Application of Immobilized White Rot Fungi in the Treatment of Anaerobic Digestion Sludge
Anaerobic digestion sludge (ADS) contains recalcitrant organic matter and exhibits poor dewaterability, posing challenges for disposal. This study evaluated the immobilization of white rot fungi (WRF) on four carriers—polyvinyl alcohol, cotton thread, wood chips, and sodium alginate—for ADS treatment. Cotton thread immobilization yielded the earliest and most sustained enzyme activity, highest biomass retention, and minimal biomass loss. WRF treatment achieved a 10.09% removal of total chemical oxygen demand (TCOD) and significantly disrupted extracellular polymeric substances (EPS), selectively degrading soluble EPS. To maintain fungal activity, periodic carrier replacement was required. Compared to the control, the experimental group showed an 8.9 mg·L−1 reduction in total protein and polysaccharide content in soluble EPS, a 27.33% decrease in capillary suction time (CST), and improved sludge dewaterability. These results demonstrate the potential of WRF for ADS treatment.