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In-situ sludge reduction based on Mn^(2+)-catalytic ozonation conditioning:Feasibility study and microbial mechanisms

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Journal of Environmental Sciences 2024年第1期135卷 185-197页

作者： Haozhe Huang Tingting Wei Hui Wang Bing Xue Sisi Chen Xiankai Wang Haibin Wu Bin Dong Zuxin Xu College of Environmental Science and engineering Tongji UniversityShanghai 200092China YANGTZE Eco-Environment engineering Research Center China Three Gorges CorporationBeijing 100038China

To improve the sludge conditioning efficiency without increasing the ozone dose,an in-situ sludge reduction process based on Mn^(2+)-catalytic ozonation conditioning was proposed.Using ozone conditioning alone as a control,a lab-scale sequencing batch reactor coupled with ozonated sludge recycle was evaluated for its operating performance at an ozone dose of 75 mg O_(3)/g VSS and 1.5 mmol/L Mn^(2+)addition.The results showed a 39.4%reduction in MLSS and an observed sludge yield of 0.236 kg MLSS/kg COD for the O_(3)+Mn^(2+)group compared to the O_(3)group (15.3%and 0.292 kg MLSS/kg COD),accompanied by better COD,NH_(4)^(+)-N,TN and TP removal,improved effluent SS and limited impact on excess sludge properties.Subsequently,activity tests,BIOLOG ECO microplates and 16S rRNA sequencing were applied to elucidate the changing mechanisms of Mn^(2+)-catalytic ozonation related to microbial action:(1) Dehydrogenase activity reached a higher peak.(2) Microbial utilization of total carbon sources had an elevated effect,up to approximately 18%,and metabolic levels of six carbon sources were also increased,especially for sugars and amino acids most pronounced.(3) The abundance of Defluviicoccus under the phylum Proteobacteria was enhanced to 12.0%and dominated in the sludge,they had strong hydrolytic activity and metabolic capacity.Denitrifying bacteria of the genus Ferruginibacter also showed an abundance of 7.6%,they contributed to the solubilization and reduction of sludge biomass.These results could guide researchers to further reduce ozonation conditioning costs,improve sludge management and provide theoretical support.

关键词： Activated sludge In-situ reduction Catalytic ozonation conditioning Dehydrogenase activity Carbon source utilization Microbial community

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Survey on performance of vertical slot and nature-like fishways at Angu hydropower station, Southwest china

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Water Science and engineering 2024年第1期17卷 83-91页

作者： Jun-jian Sun Jia-yue Shi Qi Zhang Xiao-tao Shi Jun-jun Tan Powerchina Huadong engineering corporation Limited Hangzhou 311122China Hubei International Science and Technology Cooperation Base of Fish Passage China Three Gorges UniversityYichang 443002China

To restore dam-blocked natural fish migratory passages,a growing number of artificial fishways have been built in water conservancy and hydropower projects in china.The Angu hydropower station involved diverse important fish habitats in the lower reaches of the Daduhe River in Southwest china.Therefore,a vertical slot fishway(VSF)and a nature-like fishway(NLF)were built near the backwater area of the reservoir to connect the upstream and downstream habitats.Hydrodynamic and aquatic ecological surveys were conducted after the completion of the project to estimate the fish passing effect of the two fishways.The results indicated that both fishways were in effective operation and could maintain the desired hydrodynamic conditions and be used by several local fish species.During the survey,149 fish from 15 species and 111 fish from 17 species were captured by the traps in the VSF and NLF,respectively,while 1263 fish from 27 species were found in the downstream area.Some species captured in the VSF were not found in the NLF,and vice versa,which implied the different preferences of fish.Meanwhile,3789 signals including 2099 upward ones and 1690 downward ones were monitored with an ultrasonic fish detector at the inlet of the VSF.These findings revealed the characteristics of fish species observed in and near the fishways and provided valuable insights into the different fish passing capabilities of VSFandNLF.

