Publications by authors named "Chunxing Li"

34 Publications

Parallel optically detected magnetic resonance spectrometer for dozens of single nitrogen-vacancy centers using laser-spot lattice.

Rev Sci Instrum 2021 Apr;92(4):045107

Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China.

We develop a parallel optically detected magnetic resonance (PODMR) spectrometer to address, manipulate, and read out an array of single nitrogen-vacancy (NV) centers in diamond in parallel. In this spectrometer, we use an array of micro-lenses to generate a 20 × 20 laser-spot lattice (LSL) on the objective focal plane and then align the LSL with an array of single NV centers. The quantum states of NV centers are manipulated by a uniform microwave field from a Ω-shape coplanar coil. As an experimental demonstration, we observe 80 NV centers in the field of view. Among them, magnetic resonance (MR) spectra and Rabi oscillations of 18 NV centers along the external magnetic field are measured in parallel. These results can be directly used to realize parallel quantum sensing and multiple times speedup compared with the confocal technique. Regarding the nanoscale MR technique, PODMR will be crucial for a high throughput single molecular MR spectrum and imaging.
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http://dx.doi.org/10.1063/5.0039110DOI Listing
April 2021

Biosynthesis of polyhydroxyalkanoate from food waste oil by Pseudomonas alcaligenes with simultaneous energy recovery from fermentation wastewater.

Waste Manag 2021 Jun 25;131:268-276. Epub 2021 Jun 25.

Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, PR China. Electronic address:

Bioconversion of food waste oil (FWO) into biodegradable plastic is a promising method for converting waste into high-value products. In this study, a strain (Pseudomonas sp. H3) was isolated for polyhydroxyalkanoate (PHA) synthesis from FWO. After 72 h of cultivation with 20 g/L of FWO, the high cell dry weight (CDW) of 3.6 g/L, PHA yield of 2.4 g/L, and PHA content of 65 wt% were obtained under the optimal temperature (25 °C) and inoculum amount (6% (v/v)). Fed-batch fermentation was conducted in a 5 L bioreactor with a maximum CDW of 16 g/L, PHA content of 54 wt%, and PHA productivity of 0.23 g/(L·h) after 36 h. The PHA had a molecular weight of 54 782 Da and a low polydispersity index of 1.41 with glass transition, melting, and degradation temperatures of -20 °C, 34 °C, and 210 °C, respectively. To further utilize the wastewater after PHA production, anaerobic digestion was employed for CH production, and the CH yield was 284 mL/g volatile solids. Microbial community analysis showed that the abundance of acetate-oxidizing bacteria and Methanobacterium significantly increased during anaerobic digestion. This study describes a new strain for the economical synthesis of biodegradable plastics and presents a novel framework for fully utilizing FWO with the production of PHA and CH.
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http://dx.doi.org/10.1016/j.wasman.2021.06.008DOI Listing
June 2021

Novel insights into the anaerobic digestion of propionate via Syntrophobacter fumaroxidans and Geobacter sulfurreducens: Process and mechanism.

Water Res 2021 Jul 19;200:117270. Epub 2021 May 19.

Department of Chemical and Biochemical Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark.

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 H and acetate via direct interspecific electron transfer in propionate degradation. These findings indicate that G. sulfurreducens plays an unidentified functional role in propionate degradation.
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http://dx.doi.org/10.1016/j.watres.2021.117270DOI Listing
July 2021

Disintegrable, transparent and mechanically robust high-performance antimony tin oxide/nanocellulose/polyvinyl alcohol thermal insulation films.

Carbohydr Polym 2021 Aug 7;266:118175. Epub 2021 May 7.

State Key Lab of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China. Electronic address:

Polymer-based thermal insulation films are widely utilized to reduce the influence of solar radiation. However, current thermal insulation films face several challenges from poor thermal insulation performance and severe environmental pollution, which are caused by the non-disintegratability of polymer substrates. Here, cellulose nanofiber (CNF)/antimony tin oxide (ATO) hybrid films with and without polyvinyl alcohol (PVA) are presented and they can be used as window thermal barrier films and personal thermal management textiles. The hybrid films exhibit prominent thermal insulation performance, blocking 91.07% ultraviolet(UV) light, reflecting 95.19% near-infrared(NIR) light, and transmitting 44.89% visible(VIS) light. Meanwhile, the hybrid films demonstrate high thermal stability, high anti-UV aging stability, and robust mechanical properties. Moreover, the used-up hybrid films based on natural cellulose are of high disintegratability and recyclability. Our present work is anticipated to open up a new avenue for the fabrication of next-generation high-performance thermal insulation films with sustainable and environmentally friendly processes.
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http://dx.doi.org/10.1016/j.carbpol.2021.118175DOI Listing
August 2021

Deeper investigation on methane generation from synthetic wastewater containing oxytetracycline in a scale up acidic anaerobic baffled reactor.

