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Effects of nitrate concentration on biological
hydrogen production by mixed cultures
Bo WANG, Wei WAN, Jianlong WANG,
Front.Environ.Sci.Eng.. 2009, 3 (4): 380-386.
https://doi.org/10.1007/s11783-009-0142-0
The effects of nitrate on fermentative hydrogen production and soluble metabolites from mixed cultures were investigated by varying nitrate concentrations from 0 to 10g N/L at 35°C with an initial pH of 7.0. The results showed that the substrate degradation rate, hydrogen production potential, hydrogen yield, and average hydrogen production rate initially increased with increasing nitrate concentrations from 0 to 0.1g N/L, while they decreased with increasing nitrate concentrations from 0.1 to 10g N/L. The maximum hydrogen production potential of 305.0mL, maximum hydrogen yield of 313.1mL/g glucose, and maximum average hydrogen production rate of 13.3mL/h were obtained at a nitrate concentration of 0.1g N/L. The soluble metabolites produced by the mixed cultures contained only ethanol and acetic acid (HAc) without propionic acid (HPr) and butyric acid (HBu). This study used the Modified Logistic model to describe the progress of cumulative hydrogen production in batch tests. A concise model was proposed to describe the effects of nitrate concentration on average hydrogen production rate.
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Application of proteomics in environmental science
Xiaona CHU, Jiangyong HU, Say Leong ONG,
Front.Environ.Sci.Eng.. 2009, 3 (4): 393-403.
https://doi.org/10.1007/s11783-009-0145-x
Proteomics involves the separation of proteins, identification of the amino acid sequence of the interested or target proteins, study of the function of the proteins, modification, structure and ultimate assignments to functional pathways in the cell. The proteomic investigations have contributed greatly to human diseases studies, new drugs discovery researches, and environmental science in recent years. This article provides a review on the development of the main proteomic technologies, including both the gel based and non-gel based technologies, and their applications in environmental science. Proteomic technologies have been utilized in the environmental stresses studies to analyze the induction or reduction of proteins at expression level and identify the target proteins to investigate their function in response to environmental stresses, such as high or low pH, oxidation stress, and toxic chemicals. Such protein responses are also helpful to understand the mechanisms of some cellular activities and the functions of some proteins.
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Anaerobic treatment of fresh leachate from a
municipal solid waste incinerator by upflow blanket filter reactor
Pinjing HE, Min LI, Suyun XU, Liming SHAO,
Front.Environ.Sci.Eng.. 2009, 3 (4): 404-411.
https://doi.org/10.1007/s11783-009-0149-6
This paper describes the feasibility of fresh leachate treatment by an upflow blanket filter (UBF). Through dilution and partial effluent recycling, the organic loading rates increased from 0.51to 14.56kg COD/(m3·d), meanwhile the corresponding hydraulic retention time decreased from 9.0d to 3.6d. The reactor was able to achieve steady-state within 80d. Based on the distribution of COD fluxes in the process, it was concluded that anabolism was the main pathway of COD removal in the initial phase (1―33d), accounting for 57%―85% of total COD removed. As the anaerobic consortium of bacteria reached steady-state (after 70―86d), the majority of COD removed was transformed into methane, because the specific methane yield was close to the theoretical value (0.36L CH4/(g CODdeg)).
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Comparison and modeling of two biofilm processes
applied to decentralized wastewater treatment
Guanglei QIU, Yonghui SONG, Peng YUAN, Liancheng XIANG, Jianfeng PENG, Ping ZENG,
Front.Environ.Sci.Eng.. 2009, 3 (4): 412-420.
https://doi.org/10.1007/s11783-009-0141-1
In order to control water pollution in the rapidly urbanizing South China area, biological contact oxidation (BCO) process and biological aerated filter (BAF) process were applied in a pilot-scale experiment for decentralized wastewater treatment. An investigation to find the optimal parameters of the two biofilm systems was conducted on hydraulic loading, organic loading, and aeration rate. The results indicated that the water reuse criteria required a maximum hydraulic and organic loading of 30.0 m 3/(m 2·d) and 4.0 kg COD/(m 3·d), respectively, as well as a minimum effluent DO of 4.0 mg/L. The utilization of a new media allowed BAF to perform better than BCO. The kinetic description of the COD removal process for BAF and BCO are , and , respectively. The correlativity analysis showed that the two models could predict the effluent water quality based on the hydraulic retention time. Thus, the appropriate hydraulic loading for certain effluent water quality demands could be determined. The two models could be applied to wastewater treatment practice.
