Enhancement of sewage sludge dewaterability by fungal conditioning with Penicillium simplicissimum NJ12: from bench- to pilot-scale consecutive multi-batch investigations

Abstract

Bench-and pilot-scale successive multi-batch trials were conducted to investigate the performance and sustainability of fungal conditioning with Penicillium simplicissimum NJ12 for improving sludge dewatering. The dominant factors affecting the sludge dewaterability improvement by P. simplicissimum NJ12 were also identi ed. Fungal treatment with P. simplicissimum NJ12 at a volume fraction of 5% of the inoculum greatly improved the sludge dewaterability. This improvement was characterized by sharp decreases in the speci c resistance to ltration from 1.97 × 10 13 to 3.52 × 10 11 m/kg and capillary suction time from 32 to 12 s within 3 days. Stepwise multiple linear regression analysis showed that a marked decrease (58.8%) in the protein content in slime extracellular polymeric substances and an increase in the zeta potential of the sludge (from − 35 to − 10 mV) were the most important factors that improved the dewaterability of sludge after fungal treatment. Consecutive processes of fungal treatment could be realized by recirculating the fungal-treated sludge with a recycling rate of 1:2 (V biotreated sludge /V total sludge ). The treatment effectiveness was maintained only over three successive cycles, but replenishment with fresh P. simplicissimum NJ12 would be provided periodically at set batch intervals. These ndings demonstrate the possibility of P. simplicissimum NJ12-assisted fungal treatment for enhancing sludge dewatering.

Enhancing sludge dewaterability in sequential bioleaching: Degradation of dissolved organic matter (DOM) by filamentous fungus Mucor sp. ZG-3 and the influence of energy source

“…Throughout the incubation period, the mycelium exhibited a filamentous and evenly dispersed morphology, facilitating optimal contact between the mycelium and sludge DOM, thereby enhancing DOM degradation efficiency. Indeed, filamentous fungi can augment their biomass by redirecting their secondary metabolism to assimilate soluble substances from sludge, a phenomenon consistent with previous findings [ 19 , 28 , 31 – 33 ]. As the metabolism of DOM progressed and nutritional sources were depleted by Mucor sp.…”

“…from sludge, a phenomenon consistent with previous findings [19,28,[31][32][33]. As the metabolism of DOM progressed and nutritional sources were depleted by Mucor sp.…”

“…A notable increase in the median particle size (d50) of the sludge flocs occurred, rising from 17.90 μm of raw sludge to 21.87–34.32 μm. Fungal mycelia entrapped sludge particles, leading to the formation of larger sludge flocs, which enhanced the strength and rigidity of the fungal-treated sludge [ 33 ]. This entanglement with fungal mycelia enabled the sludge to maintain high permeability during pressure filtration and created spaces for the outflow of free water [ 33 ].…”

“…Fungal mycelia entrapped sludge particles, leading to the formation of larger sludge flocs, which enhanced the strength and rigidity of the fungal-treated sludge [ 33 ]. This entanglement with fungal mycelia enabled the sludge to maintain high permeability during pressure filtration and created spaces for the outflow of free water [ 33 ]. However, with the increase in energy source supplementation, the d50 of the sludge particles gradually decreased due to the breakdown of sludge flocs through bio-acidification, releasing trapped water within the flocs.…”

“…Furthermore, after sequential bioleaching treatment for 2 days, the particle size of the sludge is depicted in Fig 8 . A notable increase in the median particle size (d50) of the sludge flocs occurred, rising from 17.90 μm of raw sludge to 21.87-34.32 μm. Fungal mycelia entrapped sludge particles, leading to the formation of larger sludge flocs, which enhanced the strength and rigidity of the fungal-treated sludge [33]. This entanglement with fungal mycelia…”