Bioresour Technol 2021 Aug 20;333:125156. Epub 2021 Apr 20.

School of Environment and Nature Resources, Renmin University of China, Beijing 100872, PR China. Electronic address:

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/m/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.
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http://dx.doi.org/10.1016/j.biortech.2021.125156DOI Listing
August 2021

Syntrophic butyrate-oxidizing methanogenesis promoted by anthraquinone-2-sulfonate and cysteine: Distinct tendencies towards the enrichment of methanogens and syntrophic fatty-acid oxidizing bacteria.

Bioresour Technol 2021 Jul 29;332:125074. Epub 2021 Mar 29.

Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.

Interspecies electron transfer (IET) between syntrophic fatty-acid oxidizing bacteria (SFOBs) and methanogens decided the performance of anaerobic digestion. Electron shuttles, as potential IET accelerators, were controversial concerning their influences on methanogenesis. In this study, concentration-dependent effects of anthraquinone-2-sulfonate (AQS) and cysteine on glucose digestion were firstly demonstrated: low dosage of AQS and cysteine (50 and 100 µM, respectively) had highest methane yield (133.5% and 148.6%, respectively). Using butyrate as substrate, distinct tendencies towards the enrichment of methanogenic community were further revealed. Cysteine just acted as a reductant which lowered ORP quickly and enriched most methanogens. It benefited methanogenesis right until methanogenic substrates accumulated. AQS, however, showed characteristic features of electron shuttles: it was firstly oxidized by SFOBs and then reduced by hydrogenotrophic methanogens, which accelerated methanogenic butyrate degradation. This study showed wide spectrum of SFOBs and methanogens benefited from the addition of electron shuttles, which laid foundation for future application.
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http://dx.doi.org/10.1016/j.biortech.2021.125074DOI Listing
July 2021

Novel strategy for enhancing acetic and formic acids generation in acidogenesis of anaerobic digestion via targeted adjusting environmental niches.

Water Res 2021 Apr 2;193:116896. Epub 2021 Feb 2.

School of Environment and Nature Resources, Renmin University of China, Beijing 100872, China; Key Laboratory of Energy Resource Utilization from Agriculture Residue, Ministry of Agriculture and Rural Affairs, China. Electronic address:

Optimization of acetic acid and formic acid production efficient methanogenesis is always the research hot spot in anaerobic digestion. It is a promising approach to adjust the operation parameters to influence the functional microorganisms for better acetic acid and formic acid production in acidogenesis. Herein, the effects of pH, oxidation-reduction potential (ORP) and carbon-nitrogen (C/N) ratio were determined in batch experiments to probe acetic and formic acids production, and were further verified in continuous stirred tank reactor (CSTR). The results revealed that the content of volatile fatty acids (VFAs) reached to maximum at pH 6.0 or ORP -350 mV, while the production of acetic and formic acids was the highest at pH 7.0 or ORP -450 mV in 9 h fermentation. Also, fermentation products dominated by acetic and formic acids were adjusted in the CSTR under the operating conditions of pH 7.0 and ORP -450 mV. Microbiological analysis from batch test showed that fermentation at pH value of 7.0 enriched the diversity of microorganism, and provided a niche for microbes (Petrimonas, norank_f__Synergistaceae, vadinBC27_wastewater-sludge_group, and Trichococcus) to produce acetic and formic acids. Correspondingly, 78.70% of the carbon was converted to acetic and formic acids in pH 7.0. This study provides a promising strategy for the targeted regulation of acetic and formic acids production in acidogenesis of anaerobic digestion.
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http://dx.doi.org/10.1016/j.watres.2021.116896DOI Listing
April 2021

Deeper insights into effect of activated carbon and nano-zero-valent iron addition on acidogenesis and whole anaerobic digestion.

Bioresour Technol 2021 Mar 7;324:124671. Epub 2021 Jan 7.

Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; School of Environment and Nature Resources, Renmin University of China, Beijing 1000872, PR China. Electronic address:

Conductive materials presented promising advantages for enhancing anaerobic digestion (AD) performance. This study evaluated the effects of activated carbon (AC) and nano-zero-valent iron (nZVI) on the acidogenesis and whole AD to explore their potential mechanisms. AC increased the content of lactic and propionic acids in acidogenesis. nZVI increased the production of formic acid, acetic acid and H in acidogenesis, thus significantly promoted the methane yield in the whole AD. Mechanism exploration proved that AC enriched Trichococcus, and norank_f__Bacteroidetes_vadinHA17, and then improved the activity of enzymes involved in the production of lactic and propionic acids. nZVI buffered the pH to increase the activity of pyruvate formate-lyase (PFL) in formic acid production. Furthermore, nZVI enriched the Methanobacterium which use H and formic acid as substrate. The research paves pathway for the efficient enhancement of conductive materials added novel AD process.
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http://dx.doi.org/10.1016/j.biortech.2021.124671DOI Listing
March 2021

Deep insights into the network of acetate metabolism in anaerobic digestion: focusing on syntrophic acetate oxidation and homoacetogenesis.

