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High-level erythromycin (ERY) fermentation wastewater will pose serious threats to lake environments. Anaerobic digestion (AD) has advantages in treating high-level antibiotic wastewater. However, the fate of antibiotic resistance genes (ARGs) and microbial communities in AD after stepwise exposure to high-level ERY remains unclear. In this study, an AD reactor was first exposed to 0, 5, 10, 50, 100 and 200 mg/L ERY and then re-exposed to 0, 50, 200 and 500 mg/L ERY to investigate the effect of ERY on AD. The results show that AD could adapt to the presence of high-level ERY (500 mg/L) and could maintain efficient CH4 production after domestication with low-level ERY (50 mg/L). The AD process could achieve higher removal of ERY (>94%), regardless of the initial ERY concentration. ErmB and mefA, conferring resistance through target alteration and efflux pumps, respectively, were dominant in the AD process. The first exposure to ERY stimulated an increase in the total ARG abundance, while the AD process seemed to discourage ARG maintenance following re-exposure to ERY. ERY inhibited the process of acetoclastic methanogenesis, but strengthened the process of hydrogenotrophic methanogenesis. This work provides useful information for treating high-level ERY fermentation wastewater by the AD process.

The safety of lithium-ion batteries (LIBs) is paramount for all users. One effective way to improve safety is incorporating heat-resistant polyimide (PI) separators, which can increase the thermal stability of batteries and minimize the risk of thermal runaway. However, preparing PI separators with both an ideal pore structure and adequate mechanical properties remains as a challenge. Here, we introduced decabromodiphenyl ethane (DBDPE) and cellulose nanofibers (CNFs) into PI and produced a hybrid separator with an outstanding pore structure and excellent mechanical properties. Aided with DBDPE, the separators attain a well-defined and uniform pore size (20 nm), while demonstrating high porosities (78%) through phase inversion processes. Owing to the addition of CNFs, the mechanical properties of the separators were significantly improved, with a tensile strength of 25.4 MPa and an elastic modulus of 550.1 MPa. Moreover, the separators demonstrate high ion conductivity (0.45 mS cm-1), excellent thermal-dimensional stability (up to 200 degrees C), remarkable flame retardancy, and outstanding electrolyte wettability. At room temperature, the batteries with the separators demonstrate comparable performance with those of polypropylene (PP) separators. However, when subjected to thermal shock treatments, the batteries with the separators outperform those with PP, showcasing their superior performance. The work introduces a novel strategy for designing high-performance separators, thereby paving the way for advancements in the fabrication of LIBs with enhanced safety features. A porous, robust, and thermally stable hybrid separator was developed to solve the dilemma between desired pore structures and mechanical properties in polyimide separators by introducing decabromodiphenyl ethane and cellulose nanofibers., QC 20231128

Enriching suitable fermentative products by optimizing operation conditions could effectively improve the efficiency of anaerobic digestion. In the present study, pH (5.0–6.0) and hydraulic retention time (HRT) (2 h-12 h) were regulated for volatile fatty acids (VFAs) production during glucose fermentation in acidogenic continuous stirred tank reactor (CSTR). Results showed that acetate and butyrate dominated during pH regulation. HRT reduction favored butyrate production and formate retainment. Maximum total VFAs production with highest acetate content was achieved at pH of 6.0 and HRT of 6 h. Microbial analysis revealed that Clostridium_sensu_stricto_1 was predominant butyrate producer during pH regulation, and Bacteroides was main contributor when HRT shorter than 6 h. In addition to acetyl-CoA pathway, acetate could also be produced via homoacetogenesis by Parabacteroides, UCG-004 and norank_f__Acidaminococcaceae. These results would give guidance for enhancing targeted VFAs products by optimizing operational parameters or bio-augmentation with specific bacteria.

Anaerobic digestion (AD) is one of the most widely used bioconversion technologies for renewable energy production from wet biowaste. However, such an AD system is so complicated that it is challenging to fully comprehend this process and design the operational conditions for a specific biowaste to achieve CH4-rich biogas. In this context, ensemble machine learning (ML) algorithms were employed to develop multitask models for jointly predicting the CH4 yield and content in biogas and understanding this complicated process. Based on the best ensemble model with the R2 values of 0.82 and 0.86 for the multitask prediction of CH4 yield and content, the top three critical factors for CH4 yield/contents were identified and their interactions with process acid generation and microbial community in the AD process were comprehensively interpreted to unveil their importance on CH4 generation. Moreover, the well-developed ensemble model was integrated with an optimization algorithm to inversely design the AD process for a real-world food waste, in which the CH4 yield was as high as 468.7 mL/gVS and the calculation results were experimentally validated with relative errors of 9–16%. This work provides a creative approach to gain insights and inverse design for AD reactors, which is helpful to waste-to-energy technologists and practitioners.

