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1.
Huan Jing Ke Xue ; 37(5): 1845-51, 2016 May 15.
Article Zh | MEDLINE | ID: mdl-27506039

The inflow and infiltration problems cause large fluctuation in wastewater quantity and quality in hybrid sewage system. This seriously challenges the operation and management of sewage system. A multi-point on-line simultaneous monitoring system was established in a typical hybrid sewage system. The key characteristic parameters and their variation features under different circumstances were studied. The result indicated that the daily variation rule was obvious and appeared synchronous among multiple points at normal water level under dry weather flow, but there was no synchronization in conductivity variation among multiple points at high water level under dry weather flow. The statistical distribution range of water level and conductivity was significantly impacted by the seasonal rainfall change under dry weather. The statistical distribution ranges of water level variation rate and conductivity variation rate in specific time were significantly impacted by the rainfall. The response features of water level and conductivity to rainfall intensity and pattern were significantly different under different circumstances. The response sensitivity of conductivity was higher than water level at normal water level and lower at high water level. The database which could support the optimization of operation and management in the hybrid sewage system was proposed based on the distribution law of wastewater quality and quantity fluctuation under dry and wet weather, as well as the variation rate features of wastewater quality and quantity during rainfall obtained using the multi-point on-line simultaneous monitoring system.


Environmental Monitoring , Sewage , Wastewater/analysis , Weather
2.
Biosens Bioelectron ; 72: 300-5, 2015 Oct 15.
Article En | MEDLINE | ID: mdl-26000463

As food safety is gaining prominence as a global issue, the demand for developing rapid, simple, on-site, accurate and low-cost biosensor technologies will continue to grow. This study demonstrates an evanescent wave optical aptasensor with a reversible ligand-grafted biosensing surface for rapid, sensitive and highly selective detection of ochratoxin A (OTA) in food. In this system, the OTA molecules were covalently immobilized onto the surface of an optical fiber using glutaraldehyde and ethylenediamine as space linkers. An integrated evanescent wave all-fiber (EWA) biosensing platform was developed for investigating the binding kinetics between the tethered ligand and free OTA-aptamer, the performance of the aptamer-based bioassay and the reversibility of biosensing surface. The affinity constant (Ka) of aptamer with tethered OTA was measured to be 2.2 × 10(8)M(-1) based on the EWA biosensing platform. With a competitive detection mode, the quantification of OTA over concentration ranges from 0.73 µg L(-1) to 12.50 µg L(-1) with a detection limit of 0.39 µg L(-1). The performance of the aptasensor with other interfering mycotoxins and spiked real wheat samples shows high specificity and selectivity, good recovery, precision, and accuracy, indicating that it can be applied for on-site, inexpensive and easy-to-use monitoring of OTA in real samples. Moreover, since the organic ligands are grafted onto the fiber surface, this strategy may avoid the potential disadvantages caused by immobilizing the nucleic acid biomolecules, such as weak restoration to the original DNA conformation after repeated uses.


Aptamers, Nucleotide/chemistry , Biosensing Techniques/instrumentation , Fiber Optic Technology/instrumentation , Food Contamination/analysis , Mycotoxins/analysis , Ochratoxins/analysis , Triticum/microbiology , Biosensing Techniques/economics , Equipment Design , Fiber Optic Technology/economics , Fluorescence , Limit of Detection , Optical Fibers , Time Factors , Triticum/chemistry
3.
Huan Jing Ke Xue ; 36(1): 338-42, 2015 Jan.
Article Zh | MEDLINE | ID: mdl-25898684

As a kind of environmental endocrine disruptors, bisphenol A received a wide attention around the world. The planar waveguide fluorescent biosensor can rapidly and sensitively detect traceable bisphenol A in water samples. Under the optimized test conditions, the typical calibration curve for BPA determination by the biosensor showed a detection limit of (0.04 +/- 0.007) microg x L(-1) The linear response ranged from 0.16 microg x L(-1) to 22.40 microg x L(-1). The 50% inhibition concentration (IC50) was (1.67 +/- 0.47) microg x L(-1). By means of adding 0.5% EDTA to sample solutions could weaken the interference of water hardness. Under the optimal conditions, the recovery ratios for four kinds of real water samples were in the range of 88% to 111%, with R.S.D. less than 15%. The results indicate that this method features the potential in the practical detections of bisphenol A in real water samples.