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Response of soil microorganisms to vegetational
succession in Ziwuling Forest
Hong ZHANG, Jialong LU, Shiwei ZHAO,
Front.Environ.Sci.Eng.. 2009, 3 (4): 421-427.
https://doi.org/10.1007/s11783-009-0147-8
This study investigates the changes in soil microbial populations as vegetational succession progress from abandoned farmland to climax forest in the Ziwuling Forest, which is located in the northern part of the Loess Plateau, China. Different organic C and total extractable N between the fumigated and non-fumigated soils were assumed to be released from soil microorganisms. Soil microbial C was calculated using Kec=0.38 and microbial N was calculated using Ken=0.45. The released P was converted to microbial biomass P using Kep=0.40. Soil bacteria, fungi, and actinomycetes increased as the vegetational succession progressed. Microbial C was of the highest amount in farmland. Microbial C, N, and P generally increased from abandoned land to climax community. The results indicated significant (P<0.05) diversities of soil microbial biomass under different vegetation. There was a significant correlation between microbial biomass and soil nutrients. Knowledge about soil microbial populations is important for forecasting vegetational succession and determining the ecological condition of the environment.
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Arsenic (V) removal from groundwater by GE-HL
nanofiltration membrane: effects of arsenic concentration, pH, and
co-existing ions
Xiaowei WANG, Wenjun LIU, Weifang MA, Desheng LI,
Front.Environ.Sci.Eng.. 2009, 3 (4): 428-433.
https://doi.org/10.1007/s11783-009-0146-9
A laboratory-scale investigation was performed to study arsenic (As (V)) removal by negatively charged GE-HL nanofiltration (NF) membrane in simulated drinking water. Effects of As (V) concentration (0–200μg·L−1), pH, and co-ions and counter-ions were investigated. The NF membrane presented good stability, and the rejection rates exceeded 90%. The rejection rates of As (V) decreased with the increase of As (V) concentration, while it increased with the increase of pH (reached 96% at pH 6.75). Moreover, a negative relationship was observed between the co-existing ions of Cl−, Na+, SO42−, and Ca2+ and the removal of As (V), in which bivalent ions presented more significant effects than monovalent ions.
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Phenanthrene sorption to environmental black
carbon in sediments from the Song-Liao watershed (China)
Jinghuan ZHANG, Mengchang HE, Chunye LIN, Ke SUN, Bin MEN, John L. ZHOU,
Front.Environ.Sci.Eng.. 2009, 3 (4): 434-442.
https://doi.org/10.1007/s11783-009-0150-0
Black carbon (BC) in ten contaminated sediments from the Song-Liao watershed, NE China, was isolated upon treatments using a combustion method at 375°C, and the isolates’ sorption isotherms for phenanthrene (Phen) were determined. All sorption isotherms were nonlinear and fitted well by the Freundlich model. A negative relation was found between Freundlich sorption nonlinearity parameter (n values) and BC/total organic carbon (TOC) content of the original sediments (r2=0.687, p<0.01), indicating the dominance of BC in Phen sorption nonlinearity. The BC isolates from this industrialized region had n values of 0.342 to 0.505 and logKFOC values of 6.02 to 6.42(μg·kg−1·OC−1)/(μg·L−1) n for Phen. At a given Ce, the BC had higher Koc value than the original sediments, revealing a higher sorption capacity for BC. BC was responsible for 50.0% to 87.3% of the total sorption at Ce=0.05 Sw, clearly indicating the dominance of BC particles in overall sorption of Phen by sediments.
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System engineering for water pollution control
at the watershed level in China
Wei MENG,
Front.Environ.Sci.Eng.. 2009, 3 (4): 443-452.
https://doi.org/10.1007/s11783-009-0037-0
The present water pollution situation at watershed level in China has been systematically analyzed. The causes of water pollution are attributed to the extensive economic developmental pattern, poor wastewater treatment, and a lack of nonpoint pollution control. The problems of water pollution control at watershed level include a lack of thought and approach, developmental delay in the environmental standard system, an inadequate monitoring ability, and an inefficient implementation of laws and regulations. From 2006 to 2020, water pollution control and governance will be a national key specific project of science and technology in China. The strategies of this project include establishing a water pollution control system at watershed level, orienting a healthy aquatic ecosystem, conducting risk management, and using comprehensive methods. The goal is to establish and complete a technological system of pollution control and management in three five-year phases. The main tasks are to develop common technologies, management systems, and mechanisms for lake eutrophication control, river pollution control, urban water environmental pollution control, potable water safety, and water environmental management. The bottlenecks of water pollution control and management in China could be systematically removed, and the demonstration of the system engineering approach will be conducted at selected key watersheds.