Syngas biomethanation is a complex process mediated by an intricate microbial consortium, with methane as the final targeted product. In the past decades, syngas biomethanation gained much attention because it can be integrated into the existing biogas facilities and thereby save installation costs. Moreover, compared to the catalytic methanation, biological syngas methanation has many benefits, such as the requirement for milder operating conditions, reduced sensitivity to gas composition and higher tolerance to trace contaminants. The operational conditions such as pH, temperature, and gas partial pressure play important role in syngas biomethanation, which have been extensively investigated in lab-scale experiments. Due to the toxicity of CO to microbes, its conversion and metabolism attract much more attention in syngas biomethanation. There are two main conversion pathway for CO metabolism with acetate and H2/CO2 as the main precursors for the following methanogenesis. Due to the poor solubility of H2 and CO, it is necessary to study efficient methods to improve the gas liquid transfer as well as the conversion efficiency of syngas fermentation. Cultivation of synthetic cocultures can be used to improve overall rates of CO bioconversion, and also the CO-enriched mixed culture presents advantage in CO-conversion rate than that of pure culture. Up to now, there is still needing deeper conclusion on how the parameters affect the syngas biomethanation related to change of functional microbes and involved conversion pathway. Therefore, the aim of the present thesis is to 1) study the effect of main parameters, including syngas composition, partial pressure of CO, biomass-syngas ration (BGR), and pH-buffer on syngas biomethanation; 2) elucidate the involved functional microbes and metabolic relationship in CO/syngas biomethanation via genome-centric metagenomics analysis; 3) analyze the CO consumption enhancement in co-fermentation of

The concept of syngas biomethanation is attractive, however, it still needs improvement in optimizing the operational conditions. In the present study, syngas fermentations under different carbon monoxide (CO), carbon dioxide (CO2) and hydrogen (H2) compositions were conducted under two different biomass-gas ratio (BGR) systems. The results showed that high BGR enhanced the CO consumption rate, achieving a 60% enhancement with CO as the sole substrate. Stoichiometric H2 addition could successfully convert all the CO and CO2 to pure methane, however, higher H2 partial pressure might decline the CO consumption due to pH inhibition from consumption of bicarbonate. Microbial analysis showed different syngas composition could affected the bacteria community, while, archaea community was only slightly affected with Methanothermobacter as the dominant methanogen. This study provided strategy for efficient syngas biomethanation and deeper insight into effect of H2 addition on CO conversion under different BGR systems.

In this study, anaerobic batch experiments were conducted to investigate the effect of carbon-based (biochar) and metal-based (nanoscale zero-valent iron, NZVI and zero valent iron, ZVI) mediators on the AD process treating phenolic wastewater. Fresh apricot shell- and wood-derived biochar (BiocharA, BiocharB) could remove the phenol efficiently (77.1% and 86.2%), suggesting that biodegradation cooperated with adsorption had advantage in phenol removal. BiocharB, NZVI and ZVI enhanced the methane production by 17.6%, 23.7% and 23.2%, respectively. Apart from serving as carrier for microbial growth, BiocharB might promote the direct interspecies electron transfer (DIET) since the Anaerolineaceae/Clostridium sensu stricto, which have potential for DIET, were enriched. NZVI and ZVI added systems mainly enhanced the abundance of Clostridium sensu stricto (24.5%, 37.6%) and Methanosaeta. Interestingly, BiocharA inhibited the methanogenesis completely. An inhibitory mechanism was proposed: the exposure of absorbed microbes on the BiocharA to the highly concentrated phenol in biochar’ pores resulted in the inhibition of methanogens, especially for Methanosarcina. In conclusion, this study showed that suitable biochar (BiocharB) could serve as an alternative redox mediator for realizing simultaneously the efficient phenol removal and methane production.

The accumulation of volatile fatty acids, particularly propionic acid, significantly inhibits the efficiency of the anaerobic digestion system. In propionate degradation metabolism, the unfavorable thermodynamics of syntrophic reactions, strict ecological niche of syntrophic priopionate oxidizing bacteria, and slow metabolic rate of methanogens are regarded as major limitations. In this study, Geobacter sulfurreducens was co-cultured with Syntrophobacter fumaroxidans in bioelelectrochemical cells to analyze the propionate degradation process, impact factor, mechanism metabolic pathways, and electron transfer comprehensively. The results revealed that the syntroph S. fumaroxidans and syntrophic partner G. sulfurreducens achieved more efficient propionate degradation than the control group, comprising S. fumaroxidans and methanogens. Moreover, the carbon resource concentration and pH were both significantly correlated with propionate degradation (P < 0.01). The results further confirmed that G. sulfurreducen strengthened the consumption of H2 and acetate via direct interspecific electron transfer in propionate degradation. These findings indicate that G. sulfurreducens plays an unidentified functional role in propionate degradation.