关键词： Vertical slot fishway Nature-like fishway Aguatic ecological survey Fishwaymonitoring Statistical analysis

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Study on Shear Strength Characteristics of Basalt-Concrete Bonding Interface Based on in-situ Direct Shear Test

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Journal of Earth Science 2024年第2期35卷 553-567页

作者： Peng Xia Xinli Hu Chunye Ying Shuangshuang Wu Chu Xu Xuan Wang Hao Chen Hang Duan College of Harbour and Coastal engineering Jimei UniversityXiamen361021China Faculty of engineering China University of GeosciencesWuhan430074China china three gorges construction Group Ltd.Beijing100038China

In rock engineering,the shear strength of the basalt-concrete bonding interface is a key factor affecting the shear performance of hydroelectric dam foundations,embedded rock piles and rock bolts.In this study,30 sets of in-situ direct shear tests were conducted on the basalt-concrete bond interface in the Baihetan dam area to investigate the shear strength characteristics of the basalt-concrete bonding interface.The bonding interface contains two states,i.e.,the bonding interface is not sheared,termed as se(symbolic meaning see Table 1);the bonding interface is sheared with rupture surface,termed as si.The effects of lithology,Joints structure,rock type grade and concrete compressive strength on the shear strength of the concrete-basalt contact surface were investigated.The test results show that the shear strength of the bonding interface(s_(e)&s_(i))of columnar jointed basalt with concrete is greater than that of the bonding interface(s_(e)&s_(i))of non-columnar jointed one with the same rock type grade.When the rock type grade isⅢ_(2),fcol is 1.22 times higher than fncol and ccol is 1.13 times greater than cncol.The shear strength parameters of the basalt-concrete bonding interface differ significantly for different lithologies.The cohesion of the bonding interface(s_(i))of cryptocrystalline basalt with concrete is 2.05 times higher than that of the bonding interface(s_(i))of breccia lava with concrete under the same rock type grade condition.Rock type grade has a large influence on the shear strength of the non-columnar jointed basalt-concrete bonding interface(s_(e)&s_(i)).cnol increases by 33%when the grade of rock type rises fromⅢ_(1)toⅡ_(1).the rock type grade has a greater effect on bonding interface(s_(i))cohesion than the coefficient of friction.When the rock type grade is reduced fromⅢ_(2)toⅢ_(1),f_(ncol)′increases by 2%and c_(ncol)′improves by 44%.The shear strength of the non-columnar jointed basalt-concrete bonding interface(s_(e)&s_(i))increases with the increase of the compressive strength of co

关键词： direct shear test basalt-concrete bonding interface shear strength parameters engineering geogolgy

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Conservation genomics provides insights into genetic resilience and adaptation of the endangered Chinese hazelnut, Corylus chinensis

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Plant Diversity 2024年第3期46卷 294-308页

作者： Zhen Yang Lisong Liang Weibo Xiang Lujun Wang Qinghua Ma Zhaoshan Wang Key Laboratory of Tree Breeding and Cultivation National Forestry and Grassland AdministrationResearch Institute of ForestryChinese Academy of ForestryBeijing 100091China National engineering Research Center of Eco-Environment Protection for Yangtze River Economic Belt China Three Gorges CorporationBeijing 100083China Rare Plants Research Institute of Yangtze River China Three Gorges CorporationYichang 443133China Research Institute of Economic Forest Cultivation and Processing Anhui Academy of ForestryHefei 230031China

Global climate change has increased concerns regarding biodiversity loss.However,many key conservation issues still required further research,including demographic history,deleterious mutation load,adaptive evolution,and putative introgression.Here we generated the first chromosome-level genome of the endangered Chinese hazelnut,Corylus chinensis,and compared the genomic signatures with its sympatric widespread C.kwechowensis-C yunnanensis complex.We found large genome rearrangements across all Corylus species and identified species-specific expanded gene families that may be involved in adaptation.Population genomics revealed that both C.chinensis and the C.kwechowensis-C.yunnanensis complex had diverged into two genetic lineages,forming a consistent pattern of southwestern-northern differentiation.Population size of the narrow southwestern lineages of both species have decreased continuously since the late Miocene,whereas the widespread northern lineages have remained stable(C.chinensis) or have even recovered from population bottlenecks(C.kwechowensis-C.yunnanensis complex) during the Quaternary.Compared with C.kwechowensis-C. yunnanensis complex,C.chinensis showed significantly lower genomic diversity and higher inbreeding level.However,C.chinensis carried significantly fewer deleterious mutations than C.kwechowensis-C. yunnanensis complex,as more effective purging selection reduced the accumulation of homozygous variants.We also detected signals of positive selection and adaptive introgression in different lineages,which facilitated the accumulation of favorable variants and formation of local adaptation.Hence,both types of selection and exogenous introgression could have mitigated inbreeding and facilitated survival and persistence of C.chinensis.Overall,our study provides critical insights into lineage differentiation,local adaptation,and the potential for future recovery of endangered trees.

