Determination of solvents permeating through chemical protective clothing with a microsensor array

The performance of a novel prototype instrument in determining solvents and solvent mixtures permeating through samples of chemical protective clothing (CPC) materials was evaluated. The instrument contains a mini-preconcentrator and an array of three polymer-coated surface-acoustic-wave (SAW) microsensors whose collective response patterns are used to discriminate among multiple permeants. Permeation tests were performed with a 2.54 cm diameter test cell in an open-loop configuration on samples of common glove materials challenged with four individual solvents, three binary mixtures, and two ternary mixtures. Breakthrough times, defined as the times required for the permeation rate to reach a value of 1 microg cm(-2) min(-1), determined by the instrument were within 3 min of those determined in parallel by manual sampling and gas chromatographic analysis. Permeating solvents were recognized (identified) from their response patterns in 59 out of 64 measurements (92%) and their vapor concentrations were quantified to an accuracy of +/- 31% (typically +/- 10%). These results demonstrate the potential for such instrumentation to provide semi-automated field or bench-top screening of CPC permeation resistance.     

Evaluation of rural wastewater treatment processes in a county of eastern China

With the rapid urbanization and industrialization in China, wastewater treatment in rural areas has become an increasing national concern. The selection of appropriate treatment processes closely based on the actual local status is crucial for the prevention of water quality deterioration in rural areas of China. This study presents a full year survey on the performances of various rural wastewater treatment processes at a county level in eastern China including seven three-chamber septic tanks (ST), five micro-power biological facilities (MP), seven constructed wetlands (CW), three stabilization ponds (SP) and five centralized activated sludge treatment plants (AS). It was found that although ST could remove a notable portion of total suspended solids (TSS) and chemical oxygen demand (COD(Cr)), it was ineffective in reducing nutrients and pathogens. Reliability and stability analyses showed that the centralized AS and decentralized CW processes outperformed the SP and MP processes. There were obvious discrepancies between the mean design concentrations, which ensure that 95% of the effluents meet the discharge standards, and the actual effluent concentrations determined for each process. The expected compliance with the tentatively adopted second-grade discharge standards (GB 18918-2002) was unsatisfactory for most of the water quality parameters examined, indicating an urgent need to design more practical discharge standards for decentralized treatment processes. Based on an overall assessment of reliability, stability and cost-effectiveness, the centralized AS was suitable for densely populated towns while the decentralized CW was suitable for sparsely populated villages.     

Simultaneous determination of hydroxylamine and phenol using a nanostructure-based electrochemical sensor

The electrochemical oxidation of hydroxylamine on the surface of a carbon paste electrode modified with carbon nanotubes and 2,7-bis(ferrocenyl ethyl)fluoren-9-one is studied. The electrochemical response characteristics of the modified electrode toward hydroxylamine and phenol were investigated. The results showed an efficient catalytic activity of the electrode for the electro-oxidation of hydroxylamine, which leads to lowering its overpotential. The modified electrode exhibits an efficient electron-mediating behavior together with well-separated oxidation peaks for hydroxylamine and phenol. Also, the modified electrode was used for determination of hydroxylamine and phenol in some real samples.     

Detection of hormone mimics in water using a miniturised SPR sensor

The ubiquitous presence of chemicals, both natural andsynthetic, in the environment with the potential to mimichormones that may in turn interfere with the endocrinesystem in both wildlife and humans has in the last decadebecome a major international concern. Hormone mimics orendocrine disrupting compounds (EDCs) are especiallyprevalent in surface and waste-waters and therefore, thereis a need for an at-source or at-line analytical device forthe monitoring of EDC levels.We have incorporated a miniature integrated surface plasmonresonance (SPR) liquid sensor from Texas Instruments into afield analyser and developed a competition/inhibition assayfor a model estrogenic compound in aqueous samples. Theanalyser has the potential for in situ and semi-continuous analysis of EDCs. A novel regeneration schemeemploying the use of a domestic laundry detergent has beenused to remove immobilised assay components between eachassay cycle. The resultant re-usable sensor has beendemonstrated using estrone-3-glucuronide (E3G) as a modelEDC and an anti-E3G antibody producing a current detectionrange of 10 to 150 ng mL^-1.     