Water Res 2021 Feb 24;190:116774. Epub 2020 Dec 24.

Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen361021, China. Electronic address:

Acetate is a pivotal intermediate product during anaerobic decomposition of organic matter. Its generation and consumption network is quite complex, which almost covers the most steps in anaerobic digestion (AD) process. Besides acidogenesis, acetogenesis and methanogenesis, syntrophic acetate oxidation (SAO) replaced acetoclastic methanogenesis to release the inhibition of AD at some special conditions, and the importance of considering homoacetogenesis had also been proved when analysing anaerobic fermentations. Syntrophic acetate-oxidizing bacteria (SAOB), with function of SAO, can survive under high temperature and ammonia/ volatile fatty acids (VFAs) concentrations, while, homoacetogens, performed homoacetogenesis, are more active under acidic, alkaline and low temperature (10°C-20°C) conditions, This review summarized the roles of SAO and homoacetogenesis in AD process, which contains the biochemical reactions, metabolism pathways, physiological characteristics and energy conservation of functional bacteria. The specific roles of these two processes in the subprocess of AD (i.e., acidogenesis, acetogenesis and methanogenesis) were also analyzed in detail. A two phases anaerobic digester is proposed for protein-rich waste(water) treatment by enhancing the functions of homoacetogens and SAOB compared to the traditional two-phases anaerobic digesters, in which the first phase is fermentation phase including acidogens and homoacetogens for acetate production, and second phase is a mixed culture coupling syntrophic fatty acids bacteria, SAOB and hydrogenotrophic methanogens for methane production. This review provides a new insight into the network on production and consumption of acetate in AD process.
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http://dx.doi.org/10.1016/j.watres.2020.116774DOI Listing
February 2021

The application status, development and future trend of nano-iron materials in anaerobic digestion system.

Chemosphere 2021 Apr 21;269:129389. Epub 2020 Dec 21.

Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China. Electronic address:

Growing environment problem and emphasis of environmental protection motivate intense research efforts in exploring technology to improve treatment efficiency on refractory organic pollutants. Hence, finding a method to make up for the deficiency of anaerobic digestion (AD) is very attractive and challenging tasks. The recent spark in the interest for the usage of some nanomaterials as an additive to strengthen AD system. The adoption of iron compounds can influence the performance and stability in AD system. However, different iron species and compounds can influence AD system in significantly different ways, both positive and negative. Therefore, strengthening mechanism, treatment efficiency, microbial community changes in Nanoscale Zero Valent Iron (nZVI) and FeO nanoparticles (FeO NPs) added AD systems were summarized by this review. The strengthening effects of nZVI and FeO NPs in different pollutants treatment system were analyzed. Previous study on the effects of nZVI and FeO NPs addition on AD have reported the concentration of nZVI and FeO NPs, and the types and biodegradability of pollutants might be the key factors that determine the direction and extent of effect in AD system. This review provides a summary on the nZVI and FeO NPs added AD system to establish experiment systems and conduct follow-up experiments in future study.
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http://dx.doi.org/10.1016/j.chemosphere.2020.129389DOI Listing
April 2021

Synergetic effect of nano zero-valent iron and activated carbon on high-level ciprofloxacin removal in hydrolysis-acidogenesis of anaerobic digestion.

Sci Total Environ 2021 Jan 7;752:142261. Epub 2020 Sep 7.

Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China. Electronic address:

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 to 3.48 mg L. 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.
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http://dx.doi.org/10.1016/j.scitotenv.2020.142261DOI Listing
January 2021

Heavy metal stabilization and improved biochar generation via pyrolysis of hydrothermally treated sewage sludge with antibiotic mycelial residue.

Waste Manag 2021 Jan 13;119:152-161. Epub 2020 Oct 13.

Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark.

Hydrothermally treated sewage sludge was pyrolyzed at temperatures of 300, 500, and 700 °C with antibiotic mycelial residue addition ratios of 0, 10, 25, and 50 wt%. The results showed that co-pyrolysis could obviously improve biochar properties. Specifically, adding antibiotic mycelial residue increased the aromaticity and raised the higher heating value of the biochar, which indicates its better potential as fuel. The enrichment in functional groups improved the surface properties of biochar, indicating its better applicability. Additionally, the heavy metal concentrations in biochar were diluted by adding antibiotic mycelial residue, which led to lower toxic inputs to the environment. Moreover, heavy metals were transformed to more stable fractions after co-pyrolysis. A higher pyrolysis temperature and greater antibiotic mycelial residue amounts led to better immobilization of heavy metals, thus preventing their leaching to the environment. This work proposes a promising technique for the synergetic treatment of sewage sludge and antibiotic mycelial residue for improved biochar formation.
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http://dx.doi.org/10.1016/j.wasman.2020.09.050DOI Listing
January 2021

Synthesis of an easily recyclable and safe adsorbent from sludge pyrochar for ciprofloxacin adsorption.

