Natural defence mechanisms of electrochemically active biofilms: From the perspective of microbial adaptation, survival strategies and antibiotic resistance.

Electrochemically active biofilms (EABs) play an ever-growingly critical role in the biological treatment of wastewater due to its low carbon footprint and sustainability. However, how the multispecies biofilms adapt, survive and become tolerant under acute and chronic toxicity such as antibiotic stress still remains well un-recognized. Here, the stress responses of EABs to tetracycline concentrations (CTC) and different operation schemes were comprehensively investigated. Results show that EABs can quickly adapt (start-up time is barely affected) to low CTC (≤ 5 µM) exposure while the adaptation time of EABs increases and the bioelectrocatalytic activity decreases at CTC ≥ 10 µM. EABs exhibit a good resilience and high anti-shocking capacity under chronic and acute TC stress, respectively. But chronic effects negatively affect the metabolic activity and extracellular electron transfer, and simultaneously change the spatial morphology and microbial community structure of EABs. Particularly, the typical exoelectrogens Geobacter anodireducens can be selectively enriched under chronic TC stress with relative abundance increasing from 45.11% to 85.96%, showing stronger TC tolerance than methanogens. This may be attributed to the effective survival strategies of EABs in response to TC stress, including antibiotic efflux regulated by tet(C) at the molecular level and the secretion of more extracellular proteins in the macro scale, as the C=O bond in amide I of aromatic amino acids plays a critical role in alleviating the damage of TC to cells. Overall, this study highlights the versatile defences of EABs in terms of microbial adaptation, survival strategies, and antibiotic resistance, and deepens the understanding of microbial communities' evolution of EABs in response to acute and chronic TC stress.

Divergent assembly of soil microbial necromass from microbial and organic fertilizers in Chimonobambusa hejiangensis forest.

Introduction: Variability in microbial residues within soil aggregates are becoming progressively essential to the nutritive and sustainability of soils, and are therefore broadly regarded as an indispensable part of soil organic matter. It is unexplored how the widespread implementation of microbial fertilisers in agricultural production impacts soil organic nutrients, in particular the microbial residue fraction. Methods: We performed a three-year field experiment to verify the distinct impacts of microbial and organic fertilizers on carbon accumulation in soil microbial leftovers among aggregate fractions. Results: Microbial residual carbon was shown to decrease insignificantly during the application of microbial fertilizer and to rise marginally afterwards with the utilization of organic fertilizer. However, the combined effects of the two fertilizers had substantial impacts on the accumulation of microbial residual carbon. Changes in the structure of the fungi and bacteria shown in this study have implications for the short-term potential of microbial fertilizer shortages to permanent soil carbon sequestration. Additionally, our findings revealed variations in microbial residue accumulation across the microbial fertilizers, with Azotobacter chroococcum fertilizer being preferable to Bacillus mucilaginosus fertilizer due to its higher efficiency. In this scenario of nutrient addition, fungal residues may serve as the primary binding component or focal point for the production of new microaggregates, since the quantity of SOC provided by fungal residues increased while that supplied by bacterial residues decreased. Discussion: Our findings collectively suggested that the mechanisms behind the observed bacterial and fungal MRC (microbial residue carbon) responses to microbial fertilizer or organic fertilizer in bamboo forest soils are likely to be distinct. The application of microbial fertilizers for a limited duration led to a decline soil stable carbon pool, potentially influencing the regulation of soil nutrients in such hilly bamboo forests.

Bioelectrochemically altering microbial ecology in upflow anaerobic sludge blanket to enhance methanogenesis fed with high-sulfate methanolic wastewater.