An evaluation of a fast sampling procedure for the trace analysis of volatile organic compounds in ambient air

This study deals with the evaluation of a fast method for sampling of volatile organic compounds in ambient air. Special bags made of an inert material are used together with a large handpump which allows a sampling of one liter per second. After the sampling, the pollutants are concentrated by adsorption on Tenax and transfered by heat desorption, to a small capillary precolumn cooled with liquid nitrogen, or directly trapped on the precolumn. The suitability of this technique was evaluated by sampling complex synthetic mixtures of known concentration and composition, after which the samples were submitted to a series of operations such as transport, aging, changing of the humidity, heating and cooling, irradiation, etc. Changes in the original mixtures, caused by adsorption, diffusion, chemical or photochemical reactions were investigated by GC-MS analysis. The results of the study show that under certain conditions the samples can be preserved for a rather long period of time without noticeable changes in composition. However for certain compounds, severe quantitative losses occur after one day storage. Finally a practical application of this method is described in a recent case of strong odour annoyance by a chemical plant in the north of Belgium.     

Treatment of wastewater containing arsenic using Rhazya stricta as a new adsorbent

The effective removal of heavy metals from aqueous wastes is among the most important issues for many industrialized countries. Removal of arsenic (As) from aqueous solutions was studied using Rhazia stricta biomass. The batch experiments are carried out to investigate the effect of the significant process parameters such as pH, contact time, solute concentration and adsorbent dose. The optimum pH required for maximum adsorption was found to be 5. The equilibrium data for the adsorption of As(V) on R. stricta are tested with various adsorption isotherm models such as Langmuir, Freundlich, Tempkin and Generalized equation. Results indicate the following order to fit the isotherm: Langmuir (1 and 2)?>?Tempkin?>?Generalized form?>?Freundlich. A comparison of two kinetic models showed that our data fitted well to the Elovich model.     

高氯离子废水化学需氧量分析方法的研究

提出一种测定高氯离子废水 COD的新方法。其消解条件与现行国标法基本相同 ,消解过程产生的氯气用Na OH吸收并测定出氯离子的 COD校正值。由表观 COD值减去氯离子的 COD校正值 ,即为水样的真实 COD值。标样的相对误差在 -1.5 %～ 5 %之间 ,RSD%≤ 5 .5 %。高氯废水的 RSD%≤ 8.0 %。     

Determination of heavy metals in lower Sakarya river sediments using a BCR-sequential extraction procedure

A BCR-sequential extraction procedure for the determination of extractable heavy metals was applied to sediments of various rivers and lakes. There are many rivers basins in Turkey. Sakarya River Basin is one of the most important basins, which consists of three parts: Upper, Middle and Lower Sakarya River Basins. In this study, the Lower Sakarya River was selected as the study area for sediments. The samples were collected monthly from 10 pre-determined stations through the river for 10 months time and analysed for the distribution of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn elements. The determination of extractable heavy metals in sediments was carried out by using Flame Atomic Absorption Spectrometer. The validation of the results was performed by the analysis of a BCR 701 standard reference material.     

Assessment of odour problem in sewage-treated effluent in a closed loop irrigation system

Uses of wastewater drives significant economic activity, supports countless livelihoods particularly those for developing countries. While using wastewater, the challenge is to identify practical, affordable safeguards that do not threaten the health of users. In Yanbu Al-Sinaiyah, treated sewage effluent (TSE) is used for landscape purposes. In the present study, the odour problem caused by TSE in community area has been addressed. Samples were collected and analysed for total coliform, odour, trihalomethanes (THMs), total organic carbon (TOC) and other physicochemical parameters. Results show that in distribution network, residual chlorine was below the detection limit, turbidity, THMs, TOC and total coliform concentration was much higher than point source, and concentration of these parameters was further increased in problematic areas. It was also observed that areas with odourous problem were at the tail of irrigation network. This indicates that odour problem was due to less residual chlorine high turbidity, high rate of coliform and TOC. In odourous water samples, carbon disulphide and dimethyl sulphide were also identified by GC/MS, while in other areas where there was no odour, both these compounds were not detected. Odour problem was successfully resolved by improving sand filtration system to minimise turbidity the main cause of odour, increasing the residual chlorine at the treatment plant and regularly flushing the distribution network.     

