Odor emission and microbial community succession during biogas residue composting covered with a molecular membrane

A membrane-covered composting system was used to investigate the odor emission and microbial community succession during biogas residue composting. Results showed that in comparison with the control (CK) group, the NH₃ and H₂S emissions outside the membrane of the membrane-covered (CT) group decreased by 58.64% and 38.13%, respectively. The nitrogen preservation rate of the CT group was increased by 17.27% in comparison with the CK group. Moreover, the ammonium nitrogen and nitrate nitrogen contents of the CT group were 37.68% and 11.77% higher than those of the CK group, respectively. Microbial analysis showed that the average abundance and co-occurrence rate of ammonification bacteria dominated by Pseudomonas and Bacillus in the CT group were lower than those in the CK group, and the abundance of anaerobic sulfate-reducing bacteria (SRB) dominated by Desulfovibrio in the CT group was higher than that in the CK group.

Enhanced bioelectricity generation by improving pyocyanin production and membrane permeability through sophorolipid addition in Pseudomonas aeruginosa-inoculated microbial fuel cells

Improvement on electron shuttle-mediated extracellular electron transfer (EET) is of great potential to enhance the power output of MFCs. In this study, sophorolipid was added to enhance the performance of Pseudomonas aeruginosa-inoculated MFC by improving the electron shuttle-mediated EET. Upon sophorolipid addition, the current density and power density increased ∼ 1.7 times and ∼ 2.6 times, respectively. In accordance, significant enhancement on pyocyanin production (the electron shuttle) and membrane permeability were observed. Furthermore, the conditions for sophorolipid addition were optimized to achieve maximum pyocyanin production (14.47 ± 0.23 μg/mL), and 4 times higher power output was obtained compared to the control. The results substantiated that enhanced membrane permeability and pyocyanin production by sophorolipid, which promoted the electron shuttle-mediated EET, underlies the improvement of the energy output in the P. aeruginosa-inoculated MFC. It suggested that addition of biosurfactant could be a promising way to enhance the energy generation in MFCs.

Enhancement of bioelectricity generation by manipulation of the electron shuttles synthesis pathway in microbial fuel cells

Microbial fuel cells (MFCs) are promising for generating bioenergy and treating organic waste simultaneously. However, low extracellular electron transfer (EET) efficiency between electrogens and anodes remains one of the major bottlenecks in practical applications of MFCs. In this paper, pyocyanin (PYO) synthesis pathway was manipulated to improve the EET efficiency in Pseudomonas aeruginosa-inoculated MFCs. By overexpression of phzM (methyltransferase encoding gene), the maximum power density of P. aeruginosa-phzM-inoculated MFC was enhanced to 166.68 μW/cm(2), which was four folds of the original strain. In addition, the phzM overexpression strain exhibited an increase of 1.6 folds in PYO production and about a onefold decrease in the total internal resistance than the original strain, which should underlie the enhancement of the EET efficiency and the electricity power output (EPT). On the basis of these results, the manipulation of electron shuttles synthesis pathways could be an efficient approach to improve the EPT of MFCs.

Optimization of the production of poly-γ-glutamic acid by Bacillus amyloliquefaciens C1 in solid-state fermentation using dairy manure compost and monosodium glutamate production residues as basic substrates

Poly-γ-glutamic acid (γ-PGA) is a polymer with uses in foods, cosmetics, medicine and agriculture. The medium for the production of γ-PGA by Bacillusamyloliquefaciens C1 was optimized by response surface methodology using agro-industrial wastes in solid-state fermentation (SSF). The optimal SSF medium (20g substrates with 50% initial moisture) for producing γ-PGA was determined to contain 5.51g dairy manure compost, 1.91g soybean cake, 0.57g corn flour, 2.15g monosodium glutamate production residues, 1.5g wheat bran, 0.5g rapeseed cake, 0.1g citric acid, 0.05g MgSO(4)·7H(2)O and 0.03g MnSO(4)·H(2)O. In this medium the strain produced up to 0.0437g γ-PGA per gram of substrates when cultured for 48h at 37°C. SDS-PAGE showed that the molecular weight of the γ-PGA was more than 130kDa. Due to the high-yields observed and the low-cost nature of the optimal medium, this study indicates a possibility to establish economical large-scale production of γ-PGA.

