Publications
98 results found
Uali AS, Lam TYC, Huang X, et al., 2024, Role and potential of the semi-classical/-quantum mechanism of the extracellular environment and cell envelope in Direct Interspecies Electron Transfer (DIET)-driven biomethanation, Critical Reviews in Environmental Science and Technology, Vol: 54, Pages: 581-601, ISSN: 1064-3389
The extracellular electron transfer (EET) capability of Methanosarcina spp. in direct interspecies electron transfer (DIET) has profoundly increased our understanding of microbial kinetics and energetics in biomethanation systems. In Methanosarcina spp., such EET mechanisms occur in the cell envelope and biofilm matrix. These substances are composed of protein-like, polysaccharide-rich biomolecular structures that were previously thought to contribute only to cell support and shape; while their participation in dynamic processes remains unclear and has gathered widespread interest. This review first addresses the molecular structure and chemical characteristics of the extracellular matrix and cell wall polymers in Methanosarcina spp. Next, we focus on recent theoretical studies on the conduction and EET mechanisms of the extracellular matrix and cell wall polymers: tunnelling, hopping, proton-activated electron transfer and voltage-dependent electron transport. We conclude this review by discussing the state-of-the-art electrochemical techniques and experiments and the associated challenges, i.e., the kinetic isotope effect and on–off resonance switching. The border impacts of such conductive pathways may offer a semi-classical/quantum perspective on microbiology and mark the renaissance of anaerobic biotechnology.
Bai Y, Hu H, Lee P-H, et al., 2023, Nitrate removal in iron sulfide-driven autotrophic denitrification biofilter: Biochemical and chemical transformation pathways and its underlying microbial mechanism., Sci Total Environ, Vol: 901
Iron sulfides-based autotrophic denitrification (IAD) is effective for treating nitrate-contaminated wastewater. However, the complex nitrate transformation pathways coupled with sulfur and iron cycles in IADs are still unclear. In this study, two columns (abiotic vs biotic) with iron sulfides (FeS) as the packing materials were constructed and operated continuously. In the abiotic column, FeS chemically reduced nitrate to ammonium under the ambient condition; this chemical reduction reaction pathway was spontaneous and has been overlooked in IAD reactors. In the biotic column (IAD biofilter), the complex nitrogen-transformation network was composed of chemical reduction, autotrophic denitrification, dissimilatory nitrate reduction to ammonium (DNRA) and sulfate reducing ammonium oxidation (Sulfammox). Metagenomic analysis and XPS characterization of the IAD biofilter further validated the roles of functional microbial communities (e.g., Acidovorax, Diaphorobacter, Desulfuromonas) in nitrate reduction process coupled with iron and sulfur cycles. This study gives an in-depth insight into the nitrogen transformations in IAD system and provides fundamental evidence about the underlying microbial mechanism for its further application in biological nitrogen removal.
Wu Z, Nguyen D, Shrestha S, et al., 2023, Evaluation of Nanaerobic Digestion as a Mechanism to Explain Surplus Methane Production in Animal Rumina and Engineered Digesters, ENVIRONMENTAL SCIENCE & TECHNOLOGY, Vol: 57, Pages: 12302-12314, ISSN: 0013-936X
Yang P, Leng L, Zhuang H, et al., 2023, Significant enhancement by casamino acids of caproate production via chain elongation, Biochemical Engineering Journal, Vol: 193, ISSN: 1369-703X
In this study, the effects of casamino acids, as the main component in yeast extract, on the bioproduction of caproate were evaluated. A dosage of 5 g/L casamino acids addition significantly promoted caproate production and shortened the lag phase for caproate production by 7.6-folds compared with the control. Both the net carbon and electron conversion efficiencies were enhanced. The addition of casamino acids shaped a dissimilar microbial community from that of the control and that of the inoculum. The caproate-producing Clostridium and Caproiciproducens, the proteolytic Proteiniphilum and Brassicibacter, and the saccharide-utilizing Hydrogenoanaerobacteriu were enriched, and their abundance were distinguished between with and without the addition of casamino acids as fermentation progressed. Further metagenomics analysis recovered genome bins of Clostridium kluyveri, Clostridium cochlearium, Caprobacter fermentans and Proteiniphilum acetatigenes, representing the majority of the functional bacteria with casamino acids addition. The complete reverse β-oxidation and amino acids (serine/glycine) metabolic pathway for caproate production and butyrate formation, respectively, were fully recovered. Furthermore, all the genes involved were highly expressed and metabolically active in meta-transcriptomics analysis. The finding proved that casamino acids was able to enhance caproate formation by promoting ethanol utilization and butyrate formation. In general, yeast extract could not only support microbial growth but also contribute to the formation of medium chain fatty acids, therefore promoting the efficiency of chain elongation process.
