Underestimated humic acids release and influence on anaerobic digestion during sludge thermal hydrolysis

Novel Insights into the Mechanisms of Periodate-Based Pretreatment in Enhancing Short-Chain Fatty Acids from Waste Activated Sludge

“…Among these recalcitrant organics, lignocellulose and humic-like acids should be given more attention considering their substantial release with the disintegration of the EPS matrix, due to which they are identified as the key inhibitory substances for hydrolytic processes. 23,39 To overcome the difficulty in identifying the specific role of PI in these typical recalcitrant organics in the complicated fermentative system and provide a better understanding of the potential of PI-based pretreatment S3). (B) Degradation rates of the model substrates for hydrolysis, acidogenesis, acetogenesis, and methanogenesis, and (C) relative activities of protease, α-glucosidase, acetate kinase (AK), and F 420 .…”

“…Otherwise, the prerequisite process of refractory organics transformation was the breakage of benzene rings and CC bonds, which could be destroyed by radicals . The decrease in aromaticity could greatly diminish the suppression on anaerobes . More detailed mechanisms are discussed in the following sections.…”

“…The above discussions reflected that PI pretreatment could not only promote the WAS solubilization for providing more bioavailable substrates for the utilization of SCFA generation but also improve the nonbiodegradable substances’ transformation, thereby avoiding the inhibition to anaerobes. Among these recalcitrant organics, lignocellulose and humic-like acids should be given more attention considering their substantial release with the disintegration of the EPS matrix, due to which they are identified as the key inhibitory substances for hydrolytic processes. , To overcome the difficulty in identifying the specific role of PI in these typical recalcitrant organics in the complicated fermentative system and provide a better understanding of the potential of PI-based pretreatment technology in the degradation and utilization of recalcitrant organics containing WAS during the acidogenic fermentation, batch tests using model substrates were performed. As shown in Figure A,B, the fluorescence intensity of the nonbiodegradable region with addition of PI was apparently less than that of control (without PI addition).…”

“…Besides the low intensity, the fluorescence peak with PI treatment was located at a shorter wavelength, indicating the existence of simple structural components, namely, a relatively small molecular weight and a low degree of aromatic polycondensation . It was in good agreement with the decreased color coefficients ratio of E 4 / E 6 (Table S2), which was inversely proportional to the aromatic condensation. Xu et al reported that KMnO 4 ( E 0 = +1.68 V) could damage the benzene and aromatic CC from the structure of lignocellulose and humus.…”

Electron shuttles enhanced the removal of antibiotics and antibiotic resistance genes in anaerobic systems: A review

“…Anaerobic biological treatment plays a pivotal role due to the advantages of low operating costs, low sludge production, and biogas recovery ( Chen et al, 2008 ; Cao and Pawlowski, 2012 ; Rizzo et al, 2013 ; Zhang et al, 2022c ). However, current anaerobic treatment technologies still have limits such as vulnerability to environmental impacts, long conversion time of intermediates fermentation and low organic matter conversion rates ( Meng et al, 2017a ; Zhao et al, 2017 ; Huang et al, 2021 ). In addition, the bactericidal or bacteriostatic properties make it inevitable that antibiotics entering the biological treatment unit will markedly reduce the efficiency of the biological treatment system and even collapse it ( Khurana et al, 2021 ).…”