Benzhydryl Compounds/analysis , Biosensing Techniques , Endocrine Disruptors/analysis , Phenols/analysis , Water Pollutants, Chemical/analysis , Fluorescence , Limit of Detection
4.
Sensors (Basel) ; 15(4): 8302-13, 2015 Apr 09.
Article En | MEDLINE | ID: mdl-25860072

Sulfadimidine (SM2) is a highly toxic and ubiquitous pollutant which requires rapid, sensitive and portable detection method for environmental and food monitoring. Herein, the use for the detection of SM2 of a portable optofluidics-based biosensing platform, which was used for the accurate detection of bisphenol A, atrazine and melamine, is reported for the first time. The proposed compact biosensing system combines the advantages of an evanescent wave immunosensor and microfluidic technology. Through the indirect competitive immunoassay, the detection limit of the proposed optofluidics-based biosensing platform for SM2 reaches 0.05 µg·L(-1) at the concentration of Cy5.5-labeled antibody of 0.1 µg·mL(-1). Linearity is obtained over a dynamic range from 0.17 µg·L(-1) to 10.73 µg·L(-1). The surface of the fiber probe can be regenerated more than 300 times by means of 0.5% sodium dodecyl sulfate solution (pH = 1.9) washes without losing sensitivity. This method, featuring high sensitivity, portability and acceptable reproducibility shows potential in the detection of SM2 in real milk and other dairy products.


Biosensing Techniques/methods , Dairy Products/analysis , Sulfamethazine/analysis , Immunoassay
5.
Sci Rep ; 5: 8125, 2015 Jan 30.
Article En | MEDLINE | ID: mdl-25634469

This work was the first to report that the kanamycin-binding DNA aptamer (5'-TGG GGG TTG AGG CTA AGC CGA-3') can form stable parallel G-quadruplex DNA (G4-DNA) structures by themselves and that this phenomenon can be verified by nondenaturing polyacrylamide gel electrophoresis and circular dichroism spectroscopy. Based on these findings, we developed a novel label-free strategy for kanamycin detection based on the G4-DNA aptamer-based fluorescent intercalator displacement assay with thiazole orange (TO) as the fluorescence probe. In the proposed strategy, TO became strongly fluorescent upon binding to kanamycin-binding G4-DNA. However, the addition of kanamycin caused the displacement of TO from the G4-DNA-TO conjugate, thereby resulting in decreased fluorescent signal, which was inversely related to the kanamycin concentration. The detection limit of the proposed assay decreased to 59 nM with a linear working range of 0.1 µM to 20 µM for kanamycin. The cross-reactivity against six other antibiotics was negligible compared with the response to kanamycin. A satisfactory recovery of kanamycin in milk samples ranged from 80.1% to 98.0%, confirming the potential of this bioassay in the measurement of kanamycin in various applications. Our results also served as a good reference for developing similar fluorescent G4-DNA-based bioassays in the future.


Aptamers, Nucleotide/metabolism , Biological Assay/methods , DNA/metabolism , Fluorescent Dyes/metabolism , G-Quadruplexes , Intercalating Agents/metabolism , Kanamycin/analysis , Animals , Biosensing Techniques , Circular Dichroism , Electrophoresis, Polyacrylamide Gel , Milk/chemistry , Spectrometry, Fluorescence , Staining and Labeling
6.
Guang Pu Xue Yu Guang Pu Fen Xi ; 35(11): 3151-4, 2015 Nov.
Article Zh | MEDLINE | ID: mdl-26978926

