Exploring the Performance of Magnetic Immobilized Lysozyme on Sludge Hydrolysis and Mechanism of Improving Dewaterability of Excess Sludge

The performance of the immobilized lysozyme and the native lysozyme on enhancing the excess sludge dewaterability was investigated. The results indicated that the specific resistance to filtration(SRF) decreased by 62.8% for native lysozyme and 53.6% for immobilized lysozyme at the enzyme dosage of 9 mg/g(dry sludge). Correlation analysis was carried out to explore the role of different extracellular polymeric substance(EPS) fractions on excess sludge dewaterability. The results illustrated that the SRF negatively correlated with protein, polysaccharide from soluble EPS(S-EPS) and loosely bound EPS(LB-EPS) and positively correlated with that from tightly bound EPS(TB-EPS). Three-dimensional excitation emission matrix(3D-EEM) fluorescence analysis combined with the scanning electron microscope(SEM) images, revealed that sludge floc structure and microbial cells were destroyed by enzymatic treatment, and that the enzymatic hydrolysis could help to improve the transformation of hydrophilic groups from TB-EPS and the performance of the excess sludge dewatering process. The assessment of hydrolysis using the immobilized enzyme provided a new insight for the safe disposal of the sludge.