关键词： Conservation genomics Demographic history Inbreeding Genetic load Runs of homozygosity Local adaptation

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Exploration on electrical resistance tomography in characterizing the slurry spatial distribution in cemented granular materials

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Frontiers of Structural and Civil engineering 2024年第3期18卷 365-379页

作者： Bohao WANG Wei WANG Feng JIN Handong TAN Ning LIU Duruo HUANG State Key Laboratory of Hydroscience and engineering Tsinghua UniversityBeijing 100084China Institute of Science and Technology China Three Gorges CorporationBeijing 100038China School of Geophysics and Information Technology China University of GeosciencesBeijing 100083China

This study investigated the application of electrical resistance tomography(ERT)in characterizing the slurry spatial distribution in cemented granular materials(CGMs).For CGM formed by self-flow grouting,the voids in the accumulation are only partially filled and the bond strength is often limited,which results in difficulty in obtaining in situ samples for quality evaluation.Therefore,it is usually infeasible to evaluate the grouting effect or monitor the slurry spatial distribution by a mechanical method.In this research,the process of grouting cement paste into high alumina ceramic beads(HACB)accumulation is reliably monitored with ERT.It shows that ERT results can be used to calculate the cement paste volume in the HACB accumulation,based on calibrating the saturation exponent n in Archie’s law.The results support the feasibility of ERT as an imaging tool in CGM characterization and may provide guidance for engineering applications in the future.

关键词： electrical resistance tomography cemented granular material grouting spatial distribution Archie’s law

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Effect of coral sand on the mechanical properties and hydration mechanism of magnesium potassium phosphate cement mortar

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Journal of Zhejiang University-Science A(Applied Physics & engineering) 2024年第2期25卷 116-129页

作者： Hao LIU Huamei YANG Houzhen WEI Jining YU Qingshan MENG Rongtao YAN College of Civil engineering and Architecture Guilin University of TechnologyGuilin541004China Guangxi Key Laboratory of Geomechanics and Geotechnical engineering Guilin University of TechnologyGuilin541004China State Key Laboratory of Geomechanics and Geotechnical engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China School of Intelligent construction Wuchang University of TechnologyWuhan430002China Hydraulic Concrete Institute China Three Gorges CorporationBeijing100038China The First Railway Survey and Design Institute Group corporation Xi’an710043China

Damaged structures on coral islands have been spalling and cracking due to the dual corrosion of tides and waves.To ensure easy access to aggregate materials,magnesium potassium phosphate cement(MKPC)and coral sand(CS)are mixed to repair damaged structures on coral islands.However,CS is significantly different from land-sourced sand in mineral composition,particle morphology,and strength.This has a substantial impact on the hydration characteristics and macroscopic properties of MKPC mortar.Therefore,in this study we investigated the compressive strength,interfacial mechanical properties,and corrosion resistance of MKPC CS mortar.Changes in the morphology,microstructure,and relative contents of hydration products were revealed by scanning electron microscope-energy dispersive spectrometer(SEM-EDS)and X-ray diffraction(XRD).The results indicated that the compressive strength increased linearly with the interfacial micro-hardness,and then stabilized after long-term immersion in pure water and Na2SO4 solution,showing excellent corrosion resistance.Compared with MKPC river sand(RS)mortar,the hydration products of CS mortar were an intermediate product 6KPO2·8H2O with a relative content of 3.9%at 1 h and 4.1%at 12 h.The hydration product MgKPO_(4)·6H_(2)O increased rapidly after 7-d curing,with an increased growth rate of 1100%.Our results showed that CS promoted the nucleation and formation of hydration products of MKPC,resulting in better crystallinity,tighter overlapping,and a denser interfacial transition zone.The results of this study provide technical support for applying MKPC mortar as a rapid repair material for damaged structures on coral islands.