Evaluation of phosphorus loads from Ontario municipal wastewater treatment plants

Results are presented from an evaluation of the nature and accuracy of phosphorus loads discharged by Ontario municipal wastewater treatment plants into the Great Lakes. Data were examined for the 96 plants treating flows in excess of 4546 m³d^-1 for the period 1981 to 1985. For the Lake Erie, Lake Ontario/St. Lawrence River and Upper Great Lakes basins, total basin phosphorus loads were classified according to type of wastewater treatment system, the type of chemical added for phosphorus removal, plant capacity, and sampling frequency. Load estimation techniques were compared using the 1985 daily data from three representative treatment plants. Annual phosphorus loads were compared using the complete data records for the plants and using Monte Carlo techniques to simulate an incomplete data record typical of once per week effluent phosphorus sampling. Potential sources of bias were identified in annual phosphorus load estimates from municipal treatment plants.     

Evaluation of germination, root growth and cytological effects of wastewater of sugar factory (Afyonkarahisar) using Hordeum vulgare bioassays

In this study, the effect of Afyonkarahisar Sugar Factory's discharge water on germination percentage, root growth and mitotic divisions of the root tip cells of Hordeum vulgare L. were investigated. Six concentrations of wastewater and ranging from 10(0), 10(?-1), 10(?-2), 10(?-3), 10(?-4), 10(?-5), were applied for 6, 12, 18 and 24 h, respectively. It was observed that the treatments reduced the germination percentages of H. vulgare grains and inhibited the root growth as well as reduced mitotic index compared to the control group at all concentrations. It was also observed that the increase of the concentrations of wastewater decreased the cell division, and several mitotic anomalies such as c-mitosis, lagging chromosomes, multipolar anaphases and chromosome bridges increased.     

Bio-analytical and chemical characterisation of offshore produced water effluents for estrogen receptor (ER) agonists

The in vitro estrogen receptor (ER) agonist potency and C1 to C9 alkyl substituted phenol content of offshore produced water effluents collected from the UK sector of the North Sea were determined using a combination of bio-analytical and chemical analysis techniques. An in vitro reporter gene assay was used to determine ER agonist potency, whilst gas chromatography coupled to mass spectrometry (GC-MS) was used to quantify the concentration of alkylphenols. The in vitro ER agonist potency was highly variable and ranged from less than the limit of detection (theoretically 0.03 ng 17beta-estradiol (E2) l(-1)) to 91 ng E2 l(-1). C1 to C5 alkylphenol concentrations were also highly variable ranging from 5 to 1600 microg l(-1) with a median concentration of 206 microg l(-1). These data reflect the highly variable composition of produced water discharges from different fields. The observed poor correlation of the alkylphenol isomer content and ER agonist activity suggests that other compounds present in the produced water discharges may be responsible for the ER agonist activity observed. It is recommended that further work be performed to characterise the full range of ER agonists present in offshore produced water discharges.     

Biological treatment of textile wastewater using sequencing batch reactor technology

This study was conducted to biologically treat wastewater discharged from the textile industry (textiles made of cotton and/or synthetic fiber) using sequencing batch reactor (SBR) technology (activated sludge process operating on batch mode). To achieve the objectives of the study, the characteristics of textile wastewater and the biodegradation of its organic constituents under unsteady state conditions were studied. Then, a bench-scale pilot plant was used to study the performance of SBR by monitoring the settleability and change in the constituents (chemical oxygen demand and solids) over time. Results of the study showed that textile wastewater has different types of pollutants: heat, basicity, suspended solids, organic and inorganic matter, and heavy metals. The factors affecting the biodegradation of organic matter were determined as the reaction time and the ratio of initial substrate to sludge concentrations. Also, removal of solids was monitored, and the settling velocity as affected by sludge concentration was graphically presented to enable the determination of settling time. Finally, the outcome of this study was used to suggest a procedure for the design of a full-scale SBR unit for treatment of textile wastewater.     