Bai Y, Wang S, Zhussupbekova A, et al., 2023, High-rate iron sulfide and sulfur-coupled autotrophic denitrification system: Nutrients removal performance and microbial characterization, WATER RESEARCH, Vol: 231, ISSN: 0043-1354
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- Citations: 14
Huang X, Mi W, Chan YH, et al., 2023, C-N-S synergy in a pilot-scale mainstream anammox fluidized-bed membrane bioreactor for treating chemically enhanced primary treatment saline sewage, WATER RESEARCH, Vol: 229, ISSN: 0043-1354
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- Citations: 3
Heo J, Kwon D, Beirns E, et al., 2023, Superior methylparaben removal by anaerobic fluidized bed ceramic membrane bioreactor with PVDF tubular fluidized biocarrier: Reactor performance and microbial community, JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING, Vol: 11, ISSN: 2213-2929
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- Citations: 2
Lee M, Yoo K, Kim H, et al., 2023, Metatranscriptional characterization of metabolic dynamics in anaerobic membrane bioreactor producing methane from low-strength wastewater, BIORESOURCE TECHNOLOGY, Vol: 370, ISSN: 0960-8524
Kwon D, Beirns E, Yoon J, et al., 2022, Polyaniline-coated conductive media promotes direct interspecies electrons transfer (DIET) and kinetics enhancement of low-strength wastewater treatment in anaerobic fluidized bed membrane bioreactor (AFMBR), CHEMICAL ENGINEERING JOURNAL, Vol: 446, ISSN: 1385-8947
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- Citations: 1
Ji XM, Wang YL, Zhan X, et al., 2022, Meta-Omics reveal the metabolic acclimation of freshwater anammox bacteria for saline wastewater treatment, Journal of Cleaner Production, Vol: 362, ISSN: 0959-6526
Saline wastewater is a big challenge for the application of anammox processes. Although the feasibility of freshwater anammox bacteria for saline wastewater treatment was revealed, its metabolic acclimation to different saline concentrations is still elusive. Here, one low-strength-fed anammox reactor was operated with the shift of saline concentrations. The results showed that one Ca. Brocadia genome with a relative abundance of 31.5% was recovered. Meta-Omics analyses showed that salinity (around 12.5 g L−1 NaCl) could promote the nitrogen transformation in Ca. Brocadia through the driven of dissimilatory nitrate reduction to ammonium (DNRA). Specific sodium translocations pump (Na+-NADH:quinone oxidoreductase), as well as more genes associated with H+- dependent membrane-bound ATP formation and Na+-dependent membrane-bound ATP formation, was highly expressed in Ca. Brocadia under saline conditions than that under fresh conditions. This implied that such Na + transduction was likely associated with the NADPH/NADH via the hydrazine oxidation pathway. Notably, sodium extrusion was also associated with energy exploitation from the hydrolysis of pyrophosphatase (PPi) through K+-stimulated pyrophosphate-energized sodium pump. This study shed light on the metabolic acclimation, such as nitrogen transformation and cation-induced energy transduction (i.e., Na+, K+, and Ca2+) in Ca. Brocadia, illustrating their feasibility for saline and freshwater wastewater treatment.