Environ Res 2021 01 2;192:110258. Epub 2020 Oct 2.

Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.

Utilization of sludge pyrochar (SP) is the terminal step to loop the entire harmless disposal process of sewage sludge with pyrolysis. A new, easily recyclable, and safe adsorbent with well-immobilized heavy metals (HMs) was prepared from SP for ciprofloxacin (CIP) adsorption. The operational conditions for the adsorbent preparation were systematically optimized based on recycling rate and adsorption performance. Additionally, the adsorption conditions, adsorption kinetics, isotherms, and regeneration of adsorbents were further investigated in the present study. The results showed that easily recyclable and safe adsorbents were successfully prepared at 1100 °C under N atmospheric conditions (SPA-N-1100) with a maximum CIP adsorption capacity of 10.42 mg/g. SPA-N-1100 exhibited good CIP adsorption performance at an adsorption temperature of 45 °C and pH between 8.0 and 9.0. The adsorbents were regenerated by thermal desorption at 450 °C with a thorough decomposition of CIP. The adsorption mechanism was mainly dominated by its special porous microspheres-accumulation structure and surface species (e.g., FeP and graphite). Moreover, HMs in the adsorbents were well immobilized in SPA-N-1100 by the generation of new metal mineral phases and encapsulation of melting minerals, which had an ultralow potential for ecological risk during application.
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http://dx.doi.org/10.1016/j.envres.2020.110258DOI Listing
January 2021

Chemical speciation and distribution of potentially toxic elements in soilless cultivation of cucumber with sewage sludge biochar addition.

Environ Res 2020 12 11;191:110188. Epub 2020 Sep 11.

Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark.

Potentially toxic elements in municipal sewage sludge can be effectively immobilized during biochar production via pyrolysis. However, the bioavailability of these elements when biochar is applied in soilless cultivation to improve substrate quality has yet to be sufficiently established. In this study, we investigated the chemical speciation and cucumber plant uptake of potentially toxic elements in soilless cultivation when the growth substrate was amended with sewage sludge biochar (0, 5, 10, 15, and 20 wt%). It was found that the addition of 10 wt% biochar was optimal with respect to obtaining a high cucumber biomass and achieving low environmental risk considering the occurrence of hormesis. When the substrate was amended with 10 wt% biochar, cucumber fruit contained lower concentrations of As, Cr, and Zn and smaller bioavailable fractions of As, Cd, Cr, Ni, Cu, and Zn compared with the fruit of control plants, thereby meeting national safety requirements (standard GB 2762-2012, China). Most of the As and Cd taken up by cucumbers accumulated in the leaves and fruit, whereas Cr was found primarily in the roots, and most Ni, Cu, and Zn was detected in the fruit. Importantly, only small proportions of the potentially toxic elements in biochar were taken up by cucumber plants (As: 0.0075%; Cd: 0.038%; Ni: 0.0064%; Cu: 0.0016%; and Zn: 0.0015%). Given that the As, Cd, Ni, and Zn speciation in sewage sludge biochar was effectively immobilized after cultivation, the findings of this study indicate that sewage sludge biochar is a suitable substrate amendment in terms of the risk posed by potentially toxic elements.
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http://dx.doi.org/10.1016/j.envres.2020.110188DOI Listing
December 2020

Novel strategy for relieving acid accumulation by enriching syntrophic associations of syntrophic fatty acid-oxidation bacteria and H/formate-scavenging methanogens in anaerobic digestion.

Bioresour Technol 2020 Oct 17;313:123702. Epub 2020 Jun 17.

Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China. Electronic address:

Aiming at relieving acid accumulation in anaerobic digestion (AD), syntrophic associations of syntrophic fatty acid-oxidation bacteria and H/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 H/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.
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http://dx.doi.org/10.1016/j.biortech.2020.123702DOI Listing
October 2020

Carbon monoxide conversion and syngas biomethanation mediated by different microbial consortia.

Bioresour Technol 2020 Oct 25;314:123739. Epub 2020 Jun 25.

Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark.