Bio-Electron-Fenton (BEF) process driven by microbial fuel cells for triphenyltin chloride (TPTC) degradation

The intensive use of triphenyltin chloride (TPTC) has caused serious environmental pollution. In this study, an effective method for TPTC degradation was proposed based on the Bio-Electron-Fenton process in microbial fuel cells (MFCs). The maximum voltage of the MFC with graphite felt as electrode was 278.47% higher than that of carbon cloth. The electricity generated by MFC can be used for in situ generation of H₂O₂ to a maximum of 135.96μmolL^-1 at the Fe@Fe₂O_3(*)/graphite felt composite cathode, which further reacted with leached Fe²⁺ to produce hydroxyl radicals. While 100μmolL^-1 TPTC was added to the cathodic chamber, the degradation efficiency of TPTC reached 78.32±2.07%, with a rate of 0.775±0.021μmolL^-1h^-1. This Bio-Electron-Fenton driving TPTC degradation might involve in SnC bonds breaking and the main process is probably a stepwise dephenylation until the formation of inorganic tin and CO₂. This study provides an energy saving and efficient approach for TPTC degradation.

Effects of different biofilm carriers on biogas production during anaerobic digestion of corn straw

This study investigated the performance of anaerobic digestion systems using four types of fibrous biofilm carriers, a polypropylene, a polyester, a polyamide, and a polyurethane fiber material. The biogas and methane production, pH, chemical oxygen demand, total solids content, volatile solids content, residual coenzyme F₄₂₀, and microbial community compositions were determined during the experimental runs. Furthermore, scanning electron microscopy was employed to identify the microbial consortium and examine their attachment onto the surface of the four fibrous biofilm carriers. The polypropylene fiber system maintained the highest biogas and methane production in the reactor, which was 44.80% and 49.84% higher than that noted in the control, respectively, during the entire anaerobic fermentation cycle. Meanwhile, the polypropylene fiber system exhibited the highest TS, VS, and COD removal efficiency. The results of high-throughput sequencing indicated that the dominant species in the polypropylene fiber system were Methanoregula and Methanobacterium.

Trace heavy metal ions promoted extracellular electron transfer and power generation by Shewanella in microbial fuel cells

Although microbial fuel cells (MFCs) is considered as one of the most promising technology for renewable energy harvesting, low power output still accounts one of the bottlenecks and limits its further development. In this work, it is found that Cu(2+) (0.1μgL(-1)-0.1mgL(-1)) or Cd(2+) (0.1μgL(-1)-1mgL(-1)) significantly improve the electricity generation in MFCs. The maximum power output achieved with trace level of Cu(2+) (∼6nM) or Cd(2+) (∼5nM) is 1.3 times and 1.6 times higher than that of the control, respectively. Further analysis verifies that addition of Cu(2+) or Cd(2+) effectively improves riboflavin production and bacteria attachment on the electrode, which enhances bacterial extracellular electron transfer (EET) in MFCs. These results unveil the mechanism for power output enhancement by Cu(2+) or Cd(2+) addition, and suggest that metal ion addition should be a promising strategy to enhance EET as well as power generation of MFCs.

Effects of copper salts on performance, antibiotic resistance genes, and microbial community during thermophilic anaerobic digestion of swine manure

This study investigated methane production and ARGs reduction during thermophilic AD of swine manure with the addition of different Cu salts (cupric sulfate, cupric glycinate, and the 1:1 mixture of these two salts). Results showed methane production was increased by 28.78% through adding mixed Cu salts. The mixed Cu group effectively reduced total ARGs abundance by 26.94%, suggesting mixed Cu salts did not promote the potential ARGs risk. The positive effects of mixed Cu salts on AD performance and ARGs removal might be ascribed to the low bioavailability. Microbial community analysis indicated the highest abundances of Clostridia_MBA03 and Methanobacterium in the mixed Cu group might cause the increased methane production. Spearman's rank correlation analysis elucidated the succession in microbial community induced by environmental factors was the main driver for shaping ARGs profiles. Thus, mixed Cu salts could be an alternative to replace the inorganic Cu salt in animal feed additives.