Rohan R, Jing H, Lee P-H, 2022, Theoretical characterisation of electron tunnelling from granular activated carbon to electron accepting organisms in direct interspecies electron transfer, Scientific Reports, Vol: 12, Pages: 1-10, ISSN: 2045-2322
Direct interspecies electron transfer (DIET) has been identified as an efficient metabolism between symbiotically interacting organisms. One method of DIET uses conductive materials (e.g., granular activated carbon (GAC)) as a medium to shuttle electrons from electron donating organisms (eg., Geobacter metallireducens) to electron accepting organisms (e.g., Geobacter sulfurreducens and Methanosarcina barkeri). Conductive materials such as GAC, become negatively charged in DIET processes due to reduction by electron donating organisms. This high excess electron density in GAC leads to quantum tunnelling of electrons being a significant electron transfer mechanism for DIET. Thus, a theoretical model obeying the Wentzel–Kramers–Brillouin (WKB) approximation and Fermi–Dirac statistics was developed and simulated. In the model, the electron tunnelling transfer barrier was described by an effective rectangular barrier. The result of our 1D tunnelling simulations indicates that within 29.4 nm of the GAC, tunnelling can sufficiently supply electrons from GAC to G. sulfurreducens and M. barkeri. The phenomenon of tunnelling may also have significance as a stimulant of chemotaxis for G. sulfurreducens and other electron accepting microbes when attempting to adsorb onto GAC. This study sheds light on quantum tunnelling’s significant potential in both bacterium and archaeon DIET-centric processes.
Alvarado V, Hsu S-C, Wu Z, et al., 2022, Roadmap from Microbial Communities to Individuality Modeling for Anaerobic Digestion of Sewage Sludge, ENVIRONMENTAL SCIENCE & TECHNOLOGY, Vol: 56, Pages: 6596-6607, ISSN: 0013-936X
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- Citations: 2
Zhuang H, Tan G-YA, Jing H, et al., 2022, Enhanced primary treatment for net energy production from sewage - The genetic clarification of substrate-acetate-methane pathway in anaerobic digestion, CHEMICAL ENGINEERING JOURNAL, Vol: 431, ISSN: 1385-8947
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- Citations: 16
Kakadellis S, Lee P-H, Harris ZM, 2022, Two birds with one stone: bioplastics and food wase anaerobic co-digestion, Environments, Vol: 9, Pages: 9-9, ISSN: 0711-6780
Following the BBC’s Blue Planet II nature documentary series on marine ecosystems, plastic packaging has come under public fire, with consumers demanding greener alternatives. The biodegradable properties of some bioplastics have offered a potential solution to the global challenge of plastic pollution, while enabling the capture of food waste through anaerobic digestion as a circular and energy-positive waste treatment strategy. However, despite their increasing popularity, currently bioplastics are being tested in environments that do not reflect real-life waste management scenarios. Bioplastics find their most useful, meaningful and environmentally-sound application in food packaging—why is there so little interest in addressing their anaerobic co-digestion with food waste? Here, we provide a set of recommendations to ensure future studies on bioplastic end-of-life are fit for purpose. This perspective makes the link between the environmental sustainability of bioplastics and the role of food waste anaerobic digestion as we move towards an integrated food–energy–water–waste nexus. It shines light on a novel outlook in the field of bioplastic waste management while uncovering the complexity of a successful path forward. Ultimately, this research strives to ensure that the promotion of bioplastics within a circular economy framework is supported across waste collection and treatment stages.
Kraakman B, Romero A, Diaz I, et al., 2022, Micro-Aerobic Digestion for Advanced Process Stability and Biogas Desulfurization, Pages: 1625-1642
Many traditional anaerobic digesters can benefit from a facelift that maximizes biogas production and enhancing process stability without major infrastructure modification. Moreover, a simple method to limit H2S in the biogas without expensive gas conditioning would all contribute to the sustainability and economic efficiency of the energy recovery process as operated at many water resource recovery facilities. Micro-aeration can provide this facelift without major infrastructure modification. Micro-aerobic digestion is a relatively new process-integrated technology that may be defined as the trace consumption of oxygen with zero concentration of oxygen present in the sludge. Micro-aeration has been researched and applied for biogas desulfurization with H2S removal efficiency of more than 80% in most cases. Moreover, Micro-aeration has shown to improve the degradability of the feedstock and enhance the methane production in cases with high loading rates, while it can enrich the diversity of the microbial community improving process stability.