Syngas biomethanation is an attractive process for extending application of gasification products. In the present study, anaerobic sludges from three methanogenic reactors feeding cattle manure (CS), sewage sludge (SS) and gaseous H/CO (GS) were used to investigate the effect of microbial consortia composition on syngas biomethanation. The results showed that CS presented the highest CO consumption rate due to its highest relative abundance of CO consuming bacteria. The CO was mainly converted to acetate, and syntrophic acetate oxidization (SAO) bacteria converted acetate to H/CO for hydrogenotrophic methanogenesis in CS and SS. However, acetate was accumulated in GS for lacking acetoclastic methanogens and SAO bacteria, leading to lower biomethanation efficiency. Additionally, adding stoichiometric H could convert CO and CO to nearly pure methane, while, the CO consumption rate declined in H added systems. The results present novel insights into microbial consortia on CO conversion and syngas biomethanation.
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http://dx.doi.org/10.1016/j.biortech.2020.123739DOI Listing
October 2020

Simultaneous heavy metal immobilization and antibiotics removal during synergetic treatment of sewage sludge and pig manure.

Environ Sci Pollut Res Int 2020 Aug 26;27(24):30323-30332. Epub 2020 May 26.

Department of Environmental Engineering, Technical University of Denmark, DK-2800, Kongens Lyngby, Denmark.

The safe handling of heavy metals and antibiotics during waste disposal has attracted wide attention. In the present study, hydrothermally treated sewage sludge was used for co-pyrolysis with different concentration ratios of pig manure at 600 °C for heavy metal immobilization and antibiotic removal. Heavy metals (except Cd) were mainly retained in the biochar samples due to a high degree of decomposition characteristic of organic matter. Pyrolysis significantly immobilized the heavy metals via converting unstable F1 + F2 + F3 fractions (acid-soluble fraction + reducible fraction + oxidizable fraction) to stable F4 fraction (residual fraction), and more pig manure addition led to improved immobilization performance. After co-pyrolysis, the potential environmental risk of feedstocks reduced significantly and the addition of 50 wt.% of pig manure gave a minimum potential ecological risk index of 10.36 with a low risk of contamination. In addition, six types of antibiotics in feedstocks were decomposed completely during pyrolysis. The co-pyrolysis process showed numerous advantages in the synthetic treatment of sewage sludge and pig manure by reducing the heavy metal toxicity and antibiotic levels.
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http://dx.doi.org/10.1007/s11356-020-09230-0DOI Listing
August 2020

Ciprofloxacin adsorption by biochar derived from co-pyrolysis of sewage sludge and bamboo waste.

Environ Sci Pollut Res Int 2020 Jun 22;27(18):22806-22817. Epub 2020 Apr 22.

Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.

Antibiotics residues in aqueous environment and sewage sludge accumulation have become serious environmental issues. The aim of this study is to investigate the potential of ciprofloxacin (CIP) removal by sludge-based biochar prepared from co-pyrolysis of sewage sludge and bamboo waste (BW). The stability and environmental risk of heavy metals (HMs) in the biochar were further investigated to evaluate potential risks for biochar utilization. Results showed that BW was an outstanding additive to prepare co-pyrolyzed biochar from sludge. A higher CIP removal rate (95%) of BW-sludge biochar (SBC) was obtained under initial CIP concentration of 10 mg/L, and its maximum adsorption capacity was 62.48 mg/g which was calculated from the Langmuir model. The pseudo-second-order and Freundlich model also well fit the CIP adsorption process, indicating a chemical and multilayer adsorption of CIP on a heterogeneous surface of biochar. Adsorption mechanism analysis indicated that the diverse functional groups and Fe species in biochar probably were the dominant factors in the adsorption of CIP. The π-π interaction, H-bond, ion exchange, and Fe-complexation might be the main interactions between the functional species and CIP molecules. Besides, HMs, especially the Cr, Cd, and As, were well immobilized in SBC compared with pure sludge biochar. This work suggested that sludge-based biochar, especially the co-pyrolyzed SBC, could be a potential adsorbent for CIP removal from aqueous solutions.
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http://dx.doi.org/10.1007/s11356-020-08333-yDOI Listing
June 2020

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

Water Res 2020 Mar 21;170:115329. Epub 2019 Nov 21.

Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China; University of Chinese Academy of Sciences, Beijing, 100049, China.

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 COD. Furthermore, the economic evaluation indicated that the energy consumption of electrodes was 0.600 kWh/m of sludge filtrate, the net energy profited from increased methane was 2.344 kWh/m 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.
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http://dx.doi.org/10.1016/j.watres.2019.115329DOI Listing
March 2020

Anaerobic digestion of sludge filtrate assisted by symbionts of short chain fatty acid-oxidation syntrophs and exoelectrogens: Process performance, methane yield and microbial community.

J Hazard Mater 2020 02 12;384:121222. Epub 2019 Sep 12.

Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China. Electronic address:

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.
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http://dx.doi.org/10.1016/j.jhazmat.2019.121222DOI Listing
February 2020

Application of mesocolon rotation and reverse puncture in total laparoscopic sigmoid vaginoplasty.

Exp Ther Med 2019 Oct 20;18(4):3191-3196. Epub 2019 Aug 20.

