Feasibility analysis of continuous extraction of biomaterials from flocculant sludge and potential applications in the fire protection field

The sludge contains many high-value biological materials. However, current extraction methods focus only on individual materials, neglecting the further extraction potential of the residual after extraction. This study used continuous extraction to extract extracellular polymeric substances (EPS) and proteins (PN) from sludge, verified the flame retardancy of EPS and the foaming properties of PN and finally analyzed the economic feasibility of continuous extraction. The results showed that continuous extraction increased the protein extraction from 857.11 mg/L to 1089.41 mg/L. EPS reduced the heat release rate of linen fabric from 379.2 (J/g center dot K) to 38.3 (J/ g center dot K), and PN achieved foaming capacity and stability reaching 770% and 71%, meeting the standards of foam extinguishing agents. The binding form of EPS with linen fabric and the peptide content in PN are crucial factors affecting their application effectiveness. Economic analysis showed that continuous extraction reduced processing costs by 37.64% compared to traditional sludge disposal methods.