Wei SP, Stensel HD, Ziels RM, et al., 2021, Partitioning of nutrient removal contribution between granules and flocs in a hybrid granular activated sludge system., Water Res, Vol: 203
Sludge granulation in continuous-flow systems is an emerging technology to intensify existing activated sludge infrastructure for nutrient removal. In these systems, the nutrient removal contributions and partitioning of microbial functions between granules and flocs can offer insights into process implementations. To this end, a reactor system that simulates the continuous-flow environment using an equal amount of initial granule and floc biomass was investigated. The two operational strategies for maintaining granule growth in the continuous-flow system were (a) the higher solids retention time (SRT) for the granules versus flocs, as well as (b) selective feeding of carbon to the granules. The SRT of the large granule fractions (>425 µm, LG) and floc/small granule fractions (<425 µm, FSG) were controlled at 20 and 2.7-6.0 days, respectively. Long term operation of the hybrid granule/floc system achieved high PO43- and NH4+ removal efficiencies. Higher polyphosphate-accumulating organisms (PAO) activity was observed in the FSG than LG, while ammonia-oxidizing bacteria (AOB) activities were similar in the two biomass fractions. Nitrite shunt was observed in the FSG, possibly due to out-competition by the high NOB activity in LG. More importantly, washing out the FSG caused a reduction in LG's AOB and PAO activity, indicating a possible dependency of LG on FSG for maintaining its nutrient removal capacity. Our findings highlighted the partitioning and potential competition/cooperation of key microbial functional groups between LG and FSG, facilitating nutrient removal in a hybrid granular activated sludge system, as well as implications for practical application of the treatment platform.
Zhuang H, Lee P-H, Wu Z, et al., 2021, Genomic driven factors enhance biocatalyst-related cellulolysis potential in anaerobic digestion., Bioresour Technol, Vol: 333
Anaerobic digestion (AD) is a promising technology to recover bioenergy from biodegradable biomass, including cellulosic wastes. Through a few fractionation/separation techniques, cellulose has demonstrated its potential in AD, but the performance of the process is rather substrate-specific, as cellulolysis bacteria are sensitive to the enzyme-substrate interactions. Cellulosome is a self-assembled enzyme complex with many functionalized modules in the bacteria which has been gradually studied, however the genomic fingerprints of the culture-specific cellulosome in AD are relatively unclear especially under processing conditions. To clarify the key factors affecting the cellulosome induced cellulolysis, this review summarized the most recent publications of AD regarding the fates of cellulose, sources and functional genes of cellulosome, and omics methods for functional analyses. Different processes for organic treatment including applying food grinds in sewer, biomass valorization, cellulose fractionation, microaeration, and enzymatic hydrolysis enhanced fermentation, were highlighted to support the sustainable development of AD technology.
Kwon D, Lam TYC, Kim M, et al., 2021, Combined Effect of Activated Carbon Particles and Non-Adsorptive Spherical Beads as Fluidized Media on Fouling, Organic Removal and Microbial Communities in Anaerobic Membrane Bioreactor, MEMBRANES, Vol: 11
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- Citations: 4
Wu Z, Duc N, Lam TYC, et al., 2021, Synergistic association between cytochrome <i>bd</i>-encoded <i>Proteiniphilum</i> and reactive oxygen species (ROS)-scavenging methanogens in microaerobic-anaerobic digestion of lignocellulosic biomass, WATER RESEARCH, Vol: 190, ISSN: 0043-1354
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- Citations: 52
Ji X, Leng L, Wu Z, et al., 2021, Underpinning unique genes in Ca. Brocadia sp. and its interspecies association potentials in a partial nitrification/anammox system with low-strength wastewater, Chemical Engineering Journal, Vol: 405, ISSN: 1385-8947
Anaerobic ammonia oxidation (anammox) incorporated with anaerobic treatment with sewage offers an energy-efficient option. With the substrate in scare from anaerobically-treated sewage, the dominated anammox species, their mechanisms, and interspecies interaction remain unclear. Here, we enriched and operated a partial nitrification (PN)- anammox (A) fluidized-bed bioreactor (FBR) containing granular activated carbon (GAC) inoculated from a conventional activated sludge with a synthetic low-strength wastewater under a dissolved oxygen concentration of 0.7 mg/L. It achieved over 53% of total nitrogen removal without anammox seed. Our meta-omics analyses revealed an enriched anammox strain affiliated to Ca. Brocadia sp. with a relative abundance of 11.18% and 26.96% in the bulk and biofilm, respectively. Genes encoding dissimilatory nitrate reduction to ammonium (DNRA) and heterotrophic anabolism in this strain were recovered, suggesting its potential in a flexible nitrogen stochiometric feed ratio through organics utilization. Furthermore, 17 and 19 high-quality draft genomes yielded from the bulk and biofilm, respectively support the interspecies interaction capacity between Ca. Brocadia sp. and other nitrogen cycle microorganisms through nitrite loop and vitamin B12 exchange. By offering such overlooked pathways and their interspecies linkages between Ca. Brocadia sp. and other microbes, our study facilitates its mainstream application.