关键词： Magnesium potassium phosphate cement(MKPC) Coral sand(CS) Mechanical properties Corrosion resistance Hydration mechanism

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Long-Term Performance and Microstructural Characterization of Dam Concrete in the three gorges Project

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engineering 2024年第2期33卷 237-262页

作者： Chen Lyu Cheng Yu Chao Lu Li Pan Wenwei Li Jiaping Liu School of Materials Science and engineering Southeast UniversityNanjing 211189China State Key Laboratory of High Performance Civil engineering Materials Sobute New Materials Co.Ltd.Nanjing 211103China china three gorges corporation Wuhan 430010China

This study investigates the long-term performance of laboratory dam concrete in different curing environments over ten years and the microstructure of 17-year-old laboratory concrete and actual concrete cores drilled from the three gorges Dam.The mechanical properties of the laboratory dam concrete,whether cured in natural or standard environments,continued to improve over time.Furthermore,the laboratory dam concrete exhibited good resistance to diffusion and a refined microstructure after 17 years.However,curing and long-term exposure to the local natural environment reduced the frost resistance.Microstructural analyses of the laboratory concrete samples demonstrated that moderate-heat cement and fine fly ash(FA)particles were almost fully hydrated to form compact micro structures consisting of large quantities of homogeneous calcium(alumino)silicate hydrate(C-(A)-S-H)gels and a few crystals.No obvious interfacial transition zones were observed in the microstructure owing to the longterm pozzolanic reaction.This dense and homogenous microstructure was the crucial reason for the excellent long-term performance of the dam concrete.A high FA volume also played a significant role in the microstructural densification and performance growth of dam concrete at a later age.The concrete drilled from the dam surface exhibited a loose microstructure with higher microporosity,indicating that concrete directly exposed to the actual service environment suffered degradation caused by water and wind attacks.In this study,both macro-performance and microstructural analyses revealed that the application of moderate-heat cement and FA resulted in a dense and homogenous microstructure,which ensured the excellent long-term performance of concrete from the three gorges Dam after 17 years.Long-term exposure to an actual service environment may lead to microstructural degradation of the concrete surface.Therefore,the retained long-term dam concrete samples need to be further researched to better understand its microstructural evolution

关键词： three gorges Dam Long-term performance Microstructural analysis Moderate-heat cement Fly ash

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Quantifying the impact of earthquakes and geological factors on spatial heterogeneity of debris-flow prone areas:A case study in the Hengduan Mountains

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Journal of Mountain Science 2024年第5期21卷 1522-1533页

作者： HU Xudong SHEN Yitong HU Kaiheng XU Wennian LIU Daxiang HE Songtang GAO Jiazhen WEI Li LIU Shuang Hubei Provincial engineering Research Center of Slope Habitat construction Technique Using Cement-based Materials(china three gorges University) Yichang 443002China Hubei Key Laboratory of Disaster Prevention and Mitigation(china three gorges University) Yichang 443002China College of Civil engineering and Architecture China Three Gorges UniversityYichang 443002China Shanghai Investigation Design&Research Institute Co.Ltd.Shanghai 200335China Key Laboratory of Mountain Hazards and Earth Surface Processes Chinese Academy of SciencesChengdu 610041China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China Wuhan Polytechnic Wuhan 430074China

Understanding the spatial heterogeneity of debris-flow-prone areas holds significant implications for regional risk management, particularly in seismically active regions with geological faults. Despite the significance of this knowledge, a comprehensive quantification of the influence of regional topographical and geological factors on the spatial heterogeneity of debris-flow-prone areas has been lacking. This study selected the Hengduan Mountains, an earthquake-prone region characterized by diverse surface conditions and complex landforms, as a representative study area. An improved units zoning and objective factors identification methodology was employed in earthquake and fault analysis to assess the impact of seismic activity and geological factors on spatial heterogeneity of debrisflow prone areas. Results showed that the application of GIS technology with hydrodynamic intensity and geographical units analysis can effectively analyze debris-flow prone areas. Meanwhile, earthquake and fault zones obviously increase the density of debrisflow prone catchments and make them unevenly distributed. The number of debris-flow prone areas shows a nonlinear variation with the gradual increase of geomorphic factor value. Specifically, the area with 1000 m-2500 m elevation difference, 25°-30° average slope, and 0.13-0.15 land use index is the most favorable conditions for debris-flow occurrence;The average annual rainfall from 600 to 1150 mm and landslides gradient from 16° to 35° are the main causal factors to trigger debris flow. Our study sheds light on the quantification of spatial heterogeneity in debris flow-prone areas in earthquake-prone regions, which can offer crucial support for post-debris flow risk management strategies.