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Flow characteristic and wastewater treatment
performance of a pilot-scale airlift oxidation ditch
Hongtao PANG, Hanchang SHI, Huiming SHI,
Front.Environ.Sci.Eng.. 2009, 3 (4): 470-476.
https://doi.org/10.1007/s11783-009-0143-z
A pilot-scale airlift oxidation ditch using bubble diffuser and baffle as aerator was operated in a wastewater treatment plant (WWTP) to investigate its flow characteristic and wastewater treatment performance. Compared with the conventional oxidation ditch process, effective depth and oxygen utilization efficiency of this new process was improved by underwater aeration. Furthermore, it had a reversed velocity distribution, which decreased from the bottom to the top on vertical section. Velocity measurement showed that a velocity over 0.2m/s at the bottom was sufficient to prevent sludge settlement during long term operation. Application of these concepts would save land area and energy consumption by about 25%―50% and 55%, respectively. In this new system, organic biodegradation and nitrification could be well achieved. Denitrification could occur steadily in the straight part by adjusting the airflow rate. An average TN removal rate of 63% was achieved with dissolved oxygen (DO) concentrations between 0.6mg/L and 1.5mg/L. The main pollutants in the effluent could meet the strictest discharge standard (COD<50mg/L, NH4+―N<5mg/L, and TN<15mg/L) in China now.
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Pilot-scale studies of domestic wastewater treatment
by typical constructed wetlands and their greenhouse gas emissions
Chaoxiang LIU, Kaiqin XU, Ryuhei INAMORI, Yuhei INAMORI, Yoshitaka EBIE, Jie LIAO,
Front.Environ.Sci.Eng.. 2009, 3 (4): 477-482.
https://doi.org/10.1007/s11783-009-0155-8
Three typical constructed wetlands (CWs) including Vertical Flow (VF), Free Water Surface (FWS), and Subsurface Flow (SF), and combined VF-SF-FWS constructed wetlands were investigated for the treatment of domestic wastewater with low C/N ratio. The performance of nutrient removal and the characteristics of greenhouse gas emissions, such as CH4 and N2O, from these CWs were compared. The results indicated that the four types of CWs had high removal efficiencies for organic matter and suspended solid (SS). The combined wetland also showed a comparatively good performance for nitrogen and phosphorus removal, and the removal efficiencies for total nitrogen (TN) and total phosphorus (TP) were 81.3% and 84.5%, respectively. The combined CWs had a comparative lower global warming potential. The FWS CW had the highest tendency to emit CH4 and led to a higher global warming potential among the four types of CWs, which was about 586 mg CO2/m2·h.
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Removal of multicomponent VOCs in off-gases from
an oil refining wastewater treatment plant by a compost-based biofilter
system
Dan WU, Chunyan ZHANG, Li HAO, Changjun GENG, Xie QUAN,
Front.Environ.Sci.Eng.. 2009, 3 (4): 483-491.
https://doi.org/10.1007/s11783-009-0144-y
Waste gases from oil refining wastewater treatment plants are often characterized by the presence of multicomponent and various concentrations of compounds. An evaluation of the performance and feasibility of removing multicomponent volatile organic compounds (VOCs) in off-gases from oil refining wastewater treatment plants was conducted in a pilot-scale compost-based biofilter system. This system consists of two identical biofilters packed with compost and polyethylene (PE). This paper investigates the effects of various concentrations of nonmethane hydrocarbon (NMHC) and empty bed residence time (EBRT) on the removal efficiency of NMHC. Based on the experimental results and practical applications, an EBRT of 66 s was applied to the biofilter system. The removal efficiencies of NMHC were within the range of 47%―100%. At an EBRT of 66 s, the average removal efficiency of benzene, toluene, and xylene were more than 99%, 99%, and 100%, respectively. The results demonstrated that multicomponent VOCs in off-gases from the oil refining wastewater treatment plant could be successfully removed in the biofilter system, which may provide useful information concerning the design criteria and operation of full-scale biofilters.
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