Heavy metal pollution has received great attentions in recent years. The traditional methods for heavy metal detection rely on the expensive laboratory instruments and need time-consuming preparation steps; therefore, it is urgent to develop quick and highly sensitive new technologies for heavy metal detection. The colorimetric method based on the gold nanoparticles (AuNPs) features with simple operation, high sensitivity and low cost, therefore, enabling it widely concerned and used in the environmental monitoring, food safety and chemical and biological sensing fields. This work developed a simple, rapid and highly sensitive strategy based on the Fenton reaction and unmodified AuNPs for the detection of Cu²âº in water samples. The hydroxyl radical ( · OH) generated by the Fenton reaction between the Cu²âº and sodium ascorbate (SA) oxidized the single stranded DNA (ssDNA) attached on the AuNPs surface into variable sequence fragments. The cleavage of ssDNA induced the aggregation of AuNPs in a certain salt solution, therefore, resulting in the changes on the absorbance of solution. The assay conditions were optimized to be pH value of 7.9, 11 mg · L⁻¹ ssDNA, 8 mmol · L⁻¹ SA and 70 mmol · L⁻¹ NaCl. Results showed that the absorbance ratio values at the wavelengths of 700 and 525 nm (A700/A525) were linearly correlated with the Cu²âº concentrations. The linear detection range was 0.1-10.0 µmol · L⁻¹ with a detection limit of 24 nmol · L⁻¹ (3σ). Spiked recoveries ranged from 87%-120% in three sorts of water, including drinking water, tap water and lake water, which confirmed that the potentials of the proposed assay for Cu²âº detection in reality.


Copper/analysis , Drinking Water/analysis , Gold/chemistry , Metal Nanoparticles/chemistry , Water Pollutants/analysis , DNA, Single-Stranded/chemistry , Hydrogen Peroxide , Iron , Lakes/chemistry
7.
Chemosphere ; 119: 568-576, 2015 Jan.
Article En | MEDLINE | ID: mdl-25127355

The ever-increasing daily use of engineered nanoparticles will lead to heightened levels of these materials in the environment. These nanomaterials will eventually go into the wastewater treatment plant (WWTP), therefore, resulting into a pressing need for information on their aggregation behavior and kinetics in the wastewater aqueous matrix. In this work, we dispersed two different metal oxide nanoparticles (ZnO and TiO2) into the influent of two different WWTPs. Through the time-resolved dynamic light scattering analysis and transmission electron microscopy, the metal oxide nanoparticles (NPs) were quite stably existed in the wastewater matrix with aggregates of diameter 300-400 nm after 4.5h or more suspension. We confirmed that the dissolved organic matters (DOMs) attributed to the stability of nanoparticles. No propensity of NPs to aggregate were observed in the presence of both monovalent and divalent electrolytes even at high concentrations up to 0.15 M in NaCl or 0.025 M in CaCl2, indicating that the destabilization of nanoparticles in the complicated wastewater matrix was not achieved by the compression of electrical double layer, therefore, their aggregation kinetics cannot be simply predicted by the classic Derjaguin-Landau-Verwey-Overbeek theory of colloidal stability. However, obvious aggregation of nanoparticles in the Al2(SO4)3 solution system was observed with the likely mechanism of bridging of the metal oxide nanoparticles and aggregates due to the formation of hydrous alumina (Al(OH)3·H2O) in the Al2(SO4)3 solution. In the wastewater matrix, we used the noninvasive measurement technology to detect the O2 flux of activated sludge before and after treatment with 1, 10 and 100 mg L(-1) NPs. The results confirmed that both ZnO and TiO2 NPs showed an adverse impact on the O2 uptake of activated sludge when the exposure time extended to 4.5 h.