关键词： debris-flow prone areas causal factors GIS-based method spatial heterogeneity Hengduan Mountains

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Performance Enhancement of Parabolic Trough Collector by Using Homogenizer and Spiral

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Journal of Thermal Science 2024年第2期33卷 658-674页

作者： LI Peijing LIU Taixiu QIN Yuanlong ZHENG Zhimei ZHAO Kai LIU Qibin School of Energy Powerand Mechanical EngineeringNorth China Electric Power UniversityBeijing102206China Institute of engineering Thermophysics Chinese Academy of SciencesBeijing100190China University of Chinese Academy of Science Beijing100049China Department of Thermal Science and Energy engineering University of Science and Technology of ChinaHefei230027China Research Institute of Science and Technology of china three gorges Group corporation Beijing100038China

In conventional parabolic trough collectors(PTCs),sunlight is concentrated at the bottom of the absorber tube,resulting in a significant circumferential temperature gradient across the absorber tube,heat loss and thermal deformation,which affects the safety and thermal performance of PTCs.In this study,a new receiver with homogenizer and spiral(RHS) is proposed,achieving the optical and thermal synergy to ameliorate the thermal deformation of the absorber tube and enhance thermal efficiency.A plane structure homogenizer is designed to improve uniformity of the concentrated solar flux of absorber tube through second reflection.In combination with the spiral,it improves the optical-thermal efficiency of the PTC by enhancing heat exchange between the fluid and the backlight side of the absorber tube.The performance of the collector is numerically studied by building a three-dimensional coupled light-thermal-structure model.The results show that the thermal deformation of the RHS is reduced by more than 96% and the optical-thermal efficiency is improved by 1.2%-0.63% compared with conventional receivers(CRs) under the same inlet temperature conditions.The proposed receiver is validated to be effective in reducing thermal deformation and improving optical-thermal efficiency.

关键词： parabolic trough collector homogenizer thermal deformation spiral

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Progressive fragmentation of granular assemblies within rockslides: Insights from discrete-continuous numerical modeling

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Journal of Mountain Science 2024年第4期21卷 1174-1189页

作者： JIANG Hui ZHOU Yuande WANG Jinting DU Xiuli HUANG Hailong Key Laboratory of Urban Security and Disaster engineering of Ministry of Education Beijing University of TechnologyBeijing 100124China. Key Laboratory of the Hydrosphere Sciences of the Ministry of Water Resources Tsinghua UniversityBeijing 100084China china three gorges construction Management Co. Ltd.Chengdu 610000China

Rock fragmentation plays a critical role in rock avalanches,yet conventional approaches such as classical granular flow models or the bonded particle model have limitations in accurately characterizing the progressive disintegration and kinematics of multi-deformable rock blocks during rockslides.The present study proposes a discrete-continuous numerical model,based on a cohesive zone model,to explicitly incorporate the progressive fragmentation and intricate interparticle interactions inherent in rockslides.Breakable rock granular assemblies are released along an inclined plane and flow onto a horizontal plane.The numerical scenarios are established to incorporate variations in slope angle,initial height,friction coefficient,and particle number.The evolutions of fragmentation,kinematic,runout and depositional characteristics are quantitatively analyzed and compared with experimental and field data.A positive linear relationship between the equivalent friction coefficient and the apparent friction coefficient is identified.In general,the granular mass predominantly exhibits characteristics of a dense granular flow,with the Savage number exhibiting a decreasing trend as the volume of mass increases.The process of particle breakage gradually occurs in a bottom-up manner,leading to a significant increase in the angular velocities of the rock blocks with increasing depth.The simulation results reproduce the field observations of inverse grading and source stratigraphy preservation in the deposit.We propose a disintegration index that incorporates factors such as drop height,rock mass volume,and rock strength.Our findings demonstrate a consistent linear relationship between this index and the fragmentation degree in all tested scenarios.

关键词： Rock fragmentation Rockslide Numerical modelling Discrete-continuous modelling Runout Cohesive zone model

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