Enhanced acidogenic fermentation from Al-rich waste activated sludge by combining lysozyme and sodium citrate pretreatment: Perspectives of Al stabilization and enzyme activity

Facilitating effects of the synergy with zero-valent iron and peroxysulfate on the sludge anaerobic fermentation system: Combined biological enzyme, microbial community and fermentation mechanism assessment

This study evaluated a synergetic waste activated sludge treatment strategy with environmentally friendly zero-valent iron nanoparticles (Fe0) and peroxysulfate. To verify the feasibility of the synergistic treatment, Fe0, peroxysulfate, and the mixture of peroxysulfate and Fe0 (synergy treatment) were added to different sludge fermentation systems. The study demonstrated that the synergy treatment fermentation system displayed remarkable hydrolysis performance with 435.50 mg COD/L of protein and 197.67 mg COD/L of polysaccharide, which increased 1.13-2.85 times (protein) and 1.12-1.49 times (polysaccharide) for other three fermentation system. Additionally, the synergy treatment fermentation system (754.52 mg COD/L) exhibited a well acidification performance which was 1.35-41.73 times for other systems (18.08-557.27 mg COD/L). The synergy treatment fermentation system had a facilitating effect on the activity of protease, dehydrogenase, and alkaline phosphatase, which guaranteed the transformation of organic matter. Results also indicated that Comamonas, Soehngenia, Pseudomonas, and Fusibacter were enriched in synergy treatment, which was beneficial to produce SCFAs. The activation of Fe0 on peroxysulfate promoting electron transfer, improving the active groups, and increasing the enrichment of functional microorganisms showed the advanced nature of synergy treatment. These results proved the feasibility of synergy treatment with Fe0 and peroxysulfate to enhance waste activated sludge anaerobic fermentation.

Synergistic promotion of sludge reduction by surfactant-producing and lysozyme-producing bacteria: Optimization and effect of Na. BIORESOURCE TECHNOLOGY 2024;393:130065. [PMID: 37984671 DOI: 10.1016/j.biortech.2023.130065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

To improve the efficiency of aerobic digestion, this investigation utilized the synergistic effect of lysozyme-producing strain YH14 and surfactant-producing strain ZXY4 to promote sludge hydrolysis, and added NaCl to enhance this promoting effect. The best performance in promoting sludge hydrolysis was achieved when the inoculum of functional bacteria was 12 % (inoculum ratio of strain YH14: strain ZXY4 = 1:3) and the dosage of NaCl was 5 g L-1, which caused an increase of 19.25 % in the SS removal rate and 2588.21 mg L-1 in the SCOD release, as compared with the control. Fluorescence region integral analysis shows that the synergy of two functional bacteria and NaCl can enhance the biodegradability of sludge. Protein secondary structure analysis shows that strain ZXY4 and Na+ cause the EPS structure to loosen, increasing the chances of lysozyme lysis of bacteria. Nucleotide metabolism, metabolism of other amino acids and membrane transport enhanced in a co-processing system.

Enantioselective effects of chiral prothioconazole and its metabolites: Oxidative stress in HepG2 cells and lysozyme activity

Chiral pesticides may exhibit enantioselectivity in terms of bioconcentration, environmental fate, and reproductive toxicity. Here, chiral prothioconazole and its metabolites were selected to thoroughly investigate their enantioselective toxicity and mechanisms at the molecular and cellular levels. Multispectral techniques revealed that the interaction between chiral PTC/PTCD and lysozyme resulted in the formation of a complex, leading to a change in the conformation of lysozyme. Meanwhile, the effect of different conformations of PTC/PTCD on the conformation of lysozyme differed, and its metabolites were able to exert a greater effect on lysozyme compared to prothioconazole. Moreover, the S-configuration of PTCD interacted most strongly with lysozyme. This conclusion was further verified by DFT calculations and molecular docking as well. Furthermore, the oxidative stress indicators within HepG2 cells were also affected by chiral prothioconazole and its metabolites. Specifically, S-PTCD induced more substantial perturbation of the normal oxidative stress processes in HepG2 cells, and the magnitude of the perturbation varied significantly among different configurations (P > 0.05). Overall, chiral prothioconazole and its metabolites exhibit enantioselective effects on lysozyme conformation and oxidative stress processes in HepG2 cells. This work provides a scientific basis for a more comprehensive risk assessment of the environmental behaviors and effects caused by chiral pesticides, as well as for the screening of highly efficient and less biotoxic enantiomeric monomers.

Revealing the mechanism of novel nitrogen-doped biochar supported magnetite (NBM) enhancing anaerobic digestion of waste-activated sludge by sludge characteristics

Anaerobic digestion (AD) is a promising technology in waste treatment and energy recovery. However, it suffers from long retention time and low biogas yield. In this study, novel nitrogen-doped biochar supported magnetite (NBM) was synthesized and applied to enhance the AD of waste-activated sludge. Results showed that NBM increased cumulative methane production and SCOD removal efficiency by up to 1.75 times and 15% respectively at 5 g/L compared with the blank. NBM enhanced both hydrolysis and methanogenesis process during AD and the activities of α-glucosidase, protease, coenzyme F₄₂₀ and electron transport system were increased by 19%, 163%, 104% and 160% respectively at 5 g/L NBM compared with the blank. NBM also facilitated the secretion of conductive protein in extracellular polymeric substances as well as the formation of conductive pili, leading to 3.18-7.59 times higher sludge electrical conductivity. Microbial community analysis revealed that bacteria Clostridia and archaea Methanosarcina and Methanosaeta were enriched by the addition of NBM, and direct interspecies electron transfer might be promoted between them. This study provides a practical reference for future material synthesis and its application.