Endogenously enhanced biosurfactant production promotes electricity generation from microbial fuel cells

Microbial fuel cell (MFC) is considered as a promising green energy source and energy-saving pollutants treatment technology as it integrates pollutant biodegradation with energy extraction. In this work, a facile approach to enhance endogenous biosurfactant production was developed to improve the electron transfer rate and power output of MFC. By overexpression of rhlA, the key gene responsible for rhamnolipids synthesis, over-production of self-synthesized rhamnolipids from Pseudomonas aeruginosa PAO1 was achieved. Strikingly, the increased rhamnolipids production by rhlA overexpression significantly promoted the extracellular electron transfer of P. aeruginosa by enhancing electron shuttle (pyocyanin) production and increasing bacteria attachment on the anode. As a result, the strain with endogenously enhanced rhamnolipids production delivered 2.5 times higher power density output than that of the parent strain. This work substantiated that the enhancement on endogenous biosurfactant production could be a promising approach for improvement on the electricity output of MFC.

Different organic loading rates on the biogas production during the anaerobic digestion of rice straw: A pilot study

The aim of this work was to investigate the mesophilic methane fermentation of rice straw at different organic loading rates (OLRs) in a 300m³ bioreactor. It was found that biogas production increased when the OLR was below 2.00kg VS_substrate/(m³·d). The average volumetric biogas production reached 0.86m³/(m³·d) at an OLR of 2.00kg VS_substrate/(m³·d). Biogas production rate was 323m³/t dry rice straw over the whole process. The pH, chemical oxygen demand, volatile fatty acid, and NH₄⁺-N concentrations were all in optimal range at different OLRs. High-throughput sequencing analysis indicated that Firmicutes, Fibrobacteres, and Spirochaetes predominated in straw samples. Chloroflexi, Proteobacteria, and Planctomycetes were more abundant in the slurry. The hydrogenotrophic pathway was the main biochemical pathway of methanogenesis in the reactor. This study provides new information regarding the OLR and the differences in the spatial distribution of specific microbiota in a rice straw biogas plant.

Effect of NaX zeolite-modified graphite felts on hexavalent chromium removal in biocathode microbial fuel cells

Two kinds of NaX zeolite-modified graphite felts were used as biocathode electrodes in hexavalent chromium (Cr(VI))-reducing microbial fuel cells (MFCs). The one was fabricated through direct modification, and the other one processed by HNO3 pretreatment of graphite felt before modification. The results showed that two NaX zeolite-modified graphite felts are excellent bio-electrode materials for MFCs, and that a large NaX loading mass, obtained by HNO3 pretreatment (the HNO3-NaX electrode), leads to a superior performance. The HNO3-NaX electrode significantly improved the electricity generation and Cr(VI) removal of the MFC. The maximum Cr(VI) removal rate increased to 10.39±0.28 mg/L h, which was 8.2 times higher than that of the unmodified control. The improvement was ascribed to the strong affinity that NaX zeolite particles, present in large number on the graphite felt, have for microorganisms and Cr(VI) ions.

Effect of biochar combined with a biotrickling filter on deodorization, nitrogen retention, and microbial community succession during chicken manure composting

The high-nitrogen content and dense structure of poultry manure compost cause volatilization of N to ammonia (NH₃). This study evaluated the combined application of biochar and biotrickling filtration (BTF) to remove of odor in chicken manure mixed straw compost (w/w, 2.5:1). Adding of 10% biochar reduced NH₃, hydrogen sulfide (H₂S), and total volatile organic compounds (TVOCs) contents by 20.04%, 16.18%, and 17.55% respectively, and decreased the N loss rate by 8.27%, compared with those observed in control. The organic matter content decreased by 28.11% and germination index reached 97.36% in the experimental group. Meanwhile, the N-cycling microorganisms such as Pusillimonas and Pseudomonas became more active, and the relative abundance of sulfur-cycling microorganisms Hydrogenispora decreased in the experimental group. Following BTF application, the NH₃, H₂S, and TVOCs removal rates reached 95%, 97%, and 53%, respectively.

Anode modification by biogenic gold nanoparticles for the improved performance of microbial fuel cells and microbial community shift

In this study, carbon cloth anodes were modified using biogenic gold nanoparticles (BioAu) and nanohybrids of multi-walled carbon nanotubes blended with BioAu (BioAu/MWCNT) to improve the performance of microbial fuel cells (MFCs). The results demonstrated that BioAu modification significantly enhanced the electricity generation of MFCs. In particular, BioAu/MWCNT nanohybrids as the modifier displayed a better performance. The MFC with the BioAu/MWCNT electrode had the shortest start-up time (6.74 d) and highest power density (178.34 ± 4.79 mW/m²), which were 141.69% shorter and 56.11% higher compared with those of the unmodified control, respectively. These improvements were attributed to the excellent electrocatalytic activity and strong affinity towards exoelectrogens of the BioAu/MWCNT nanohybrids on the electrode. High throughput sequencing analysis indicated that the relative abundance of electroactive bacteria in the biofilm community, mostly from the classes of Gammaproteobacteria and Negativicutes, increased after anode modification.

