Sep 2007, Volume 1 Issue 3

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  • QU Jiuhui, YIN Chengqing, YANG Min, LIU Huijuan
    The continuously deteriorating quality of source water is threatening the safety of drinking water in China. Various efforts have been made to update water treatment processes to decrease the pollution problems of drinking water, such as protection of drinking water sources, enhancement of conventional treatment processes, and development of new or advanced treatment technologies. This paper reviews a variety of protection and remediation methods for drinking water sources, development and application of drinking water treatment technologies, new technologies for special pollutants removal from groundwater, and the latest research progress on water distribution systems in China. treatment plant improvement is the key to ensure the quality of drinking water. There have been many researches on innovative treatment technologies in China and they have been applied in quite a number of water treatment plants. These innovations include key technique development and combination of technologies in the scope of economic optimization. On the basis of water quality from the plant, the distribution system is also important. This paper describes the latest development in the above respects.
  • LIU Wenjun, DU Zhipeng, JIN Junwei
    In this paper, the main factors impacting the plug flow pattern of a clearwell were investigated by integrating pilot-scale, full-scale clearwell tracer testing and computational fluid dynamics (CFD) simulation. It was found that pilot tracer testing, full-scale tracer testing and CFD simulation all demonstrated that the correlation between the ratio of t10/T and L/W can be approximately expressed by: t10/T = 0.189 4ln(L/W)-0.049 4. This study confirmed that the installation of baffles within clearwells is an efficient way to optimize their configuration. In addition, the inlet velocity has a minimal contribution to the ratio of t10/T. However, the ratio of turning channel width to channel width (d/W) significantly contributes to the ratio oft10/T. The optimal ratio of d/W is 0.8–1.2 for maintaining better plug flow pattern. The number of turning channels is one of the main factors that impact the ratio of t10/T. When increasing the number of turning channels, a lower ratio of t10/T is obtained.
  • ZHONG Runsheng, ZHU Chunwei, ZHANG Xihui, GUAN Yuntao
    The turbidity variation in artificial water and samples from a water plant was investigated in the presence of organics with different relative molecular mass. The results show that recessive turbidity existed when water chemical conditions were changing. The formation of turbidity depended on organic relative molecular mass and their conformations on particles. At higher pH and lower ionic strength, the organic chains with a more extended conformation resulted in rising turbidity of the suspension. At lower pH, the reconformation of organics took place due to charge neutralization by the proton, resulting in a decline in turbidity. The addition of NaCl and MgCl2 at pH 7.00 also resulted in a decrease of turbidity in the suspension. It is believed that the occurrence of recessive turbidity has a significant influence on the stability of water supply quality.
  • CHEN Wei, LIN Tao, WANG Leilei
    In this paper, the drinking water biotic safety of particles and bacteria attached to fines in activated carbon process was investigated by actual treatment process and advanced treatment pilot trial with granular activated carbon. In the experiment, the particles were detected by IBR particle calculating instrument, the activated carbon fines were counted on the basis of the most probable number (MPN) with a microscope, the total number of bacteria was analyzed between the conventional agar culture medium and the one with R2A, and the bacteria attached to activated carbon fines was resolved by the homogenization technique. The experimental results showed that the average total number of particles was 205 CNT/mL in the activated carbon effluent during a filter cycle, of which the number of particles with sizes >2 μm was 77 CNT/mL more than the present particle control criterion of the American drinking water product standard (50 CNT/mL). The backwash of low density and long duration lowered particle number in the effluent. The MPN of activated carbon fines in the effluent was between 400 and 600 CNT/L, which accounted for less than 5 0 of the total particles from activated carbon filtration for a poor relative level (R2 = 0.34). The microorganisms in activated carbon effluent consisted mostly of heterotrophic bacillus and the total bacteria number was five times as high as that of the inflow, i.e. the effluent from sand filter. The actual bacteria number may be truly indicated by the detection technique with R2A culture medium compared with the traditional agar cultivation. The inactivation efficiency of bacteria attached to activated carbon fines was less than 40% under 1.1 mg/L of chlorine contacting for 40 min. Results showed that the particles and bacteria attached to activated carbon fines may influence drinking water biotic safety, and that the effective control measures need to be further investigated.