Department of Gastrointestinal Tumors, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, Xinjiang 830054, P.R. China.

The aim of the present study was to explore the clinical efficacy of mesocolon rotation and reverse puncture in total laparoscopic sigmoid vaginoplasty (LSV). The clinical data of 11 patients (unmarried, n=4; married, n=7) with congenital absence of a vagina who underwent treatment of total laparoscopic sigmoid vaginoplasty at the First Affiliated Hospital of Xinjiang Medical University (Urumqi, China) between March 2013 and March 2016 were retrospectively analyzed. In all patients, the surgical method included sigmoid mesocolon rotation and reverse puncture. The vaginal depth, the first sexual intercourse time and female sexual function indexes were recorded. The average operation time was 187±19 min, the average intra-operative blood loss was 132±24 ml, the time to the first meal after surgery was 4.3±1.1 days, the average post-operative hospital stay was 7.5±1.2 days, the post-operative short-term complication rate was 36.3% and the time to the first sexual intercourse was 3.0±0.3 months. The post-operative follow-up results indicated that the anatomical standard was reached in all of the 11 patients. Among the seven married patients, five patients were satisfied with their sex lives after the operation. In terms of psychosexual desire, only one married patient felt no sexual arousal. The other married patients had good sexual relations, function and satisfaction. In conclusion, the application of mesocolon rotation and reverse puncture in total LSV is safe and feasible.
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http://dx.doi.org/10.3892/etm.2019.7920DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6755411PMC
October 2019

Dewaterability enhancement and heavy metals immobilization by pig manure biochar addition during hydrothermal treatment of sewage sludge.

Environ Sci Pollut Res Int 2019 Jun 13;26(16):16537-16547. Epub 2019 Apr 13.

CAS Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.

Hydrothermal treatment (HTT) of sewage sludge (SS) with pig manure biochar (PMB) addition at 160-200 °C was conducted in this study. The effects of PMB addition on the dewaterability of SS and the speciation evolution, leaching toxicity, and potential ecological risk of heavy metals were investigated. The results showed that the solid contents of the filter cakes after adding PMB increased from 20.24%, 24.03%, and 28.69% to 21.57%, 27.69%, and 32.91% at 160, 180, and 200 °C, respectively, compared with traditional HTT of SS. Furthermore, PMB could reduce the bioavailable fractions of Cr, Ni, As, and Cd in the filter cakes obtained at 160 and 180 °C compared with the theoretical value. The leaching toxicity of heavy metals in the filter cakes after adding PMB decreased significantly at 160 and 180 °C and the potential ecological risk index (RI) declined from 62.13 and 44.83 to 55.93 and 42.11, respectively. The obtained filter cake had low potential ecological risk when used in the environment. The mechanisms on the improvement of the dewaterability and heavy metals immobilization were related that PMB acted as the skeleton builder providing the outflow path for free water and implanting heavy metals into SS structure. And the optimal results were obtained at 180 °C during HTT of SS with PMB addition. This work provides a novel and effective method for the treatment of SS.
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http://dx.doi.org/10.1007/s11356-019-04961-1DOI Listing
June 2019

Simultaneous biogas and biogas slurry production from co-digestion of pig manure and corn straw: Performance optimization and microbial community shift.

Bioresour Technol 2019 Jun 28;282:37-47. Epub 2019 Feb 28.

Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China. Electronic address:

Anaerobic co-digestion (AcoD) is proved as an effective approach to solving a bottleneck problem of the low biogas yield in agricultural biomass waste treatment with anaerobic digestion (AD) technology. The present study investigated the effect of C/N radio, organic loading rate (OLR) and total solids (TS) contents on reactor performance in AcoD of pig manure and corn straw for simultaneous biogas and biogas slurry production. It was found that the highest biogas production was obtained at C/N ratio of 25, while the best biogas slurry performance was achieved at C/N ratio of 35. And high OLR and TS resulted in good performances in both biogas production and biogas slurry. At last, the microbial community analysis suggested that Bacteroidetes played a significant role in AcoD process. Acetoclastic methanogenesis was the main pathway for methane production in the stable system. And changing operational parameters could transform and shift the microbial community.
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http://dx.doi.org/10.1016/j.biortech.2019.02.122DOI Listing
June 2019

The synthesis of heterogeneous Fenton-like catalyst using sewage sludge biochar and its application for ciprofloxacin degradation.

Sci Total Environ 2019 Mar 5;654:1284-1292. Epub 2018 Nov 5.

Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.