A bioelectrochemical upflow anaerobic sludge blanket (BE-UASB) was constructed and compared with the traditional UASB to investigate the role of bioelectrocatalysis in modulating methanogenesis and sulfidogensis involved within anaerobic treatment of high-sulfate methanolic wastewater (COD/SO42- ratio ≤ 2). Methane production rate for BE-UASB was 1.4 times higher than that of the single UASB, while SO42- removal stabilized at 16.7%. Bioelectrocatalysis selectively enriched key functional anaerobes and stimulated the secretion of extracellular polymeric substances, especially humic acids favoring electron transfer, thereby accelerating the electroactive biofilms development of electrodes. Methanomethylovorans was the dominant genus (35%) to directly convert methanol to CH4. Methanobacterium as CO2 electroreduction methane-producing archaea appeared only on electrodes. Acetobacterium exhibited anode-dependence, which provided acetate for sulfate-reducing bacteria (norank Syntrophobacteraceae and Desulfomicrobium) through synergistic coexistence. This study confirmed that BE-UASB regulated the microbial ecology to achieve efficient removal and energy recovery of high-sulfate methanolic wastewater.

Optimizing bioelectromethanosynthesis of CO2 and membrane fouling mitigation in MECs via in-situ biogas recirculation.

The CO2 bioelectromethanosynthesis via two-chamber microbial electrolysis cell (MEC) holds tremendous potential to solve the energy crisis and mitigate the greenhouse gas emissions. However, the membrane fouling is still a big challenge for CO2 bioelectromethanosynthesis owing to the poor proton diffusion across membrane and high inter-resistance. In this study, a new MEC bioreactor with biogas recirculation unit was designed in the cathode chamber to enhance secondary-dissolution of CO2 while mitigating the contaminant adhesion on membrane surface. Biogas recirculation improved CO2 re-dissolution, reduced concentration polarization, and facilitated the proton transmembrane diffusion. This resulted in a remarkable increase in the cathodic methane production rate from 0.4 mL/L·d to 8.5 mL/L·d. A robust syntrophic relationship between anodic organic-degrading bacteria (Firmicutes 5.29%, Bacteroidetes 25.90%, and Proteobacteria 6.08%) and cathodic methane-producing archaea (Methanobacterium 65.58%) enabled simultaneous organic degradation, high CO2 bioelectromethanosynthesis, and renewable energy storage.

Biogas upgrading and membrane anti-fouling mechanisms in electrochemical anaerobic membrane bioreactor (EC-AnMBR): Focusing on spatio-temporal distribution of metabolic functionality of microorganisms.

Electrochemical anaerobic membrane bioreactor (EC-AnMBR) by integrating a composite anodic membrane (CAM), represents an effective method for promoting methanogenic performance and mitigating membrane fouling. However, the development and formation of electroactive biofilm on CAM, and the spatio-temporal distribution of key functional microorganisms, especially the degradation mechanism of organic pollutants in metabolic pathways were not well documented. In this work, two AnMBR systems (EC-AnMBR and traditional AnMBR) were constructed and operated to identify the role of CAM in metabolic pathway on biogas upgrading and mitigation of membrane fouling. The methane yield of EC-AnMBR at HRT of 20 days was 217.1 ± 25.6 mL-CH4/g COD, about 32.1 % higher compared to the traditional AnMBR. The 16S rRNA analysis revealed that the EC-AnMBR significantly promoted the growth of hydrolysis bacteria (Lactobacillus and SJA-15) and methanogenic archaea (Methanosaeta and Methanobacterium). Metagenomic analysis revealed that the EC-AnMBR promotes the upregulation of functional genes involved in carbohydrate metabolism (gap and kor) and methane metabolism (mtr, mcr, and hdr), improving the degradation of soluble microbial products (SMPs)/extracellular polymeric substances (EPS) on the CAM and enhancing the methanogens activity on the cathode. Moreover, CAM biofilm exhibits heterogeneity in the degradation of organic pollutants along its vertical depth. The bacteria with high hydrolyzing ability accumulated in the upper part, driving the feedstock degradation for higher starch, sucrose and galactose metabolism. A three-dimensional mesh-like cake structure with larger pores was formed as a biofilter in the middle and lower part of CAM, where the electroactive Geobacter sulfurreducens had high capabilities to directly store and transfer electrons for the degradation of organic pollutants. This outcome will further contribute to the comprehension of the metabolic mechanisms of CAM module on membrane fouling control and organic solid waste treatment and disposal.

Identification of extracellular polymeric substances layer barrier in chloroquine phosphate-disturbed anammox consortia and mechanism dissection on cytotoxic behavior by computational chemistry.