  • MA Xiaoyan, CHEN Beibei, LI Qingsong, ZHANG Qiaoli, GU Guofen
    Two sample preparation methods were introduced and compared in this paper to establish a simple, quick and exact analysis of geosmin and 2-methylisoborneol. LC-18 column was employed in solid phase extraction (SPE), 1.0 mL of hexane was adopted in liquid-liquid extraction (LLE), and the extracts were analyzed by gas chromatograph mass spectrum (GCMS) in selected ion mode. Mean recoveries of SPE were low for 2-methylisoborneol (2-MIB) and geosmin (GSM) with values below 50%. For LLE, the recoveries were satisfyingly above 50% for 2-MIB and 80% for GSM. Detection limits of the LLE method were as low as 1.0 ng/L for GSM and 5.0 ng/L for 2-MIB. A year-long investigation on odor chemicals of drinking water in Shanghai demonstrated that in the summer, there was a serious odor problem induced by a high concentration of 2-MIB. The highest concentration of 152.82 ng/L appeared in July in raw water, while GSM flocculation was minimal with concentrations below odor threshold.
  • WU Rui, LI Guangyi, ZHANG Zongyi, REN Yulong, HAN Weijian
    Road transport produces significant amounts of emissions by using crude oil as the primary energy source. A reduction of emissions can be achieved by implementing alternative fuel chains. The objective of this study is to carry out an economic, environmental and energy (EEE) life cycle study on natural gas-based automotive fuels with conventional gasoline in an abundant region of China. A set of indices of four fuels/vehicle systems on the basis of life cycle are assessed in terms of impact of EEE, in which natural gas produces compressed natural gas (CNG), methanol, dimethylether (DME) and Fischer Tropsch diesel (FTD). The study included fuel production, vehicle production, vehicle operation, infrastructure and vehicle end of life as a system for each fuel/vehicle system. A generic gasoline fueled car is used as a baseline. Data have been reviewed and modified based on the best knowledge available to Chongqing local sources. Results indicated that when we could not change electric and hydrogen fuel cell vehicles into commercial vehicles on a large scale, direct use of CNG in a dedicated or bi-fuel vehicle is an economical choice for the region which is most energy efficient and more environmental friendly. The study can be used to support decisions on how natural gas resources can best be utilized as a fuel/energy resource for automobiles, and what issues need to be resolved in Chongqing. The models and approaches for this study can be applied to other regions of China as long as all the assumptions are well defined and modified to find a substitute automotive energy source and establish an energy policy in a specific region.
  • GUO Xiurui, MAO Xianqiang, YANG Jurong, YANG Zhifeng
    Ecosystem health has been a focal point and research frontier of applied ecology in recent years, increasingly used in urban ecological studies. To quantify the effect of ecological improvement from eco-planning, an ecosystem health assessment method is used in eco-planning evaluation and decision support in the urban eco-planning research of Guangzhou City of China. Based on features of an urban ecosystem, five factors such as vigor, organizational structure, resilience, ability to maintain ecosystem service, and influence on people s health were selected to develop the assessment indicator system. Then, to evaluate the validity of planning measures, a cost-effect analysis of the different scenarios on eco-planning was made, taking investment of the planned projects as the cost and ecosystem health state after implementing the scenarios as the effect. To establish priority of all the proposed planning schemes or countermeasures, variation of the ecosystem health state was evaluated when the investment of eco-environmental construction projects changes by ±10%, ±20% and ±50%, respectively. Thus, the order of importance of eco-environment construction projects to the urban ecosystem health state can be worked out, providing a reference for prioritizing the implementation of such urban eco-environmental projects. The study proved the trial value of an ecosystem health evaluation method in urban eco-planning research.
  • YING Diwen, JIA Jinping, ZHANG Lehua
    An electrochemical-activated denitrifying biofilm system consisting of activated carbon fiber electrodes immobilized with denitrifying bacteria film as cathode was studied. A revised model for an electrochemical-activated denitrifying biofilm was developed and validated by electrochemical analysis of cathodal polarization curves and nitrate consumption rate. The cathodal polarization curve and nitrate consumption rate were introduced to verify the rate of electrochemical reaction and the activity of denitrifying bacteria, respectively. It was shown that the denitrification process effectively strengthened the electrochemical reaction while the electron also intensified denitrification activity. Electron was transferred between electrochemical process and biological process not only by hydrogen molecule but also by new produced active hydrogen atom. Additionally, a parameter of apparent exchange current density was deprived from the cathodal polarization curve with high overpotential, and a new bio-effect current density was defined through statistical analysis, which was linearly dependent to the activity of denitrification bacteria. Activated carbon fiber (ACF) electrode was also found to be more suitable to the electrochemical denitrifying system compared with graphite and platinum.