Chu WX, Lee PH, Tsui YY, et al., 2021, Performance analysis of a simulated container data center subject to airflow resistance, Energy Efficiency, Vol: 14, ISSN: 1570-646X
In this paper, the influence of pressure resistance in the data rack on the cooling performance of a simulated container data center is experimentally investigated. It is found that the pressure resistance may impose a significant influence on the airflow distribution. The perforated resistance with specific porosity (F) of 32% calculated by the porous jump model is identified to appropriately mimic the porous zone of real servers. The flow reversal may occur at the top part of the rack when the pressure resistance is low, and this phenomenon is verified by a dry ice experiment. Results show that the flow reversal causes severe hot spots at the top part of racks. By imposing the perforated resistance, the hot spots in the central and top part of the simulated racks can be effectively removed. However, hot spots at the entrance of the simulated rack still persist and even enlarge. The cooling performance may deteriorate pronouncedly after introducing the gap spacing between racks, and the deterioration reaches a plateau after the gap spacing is increased to 38 mm. It is indicated that the aisle containment at the entrance and exit of the cold aisle shows pronounced improvement on the cooling performance in a container data center.
Ochs P, Martin BD, Germain E, et al., 2021, Evaluation of a full-scale suspended sludge deammonification technology coupled with an hydrocyclone to treat thermal hydrolysis dewatering liquors, Processes, Vol: 9, Pages: 1-15
Suspended sludge deammonification technologies are frequently applied for sidestream ammonia removal from dewatering liquors resulting from a thermal hydrolysis anaerobic digestion (THP/AD) process. This study aimed at optimizing the operation, evaluate the performance and stability of a full-scale suspended sludge continuous stirred tank reactor (S-CSTR) with a hydrocy-clone for anaerobic ammonia oxidizing bacteria (AMX) biomass separation. The S-CSTR operated at a range of nitrogen loading rates of 0.08–0.39 kg N m−3 d−1 displaying nitrogen removal efficiencies of 75–89%. The hydrocyclone was responsible for retaining 56–83% of the AMX biomass and the washout of ammonia oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) was two times greater than AMX. The solid retention time (SRT) impacted on NOB washout, that ranged from 0.02–0.07 d−1 . Additionally, it was demonstrated that an SRT of 11–13 d was adequate to wash-out NOB. Microbiome analysis revealed a higher AMX abundance (Candidatus scalindua) in the reactor through the action of the hydrocyclone. Overall, this study established the optimal operational envelope for deammonification from THP/AD dewatering liquors and the role of the hydrocyclone towards maintaining AMX in the S-CSTR and hence obtain process stability.
Huang X, Lee PH, 2021, Shortcut nitrification/denitrification through limited-oxygen supply with two extreme COD/N-and-ammonia active landfill leachates, Chemical Engineering Journal, Vol: 404, ISSN: 1385-8947
Shortcut nitrification/denitrification (N/DN) was carried out through limited dissolved oxygen supply (DO, 0.5–0.8 mg/L) with active air-stripping treated (COD/N of 10.1 and 615.7 mg N/L ammonia) and raw leachate (COD/N of 2.2 and 3596.3 mg N/L ammonia). The reactor demonstrated robust performance, achieving maximum removal rates of 5.33 kg COD/m3/d and 1.2 kg N/m3/d under 0.6 mg/L DO supply. 16S rRNA gene amplicon sequencing analysis revealed that Nitrosomonas holding around 1.0% responded to ammonia oxidation, while nitrite oxidizing bacteria were suppressed. For the air-stripping treated leachate, abundant and diverse denitrifying populations (e.g. Paracoccus, Pseudomonas, Roseimaritima, and Thauera) were likely responding for total nitrogen (TN) and COD removal. Feeding the raw leachate, apart from heterotrophic denitrifiers contributing to auxiliary COD and TN removal, lithotrophic denitrifiers using sulfur and/or sulfide as electron donors were associated with sulphur reducing bacteria, suggesting that the changing of feeding strength propelled a remarkable shift of denitrifying populations. An unexpected observation was found that Candidatus Anammoximicrobium sp., previously reported in dilute wastewaters, proliferated and accounted for 0.63% whilst the reactor was fed with active raw leachate (rich in ammonia nitrogen and COD). Functional profiles prediction suggested that methyl compounds metabolization and aromatic compounds degradation might actively perform. This study validated that the shortcut N/DN could be achieved by a limited oxygen supply for high COD/N wastewaters (e.g., over 9) and leads to immediately beneficial to the treatment of relevant wastewaters.