Ciprofloxacin is the most commonly prescribed antibiotic, and its widespread use poses threat to environmental safety. The removal of ciprofloxacin from contaminated water has remained a major challenge. The present study investigated adding nanoscale zero-valent iron (NZVI) and activated carbon (AC) on high-level ciprofloxacin removal in hydrolysis-acidogenesis stage of anaerobic digestion. The results showed that the degradation rate of ciprofloxacin increased from 22.61% (Blank group) to 72.41% after adding NZVI/AC with concentration of ciprofloxacin in effluent decreasing from 8.25 mg L−1 to 3.48 mg L−1. The volatile fatty acids (VFAs) yield increased by 173.7% compared with the Blank group. In addition, the NZVI/AC group achieved the highest chemical oxygen demand (COD) removal rate and acidogenesis rate. The microbial community analysis presented that hydrolytic and acidogenic bacteria and microorganisms related to degrading ciprofloxacin were obviously improved in the NZVI/AC group. Moreover, eleven transformation products and the main degradation pathways were proposed based on mass spectrometry information. In summary, the NZVI/AC addition supplied promising approach for ciprofloxacin wastewater treatment.

In view of the risks induced by the inhibitory effects of applying impracticably large amounts of sewage sludge biochar (SSB) to the alkaline soil, this field study investigated the influence of moderate biochar amendments (0, 1500, 4500, and 9000 kg/hm2) on corn growth, alkaline soil properties, and the uptake of potentially toxic elements (PTEs). The results showed that applying more SSB would decrease the ammonium nitrogen concentration and increase the available phosphorus and potassium concentrations, which inhibited corn plant growth because of high background nutrient levels of the alkaline soil. When the alkaline soil was amended with 1500 kg/hm2 SSB, the dry weight of 100 niblets increased from 32.11 g in the control to 35.07 g. There was no significant variation in the total concentration of PTEs in the soil. The concentrations of Mn, Ni, Cu, and Zn in niblets decreased from 5.54, 0.83, 2.26, and 27.15 mg/kg in the control to 4.47, 0.62, 1.30, and 23.45 mg/kg, respectively. Accordingly, the health risk from corn consumption was significantly reduced. Furthermore, the combination of SSB and fertilizer improved corn growth and reduced the risk of consumption of PTEs. Therefore, considering the increase in corn fruit yield and the decrease in consumption risk, applying 1500 kg/hm2 of biochar to alkaline soils is a realistically achievable rate, which can broaden the utilization of SSB for remediation of different types of soil.

Acidic anaerobic digestion attracted much attention and interest due to its significant advantage in wastewater treatment. In the present study, methanogenic fermentation was successfully operated under acidic condition during treating wastewater containing oxytetracycline (OTC) in a scale up anaerobic baffled reactor (ABR). After start-up process, the pH value in the first compartment was 4.60 with high activity of methanogenesis. After stabilization, different OTC loading of 1.0, 3.3 and 5.0 g/m3/d was added in the influent for OTC removal. The resulted showed that OTC addition had little impact on the methane generation with whole COD and OTC removal rate of 95% and 60%, respectively. The microbial analysis, OTC addition could significantly influence the bacteria and archaea communities. To be more specific, Methanosaeta showed the highest relative abundance and tolerance to OTC under acidic condition. The present work supplied deeper insights into methane generation from acidic condition during wastewater containing OTC treatment.

Aiming at relieving acid accumulation in anaerobic digestion (AD), syntrophic associations of syntrophic fatty acid-oxidation bacteria and H2/formate-scavenging methanogens were enriched by feeding propionate, butyrate and formate in an up-flow anaerobic sludge blanket (UASB) reactor. Results showed that methane yield increased by 50% with increasing formate concentration (0–2000 mg COD/L). In addition, the abundance and quantity of SFOB (Syntrophobacter, Smithella and Syntrophomonas) and H2/formate-scavenging methanogens (Methanobacteriales and Methanomicrobiales) were increased after microbial acclimation. The enriched syntrophic associations showed higher propionate and butyrate removal efficiencies of 98.48 ± 1.14% and 99.71 ± 0.71%, respectively. Furthermore, encoding genes of formate dehydrogenase and hydrogenases presented higher abundances after microbial enrichment, which suggested that the enhancements of interspecies formate transfer and interspecies hydrogen transfer between syntrophic associations benefited volatile fatty acids (VFAs) conversion. This research provided an effective strategy to relieve acid accumulation.