Metal Nanoparticles/analysis , Sewage/chemistry , Wastewater/chemistry , Water Pollutants, Chemical/analysis , Water Purification/methods , Alum Compounds/chemistry , Aluminum Hydroxide/chemistry , Electrolytes , Kinetics , Metal Nanoparticles/chemistry , Microscopy, Electron, Transmission , Oxides/chemistry , Oxygen/analysis , Particle Size , Surface Properties , Water Pollutants, Chemical/chemistry
8.
Talanta ; 129: 617-22, 2014 Nov.
Article En | MEDLINE | ID: mdl-25127641

A portable, rapid and cost-effective DNAzyme based sensor for lead ions detection in water samples has been developed using an optical fiber sensor platform. The presence of Pb(2+) cleaves the DNAzymes and releases the fluorescent labeled fragments, which further hybridize with the complementary strands immobilized on the optic fiber sensor surface. Subsequent fluorescent signals of the hybridized fluorescent labeled fragment provides quantitative information on the concentrations of Pb(2+) with a dynamic range from 2-75 nM with a detection limit of 1.03 nM (0.21 ng mL(-1)). The proposed sensor also shows good selectivity against other mono and divalent metal ions and thus holds great potential for the construction of general DNAzyme-based sensing platform for the monitoring of other heavy metal ions. The sensor can be regenerated with a 1% SDS solution (pH 1.9) over 100 times without significant deterioration of the sensor performance. This portable sensor system can be potentially applied for on-site real-time inexpensive and easy-to-use monitoring of Pb(2+) in environmental samples such as wastewater effluents or water bodies.


Biosensing Techniques/methods , DNA, Catalytic/chemistry , DNA/chemistry , Lead/analysis , Water Pollutants, Chemical/analysis , Calibration , Environmental Monitoring/methods , Ions , Limit of Detection , Nucleic Acid Hybridization , Optical Fibers , Optics and Photonics , Sodium Dodecyl Sulfate , Wastewater
9.
Huan Jing Ke Xue ; 35(4): 1561-5, 2014 Apr.
Article Zh | MEDLINE | ID: mdl-24946618

An immunosensor for the rapid detection of 1,3-dinitrobenzene was developed based on an evanescent wave all-fiber biosensing platform with the detection limits of 0.054 mg x L(-1), and the detection cycle was less than 10 min. Hapten-carrier conjugates NB-OVA were synthesized by mixing 4-nitrohippuric acid and OVA activated by EDC, and then the conjugates were immobilized onto the silane layer on the probe with a heterobifunctional crosslinker. The probe modified had good robustness and regeneration performance, which allowed the performance of more than 100 assay cycles without significant loss of reactivity. Several water samples of different origins were measured with less than 4.5% -10.0% deviation of the detection and the recovery rate of 1,3-dinitrobenzene was between 80% and 120%, which proved the system's precision and accuracy and negligible matrix effects. This immunosensor shows great potential in rapid detection of 1,3-dinitrobenzene in practical waters.


Biosensing Techniques , Dinitrobenzenes/analysis , Immunoassay , Water/analysis
10.
Environ Sci Process Impacts ; 16(6): 1379-86, 2014 May.
Article En | MEDLINE | ID: mdl-24788953

Bisphenol A (BPA) is a known endocrine disruptor and one of the most serious environmental contaminants, often present at low levels in various water sources. Therefore, it is very important and necessary to develop a fast, cost-effective, sensitive, and selective method for on-site detection of BPA. Herein, we developed a portable, evanescent, wave fiber-optic aptasensor for rapid, on-site detection of BPA with high sensitivity and selectivity. In this system, the probe DNA molecule, which is the complementary sequence of a small part of the BPA aptamer, was covalently immobilized onto the optical fiber sensor surface. Using an indirect competitive detection mode, samples containing different concentrations of bisphenol A were premixed with a given concentration of fluorescence-labeled BPA aptamer, which binds to bisphenol A with high specificity. Then, the sample mixture was pumped to the sensor surface, and a higher concentration of BPA led to less fluorescence-labeled BPA aptamer hybridized with surface immobilized probe DNA and thus to a lower fluorescence signal. The developed sensing system exhibits a sensitive response to BPA in the range of 2 nM to 100 nM with a low detection limit of 1.86 nM (0.45 ng ml(-1)) under the optimal conditions. The biosensors showed good reproducibility, stability, and selectivity for BPA detection. Finally, this proposed sensor was successfully employed to determine the presence of BPA in wastewater samples.