Qin W, Zheng Y, Zhao F, et al., 2020, Alternative strategies of nutrient acquisition and energy conservation map to the biogeography of marine ammonia-oxidizing archaea, ISME JOURNAL, Vol: 14, Pages: 2595-2609, ISSN: 1751-7362
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- Citations: 41
Nobu MK, Narihiro T, Mei R, et al., 2020, Catabolism and interactions of uncultured organisms shaped by eco-thermodynamics in methanogenic bioprocesses., Microbiome, Vol: 8
BACKGROUND: Current understanding of the carbon cycle in methanogenic environments involves trophic interactions such as interspecies H2 transfer between organotrophs and methanogens. However, many metabolic processes are thermodynamically sensitive to H2 accumulation and can be inhibited by H2 produced from co-occurring metabolisms. Strategies for driving thermodynamically competing metabolisms in methanogenic environments remain unexplored. RESULTS: To uncover how anaerobes combat this H2 conflict in situ, we employ metagenomics and metatranscriptomics to revisit a model ecosystem that has inspired many foundational discoveries in anaerobic ecology-methanogenic bioreactors. Through analysis of 17 anaerobic digesters, we recovered 1343 high-quality metagenome-assembled genomes and corresponding gene expression profiles for uncultured lineages spanning 66 phyla and reconstructed their metabolic capacities. We discovered that diverse uncultured populations can drive H2-sensitive metabolisms through (i) metabolic coupling with concurrent H2-tolerant catabolism, (ii) forgoing H2 generation in favor of interspecies transfer of formate and electrons (cytochrome- and pili-mediated) to avoid thermodynamic conflict, and (iii) integration of low-concentration O2 metabolism as an ancillary thermodynamics-enhancing electron sink. Archaeal populations support these processes through unique methanogenic metabolisms-highly favorable H2 oxidation driven by methyl-reducing methanogenesis and tripartite uptake of formate, electrons, and acetate. CONCLUSION: Integration of omics and eco-thermodynamics revealed overlooked behavior and interactions of uncultured organisms, including coupling favorable and unfavorable metabolisms, shifting from H2 to formate transfer, respiring low-concentration O2, performing direct interspecies electron transfer, and interacting with high H2-affinity methanogenesis. These findings shed light on how microorganisms overcome a critical obstacle in m
Wei SP, Stensel HD, Nguyen Quoc B, et al., 2020, Flocs in disguise? High granule abundance found in continuous-flow activated sludge treatment plants., Water Res, Vol: 179
To date, high performance of full-scale aerobic granular sludge (AGS) technology has been demonstrated on a global scale. Its further integration with existing continuous flow activated sludge (CFAS) treatment plants is the next logical step. All granular sludge reactors operated in sequencing batch reactors (SBR) mode with anaerobic feeding conditions select for growth of phosphorus and glycogen accumulating organisms (PAO and GAO, respectively), which are known to enhance sludge settling characteristics. Therefore, we hypothesized that AGS are commonly present at full-scale CFAS processes with enhanced biological phosphorus removal (EBPR) and low sludge volume index (SVI). This hypothesis was confirmed at 13 EBPR plants, where granules were found present (at plants where SVI was lower than 100 ml/g) with a strong correlation between high granule abundance and low SVI. A wide range of granule abundance was found among the plants, ranging from 0.5% to as high as 80%. Evaluations of the EBPR plant process configurations showed that high granule abundances may be related to selector design features such as high anaerobic food to mass (F/M) ratios, unmixed in-line fermentation, and high influent soluble COD fraction. Granules were also observed at a non-EBPR plant with an aerobic selector receiving high F/M feeds. Quantitative PCR and 16S rRNA gene sequencing analyses revealed higher relative gene abundance of Accumulibacter PAO and Competibacter GAO in the granules over flocs, as well as a correlation between granule abundance and some possible EPS producers such as Flavobacterium and Competibacter. Our results indicated that process configurations that select for slow-growing or EPS-producing heterotrophs play an important role for granule formation in full-scale CFAS systems as previously shown in SBR configurations.