The over-dosing use of chloroquine phosphate (CQ) poses severe threats to human beings and ecosystem due to the high persistence and biotoxicity. The discharge of CQ into wastewater would affect the biomass activity and process stability during the biological processes, e.g., anammox. However, the response mechanism of anammox consortia to CQ remain unknown. In this study, the accurate role of extracellular polymeric substances barrier in attenuating the negative effects of CQ, and the mechanism on cytotoxic behavior were dissected by molecular spectroscopy and computational chemistry. Low concentrations (≤6.0 mg/L) of CQ hardly affected the nitrogen removal performance due to the adaptive evolution of EPS barrier and anammox bacteria. Compact protein of EPS barrier can bind more CQ (0.24 mg) by hydrogen bond and van der Waals force, among which O-H and amide II region respond CQ binding preferentially. Importantly, EPS contributes to the microbiota reshape with selectively enriching Candidatus_Kuenenia for self-protection. Furthermore, the macroscopical cytotoxic behavior was dissected at a molecular level by CQ fate/distribution and computational chemistry, suggesting that the toxicity was ascribed to attack of CQ on functional proteins of anammox bacteria with atom N17 (f-=0.1209) and C2 (f+=0.1034) as the most active electrophilic and nucleophilic sites. This work would shed the light on the fate and risk of non-antibiotics in anammox process.

Enhanced dewaterability and triclosan removal of waste activated sludge with iron-rich mineral-activated peroxymonosulfate.

High water and pharmaceutical and care products (PPCPs) bounded in sludge flocs limit its utilization and disposal. The advanced oxidation process of perxymonosulfate (PMS) catalyzed by iron salts has been widely used in sludge conditioning. In this study, two iron-rich minerals pyrite and siderite were proposed to enhance sludge dewatering performance and remove the target contaminant of triclosan (TCS). The permanent release of Fe2+ in the activation of PMS made siderite more effective in enhancing sludge dewater with capillary suction time (CST) diminishing by 60.5 %, specific resistance to filtration (SRF) decreasing by 79.2 %, and bound water content (BWC) dropping from 37.1 % to 2.6 % at siderite/PMS dosages of 0.36/0.20 mmol/g-TSS after 20 min of pretreatment. Pyrite/PMS performed slightly inferior under the same conditions and the corresponding CST and SRF decreased by 51.5 % and 71.8 % while the BWC only declined to 17.8 %. Rheological characterization was employed to elucidate the changes in sludge dewatering performance, with siderite/PMS treated sludge showing a 48.3 % reduction in thixotropy, higher than 28.4 % of pyrite/PMS. Oscillation and creep tests further demonstrated the significantly weakened viscoelastic behavior of the sludge by siderite/PMS pretreatment. For TCS mineralization removal, siderite/PMS achieved a high removal efficiency of 43.9 %, in comparison with 39.9 % for pyrite/PMS. The reduction in the sludge solids phase contributed the most to the TCS removal. Free radical quenching assays and EPR spectroscopy showed that both siderite/PMS and pyrite/PMS produced SO4-·  and ·OH, with the latter acting as the major radicals. Besides, the dosage of free radicals generated from siderite/PMS exhibited a lower time-dependence, which also allowed it to outperform in destroying EPS matrix, neutralizing the negative Zeta potential of sludge flocs, and mineralizing macromolecular organic matter.

Simultaneous removal of antibiotic resistance genes and improved dewatering ability of waste activated sludge by Fe(II)-activated persulfate oxidation.