Benzhydryl Compounds/analysis , Biosensing Techniques/methods , Environmental Monitoring/methods , Phenols/analysis , Water Pollutants, Chemical/analysis , Endocrine Disruptors/analysis , Fiber Optic Technology , Limit of Detection
11.
Water Sci Technol ; 69(5): 909-14, 2014.
Article En | MEDLINE | ID: mdl-24622536

Microsensor techniques were used to investigate in situ the simultaneous occurrence of sulfate reduction and nitrogen removal in a membrane aerated biofilm reactor. H2S, O2, pH, ORP, NH4(+) and NO3(-) microsensors were fabricated and used to measure the profiles inside the membrane aerated biofilm. Production and consumption rates of H2S, O2, NH4(+) and NO3(-) were estimated using corresponding concentration profiles. The results showed that in anoxic zone, located from the interface between biofilm and bulk liquid to about 550 µm below the interface, both sulfate reduction and denitrification occurred. Highest H2S production rates (around 0.27 mg L(-1)s(-1)) were found about 400 to 450 µm below the interface. Below the anoxic zone, an aerobic zone was present. High H2S oxidation activity occurred at around 550-700 µm below the interface. High oxygen consumption rates (0.34 mg L(-1)s(-1)) occurred at around 750-900 µm below the interface. Nitrification activity occurred at about 500-650 µm below the interface. Along the entire biofilm depth, pH changed slightly (within 0.2 unit). Near the interface of the aerobic and anoxic zone, there was a drastic redox potential change. These results demonstrated simultaneous sulfate reduction and nitrogen removal in a piece of membrane aerated biofilm.


Bacterial Physiological Phenomena , Biological Oxygen Demand Analysis , Bioreactors , Hydrogen Sulfide/metabolism , Nitrogen Compounds/metabolism , Biofilms , Hydrogen-Ion Concentration , Oxidation-Reduction
12.
Anal Chem ; 86(6): 3131-7, 2014 Mar 18.
Article En | MEDLINE | ID: mdl-24548044

Bacterial growth inhibition tests have become a standard measure of the adverse effects of inhibitors for a wide range of applications, such as toxicity testing in the medical and environmental sciences. However, conventional well-plate formats for these tests are laborious and provide limited information (often being restricted to an end-point assay). In this study, we have developed a microfluidic system that enables fast quantification of the effect of an inhibitor on bacteria growth and survival, within a single experiment. This format offers a unique combination of advantages, including long-term continuous flow culture, generation of concentration gradients, and single cell morphology tracking. Using Escherichia coli and the inhibitor amoxicillin as one model system, we show excellent agreement between an on-chip single cell-based assay and conventional methods to obtain quantitative measures of antibiotic inhibition (for example, minimum inhibition concentration). Furthermore, we show that our methods can provide additional information, over and above that of the standard well-plate assay, including kinetic information on growth inhibition and measurements of bacterial morphological dynamics over a wide range of inhibitor concentrations. Finally, using a second model system, we show that this chip-based systems does not require the bacteria to be labeled and is well suited for the study of naturally occurring species. We illustrate this using Nitrosomonas europaea, an environmentally important bacteria, and show that the chip system can lead to a significant reduction in the period required for growth and inhibition measurements (<4 days, compared to weeks in a culture flask).


Escherichia coli/growth & development , Microfluidics , Models, Biological
13.
Huan Jing Ke Xue ; 35(12): 4627-35, 2014 Dec.
Article Zh | MEDLINE | ID: mdl-25826934

BioWin software and two sensitivity analysis methods were used to simulate the Denitrification Biological Filter (DNBF) + Biological Aerated Filter (BAF) process in Yuandang Wastewater Treatment Plant. Based on the BioWin model of DNBF + BAF process, the operation data of September 2013 were used for sensitivity analysis and model calibration, and the operation data of October 2013 were used for model validation. The results indicated that the calibrated model could accurately simulate practical DNBF + BAF processes, and the most sensitive parameters were the parameters related to biofilm, OHOs and aeration. After the validation and calibration of model, it was used for process optimization with simulating operation results under different conditions. The results showed that, the best operation condition for discharge standard B was: reflux ratio = 50%, ceasing methanol addition, influent C/N = 4.43; while the best operation condition for discharge standard A was: reflux ratio = 50%, influent COD = 155 mg x L(-1) after methanol addition, influent C/N = 5.10.