Biosynthesized iron sulfide nanoparticles by mixed consortia for enhanced extracellular electron transfer in a microbial fuel cell

The bioanode of mixed consortia was for the first time used to in-situ synthesize iron sulfide nanoparticles in a microbial fuel cell (MFC) over a long-term period (46 days). These poorly crystalline nanoparticles with an average size of 29.97 ± 7.1 nm, comprising of FeS and FeS₂, significantly promoted extracellular electron transfer and thus the electricity generation of the MFC. A maximum power density of 519.00 mW/m² was obtained from the MFC, which was 1.92 times as high as that of the control. The cell viability was promoted by a small amount of iron sulfide nanoparticles but inhibited by the thick nanoparticle "shell" covered on the bacterial cells. Some electroactive and sulfur reducing bacteria (eg. Enterobacteriaceae, Desulfovibrio, and Geobacter) were specifically enriched on the anode. This study provides a novel insight for improving the performance of bioelectrochemical systems through in-situ sustainable nanomaterials biofabrication by mixed consortia.

Enhanced Bio-Electro-Fenton degradation of phenolic compounds based on a novel Fe-Mn/Graphite felt composite cathode

Phenolic compounds are problematic byproducts generated from lignocellulose pretreatment. In this study, the feasibility degradation of syringic acid (SA), vanillic acid (VA), and 4-hydroxybenzoic acid (HBA) by Bio-Electro-Fenton (BEF) system with a novel Fe-Mn/graphite felt (Fe-Mn/GF) composite cathode were investigated. The nano-scale Fe-Mn multivalent composite catalyst with core shell structure distributed more evenly on GF surface to form a catalyst layer with higher oxygen reduction reaction performance. Accordingly, the maximum power density generated with Fe-Mn/GF cathode was 48.1% and 238.9% higher than Fe/GF and GF respectively, which further enhanced the in situ generation of H₂O₂ due to the superiority of nano-scale core shell structure and synergistic effect of Fe and Mn species. The degradation efficiency of the three phenolic compounds in the BEF system could reached 100% after optimization of influencing parameters. Furthermore, a possible SA degradation pathway by BEF process in the present system was proposed based on the detected intermediates. These results demonstrated an efficient approach for the degradation of phenolic compounds derived from lignocellulose hydrolysates.

Biogas production and microbial community shift through neutral pH control during the anaerobic digestion of pig manure

Laboratory-scale reactors, in which the pH could be auto-adjusted, were employed to investigate the mesophilic methane fermentation with pig manure (7.8% total solids) at pH 6.0, 7.0, and 8.0. Results showed that the performance of anaerobic digestion was strongly dependent on pH value. Biogas production and methane content at neutral pH 7.0 were significantly higher (16,607mL, 51.81%) than those at pH 6.0 (6916mL, 42.9%) and 8.0 (9739mL, 35.6%). Denaturing gradient gel electrophoresis fingerprinting and Shannon's index indicated that the samples contained highly diverse microbial communities. The major genus at pH 7.0 was Methanocorpusculum, compared with that was Methanosarcina at both pH 6.0 and 8.0. Our research revealed that cultures maintained at pH 7.0 could support increased biogas production, which has significant implications for the scale-up biogas engineering.

Coordinated response of Au-NPs/rGO modified electroactive biofilms under phenolic compounds shock: Comprehensive analysis from architecture, composition, and activity