Waste activated sludge properties vary widely with different regions due to the difference in living standards and geographical distribution, making a big challenge to developing a universally effective sludge dewatering technique. The Fe(II)-activated persulfate (S2O82-) oxidation process shows excellent ability to disrupt sludge cells and extracellular polymeric substances (EPS), and release bound water from sludge flocs. In this study, the discrepancies in the physicochemical characteristics of sludge samples from seven representative cities in China (e.g., dewaterability, EPS composition, surface charge, microbial community, relative abundance of antibiotic resistance genes (ARGs), etc.) were investigated, and the role of Fe(II)-S2O82- oxidation in enhancing removal of antibiotic resistance genes and dewatering ability were explored. The results showed significant differences between the EPS distribution and chemical composition of sludge samples due to different treatment processes, effluent sources, and regions. The Fe(II)-S2O82- oxidation pretreatment had a good enhancement of sludge dewatering capacity (up to 76 %). Microbial analysis showed that the microbial community in each sludge varied significantly depending on the types of wastewater, the wastewater treatment processes, and the regions, but Fe(II)-S2O82- oxidation was able to attack and rupture the sludge zoogloea indiscriminately. Genetic analysis further showed that a considerable number of ARGs were detected in all of these sludge samples and that Fe(II)-S2O82- oxidation was effective in removing ARGs by higher than 90 %. The highly active radicals (e.g., SO4-·, ·OH) produced in this process caused drastic damage to sludge microbial cells and DNA stability while liberating the EPS/cell-bound water. Co-occurrence network analysis highlighted a positive correlation between population distribution and ARGs abundance, while variations in microbial communities were linked to regional differences in living standards and level of economic development. Despite these variations, the Fe(II)-S2O82- oxidation consistently achieved excellent performance in both ARGs removal and sludge dewatering. The significant modularity of associations between different microbial communities also confirms its ability to reduce horizontal gene transfer (HGT) by scavenging microbes.

Novel ADAMTS13 mutations in a patient with congenital thrombotic thrombocytopenic purpura.

Congenital thrombotic thrombocytopenic purpura (TTP) is a rare autosomal recessive genetic disorder caused by mutations in the ADAMTS13 gene. Approximately 200 mutations of the ADAMTS-13 gene have been identified, although only a few have been characterized through in vitro expression studies. We conducted an investigation on a male congenital TTP patient with reduced plasma levels of ADAMTS13 activity. DNA sequence analysis revealed two mutations on chromosome 9 (1.9q34.2) in the patient's ADAMTS13 gene. One mutation was a non-synonymous mutation (exon 5: c.A530G: p.Y177C), while the other was a nonsense mutation (exon 21: c.G2651A: p.W884X). Both mutations were found to be heterozygous. The patient's parents had no history of thrombocytopenia or neurological symptoms. DNA sequence analysis showed the patient's father was a heterozygote for the nonsense mutation of the ADAMTS13 gene (exon 21: c.G2651A: p.W884X), while the mother was a heterozygote for the non-synonymous mutation of the ADAMTS13 gene (exon 5: c.A530G: p.Y177C). To investigate the mechanism behind ADAMTS13 deficiency in this patient, wild type (WT), ADAMTS13 p.Y177C, and ADAMTS13 p.W884X were transiently expressed in 293-6E cells. Expression studies revealed a significant reduction in enzyme activity and secretion, although the protease was detected within the cells. The 3D structures of the natural and mutated ADAMTS-13 proteins were partially reconstructed using the Phyre2 web server. The mutation that replaces the tyrosine residue at amino acid position 177 with cysteine may result in decreased steric hindrance and a looser structure. This mutation affects the binding of calcium ions and the secretion of the enzyme from intracellular to extracellular compartments.

Self-assembled electrochemically active biofilms doped with carbon nanotubes: Electron exchange efficiency and cytotoxicity evaluation.

Thick electrochemically active biofilms (EABs) will lead to insufficient extracellular electron transfer (EET) rate because of the limitation of both substrate diffusion and electron exchange. Herein, carbon nanotubes (CNTs)-doped EABs are developed through self-assembly. The highly conductive biofilms (internal resistance of ∼211 Ω) are efficiently enriched at CNTs dosage of 1 g L-1, with the stable power output of 0.568 W m-2 over three months. The embedded CNTs can act as electron tunnel to accelerate the EET rate in thick biofilm. Self-charging/discharging experiments and Nernst-Monod model stimulation demonstrate a higher net charge storage capacity (0.15 C m-2) and more negative half-saturation potential (-0.401 V) for the hybrid biofilms than that of the control (0.09 C m-2, and -0.378 V). Enzyme activity tests and the observation of confocal laser scanning microscopy by live/dead staining show a nearly negligible cytotoxicity of CNTs, and non-targeted metabonomics analysis reveals fourteen differential metabolites that do not play key roles in microbial central metabolic pathways according to KEGG compound database. The abundance of typical exoelectrogens Geobacter sp. is 2-fold of the control, resulting in a better bioelectrocatalytic activity. These finding provide a possible approach to prolong electron exchange and power output by developing a hybrid EABs doped with conductive material.