Lam TYC, Mei R, Wu Z, et al., 2020, Superior resolution characterisation of microbial diversity in anaerobic digesters using full-length 16S rRNA gene amplicon sequencing., Water Res, Vol: 178
In the past decade, the characterisation of the microbial community in anaerobic digestion was primarily done by using high-throughput short-read amplicon sequencing. However, the short-read approach has inherent primer bias and low phylogenetic resolution. Our previous study using Illumina MiSeq suggested that the heterogeneity of AD microbiome was operation-driven. To advance our knowledge towards the complexity of the AD microbiome, we performed full-length 16S rRNA gene amplicon sequencing using PacBio Sequel for a more accurate phylogenetic identification. To this end, purified DNA samples from 19 global anaerobic digesters were sequenced. Sixteen methanogenic archaea were identified at the species level. Among them, Methanosarcina horonobensis and Methanosarcina flavescens had significant presence under specific operating conditions. Methanothrix concilii presented in all digesters sequenced. Unexpectedly, over 90% of the Smithella detected were closely related to alkane-degrading Smithella strains D17 and M82, not Smithella propionica. Using LEfSe and network analysis, the interspecies relationship between the fermentative and syntrophic bacteria was addressed. Comparison of the short- and long-read sequencing results were performed and discussed. From sample preparation to data analysis, this work characterised the digester microbiomes in a superior resolution.
Kim M, Lam TYC, Tan G-YA, et al., 2020, Use of polymeric scouring agent as fluidized media in anaerobic fluidized bed membrane bioreactor for wastewater treatment: System performance and microbial, JOURNAL OF MEMBRANE SCIENCE, Vol: 606, ISSN: 0376-7388
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- Citations: 17
Xu L, Pang Y, Huang D, et al., 2020, Increasing ammonia recovery from high-level ammonium wastewater via adding sodium sulfate to prevent nitrogen generation in the cathode, ENVIRONMENTAL RESEARCH, Vol: 186, ISSN: 0013-9351
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- Citations: 2
Lee P-H, 2020, Energy-efficient single-stage nitrite shunt denitrification with saline sewage through concise dissolved oxygen (DO) supply: Process performance and microbial communities, Microorganisms, Vol: 8, Pages: 1-13, ISSN: 2076-2607
Single-stage nitrite shunt denitrification (through nitrite rather than nitrate) with low dissolved oxygen (DO) supply is a better alternative in terms of energy-efficiency, short-footprint, and low C/N-ratio requirement. This study investigates the optimal DO level with temperature effect, with saline sewage at the fixed hydraulic and solids retention times of 8 h and 8 d, respectively. Moreover, 16S rRNA gene sequencing analysis corresponding with total nitrogen (TN) and chemical oxygen demand (COD) removals in each operating condition were performed. Results showed that DO of 0.3 mg/L at 20 °C achieved over 60.7% and over 97.9% of TN and COD removal, respectively, suggesting that such condition achieved effective nitrite-oxidizing bacteria inhibition and efficient denitrification. An unexpected finding was that sulfur-reducing Haematobacter and nitrogen-fixing Geofilum and Shinella were highly abundant with the copredominance of ammonia-oxidizing Comamonas and Nitrosomonas, nitrite-oxidizing Limnohabitans, and denitrifying Simplicispira, Castellaniella, and Nitratireductor. Further, canonical correspondence analysis (CCA) with respect to the operating conditions associated with phenotype prediction via R-based tool Tax4Fun was performed for a preliminary diagnosis of microbial functionality. The effects of DO, temperature, nitrite, and nitrate in various extents toward each predominant microbe were discussed. Collectively, DO is likely pivotal in single-stage nitrite shunt denitrification, as well as microbial communities, for energy-efficient saline sewage treatment.
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