  • ZHAN Manjun, YANG Xi, KONG Lingren, YANG Hongshen
    The photochemical degradation of bisphenol A (BPA) was studied in the presence of natural humic sub stances from different origins under simulated solar irradiation. BPA underwent insignificant direct photolysis in neutral water, but rapid photosensitized degradation in four humic substances solutions via pseudo-first-order reaction occurred. The photodegradation rate of BPA was insensitive to the different initial BPA concentrations and was inhibited in aerated solution compared with the deoxygenated medium. The reactive oxygen species (ROS) such as ?·OH and 1O2 produced from excitation of humic substances under irradiation was determined from the quenching kinetic experiment using molecular probe. The five main intermediate photoproducts of BPA in Nordic lake fulvic acid (NOFA) were tentatively identified using gas chromatography/mass spectrometer (GC/MS). Based on the identification of ROS and the analysis of photoproduct formation, the possible phototransformation pathways of BPA were proposed, involving the direct photolysis due to the energy transfer from the triplet state humic substance (3HS*) to BPA molecules and hydroxyl radical addition and oxidation as well.
  • LUO Weiguo, WANG Shihe, HUANG Juan, YAN Lu, HUANG Jun
    To determine the impact of photosynthesis and transpiration on nitrogen removal in wetlands, an artificial wetland planted with reeds was constructed to treat highly concentrated domestic wastewater. Under different meteorological and hydraulic conditions, the daily changes of photosynthesis and transpiration of reeds, as well as nitrogen removal efficiency were measured. It was found that net photosynthesis rate per unit leaf area was maintained on a high level (average 19.0 yDol CO2/(m2 · s) ) from 10:00 to 14:00 in July 2004 and reached a peak of 21.1 μmol CO2/(m2 · s) when Photon Flux Density was high during the day. Meanwhile, TN and NH4+-N removal efficiency rose to 79.6% and 89.6%, respectively–the maximum values observed in the test. Correlation coefficient analysis demonstrated a positive correlation among photon flux density, net photosynthetic rate, transpiration rate, and TN and NH4+-N removal efficiency. In contrast, there was a negative correlation between stomatal conductance and TN and NH4+-N removal efficiency. Results suggest that the photosynthesis and transpiration of wetland plants have a great impact on nitrogen removal efficiency of wetlands, which can be enhanced by an increase in the photosynthesis and transpiration rate. In addition, the efficiency of water usage by reeds and nitrogen removal efficiency could be affected by the water level in wetlands; a higher level boosts nitrogen removal efficiency.
  • WANG Yan, DING Xiaowen, QIAN Longxia, WANG Hongrui
    Urban green land compensation plays an important role in county development, ecological environment management and many other fields. The concept, methods and principles of urban green land are introduced in this paper. According to the pay fee method, the value and ecological function of various types of urban green land were analyzed. The cost-benefit analysis method (CBAM) was used to estimate different external diseconomy benefits caused by green land loss. The authors applied CBAM to estimate such benefits in the case of Shanghai, China, and calculated the actual compensation value for green land. Results indicated that in 2002, the compensation value for the green land of Shanghai was RMB 8.58 × 105 Yuan/hm2.
  • JI Shulan, LIU Zhipeng, REN Haiyan, LIU Zhipei
    A bacterial strain, ZY3, growing on sex steroid hormones as the sole source of carbon and energy was isolated from the sewage treatment plant of a prophylactic steroids factory. ZY3 degrades the 3-methoxy-17β-hydroxy-1,3,5(10),8(9)-δ-4-estren (MHE). This strain was preliminarily identified as Raoultella sp. ZY3 according to its morphology and its 16S rRNA gene sequence. During the experimental period (72 h), the optimum temperature, pH and 3-MHE concentration for the degradation of hydride by the strain ZY3 were 35vH, 10 and 10 mg/L, respectively. The degradation rate of the sex steroid hormones increased to 87% and 85% after the addition of maltose and peptone, respectively.
  • SHENG Jianwu, HE Miao, YU Shaoqing, SHI Hanchang, QIAN Yi
    Microcystins (MCs) are a group of closely related toxic cyclic heptapeptides produced by common cyanobacteria, which cause lots of accidents and threatens human health. In this paper, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was established and used to detect microcystin-LR (MC-LR) in drinking and surface waters. The concentration of coating antigen was 5 ?g/mL, the dilution of monoclonal antibody MC10E7 was 1:3 000, the dilution of enzyme tracer (goat anti-mouse IgG-peroxidase) was 1:3 000, the standard concentration of MC-LR ranged from 0.001 μg/L to 30 μg/L, and o-phenylenediamine was used as substrate. The assay showed high relativity with high performance liquid chromatography (HPLC) with a correlation coefficient of more than 99%. The relative standard deviation was less than 10%, the detection limit was achieved down to 0.01 μg/L and up to 5.1 μg/L. The quantitative detection range was from 0.03 μg/L to 3 μg/L, and the antibody had high specificity for [4-arginine] microcystins. It performed well in spite of the influence of the real samples.