The terminal utilization of sewage sludge biochar (SSB) is nonnegligible and significant for sewage sludge (SS) treatment by pyrolysis. In this paper, a novel low-cost recyclable sludge biochar catalyst (SBC) that can be employed as a heterogeneous Fenton-like catalyst was prepared using SSB from SS pyrolysis in a pilot-scale platform for ciprofloxacin (CIP) degradation. The fabricated SBC was analyzed to characterize its surface micrographs, pore structures, and chemical composition. The catalytic effect of SBC on CIP degradation was also explored to determine the feasibility of using SBC to remove aquatic organic contaminants, and its degradation mechanism and pathway were also discussed. SBC can effectively remove CIP by adsorption and enhance the degradation of CIP by its catalytic effect. >80% of the CIP was removed at pH 4.0, and the antimicrobial activity of the resulting products was considerably reduced. The possible degradation mechanism is associated with the synergetic effect of adsorption and oxidative degradation. Oxidizing radical was generated from HO by the activation of Fe and Fe, which released from SBC, and HO was the dominant radical in CIP degradation. Piperazine ring cleavage, pyridine cleavage and hydroxylation, F/OH substitution, and defluorination were the dominant degradation pathways. The heavy metal risk assessment showed that SBC exhibits low environmental and ecological risk. This study provides a prospective method for high-value utilization of SSB and a novel and potentially low-cost catalyst for CIP removal from aqueous environments, which is significant for the terminal disposal of SS.
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http://dx.doi.org/10.1016/j.scitotenv.2018.11.013DOI Listing
March 2019

Effect of pyrolysis temperature on characteristics, chemical speciation and risk evaluation of heavy metals in biochar derived from textile dyeing sludge.

Ecotoxicol Environ Saf 2019 Jan 25;168:45-52. Epub 2018 Oct 25.

CAS Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China. Electronic address:

Textile dyeing sludge (TDS) was pyrolyzed at temperature ranging from 300 to 700 °C to investigate characteristics and to evaluate the risk of heavy metals (Zn, Cu, Cr, Ni, Cd, and Mn) in biochar derived from the TDS. The analyzation of characteristics and potential environmental risk evaluation of heavy metals were conducted by the BET-N, FTIR, and BCR sequential extraction procedure. The results showed that the pyrolysis treatment of the TDS contributed to the improvement of the pH value and specific surface areas with increasing pyrolysis temperature. Conversion of the TDS to biochar significantly decreased the H/C and O/C ratios, resulting in a far stronger carbonization and a higher aromatic condensation for the TDS derived biochar. The total contents of Zn, Cu, Cr, Ni and Mn in biochar increased with pyrolysis temperature owing to the thermal decomposition of organic matter in the TDS; but for Cd, the portion distributed in the biochars decreased significantly when the temperature increased up to 600 °C. However, using BCR sequential extraction procedure and analysis, it was found that pyrolysis process promoted changes in the chemical speciation and biochar matrix characteristics, leading to reduce bio-available fractions of heavy metals in the biochars. The potential environmental risk of heavy metals decreased from considerable risk in the TDS to low risk or no risk in biochar after pyrolysis above 400 °C. This work demonstrated that the pyrolysis process was a promising method for disposing of the TDS with acceptable environment risk.
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http://dx.doi.org/10.1016/j.ecoenv.2018.10.022DOI Listing
January 2019

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

Environ Technol 2020 May 5;41(12):1535-1545. Epub 2018 Nov 5.

Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, People's Republic of China.

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 COD at organic loading rate (OLR) of 6.9 kg COD m d, which were higher than those of the ABR with 77.6% and 207 ± 5 mL g COD, respectively, at OLR of 5.1 kg COD m d. 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 (5.4%), (2.0%), (43.8%), (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.
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http://dx.doi.org/10.1080/09593330.2018.1540664DOI Listing
May 2020

Study of ciprofloxacin removal by biochar obtained from used tea leaves.

J Environ Sci (China) 2018 Nov 7;73:20-30. Epub 2018 Jan 7.

Tianjin Huankelijia Environment Remediation Technology Co., Ltd., Tianjin 300191, China.

In this study, used tea leaves (UTLs) were pyrolyzed to obtain used tea-leaf biochar (UTC), and then the UTC was used as an adsorbent to remove ciprofloxacin (CIP) from aqueous solutions. Batch experiments were conducted to investigate the CIP adsorption performance and mechanism. The results showed that the CIP-adsorbing ability first increased and then declined as the UTC pyrolysis temperature increased. The UTC obtained at 450°C presented excellent CIP-absorbing ability at pH6 and 40°C. The maximum monolayer adsorption capacity was 238.10mg/g based on the Langmuir isotherm model. The pseudo-second-order kinetic equation agreed well with the CIP adsorption process, which was controlled by both external boundary layer diffusion and intra-particle diffusion. The characterization analysis revealed that the OH groups, CC bonds of aromatic rings, CH groups in aromatic rings and phenolic CO bonds play vital roles in the CIP adsorption process, and that the NC, NO, OCO and COH groups of UTC were consumed in large quantities. π-π interactions, hydrogen bonding and electrostatic attraction are inferred as the main adsorption mechanisms. The present work provides not only a feasible and promising approach for UTLs utilization but also a potential adsorbent material for removing high concentrations of CIP from aqueous solutions.
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http://dx.doi.org/10.1016/j.jes.2017.12.024DOI Listing
November 2018

Immobilization of heavy metals in ceramsite produced from sewage sludge biochar.

