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Effects of bacteria on nitrogen and phosphorus release from river sediment

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Journal of Environmental Sciences 2008年第4期20卷 404-412页

作者： WU Qunhe zhang renduo HUANG Shan zhang Hengjun School of Environmental Science and Engineering Sun Yat-Sen （Zhongshan） University Guangzhou 510275 China

To better understand the mechanisms of eutrophication, we addressed the microbial processes that influence many key aspects of water-sediment systems. In this study, a large column experiment was conducted for 30 d. Along the column, solution samples were collected at different locations at different time. The samples were analyzed for physical, chemical, and biological properties of the sediment and overlying water. The results showed that the amount of nitrogen transforming bacteria was higher than that of phosphorous bacteria. The amount of nitrogen transforming bacteria was in the order： ammonifier 〉 denitrifying bacteria 〉 nitrobacteria and nitrosomonas. Principal component analysis indicated that the three main factors accounted for more than 90% overall contributions for bacterium growth, which represented nutrition, organics and oxygen, and pH and redox potential （Eh） of the environment. Corresponding to the bacteria, the concentrations of nitrogen in the system was in the order： ammonia （NH4＋-N）〉 nitrate （NO3^--N）〉 nitrite （NO2^--N）. The fluxes of N and P clearly showed a temporal release and adsorption processes in the water-sediment system. The large magnitude of N fluxes suggested that N might act as an important contamination source for the water quality. However, P exchange between the sediment and overlying water was less intensive during the experiment.

关键词： eutrophication sediment P and N transforming bacteria

Effects of pH and soil texture on the adsorption and transport of Cd in soils

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Science China(Technological Sciences) 2009年第11期52卷 3293-3299页

作者： HUANG Shuang zhang renduo zhang JiaYing PAN Rong State Key Laboratory of Water Resources and Hydropower Engineering Science School of Water Resources and Hydroelectric EngineeringWuhan UniversityWuhan 430072China School of Environmental Science and Engineering Sun Yat-sen UniversityGuangzhou 510275China

To better understand the adsorption and transport of Cd2+ in soils, column experiments were conducted with various soils and inflow solutions with different pH values. Breakthrough curves (BTCs) of the column tests were fitted using both the equilibrium and non-equilibrium models installed in the program of CXTFIT. Results showed that the equilibrium model fitted most of BTCs reasonably well. Values of the retardation factor (R) and the distribution coefficient (kd) for Cd2+ adsorption and transport increased with increasing pH values of the inflow solution and of the soil. However, the clay content was not a key factor to affect R and kd for Cd2+ adsorption and transport. The average dispersivity values and the variance values of dispersivity increased with increasing clay content of the soils.

关键词： cadmium pH soil texture adsorption and transport

SOLUTE TRANSPORT THROUGH THE VADOSE ZONE:FIELD STUDIES

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Journal of Hydrodynamics 1995年第4期7卷 54-62页

作者： Ye, Zitong Yang, Jinzhong zhang, renduo Wu, Jinquan Wuhan Univ of Hydraulic and Electric Engineering Wuhan China

Solute concentration and water content profiles of an unsaturated soil were measured for a depth 170 cm within an area of 3×6 m2 at different locations. Soil water movement and solute transport in the field were studied and spatial variabilities of soil water content and concentration were discussed. Among the experiments for 33-day under constant leaching, it is shown that the effect of soil variability on soil water distribution is relatively small. However, the concentration distribution exhibits a significant variability in vertical profiles of the field. The coefficient of concentration variation is in the range of 12 to 150%, while less than 40% for water content in the same zone. The mobile and immobile water contents were calculated and related to solute transport. The immobile water content was about 24 to 39% of the total water content in the experimental field.

关键词： Flow of water Groundwater Mechanical permeability Soils Transport properties

Diversity and vertical distributions of sediment bacteria in an urban river contaminated by nutrients and heavy metals

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Frontiers of Environmental Science & Engineering 2013年第6期7卷 851-859页

作者： Xunan YANG Shan HUANG Qunhe WU renduo zhang Guangli LIU Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology School of Environmental Science and Engineering Sun Yat-sen University Guangzhou 510275 China