Biofilms , Bioreactors , Denitrification , Models, Theoretical , Waste Disposal, Fluid/methods , Filtration , Wastewater
14.
Environ Sci Technol ; 47(9): 4434-41, 2013 May 07.
Article En | MEDLINE | ID: mdl-23514076

The accelerated eutrophication of surface water sources and climate change have led to an annual occurrence of cyanobacterial blooms in many drinking water resources. To minimize the health risks to the public, cyanotoxin detection methods that are rapid, sensitive, real time, and high frequency must be established. In this study, an innovative automated online optical biosensing system (AOBS) was developed for the rapid detection and early warning of microcystin-LR (MC-LR), one of the most toxic cyanotoxins and most frequently detected in environmental water. In this system, the capturing molecular MC-LR-ovalbumin (MC-LR-OVA) was covalently immobilized onto a biochip surface. By an indirect competitive detection mode, samples containing different concentrations of MC-LR were premixed with a certain concentration of fluorescence-labeled anti-MC-LR-mAb, which binds to MC-LR with high specificity. Then, the sample mixture was pumped onto the biochip surface, and a higher concentration of MC-LR led to less fluorescence-labeled antibody bound onto the biochip surface and thus to lower fluorescence signal. The quantification of MC-LR ranges from 0.2 to 4 µg/L, with a detection limit determined as 0.09 µg/L. The high specificity and selectivity of the sensor were evaluated in terms of its response to a number of potentially interfering cyanotoxins. Potential interference of the environmental sample matrix was assessed by spiked samples, and the recovery of MC-LR ranged from 90 to 120% with relative standard deviation values <8%. The immunoassay performance of the AOBS was validated with respect to that of conventional high-performance liquid chromatography, and the correlation between methods agreed well (R(2) = 0.9762). This system has successfully been applied to long-term, continuous determination and early warning for MC-LR in Lake Tai from June 2011 to May 2012. Thus, the AOBS paves the way for a vital routine online analysis that satisfies the high demand for ensuring the safety of drinking water sources. The AOBS can also serve as early warning system for accidental or intentional water pollution.


Automation , Biosensing Techniques/instrumentation , Drinking Water/analysis , Microcystins/analysis , Water Pollutants, Chemical/analysis , Antibodies, Monoclonal/immunology , Limit of Detection , Marine Toxins , Microcystins/immunology , Risk Assessment
15.
Huan Jing Ke Xue ; 34(1): 194-7, 2013 Jan.
Article Zh | MEDLINE | ID: mdl-23487938

Using the aeration pool in the fourth-stage at Wuxi Lucun Waste Water Treatment Plant (WWTP) as experimental setup, off-gas method was selected to measure the oxygenating ability parameters of micropore aerators in a real WWTP operating condition and these values were compared with those in fresh water to evaluate the performance of the micropore aerators. Results showed that the micropore aerators which were distributed in different galleries of the aeration pool had significantly different oxygenating abilities under operation condition. The oxygenating ability of the micropore aerators distributed in the same gallery changed slightly during one day. Comparing with the oxygenating ability in fresh water, it decreased a lot in the real aeration pool, in more details, under the real WWTP operating condition, the values of oxygen transfer coefficient K(La) oxygenation capacity OC and oxygen utilization E(a) decreased by 43%, 57% and 76%, respectively.


