85 / 2023-07-05 08:02:24

The influence mechanisms of proteins in the extracted extracellular polymers substances on sludge dewaterability

Sludge; Extraction methods; Protein; Dewaterability; secondary structure

The amount and characteristics of EPS extracted from sludge were examined in this paper using six typical extraction techniques. Two of them are physical extraction methods: CER and heating methods. The EDTA method, formaldehyde-heating method and formaldehyde+NaOH method are chemical extraction methods. Centrifugation method was used as the control group. The effects of different extraction methods on sludge dewaterability were investigated by Capillary Suction Time (CST) and Specific Resistance to Filtration (SRF) analysis. The results showed that the formaldehyde+NaOH method had the highest efficiency in EPS extraction. Though the higher EPS extraction rate have the greater damage to the sludge flocs, which may make the dewaterability worse, especially some heating methods. Then, the impacts of different extraction methods on the secondary structure of proteins in EPS were further analyzed, and the influence of the structure on the dewaterability of sludge was also discussed. It can be found that protein functional groups play a dominant role in dewaterability of sewage sludge, and the change of the content of α-helix will have an adverse effect on the dewaterability. Also, the higher the peak strength of tyrosine in sludge proteins indicates the better dewaterability of sewage sludge.