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229 results on '"Zhu, Gefu"'

10. Promoting or Inhibiting: New Insights into the Role of Formate in Syntrophic Propionate Metabolism.

Author

Li, Yanlin, Cai, Guanjing, Pan, Xiaofang, Lv, Nan, Feng, Lin, Zhu, Gefu, Lv, Zunjing, and Ye, Zhilong

Subjects
FATTY acid oxidation, SLUDGE management, ANAEROBIC digestion, STRESS concentration, GENETIC transcription
Abstract

Anaerobic digestion is a critical technology for pollution control, resource capacity enhancement, and sludge management, necessitating improvements in its efficiency. Formate serves as an electron carrier in syntrophic oxidation of volatile fatty acids (VFAs) during anaerobic digestion. The accumulation of formate can exert an inhibitory effect on the anaerobic digestion process. However, the stress concentration and the mechanism of the formate are not as simple as theoretical calculations based on thermodynamics. Thus, we investigated the response to different concentrations of formate in the syntrophic oxidation of propionate. The anaerobic sludge system and syntrophic co-culture system were applied. The propionate showed more stable degradation when formate dosage ranged from 5 to 10 mM. However, when the formate dosage reached 50 mM, the concentration of propionate was significantly higher than that of CK group, and the propionate metabolism was significantly inhibited. The reduction in functional flora and homogeneous metabolic pathways were found to be unfavorable for the stable progression of syntrophic propionate metabolism. Thus, the enhancement of homoacetogenesis can be a strategy adopted by the sludge system to alleviate formate stress. The methylmalonyl-CoA (MMC) pathway was inhibited under formate stress; the downregulation of RNA transcription of formate dehydrogenase (FDH) and hydrogenase (Hyd) related to MMC pathway may be the main reason for the inhibition of syntrophic propionate oxidation. The anaerobic sludge experiment and the co-culture experiment elucidated the mechanism of action of formate from both macroscopic rules and microscopic molecular mechanisms, respectively. [ABSTRACT FROM AUTHOR]

Published
2024
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44. Process performance and microbial community functional structure in a thermophilic anaerobic baffled reactor coupled with biocatalysed electrolysis

Author

Wang, Tao, Lv, Nan, Pan, Xiaofang, Li, Chunxing, Zhu, Gefu, Wang, Tao, Lv, Nan, Pan, Xiaofang, Li, Chunxing, and Zhu, Gefu

Abstract

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.

Published
2020

45. Treatment of digestate residues for energy recovery and biochar production:From lab to pilot-scale verification

Author

Li, Chunxing, Li, Jie, Pan, Lanjia, Zhu, Xinyu, Xie, Shengyu, Yu, Guangwei, Wang, Yin, Pan, Xiaofang, Zhu, Gefu, Angelidaki, Irini, Li, Chunxing, Li, Jie, Pan, Lanjia, Zhu, Xinyu, Xie, Shengyu, Yu, Guangwei, Wang, Yin, Pan, Xiaofang, Zhu, Gefu, and Angelidaki, Irini

Abstract

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.

Published
2020

46. Anaerobic digestion of sludge filtrate using anaerobic baffled reactor assisted by symbionts of short chain fatty acid-oxidation syntrophs and exoelectrogens:Pilot-scale verification

Author

Wang, Tao, Zhu, Gefu, Li, Chunxing, Zhou, Mingdian, Wang, Ruming, Li, Junjie, Wang, Tao, Zhu, Gefu, Li, Chunxing, Zhou, Mingdian, Wang, Ruming, and Li, Junjie

Abstract

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.

Published
2020

47. Effects of hydraulic retention time and influent alkalinity on the performance of bio-electrochemical system assisted anaerobic baffled reactor

Author

Huang Xu, Zhang JingRui, Liu Chaoxiang, Liu Lin, Zhu Gefu, Pan Xiaofang, and Jha Ajay Kumar

Subjects
Hydraulic retention time, Chemistry, Environmental engineering, Alkalinity, Ocean Engineering, 02 engineering and technology, 010501 environmental sciences, 021001 nanoscience & nanotechnology, Electrochemistry, 01 natural sciences, Pollution, Microbial population biology, 0210 nano-technology, Anaerobic exercise, 0105 earth and related environmental sciences, Water Science and Technology
Abstract

The effect of hydraulic retention time (HRT) and influent alkalinity on the performance of bio-electrochemical system assisted anaerobic baffled reactor (BES-ABR) was investigated in this study. The results indicated that as the HRT and influent alkalinity increase, COD removal efficiencies were enhanced correspondingly. The maximum COD removal efficiency of 97.4% was obtained at HRT of 48 h and COD of 4,000 mg/L. The maximum COD removal efficiency of 87.5% was obtained at influent alkalinity of 1,300 mg CaCO3/L and COD of 5,000 mg/L. Analysis of microbial community suggested that electrogenic micro-organisms were responsible for the better performance and stability of the system. The establishment and performance of this novel and efficient partial two-phase separation of BES-ABR strongly depended on the regulation of HRT and influent alkalinity.

Published
2016
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48. Correction: Impact of physical structure of granular sludge on methanogenesis and methanogenic community structure (RSC Advances (2019) 9 (29570-29578) DOI: 10.1039/C9RA04257A)

Author

Pan, Xiaofang, Wang, Lina, Lv, Nan, Ning, Jing, Zhou, Mingdian, Wang, Tao, Li, Chunxing, and Zhu, Gefu

Abstract

Correction for ‘Impact of physical structure of granular sludge on methanogenesis and methanogenic community structure’ by Xiaofang Pan et al., RSC Adv., 2019, 9, 29570–29578.The authors regret that an incorrect grant number was shown for the Innovation Fund Project in the acknowledgements section of the original manuscript. The correct grant number for the Innovation Fund Project is WES&WQGE201901, and the full corrected acknowledgements section is as shown below.

Published
2019
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