Evaluation of pollution load of Lahore Canal by quantification of various pollutants through physicochemical characterisation

The work describes the physicochemical analysis of the water samples collected from Lahore Canal to evaluate pollution load at different points of the canal. Different physical and chemical pollutants such as temperature, pH, electrical conductivity, total dissolved and suspended solids, turbidity, chlorides, sulphates, nitrates, oils and grease, dissolved oxygen, chemical oxygen demand and biological oxygen demand (BOD) were analysed. The data was analysed through analysis of variance, which showed that the p values for dissolved oxygen (DO), chemical oxygen demand (COD), BOD, electrical conductivity, total dissolved solid (TDS), total suspended solid (TSS), turbidity, oil and grease, sulphates, and nitrates are <0.05, while p value of temperature, pH, and chlorides are 1.000, 0.984, and 0.070, respectively, which are >0.05. Further regression analysis revealed that the simple line regression modal is fit for turbidity and TSS, electrical conductivity and TDS, COD and DO, BOD and DO, and BOD and COD. The studies reveal that Lahore Canal is receiving a considerable amount of physical and chemical pollutants at different points.     

Prediction of the effluent from a domestic wastewater treatment plant of CASP using gray model and neural network

When a domestic wastewater treatment plant (DWWTP) is put into operation, variations of the wastewater quantity and quality must be predicted using mathematical models to assist in operating the wastewater treatment plant such that the treated effluent will be controlled and meet discharge standards. In this study, three types of gray model (GM) including GM (1, N), GM (1, 1), and rolling GM (1, 1) were used to predict the effluent biochemical oxygen demand (BOD), chemical oxygen demand (COD), and suspended solids (SS) from the DWWTP of conventional activated sludge process. The predicted results were compared with those obtained using backpropagation neural network (BPNN). The simulation results indicated that the minimum mean absolute percentage errors of 43.79%, 16.21%, and 30.11% for BOD, COD, and SS could be achieved. The fitness was higher when using BPNN for prediction of BOD (34.77%), but it required a large quantity of data for constructing model. Contrarily, GM only required a small amount of data (at least four data) and the prediction results were analogous to those of BPNN, even lower than that of BPNN when predicting COD (16.21%) and SS (30.11%). According to the prediction, results suggested that GM could predict the domestic effluent variation when its effluent data were insufficient.     

Preliminary studies of a fast screening method for polycyclic aromatic hydrocarbons in soil by using solvent microextraction-gas chromatography

Solvent microextraction (SME) was applied to the extraction of polycyclic aromatic hydrocarbons (PAHs) from spiked and real environmental soil samples with different matrices. Soil sample was mixed with 7 mL of acetone and 14 mL of water to allow partitioning of the PAHs from the soil to the liquid phase. A 2 microL octane drop suspended from a microsyringe needle tip was then immersed into the stirred solution-soil mixture for extraction. After an 11 min extraction, the octane drop was withdrawn into the syringe and injected directly into the GC for identification and quantification. The whole analysis procedure took 27 min, with an extraction time of 11 min, and a GC separation time of 16 min. A second extraction could be undertaken whilst the GC is running, hence the GC run time currently limits the sample throughput. In this method, a small amount of organic solvent was used for the extraction process, which produced little waste. The limits of detection for lower molecular weight (< 230) PAHs range from 0.13 to 0.36 mg kg-1, and for higher molecular weight (> 250) PAHs are estimated to be between 0.5 and 1.0 mg kg-1, with RSD values generally under 20%. Due to the small volumes of organic solvent used, the consumable cost per extraction is only US$ 0.12. This is the first report of the application of SME to solid samples, and the first report of the use of SME for the analysis of PAHs.     

Performance of an electrochemical COD (chemical oxygen demand) sensor with an electrode-surface grinding unit

An electrochemical COD (chemical oxygen demand) sensor using an electrode-surface grinding unit was investigated. The electrolyzing (oxidizing) action of copper on an organic species was used as the basis of the COD measuring sensor. Using a simple three-electrode cell and a surface grinding unit, the organic species is activated by the catalytic action of copper and oxidized at a working electrode, poised at a positive potential. When synthetic wastewater was fed into the system, the measured Coulombic yields were found to be dependent on the COD of the synthetic wastewater. A linear correlation between the Coulombic yields and the COD of the synthetic wastewater was established (10-1000 mg L(-1)) when the electrode-surface grinding procedure was activated briefly at 8 h intervals. When various kinds of wastewater samples obtained from various sewage treatment plants were measured, linear correlations (r(2)> or = 0.92) between the measured EOD (electrochemical oxygen demand) value and COD of the samples were observed. At a practical wastewater treatment plant, the measurement system was successfully operated with high accuracy and good stability over 3 months. These experimental results show that the application of the measurement system would be a rapid and practical method for the determination of COD in water industries.