Associations between composite dietary antioxidant index and estimated 10-year atherosclerotic cardiovascular disease risk among U.S. adults.

Background: Atherosclerotic cardiovascular disease (ASCVD) remains the leading cause of death and disability both in U.S. and worldwide. Antioxidants have been proved critical in mitigating the development of atherosclerosis. This study aimed to investigate the associations between composite dietary antioxidant index (CDAI) and estimated 10-year ASCVD risk among U.S. adults. Methods: Data extracted from the National Health and Nutrition Examination Survey were analyzed. A total of 10,984 adults aged 18 years and above were included in this study. CDAI was calculated based on the dietary intake reported in their 24-h recall interviews. The estimated 10-year ASCVD risk was calculated via Pooled Cohort Equations (PCE). Results: After adjusting potential confounders, it was indicated that CDAI score was negatively correlated with 10-year ASCVD risk (OR 0.97, 95% CI 0.95-0.99). Stratify CDAI score by quartile, results showed that participants in the second, third, and fourth quartiles had lower ASCVD odds ratio (Q2: OR 0.87, 95% CI 0.69-1.09; Q3: OR 0.78, 95% CI 0.62-0.98; Q4: OR 0.74, 95% CI 0.59-0.94) than those in the first quartile (Q1, lowest CDAI score group), which was confirmed by the trend test as well (p < 0.05). Subgroup analyses stratified by sex, age, race/ethnicity, and smoking status did not show significant effect modification. Conclusion: Higher dietary antioxidants intake is associated with lower ASCVD risk among U.S. adults, for which policymakers and healthcare professionals may consider increasing the consumption of antioxidant-rich foods as a preventive strategy for ASCVD.

Bioelectrochemical anaerobic membrane bioreactor enables high methane production from methanolic wastewater: Roles of microbial ecology and microstructural integrity of anaerobic biomass.

The disintegration of anaerobic sludge and blockage of membrane pores has impeded the practical application of anaerobic membrane bioreactor (AnMBR) in treating methanolic wastewater. In this study, bioelectrochemical system (BES) was integrated into AnMBR to alleviate sludge dispersion and membrane fouling as well as enhance bioconversion of methanol. Bioelectrochemical regulation effect induced by BES enhanced methane production rate from 4.94 ± 0.52 to 5.39 ± 0.37 L/Lreactor/d by accelerating the enrichment of electroactive microorganisms and the agglomeration of anaerobic sludge via the adhesive and chemical bonding force. 16 S rRNA gene high-throughput sequencing demonstrated that bioelectrochemical stimulation had modified the metabolic pathways by regulating the key functional microbial communities. Methanogenesis via the common methylotrophic Methanomethylovorans was partially substituted by the hydrogenotrophic Candidatus_Methanofastidiosum, etc. The metabolic behaviors of methanol are bioelectrochemistry-dependent, and controlling external voltage is thus an effective strategy for ensuring robust electron transfer, low membrane fouling, and long-term process stability.

[Functional analysis of functional membrane microdomains in the biosynthesis of menaquinone-7].

Functional membrane microdomains (FMMs) that are mainly composed of scaffold proteins and polyisoprenoids play important roles in diverse cellular physiological processes in bacteria. The aim of this study was to identify the correlation between MK-7 and FMMs and then regulate the MK-7 biosynthesis through FMMs. Firstly, the relationship between FMMs and MK-7 on the cell membrane was determined by fluorescent labeling. Secondly, we demonstrated that MK-7 is a key polyisoprenoid component of FMMs by analyzing the changes in the content of MK-7 on cell membrane and the changes in the membrane order before and after destroying the integrity of FMMs. Subsequently, the subcellular localization of some key enzymes in MK-7 synthesis was explored by visual analysis, and the intracellular free pathway enzymes Fni, IspA, HepT and YuxO were localized to FMMs through FloA to achieve the compartmentalization of MK-7 synthesis pathway. Finally, a high MK-7 production strain BS3AT was successfully obtained. The production of MK-7 reached 300.3 mg/L in shake flask and 464.2 mg/L in 3 L fermenter.