Air , Oxygen , Waste Disposal, Fluid/instrumentation , Oxidation-Reduction , Waste Disposal Facilities , Waste Disposal, Fluid/methods , Water Purification/methods
16.
Huan Jing Ke Xue ; 33(6): 2095-103, 2012 Jun.
Article Zh | MEDLINE | ID: mdl-22946201

Immunoassay provides very specific, highly sensitive, rapid, and cost-effective analyses for a variety of environmental contaminants. Since the immunoassay detects the environmental samples without pre-treatment, the interferences caused by various matrixes of environmental samples are a major problem, which can greatly affect the detection results. In this paper, based on the enzyme-linked immunosorbent assay (ELISA) for detection of Microcystin-LR (MC-LR), the effect of many kinds of matrixes on ELISA was systematically analyzed, and the corresponding method to control or eliminate the disbennifit effect was proposed. Finally, an integrated and packaged strategy-using the following buffer system as a diluent, i.e. 0.1 mol x L(-1) pH 7.4 PBS (10 x PBS) containing 1% BSA, 0.5% EDTA and 40 g x L(-1) sodium chloride-was given to control the overall matrix effects of environmental samples on ELISA detection. This strategy is also applicable to other kinds of immunoassays for environmental samples.


Enzyme-Linked Immunosorbent Assay/methods , Immunoassay/methods , Microcystins/analysis , Water Pollutants, Chemical/analysis , Environmental Monitoring/methods , Marine Toxins , Microcystins/immunology , Water Pollutants, Chemical/immunology
17.
Huan Jing Ke Xue ; 33(4): 1278-82, 2012 Apr.
Article Zh | MEDLINE | ID: mdl-22720578

Polymeric aluminum-iron (PAFC) was added at the end of aeration tank to enhance phosphorus removal, so that the phosphorus concentration in the effluent could meet the calss A standard in municipal sewage treatment plant pollutant discharge standard (GB 18918-2002). The characteristics of extracellular polymer substances (EPS) and bio-flocculation for the activated sludge in the A2/O system were analyzed in the experiment. The results showed that, the gross of EPS varied little with the increase in PAFC dosage, while, the ratio of albumen to polysaccharide declined from 3.30 to 2.30. When the PAFC dosage increased, the concentration of Al3+ in EPS increased during the whole anaerobic-anoxic-aerobic cycle. The flocs of activated sludge became larger after PAFC addition, Zeta potential of the effluent dropped significantly from - 15.83 mV to -21.20 mV and sludge yield increased. Therefore, bio-flocculation of the activated sludge in the A2/O system improved when a proper amount of PAFC was added, subsequently improve the water quality of the effluent.


Aluminum/chemistry , Bioreactors , Phosphorus/isolation & purification , Waste Disposal, Fluid/methods , Wastewater/chemistry , Aerobiosis , Extracellular Space/metabolism , Flocculation , Iron/chemistry , Polymers/chemistry , Sewage/chemistry
18.
Environ Sci Technol ; 46(6): 3288-94, 2012 Mar 20.
Article En | MEDLINE | ID: mdl-22296460

Required routine monitoring of endocrine disrupting compounds (EDCs) in water samples, as posed by EPA Unregulated Contaminant Regulation (UCMR3), demands for cost-effective, reliable and sensitive EDC detection methods. This study reports a reusable evanescent wave aptamer-based biosensor for rapid, sensitive and highly selective detection of 17ß-estradiol, an EDC that is frequently detected in environmental water samples. In this system, the capture molecular, ß-estradiol 6-(O-carboxy-methyl)oxime-BSA, was covalently immobilized onto the optical fiber sensor surface. With an indirect competitive detection mode, samples containing different concentrations of 17ß-estradiol were premixed with a given concentration of fluorescence-labeled DNA aptamer, which highly specifically binds to 17ß-estradiol. Then, the sample mixture is pumped to the sensor surface, and a higher concentration of 17ß-estradiol leads to less fluorescence-labeled DNA aptamer bound to the sensor surface and thus to lower fluorescence signal. The dose-response curve of 17ß-estradiol was established and a detection limit was determined as 2.1 nM (0.6 ng mL(-1)). The high specificity and selectivity of the sensor were demonstrated by evaluating its response to a number of potentially interfering EDCs. Potential interference of real environmental sample matrix was assessed by spiked samples in several tertiary wastewater effluents. The sensor can be regenerated with a 0.5% SDS solution (pH 1.9) over tens of times without significant deterioration of the sensor performance. This portable sensor system can be potentially applied for on-site real-time inexpensive and easy-to-use monitoring of 17ß-estradiol in environmental samples such as effluents or water bodies.