  • LI Xiaodong, ZENG Guangming, HUANG Guohe, LI Jianbing, JIANG Ru
    By predicting influent quantity, a wastewater treatment plant (WWTP) can be well controlled. The nonlinear dynamic characteristic of WWTP influent quantity time series was analyzed, with the assumption that the series was predictable. Based on this, a short-term forecasting chaos neural network model of WWTP influent quantity was built by phase space reconstruction. Reasonable forecasting results were achieved using this method.
  • LI Lin, HAO Jiming, HU Jingnan
    This work evaluates the influence of energy consumption on the future air quality in Beijing, using 2000 as the base year and 2008 as the target year. It establishes the emission inventory of primary PM10, SO2 and NOx related to energy utilization in eight areas of Beijing. The air quality model was adopted to simulate the temporal and spatial distribution of each pollutant concentration in the eight urban areas. Their emission, concentration distribution, and sectoral share responsibility rate were analyzed, and air quality in 2008 was predicted. The industrial sector contributed above 40% of primary PM10 and SO2 resulting from energy consumption, while vehicles accounted for about 65% of NOx. According to the current policy and development trend, air quality in the eight urban areas could become better in 2008 when the average concentrations of primary PM10, SO2 and NO2 related to energy utilization at each monitored site are predicted to be about 25, 50 and 51 μg/m3, respectively.
  • LOU Shujuan, MAO Jietai, WANG Meihua
    The objective of this study was to determine the black carbon concentration in Beijing in 2003. The aerosol properties were measured using an Aethalometer and a tapered element oscillating microbalance (TEOM) on the roof of the Physics Building of Peking University (39.99º N, 116.31º E) from July to August 2003 and from November 2003 to January 2004. The average black carbon (BC) concentrations in the summer and winter were 8.80 and 11.4 μg/m3, respectively. During winter, two different cyclone cut offs were installed at the inlet of an aethalometer. The BC mass concentration in TSP, PM10, and PM2.5 were obtained. The results indicated that in winter aerosol, 90% of BC exited in PM10 and 82.6% of BC exited in PM2.5. The BC in PM10 accounted for 5.11% of the PM10 mass.
  • XU Bin, GAO Naiyun, RUI Min, WANG Hong, WU Haihui
    The ozone oxidation of endocrine disruptor bisphenol A in drinking water was investigated. A stainless completely mixed reactor was employed to carry out the degradation experiments by means of a batch model. With an initial concentration of 11.0 mg/L, the removal efficiencies of BPA (bisphenol A) could be measured up to 70%, 82%, and 90% when the dosages of ozone were 1, 1.5, and 2 mg/L, respectively. The impacts on BPA degradation under the conditions of different ozone dosages, water background values, BPA initial concentrations, and ozone adding time were analyzed. The results showed that ozone dosage plays a dominant role during the process of BPA degradation, while the impact of the contact time could be ignored. UV wavelength scanning was used to confirm that the by-products were produced, which could be absorbed at UV254. The value of UV254 was observed to have changed during the ozonation process. Based on the change of UV254, it could be concluded that BPA is not completely degraded at low ozone dosage, while shorter adding time of total ozone dosage, high ozone dosage, and improvement of dissolved ozone concentration greatly contribute to the extent of BPA degradation. The effects of applied H2O2 dose in ozone oxidation of BPA were also examined in this study. The O3-H2O2 processes proved to have similar effects on the degradation of BPA by ozone oxidation.
  • GENG Bing, ZHU Yanfang, JIN Zhaohui, LI Tielong, KANG Haiyan, WANG Shuaima
    Catalytic reduction of nitrate in groundwater by sodium formate over the catalyst was investigated. Pd-Cu/γ-Al2O3 catalyst was prepared by impregnation and characterized by brunauer-emmett-teller (BET), inductive coupled plasma (ICP), X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX). It was found that total nitrogen was effectively removed from the nitrate solution (100 mg/L) and the removal efficiency was 87%. The catalytic activity was affected by pH, catalyst amount used, concentration of sodium formate, and initial concentration of nitrate. As sodium formate was used as reductant, precise control in the initial pH was needed. Excessively high or low initial pH (7.0 or 3.0) reduced catalytic activity. At initial pH of 4.5, catalytic activity was enhanced by reducing the amount of catalyst, while concentrations of sodium formate increased with a considerable decrease in N2 selectivity. In which case, catalytic reduction followed the first order kinetics.