[Development of biosensors highly responsive to N-acetylneuraminic acid in Bacillus subtilis].

Bacillus subtilis is recognized as a generally-regarded-as-safe strain, and has been widely used in the biosynthesis of high value-added products, including N-acetylneuraminic acid (NeuAc) which is widely used as a nutraceutical and a pharmaceutical intermediate. Biosensors responding to target products are widely used in dynamic regulation and high-throughput screening in metabolic engineering to improve the efficiency of biosynthesis. However, B. subtilis lacks biosensors that can efficiently respond to NeuAc. This study first tested and optimized the transport capacity of NeuAc transporters, and obtained a series of strains with different transport capacities for testing NeuAc-responsive biosensors. Subsequently, the binding site sequence of Bbr_NanR responding to NeuAc was inserted into different sites of the constitutive promoter of B. subtilis, and active hybrid promoters were obtained. Next, by introducing and optimizing the expression of Bbr_NanR in B. subtilis with NeuAc transport capacity, we obtained an NeuAc-responsive biosensor with wide dynamic range and higher activation fold. Among them, P535-N2 can sensitively respond to changes in intracellular NeuAc concentration, with the largest dynamic range (180-20 245) AU/OD. P566-N2 shows a 122-fold of activation, which is 2 times of the reported NeuAc-responsive biosensor in B. subtilis. The NeuAc-responsive biosensor developed in this study can be used to screen enzyme mutants and B. subtilis strains with high NeuAc production efficiency, providing an efficient and sensitive analysis and regulation tool for biosynthesis of NeuAc in B. subtilis.

Impact of sandwich-type composite anodic membrane on membrane fouling and methane recovery from sewage sludge and food waste via electrochemical anaerobic membrane bioreactor.

Membrane fouling presents a big challenge for the real-world implementation of anaerobic membrane bioreactors (AnMBRs) in digesting high-solid biowastes. In this study, an electrochemical anaerobic membrane bioreactor (EC-AnMBR) with a novel sandwich-type composite anodic membrane was designed and constructed for controlling membrane fouling whilst improving the energy recovery. The results showed that EC-AnMBR produced a higher methane yield of 358.5 ± 74.8 mL/d, rising by 12.8% compared to the AnMBR without applied voltage. Integration of composite anodic membrane induced a stable membrane flux and low transmembrane pressure through forming an anodic biofilm while total coliforms removal reached 97.9%. The microbial community analysis further provided compelling evidence that EC-AnMBR enriched the relative abundance of hydrolyzing (Chryseobacterium 2.6%) bacteria and methane-producing (Methanobacterium 32.8%) archaea. These findings offered new insights into anti-biofouling performance and provided significant implications for municipal organic waste treatment and energy recovery in the new EC-AnMBR.

Enhanced co-digestion of sewage sludge and food waste using novel electrochemical anaerobic membrane bioreactor (EC-AnMBR).

Membrane fouling remains a big challenge hindering the wide-application of anaerobic membrane bioreactor (AnMBR) technology. In this study, an electrochemical anaerobic membrane bioreactor (EC-AnMBR) was developed by coupling electrochemical regulation to enhance co-digestion of sewage sludge and food waste and mitigate membrane fouling. The highest methane production (0.12 ± 0.02 L/Lreactor/day) and net energy recovery (31.82 kJ/day) were achieved under the optimum conditions of 0.8 V, hydraulic retention time of 10 days and solids retention time of 50 days. Electrochemical regulation accelerated the mineralization of high-molecular-weight organics and reinforced the membrane antifouling ability by inducing electrostatic repulsive force and electrochemical oxidation. Besides, symbiotic relationships among functional microorganisms (Spirochaetes, Methanolinea, etc.) were enhanced, improving the hydrolysis and methanogenesis processes of complex organics and the long-term stability. This study confirms the technical feasibility of EC-AnMBR in treating high-solid biowastes, and provides the fundamental data to support its application in real-world scenarios.