Electroactive biofilms (EABs) can be integrated with conductive nanomaterials to boost extracellular electron transfer (EET) for achieving efficient waste treatment and energy conversion in bioelectrochemical systems. However, the in situ nanomaterial-modified EABs of mixed-culture, and their response under environmental stress are rarely revealed. Here, two nanocatalyst-decorated EABs were established by self-assembled Au nanoparticles-reduced graphene oxide (Au-NPs/rGO) in mixed-biofilms with different maturities, then their multi-property were analyzed under long-term phenolic shock. Results showed that the power density of Au-NPs/rGO decorated EABs was significantly enhanced by 28.66-42.82% due to the intensified EET pathways inside biofilms. Meanwhile, the electrochemical and catalytic performance of EABs were controllably regulated by 0.3-3.0 g/L phenolic compounds, which, however, resulted in differential alterations in their architecture, composition, and viability. EABs originated with higher maturity displayed more compact structure, lower thickness (110 μm), higher biomass (8.67 mg/cm²) and viability (0.85-0.91), endowing it better antishock ability to phenolic compounds. Phenolic-shock also induced the heterogeneous distribution of extracellular polymeric substances in terms of both spatial and bonding degrees of the decorated EABs, which could be regarded as an active response to strike a balance between self-protection and EET under environmental pressure. Our findings provide a broader understanding of microbe-electrode interactions in the micro-ecology interface and improve their performance in the removal of complex contaminants for sustainable remediation and new-energy development.

Anaerobic biodegradation of pyrene by Klebsiella sp. LZ6 and its proposed metabolic pathway

Pyrene is one of the polycyclic aromatic hydrocarbons, which are a potential threat to ecosystems due to their mutagenicity, carcinogenicity, and teratogenicity. In this study, several bacteria were isolated from oil contaminated sludge and their capacity to biodegrade pyrene was investigated. Of these bacteria, the monoculture strain LZ6 showed the highest pyrene anaerobic biodegradation rate of 33% after 30 days when the initial concentration was 50 mg/L, and was identified as Klebsiella sp. LZ6 by morphological observation, the GENIII technology of Biolog, and 16S rDNA gene sequence analysis. The influence of various culture parameters on the biodegradation of pyrene were evaluated, and Klebsiella sp. LZ6 all showed the high degradation rate at an inoculum of 10-20% (v/v), pH 6.0-8.4, temperature 30-38°C, and initial pyrene concentration of 50-150 mg/L. The intermediate metabolites of the anaerobic biodegradation were analyzed by GC-MS. Several metabolites were identified, such as pyrene, 4,5-dihydro-, phenanthrene, dibenzo-p-dioxin, and 4-hydroxycinnamate acid. The anaerobic metabolic pathway for the degradation of pyrene was inferred by the products. It seems that pyrene was first reduced to pyrene,4,5-dihydro- by the adding of two hydrogen atoms, and then the carbon-carbon bond cleavage at saturated carbon atoms generated phenanthrene.

Degradation of phenolic compounds with simultaneous bioelectricity generation in microbial fuel cells: Influence of the dynamic shift in anode microbial community

This study evaluated the feasibility of microbial fuel cells (MFCs) for simultaneous electricity generation and degradation of phenolic compounds. The voltage generation was inhibited by 36.18-63.90%, but the degradation rate increased by 146.15-392.31% when the initial concentration of syringic acid (SA), vanillic acid (VA), and 4-hydroxybenzoic acid (HBA) increased from 0.3 to 3.0 g/L. The collaboration among the functional microbes significantly enhanced the degradation rate of parent compounds and their intermediates in MFCs systems, while the accumulated intermediates severely inhibited their complete mineralization in fermentative systems. High-throughput sequencing showed that the growth of fermentative bacteria prevailed, but electrogenic bacteria were inhibited in the anode microbial community (AMC) under high concentrations of phenolic compounds (3.0 g/L). These findings provide a better understanding of the dynamic shift and synergy effects of the AMC to evaluate its potential for the treatment of phenolic-containing wastewater.

Effects of granular activated carbon and temperature on the viscosity and methane yield of anaerobically digested of corn straw with different dry matter concentrations

Anaerobic digestion (AD) systems with high substrate concentrations are characterized by high viscosity, which affects material and energy transfer efficiencies, thereby influencing methane production efficiency. In this study, adding granular activated carbon (GAC) and increasing the temperature decreased the viscosity by 4.56-10.19% and 27.13-28.85%, respectively, and improved AD efficiency. Adding GAC and increasing the temperature enhanced the methane yields by 34.37-38.15% and 25.60-28.31%, respectively. Distance-based redundancy analysis showed that the viscosity, temperature, and GAC had the greatest effects on the composition of the microbial community. The dominant bacteria in the medium-temperature AD system at the phylum level belonged to Firmicutes, Bacteroidetes, and Euryarchaeota. In addition to the dominant bacteria in the medium-temperature AD system, the thermophilic phylum Thermotogae was abundant in the high-temperature AD system. Moreover, the relative abundance of Euryarchaeota, which contained most of the methanogens, was higher in the high-temperature AD system than in the medium-temperature AD system.