Biosensing Techniques/methods , Endocrine Disruptors/analysis , Environmental Monitoring/methods , Estradiol/analysis , Water Pollutants, Chemical/analysis , Aptamers, Nucleotide , Endocrine Disruptors/chemistry , Estradiol/chemistry , Fluorescence , Optical Fibers , Serum Albumin, Bovine/chemistry , Water Pollutants, Chemical/chemistry
19.
Huan Jing Ke Xue ; 32(4): 1120-6, 2011 Apr.
Article Zh | MEDLINE | ID: mdl-21717757

A novel detection method of quantitative PCR combined with a DNA intercalating dye propidium monoazide (PMA-qPCR) was developed and then applied to analyze inactivation efficacy of chlorine and monochloramine on E. coli as a representative organism. The results shows that PMA removed 99.94% and 99.99% DNA from non-viable E. coli and Salmonella cells respectively and PMA-qPCR could effectively differentiate viable bacteria from non-viable bacteria; According to the first-order kinetic model, the inactivation coefficients on E. coli obtained by PMA-qPCR were 2.24 L x (mg x min)-1 and 0.0175 L x (mg x min)-1 for chlorine and monochloramine respectively, both of which were lower than those obtained by traditional plating counting method. In order to inactivate 99% of E. coli, the ct values by PMA-qPCR were 0.9 mg L(-1) min and more than 100 mg x L(-1) x min for chlorine and monochloramine while those by plating counting method were only 0.6 mg x L(-1) x min and 20 mg x L(-1) min, respectively; E. coli concentration detected by conventional qPCR kept almost the same when ct value increased, indicating that conventional qPCR was unable to evaluate inactivation efficacy of both chlorine and monochloramine disinfection. In summary, PMA-qPCR shows to be a promising method for evaluating disinfection efficacy by chlorine and monochloramine more accurately.


Azides/analysis , Chloramines/pharmacology , Chlorine/pharmacology , Microbial Viability/drug effects , Polymerase Chain Reaction/methods , Propidium/analogs & derivatives , Disinfectants/pharmacology , Escherichia coli/drug effects , Propidium/analysis , Salmonella/drug effects
20.
Huan Jing Ke Xue ; 32(2): 483-7, 2011 Feb.
Article Zh | MEDLINE | ID: mdl-21528571

The phospholipids method for the determination of the living cell content in the biofilm was established to study the wastewater biofilm. With the micro-slicing technology, the biofilm was divided into 150 microm-layer for the phospholipids analysis. Results showed the phospholipids were approximately normal distribution along the biofilm depth without no addition of pentachlorophenol (PCP). The absolute values were between (1 246.2 +/- 217.4) microg/L and (527.2 +/- 95.3) microg/L with the maximum occurring at the depth of (0.60 +/- 0.15) microm, indicating the highest concentrations of the living cell in the biofilm. With the PCP concentrations of 5 microg/L, 10 microg/L and 20 microg/L and the exposure times of 2 h, 6 h and 24 h, respectively, the results of the orthogonal experiments showed the value of phospholipids decreased greatly along the biofilm depth only with the exception of 5 microg/L PCP concentration and 2 h exposure time, with a concentration decline by up to 70% especially close to the peak of phospholipids distribution. Results proved that PCP has an adversely influence on the living cells, and the influence can be enhanced with the increase of PCP amount and the exposure time.


Biofilms , Pentachlorophenol/chemistry , Phospholipids/analysis , Waste Disposal, Fluid/methods , Cells/cytology
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