Sci Total Environ 2018 Jul 9;628-629:131-140. Epub 2018 Feb 9.

Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China. Electronic address:

Ceramsite was prepared from sewage sludge biochar (SSB). The migration, speciation evolution, leaching toxicity, and potential environmental risk of heavy metals (HMs) in sludge biochar ceramsite (SBC) were investigated. The characteristics of the SBC met the requirements for Chinese lightweight aggregate standards (GB/T 1743.1-2010 and JT/T 770-2009) and the heavy metals (HMs: Cu, Zn, Cr, Pb, and Cd) were well immobilized in the SBC. The leaching percentages of the HMs in SBC were remarkably reduced, in particular after preheating at 400°C and sintering at 1100°C. The leaching percentages of Cu, Zn, Cr, Cd, and Pb decreased from (19.099, 18.009, 0.010, 3.952, and 0.379) % to (2.122, 4.102, 0.002, 1.738, and 0.323) %, respectively. The RAC values of the HMs in SBC were all lower than 1%, and the risk index (RI) suggested that the SBC had no HMs contamination and very low potential ecological risk when used in the environment. Furthermore, the HM-immobilization mechanisms were mainly related to the formation of new crystal phases (silicate and phosphate minerals) by incorporation of HMs, and to vitrification and encapsulation with low concentration of HMs on the surface. This work provides a useful method for large-scale reuse of SSB with very low leaching toxicity and low potential ecological risk of HMs.
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http://dx.doi.org/10.1016/j.scitotenv.2018.02.036DOI Listing
July 2018

A process combining hydrothermal pretreatment, anaerobic digestion and pyrolysis for sewage sludge dewatering and co-production of biogas and biochar: Pilot-scale verification.

Bioresour Technol 2018 Apr 10;254:187-193. Epub 2018 Jan 10.

Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Science, Xiamen 36102, China. Electronic address:

To fully dispose of/utilize sewage sludge, a process combing hydrothermal pretreatment (HTPT), anaerobic digestion (AD) and pyrolysis was developed and tested at the pilot scale. First, the improvement in sludge dewaterability by HTPT at 180 °C for 30 min was verified, and the water content decreased from 85 to 33 wt% after filter pressing. Then, the resulting filtrate underwent continuous mesophilic (37 ± 2 °C) AD in an up-flow anaerobic sludge bed (UASB) reactor for producing biogas to compensate for the energy required for HTPT. Meanwhile, the filter cake was pyrolyzed in a rotary furnace (600 ± 50 °C) to generate biochar, and heavy metals were well immobilized in the biochar. Finally, the material/energy balance made according to the pilot data showed that the proposed process was effective for full resource reuse of sewage sludge.
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http://dx.doi.org/10.1016/j.biortech.2018.01.045DOI Listing
April 2018

Hydrothermal and alkaline hydrothermal pretreatments plus anaerobic digestion of sewage sludge for dewatering and biogas production: Bench-scale research and pilot-scale verification.

Water Res 2017 06 25;117:49-57. Epub 2017 Mar 25.

Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Science, Xiamen 36102, China. Electronic address:

To test the feasibility and practicability of the process combing hydrothermal pretreatment for dewatering with biogas production for full utilization of sewage sludge, hydrothermal/alkaline hydrothermal pretreatments and in turn anaerobic digestion of the filtrates obtained after dewatering the pretreated sludge were performed at bench- and pilot-scales. The hydrothermal temperature fell within the range of 140 °C-220 °C and the pretreatment time varied from 30 min to 120 min. For the alkaline hydrothermal pretreatment the pH value of the sludge was adjusted to 9.0-11.0 by adding Ca(OH). The results showed that the dewaterability of the sewage sludge was improved with increasing pretreatment temperature but the impact of the pretreatment time was not significant. The addition of Ca(OH) gave better performance on the subsequent mechanical dewatering of the pretreated sludge compared to pure hydrothermal pretreatment, and the higher the pH value was, the better the dewaterability of the pretreated sludge was. The conditions of 180 °C/30 min and 160 °C/60 min/pH = 10.0 (for hydrothermal and alkaline hydrothermal pretreatments, respectively) resulted in relatively good results in the theoretical energy balance, which were verified in the pilot-scale tests. Based on the data from the pilot tests, the alkaline hydrothermal process realized self-sufficiency in energy at the cost of a proper amount of CaO.
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http://dx.doi.org/10.1016/j.watres.2017.03.047DOI Listing
June 2017