In this study, the performances of a conventional anaerobic baffled reactor (ABR) and an ABR combined with microbial electrolysis cells (MECs) for enhancing degradation of volatile fatty acids (VFAs) were evaluated in 55°C. The ABR-MECs system achieved a total chemical oxygen demand (COD) removal rate of 97.2% and a methane yield of 236 ± 5 mL g-1 CODremoved at organic loading rate (OLR) of 6.9 kg COD m-3 d-1, which were higher than those of the ABR with 77.6% and 207 ± 5 mL g-1 CODremoved, respectively, at OLR of 5.1 kg COD m-3 d-1. The pyrosequencing analysis confirmed that the introduction of MECs into ABR was conducive to establishing stable functional communities of syntrophic fatty acids oxidizing bacteria (SFOB), exoelectrogens and hydrogenotrophic methanogens, such as Syntrophobacter (5.4%), Thermodesulfovibrio (2.0%), Methanobacterium (43.8%), Methanolinea (20.4%). The content of unclassified bacteria increased from 12.4% in the ABR system to 52.3% in the ABR-MECs system. In contrast, the proportion of aceticlastic methanogens decreased from 50.1% in the ABR to 24.5% in the ABR-MECs system. The improved performance of the thermophilic ABR-MECs system resulted from phase separation, wide ecological niche and intensification of methanogenesis process via functional microbes, which significantly enhanced the degradation of propionic acid and acetic acid.

Sludge filtrate is a kind of special organic wastewater generated from hydrothermally pretreated sewage sludge. The efficient treatment of sludge filtrate can promote the development of sludge recycling technology. Herein, the anaerobic baffled reactor (ABR) assisted by symbionts of short chain fatty acid-oxidation syntrophs (SFAS) and exoelectrogens was applied to treat the sludge filtrate. The influence of fermentation temperature and promotion of methanogenesis via symbionts were focused. The results showed that the COD removal efficiency and methane yield of the ABR system assisted by symbionts at 35 °C (R3) were 11.7% and 11.0% higher than the one at 55 °C (R2), respectively. And the COD removal efficiency and methane yield of the R2 system were 9.1% and 12.9% higher than the traditional ABR system at 55 °C (R1), respectively. Large abundances of exoelectrogens such as Thermincola and Geobacter were found in the R2 and R3 systems, respectively. Moreover, ample Syntrophobacter, Syntrophomonas and Methanobacterium were detected in both R2 and R3 systems. The present research revealed the importance of SFAS, exoelectrogens and hydrogenotrophic methanogens for the improvement of methanogenesis. Besides, the mesophilic condition is conducive to enhancing the methanogenesis rate of sludge filtrate.

Hydrothermal pretreatment was used for dewatering food waste digestate residue, and biochar/biogas were generated from the separated solid and liquid phases via pyrolysis and anaerobic digestion, respectively. Increasing hydrothermal pretreatment temperature (110–200 °C) clearly improved dewaterability, whereas enhancing treatment duration (30–90 min) had little impact. The optimal condition of 160 °C/30 min gave the best dewatering performance with relative lower energy consumption and was chosen for pilot-scale verification achieving 61.7 wt% dry weight content after mechanical squeezing. Moreover, the filtrate and filter cake obtained at optimal condition were applied for biogas and biochar production in lab scale. The methane yield of the filtrate was 335 mL/g COD. Pyrolysis temperature of 500 °C gave better biochar performance and was verified in a pilot scale test. Additionally, the heavy metals in digestate were effectively immobilized during hydrothermal dewatering and pyrolysis processes. In the end, mass/energy balance calculated using pilot-scale data presented the combined systems provided a promising strategy for accomplishing energy recovery and resource reuse of digestate residue.

The growing amount of sewage sludge from wastewater treatment plant is an emerging challenge in China. The efficient anaerobic digestion of sludge filtrate generated from hydrothermally pretreated sewage sludge can promote the disposal of sewage sludge. Herein, a pilot-scale anaerobic baffled reactor (ABR) assisted by symbionts of short chain fatty acid-oxidation syntrophs (SFAS) and exoelectrogens was developed to improve its stability and efficiency for filtrate treatment. The results demonstrated that the symbionts of exoelectrogens and SFAS, which were enriched by introduction of electrodes in the ABR system, promoted the degradation of butyric, propionic and acetic acids. Therefore, the COD removal efficiency increased from 74.1% to 86.6% and the methane content increased from 81.5% to 92.2% with methane production rising from 241 to 282 mL/g CODremoved. Furthermore, the economic evaluation indicated that the energy consumption of electrodes was 0.600 kWh/m3 of sludge filtrate, the net energy profited from increased methane was 2.344 kWh/m3 of sludge filtrate. These results confirmed that the ABR system assisted by symbionts of SFAS and exoelectrogens was feasible for treatment of sludge filtrate in terms of both technical and economic level through pilot-scale verification.