Degradation of extracellular polymeric substances (EPS) and enhancement of sludge dewaterability by filamentous fungus Penicillium rubens

In present study, the isolation of filamentous fungal (FF) strain from sewage sludge was carried out and its effectiveness in enhancing the dewaterability of sludge was appraised. The filamentous fungi of Penicillium rubens isolated from sludge was taken into employment for evaluating the treatment performance. To understand the role of P. rubens in the degradation of extracellular polymeric substances (EPS) and dewatering of sludge, the isolated fungi was inoculated with mycelium into sterilized and nonsterilized sludge. Our obtained data illustrated that by inoculating fungal mycelium to the sterilized sludge, the outstanding development (by 84% reduced SRF) was found in sludge dewaterability. Adding fungal mycelium into the both sterilized and nonsterilized sludge was associated with reducing CST values by 79% and 68%, respectively; it signifies that the fungal mycelium develops the sludge dewaterability, which is expounded by the degradation of extracellular polymeric substances. A significant reduction in slime and loosely bound EPS (LB-EPS) was observed in the treated sludge, which was about 77.6% and 56.8%, respectively. The CST and SRF of fungal-treated sludge showed a significantly positive correlation with S-EPS (0.98) and LB-EPS (0.97). Considering the achieved results, P. rubens has the potential to be used as a biological dewatering agent (which is environmentally friendly), and a bright future can be anticipated for its application for the desired purpose.

Automated summary

In this study, a filamentous fungus Penicillium rubens was isolated from sewage sludge and its effectiveness in enhancing sludge dewaterability was evaluated. The results showed that inoculating fungal mycelium into sterilized sludge significantly improved sludge dewaterability by reducing SRF and CST values. The degradation of extracellular polymeric substances by the fungal mycelium was responsible for the improved dewaterability. The treated sludge also exhibited reduced slime and loosely bound EPS. The CST and SRF of the fungal-treated sludge were positively correlated with S-EPS and LB-EPS.