  • SUI Pengzhe, WEN Xianghua, HUANG Xia
    In this study, ultrasound was used to control the membrane fouling online in an anaerobic membrane bioreactor (AMBR). Short-term running experiments were carried out under different operating conditions to explore feasible ultrasonic parameters. The experimental results indicated that when the crossflow velocity was more than 1.0 m/s, membrane fouling could be controlled effectively only by hydrodynamic methods without ultrasound. When ultrasound was applied, an ultrasonic power range of 60–150 W was suitable for the membrane fouling control in the experimental system. The experimental results showed that the membrane fouling was controlled so well that membrane filtration resistance (ΣR) could stay at 5 × 1011 m-1 for more than a week with the crossflow velocity of 0.75 m/s, which equaled the effect of crossflow velocity of more than 1.0 m/s without ultrasound.
  • GAO Baoyu, YUE Qinyan, WANG Xiaona, CHU Yongbao, KONG Chunyan
    In order to investigate the characteristics of pure Nano-Al13, Nano-Al13 was separated and purified from a series of poly-aluminum chloride (PAC) solutions which had the same Al13 percentage but different total Al concentrations, by using column chromatography, ethanol-acetone resolving and SO2-4/Ba2+ displacement. The Al13 species yield was characterized by Al-ferron timed complexation spectrophotometry and 27Al-NMR (nuclear magnetic resonance). The coagulation efficiency of Nano-Al13, PAC and AlCl3 in synthetic water was also investigated by Jar tests. The dynamic process and aggregation state of kaolin suspensions coagulating with Nano-Al13, PAC and AlCl3 were similarly investigated using a photometric dispersion analyzer 2000 (PDA2000). The experimental results indicated that the ethanol-acetone resolving method was simple and could separate the PAC solution at different concentrations, while column chromatography could separate PAC solutions at low concentrations. The SO42-/Ba2+ displacement method could separate PAC solutions at high concentrations. However, extra inorganic cation and anion could be added in the solution during separation. The coagulation efficiency and dynamic experimental results showed that Nano-Al13 with high positive-charged species was effective in removing turbidity and color. The dynamic process results showed that Nano-Al13 also had the best recovery capability after shearing compared with PAC and AlCl3 because the Nano-Al13 conformation is more effective in charge neutralization.
  • ZOU Haiyan, XI Danli
    Adding iron salt or iron hydroxide to sludgemixed liquor in an aeration tank of a conventional activated sludge processes (bioferric process) can simultaneously improve the sludge s filterability and enhance the system s treatment capacity. In view of this, Fe(OH)3 was added to a submerged membrane bioreactor (SMBR) to enhance the removal efficiency and to mitigate membrane fouling. Bioferric process and SMBR were combined to create a novel process called Bioferric-SMBR. A side-by-side comparison study of Bioferric-SMBR and common SMBR dealing with dyeing wastewater was carried out. Bioferric-SMBR showed potential superiority, which could enhance removal efficiency, reduce membrane fouling and improve sludge characteristic. When volumetric loading rate was 25% higher than that of common SMBR, the removal efficiencies of Bioferric-SMBR on COD, dye, and NH4+-N were 1.0%, 9.5%, and 5.2% higher than that of common SMBR, respectively. The trans-membrane pressure of Bioferric-SMBR was only 36% of that in common SMBR while its membrane flux was 25% higher than that of common SMBR. The stable running period in Bioferric-SMBR was 2.5 times of that in common SMBR when there was no surplus sludge discharged. The mixed liquor suspended solids concentration of Bioferric-SMBR was higher than that of common SMBR with more diversified kinds of microorganisms such as protozoans and metazoans. The mean particle diameter and specific oxygen uptake rate of Bioferric-SMBR were 3.10 and 1.23 times the common SMBR, respectively.
  • XI Haiyan, CAI Qiang, HE Miao, SHI Hanchang
    This research describes a fast detection method on the basis of enzyme-linked immunosorbent assay (ELISA) for Escherichia coli in drainage of wastewater treatment plants. Optimized conditions such as the reaction format (sandwich or direct), the concentrations of diluted horse radish peroxidase (HRP)-E. coli conjugate, and anti-HPR antibody and pretreatment of E. coli were studied. Those results showed that the linear range of detection for E. coli was 10 cfu/mL– 6 × 104 cfu/mL. Compared with conventional methods, it is a convenient and sensitive detection method with low cost.