The aim of this study was to investigate the benthic bacterial communities in different depths of an urban river sediment accumulated with high concentrations of nutrients and metals. Vertical distributions of bacterial operational taxonomic units （OTUs） and chemical para- meters （nutrients： NH4＋, NO3, dissolved organic carbon, and acid volatile sulfur; metals： Fe, Zn, and Cu） were characterized in 30 cm sediment cores. The bacterial OTUs were measured using the terminal restriction fragment length polymorphism analysis. Biodiversity indexes and multivariate statistical analyses were used to characterize the spatial distributions of microbial diversity in response to the environmental parameters. Results showed that concentrations of the nutrients and metals in this river sediment were higher than those in similar studies. Furthermore, high microbial richness and diversity appeared in the sediment. The diversity did not vary obviously in the whole sediment profile. The change of the diversity indexes and the affiliations of the OTUs showed that the top layer had different bacterial community structure from deeper layers due to the hydrological disturbance and redox change in the surface sediment. The dominant bacterial OTUs ubiquitously existed in the deeper sediment layers （5-27 cm） corresponding to the distributions of the nutrients and metals. With much higher diversity than the dominant OTUs, the minor bacterial assemblages varied with depths, which might be affected by the sedimentation process and the environmental competition pressure.

关键词： heavy metals nutrients sediment profile,terminal restriction fragment length polymorphism

Degradation of antipyrine in the Fenton-like process with a La-doped heterogeneous catalyst

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Frontiers of Environmental Science & Engineering 2019年第5期13卷 17-27页

作者： Shicheng Wei Cuiping Zeng Yaobin Lu Guangli Liu Haiping Luo renduo zhang Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology School of Environmental Science and EngineeringSun Yat-sen UniversityGuangzhou 510006China

The aim of this study was to synthesize a novel lanthanum(La)doped catalyst and to investigate antipyrine removal in wastewater using the Fenton-like process with the *** La-doped Co-Cu-Fe catalyst was synthesized using the modified hydrothermal *** showed that the Ladoped catalyst had higher specific surface area and lower particle size than the catalyst without La doping(i.e.,the control)(267 vs.163 m2/g and 14 vs.32 nm,respectively).Under the conditions of catalyst dosage 0.5 g/L,H2O2 concentration 1.70 g/L,and NaHCO3 0.1g/L,the antipyrine removal within 60 min using the Fenton-like process with the La-doped catalyst was much higher than that with the control(95%vs.54%).The hydroxyl radical concentration with the La-doped catalyst within 60 min was two times higher than that with the control(49.2 vs.22.1 gg/L).The high catalytic activity of La-doped catalyst was mainly attributed to its high specific surface area based on the X-ray photoelectron spectroscopy *** La-doped catalyst should have great potential to remove antipyrine in wastewater using the heterogeneous Fenton-like process.

关键词： Antipyrine Lanthanum Catalyst Fenton-like process

Adsorption and Desorption Characteristics of Cadmium Ion by Ash-Free Biochars

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Journal of Renewable Materials 2020年第7期8卷 801-818页

作者： Li Fu Xianying Xu Guiquan Fu renduo zhang Hujun Liu College of Forestry Gansu Agricultural UniversityLanzhou730070China State Key Laboratory Breeding Base of Desertification and Aeolian Sand Disaster Combating Gansu Desert Control Research InstituteLanzhou730070China Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology Sun Yat-sen UniversityGuangzhou510006China

The aim of this study was to investigate adsorption and desorption characteristics of cadmium ion(Cd(II))by ash-free biochars and the adsorption *** were prepared using peanut shell,bamboo,and Sophora japonica ***-free biochars were obtained by treating the biochars with acid *** and desorption data from batch experiments were analyzed using the Langmuir and Freundlich models and three adsorption kinetics models(i.e.,the Pseudo second-order,Elovich model,and the Intraparticle diffusion models).Results showed that the acid elution improved the pore structure of biochars,increased C content and aromatic functional group content,enhanced biochars hydrophobicity and adsorption capacity for Cd(II).Ash-free peanut shell biochar showed the best Cd(II)adsorption performance among the *** of ash-free peanut shell biochar reached the equilibrium within 6 h with adsorption capacity of 34.2 mg/*** adsorption conditions were optimized by orthogonal *** Cd(II)removal efficiency achieved 91.7%with the optimized condition:initial concentration of Cd(II)of 50 mg/L,pH of 5,adsorption time of 12 h,and temperature of 15°*** adsorption of Cd(II)by the six biochars was best described with the Langmuir model,indicating that the adsorption was a physical-chemical composite *** desorption isotherm showed the hysteresis between adsorption and *** main mechanism of Cd(II)adsorption of the ash-free biochars was a complex interaction of physical and chemical reactions,mainly including electrostatic adsorption,cationic-π,and ligand exchange.