Enhanced cadmium resistance and accumulation in Pseudomonas putida KT2440 expressing the phytochelatin synthase gene of Schizosaccharomyces pombe

Phytochelatins (PCs) are cysteine-rich peptides with high binding affinity for toxic metals. Expressing the PC synthase gene (PCS) in plant growth-promoting bacteria may enhance its metal resistance and accumulation, consequently increasing phytoremediation efficiency in heavy metal pollution. In this study, PCS from Schizosaccharomyces pombe was cloned and expressed in Pseudomonas putida KT2440, which was confirmed by real-time RT-PCR through an increase in SpPCS mRNA expression level when induced by 20 μmol of CdCl2 in the transformed Ps. putida cells. The recombined strain KT2440-SpPCS exhibited enhanced Cd, Ag and Hg resistance. Compared with the original strain, KT2440-SpPCS also displayed a threefold to fivefold increase in Cd accumulation (14·32 μmol g(-1) to 17·38 μmol g(-1) ; dry weight) when grown in 30 and 50 μmol CdCl2 , along with an increase in nonprotein thiols. Further experiments showed significantly enhanced germination rates and growth of wheat seeds in 0·1 mmol to 1·0 mmol Cd when inoculated with KT2440-SpPCS. This study shows potential use of Ps. putida KT2440-SpPCS in plants to construct a symbiotic system for an enhanced phytoremediation of heavy metal-contaminated environments.

SIGNIFICANCE AND IMPACT OF THE STUDY

The symbiotic system of using plant growth-promoting bacteria Pseudomonas putida to express phytochelatin synthase gene of Schizosaccharomyces pombe together in plants resulted in high heavy metal resistance and high accumulation capacity, suggesting potential enhancement in phytoremediation of heavy metal-contaminated environments.

A Facultative Electroactive Chromium(VI)-Reducing Bacterium Aerobically Isolated From a Biocathode Microbial Fuel Cell

A facultative electroactive bacterium, designated strain H, was aerobically isolated from the biocathode of a hexavalent chromium (Cr(VI))-reducing microbial fuel cell (MFC). Strain H is Gram-positive and rod shaped (1–3 μm length). 16S rRNA gene analysis suggested that this strain (accession number MH782060) belongs to the genus Bacillus and shows maximum similarity to Bacillus cereus whose electrochemical activity has never previously been reported. Moreover, this strain showed efficient Cr(VI)-reducing ability in both heterotrophic (aerobic LB broth) and autotrophic (anaerobic MFC cathode) environments. Cr(VI) removal reached 50.6 ± 1.8% after 20 h in LB broth supplemented with Cr(VI) (40 mg/L). The strain H biocathode significantly improved the performance of the Cr(VI)-reducing MFC, achieving a maximum power density of 31.80 ± 1.06 mW/m² and Cr(VI) removal rate of 2.56 ± 0.10 mg/L–h, which were 1.26 and 1.75 times higher than those of the MFC with the sterile control cathode, respectively. This study offers a novel Gram-positive Bacillus sp. strain for Cr(VI) removal in MFCs, and shows a facile aerobic isolation method could be used to screen facultative electroactive bacteria.

A novel core-shell Fe@Co nanoparticles uniformly modified graphite felt cathode (Fe@Co/GF) for efficient bio-electro-Fenton degradation of phenolic compounds

In this study, a core-shell Fe@Co nanoparticles uniformly modified graphite felt (Fe@Co/GF) was fabricated as the cathode by one-pot self-assembly strategy for the degradation of vanillic acid (VA), syringic acid (SA), and 4-hydroxybenzoic acid (HBA) in the Bio-Electro-Fenton (BEF) system. The Fe@Co/GF cathode showed dual advantages with excellent electrochemical performance and catalytic reactivity not only due to the high electron transfer efficiency but also the synergistic redox cycles between Fe and Co species, both of which significantly enhanced the in situ generation of H₂O₂ and hydroxyl radicals (OH) to 152.40 μmol/L and 138.48 μmol/L, respectively. In this case, the degradation rates of VA, SA, and HBA reached 100, 94.32, and 100%, respectively, within 22 h. Representatively, VA was degraded and ultimately mineralized via demethylation, decarboxylation and ring-opening reactions. This work provided a promising approach for eliminating typical recalcitrant organic pollutants generated by the pre-treatment of lignocellulose resources.