Insights into biodegradation behaviors of methanolic wastewater in up-flow anaerobic sludge bed (UASB) reactor coupled with in-situ bioelectrocatalysis.

Granular sludge disintegration and washing out pose a challenge to up-flow anaerobic sludge bed (UASB) reactor treating methanolic wastewater. Herein, in-situ bioelectrocatalysis (BE) was integrated into UASB (BE-UASB) reactor to alter microbial metabolic behaviors and enhance the re-granulation process. BE-UASB reactor exhibited the highest methane (CH4) production rate of 388.0 mL/Lreactor/d and chemical oxygen demand (COD) removal of 89.6 % at 0.8 V. Sludge re-granulation was strengthened with particle size over 300 µm of up to 22.4%. Bioelectrocatalysis stimulated extracellular polymeric substances (EPS) secretion and formation of granules with rigid [-EPS-cell-EPS-] matrix by enhancing the proliferation of key functional microorganisms (Acetobacterium, Methanobacterium, and Methanomethylovorans) and diversifying metabolic pathways. Particularly, a high Methanobacterium richness (10.8%) drove the electroreduction of CO2 into CH4 and reduced its emissions (52.8%). This study provides a novel bioelectrocatalytic strategy for controlling granular sludge disintegration, which will facilitate the practical application of UASB in methanolic wastewater treatment.

Effects of combined remediation of pre-ozonation and bioaugmentation on degradation of benzo[a]pyrene and microbial community structure in soils.

The combination technique of pre-ozonation and bioaugmentation is promising for remediating benzo[a]pyrene (BaP)-contaminated soil. However, little is known about the effect of coupling remediation on the soil biotoxicity, soil respiration, enzyme activity, microbial community structure, and microbial in the process of remediation. This study developed two coupling remediation strategies (pre-ozonation coupled with bioaugmentation by addition of polycyclic aromatic hydrocarbons (PAHs) specific degrading bacteria or activated sludge), compared with sole ozonation and sole bioaugmentation, to improve degradation of BaP and recovery of soil microbial activity and community structure. Results showed that the higher removal efficiency of BaP (92.69-93.19%) was found in coupling remediation, compared with sole bioaugmentation (17.71-23.28%). Meanwhile, coupling remediation significantly reduced the soil biological toxicity, promoted the rebound of microbial counts and activity, and recovered the species numbers and microbial community diversity, compared with sole ozonation and sole bioaugmentation. Besides, it was feasible to replace microbial screening with activated sludge, and coupling remediation by addition of activated sludge was more conducive to the recovery of soil microbial communities and diversity. This work provides a strategy of pre-ozonation coupled with bioaugmentation to further degrade BaP in soil by promoting the rebound of microbial counts and activity, as well as the recovery of species numbers and microbial community diversity.

Effective multipurpose sewage sludge and food waste reduction strategies: A focus on recent advances and future perspectives.

Energy crisis and increasing rigorous management standards pose significant challenges for solid waste management worldwide. Several emerging diseases such as COVID-19 aggravated the already complex solid waste management crisis, especially sewage sludge and food waste streams, because of the increasingly large production year by year. As mature waste disposal technologies, landfills, incineration, composting, and some other methods are widespread for solid wastes management. This paper reviews recent advances in key sewage sludge disposal technologies. These include incineration, anaerobic digestion, and valuable products oriented-conversion. Food waste disposal technologies comprised of thermal treatment, fermentation, value-added product conversion, and composting have also been described. The hot topic and dominant research foci of each area are summarized, simultaneously compared with conventional technologies in terms of organic matter degradation or conversion performance, energy generation, and renewable resources production. Future perspectives of each technology that include issues not well understood and predicted challenges are discussed with a positive effect on the full-scale implementation of the discussed disposal methods.