关键词： Ash-free biochars Cd(II) adsorption desorption

Estimation of Soil Water Retention Curve: An Asymmetrical Pore-Solid Fractal Model

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Wuhan University Journal of Natural Sciences 2011年第2期16卷 171-178页

作者： WANG Kang zhang renduo State Key Laboratory of Water Resources and HydropowerEngineering Science Wuhan University Wuhan 430072 Hubei China School of Environmental Science and Engineering Sun Yat-SenUniversity Guangzhou 510275 Guangdong China

The soil water retention curve is an important hydraulic function for the study of flow transport processes in unsaturated soils. The objective of this study was to develop a soil water retention function using a generalized fractal approach. The model exhibits asymmetry between the solid phase and pore phase, which is in marked contrast to the symmetry between phases present in a conventional fractal model. The retention function includes 4 parameters： the saturated water content θs, the air entry value ha, the fractal dimension Df, and an empirical parameter β, characterizing the complicated soil pore structures. Sixty one data sets, covering a wide range of soil structure and textural properties, were used to evaluate the applicability of the proposed soil water retention function. The retention function is shown to be a general model, which incorporates several existing retention models. The values of β/θs and （θs-θr ）/β were used as indexes to quantify the relationships between the proposed retention function and the existing retention models. The proposed function fits all the data very well, whereas other tested models only match about 16%-48% of the soil retention data.

关键词： soil water retention curve fractal pore-solid structure soil physical and hydraulic properties asymmetry

Comparison of the removal of monovalent and divalent cations in the microbial desalination cell

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Frontiers of Environmental Science & Engineering 2015年第2期9卷 317-323页

作者： Shanshan CHEN Haiping LUO Yanping HOU Guangli LIU renduo zhang Bangyu QIN Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology School of Environmental Science and Engineering Sun Yat-sen University Guangzhou 510275 China

Microbial desalination cell （MDC） is a promis- ing technology to desalinate water and generate electrical power simultaneously. The objectives of this study were to investigate the desalination performance of monovalent and divalent cations in the MDC, and discuss the effect of ion characteristics, ion concentrations, and electrical characteristics. Mixed salt solutions of NaC1, MgC12, KC1, and CaC12 with the same concentration were used in the desalination chamber to study removal of cations. Results showed that in the mixed salt solutions, the electrodialysis desalination rates of cations were： Ca2＋〉 Mg2＋〉 Na＋〉 K＋. Higher ionic charges and smaller hydrated ionic radii resulted in higher desalination rates of the cations, in which the ionic charge was more important than the hydrated ionic radius. Mixed solutions of NaC1 and MgC12 with different concentrations were used in the desalination chamber to study the effect of ion concentra- tions. Results showed that when ion concentrations ofNa＋ were one-fifth to five times of Mg2~, ion concentration influenced the dialysis more profoundly than electrodia- lysis. With the current densities below a certain value, charge transfer efficiencies became very low and the dialysis was the main process responsible for the desalination. And the phosphate transfer from the anode chamber and potassium transfer from the cathode chamber could balance 1%-3% of the charge transfer in the MDC.

关键词： divalent ion electrodialysis ion characteristic,microbial desalination cell monovalent ion

Selective recovery of Cu^2＋ and Ni^2＋ from wastewater using bioelectrochemical system

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Frontiers of Environmental Science & Engineering 2015年第3期9卷 522-527页

作者： Haiping LUO Bangyu QIN Guangli LIU renduo zhang Yabo TANG Yanping HOU School of Environmental Science and Engineering Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology Sun Yat-sen University Guangzhou 510275 China

As the bioelectrochemical system, the microbial fuel cell （MFC） and the microbial electrolysis cell （MEC） were developed to selectively recover Cu^2＋ and Ni^2＋ ions from wastewater. The wastewater was treated in the cathode chambers of the system, in which Cu^2＋ and Ni^2＋ ions were removed by using the MFC and the MEC, respectively. At an initial Cu^2＋ concentration of 500 mg· L^-1, removal efficiencies of Cu^2＋ increased from 97.0%±1.8% to 99.0%±0.3% with the initial Ni^2＋ concentrations from 250 to 1000 mg· L^-1, and maximum power densities increased from 3.1±0.5 to 5.4±0.6W.m-3. The Ni^2＋ removal mass in the MEC increased from 6.84-0.2 to 20.54-1.5 mg with the increase of Ni^2＋ concentrations. At an initial Ni^2＋ concentration of 500 mg· L^-1, Cu^2＋ removal etticiencies decreased from 99.1%±0.3% to 74.2%±3.8% with the initial Cu^2＋ concentrations from 250 to 1000 mg -L1, and maximum power densities increased from 3.0±0.1 to 6.3±1.2W.m^-3. Subsequently, the Ni^2＋ removal efficiencies decreased from 96.9%-4-3.1% to 73.3%4-5.4%. The results clearly demonstrated the feasibility of selective recovery of Cu2~ and Ni2~ from the wastewater using the bioelectrochemical system.

关键词： bioelectrochemical system Cu^2+ Ni^2+ selective recovery