体积 3, 问题 3 (2012)


Water Requirement Modelling for Wheat under Arid Climatic Conditions

Laaboudi A, Mouhouche B

Algeria is an agriculture country where wheat is staple food of this region. Wheat is a winter crop and sown almost throughout the country. Winter season starts from October and normally ends in April. Water requirement of wheat followed variations in terms of location and time of the season. The northern of the country receives good rains during growth stages of wheat. But the southern of the country always requires irrigation and the groundwater is used extensively. Thousands of hectares are irrigated by pivot centres in extreme weather conditions. Better manage of limited water resources is the main objective of this study. Estimation of wheat maximum evapotranspiration with a Semi empirical approach used directly by the farmers, in lack of meteorological parameters, allows reaching this objective. The water balance of wheat was obtained by using non-weighing lysimeters. It was found that the Maximum daily crop Evapotranspiration (MET) for each wheat growth stage is linked to mean of daily temperature (Tm °C) and Leaf Area Index (LAI). Multivariate analysis shows that LAI does not contribute significantly for realizing a model in case of linear correlation. Using mean temperature of each growth stage, the obtained result shows a strong correlation between the calculated values of maximum evapotranspiration and its simulated values. In case of non linear correlation, both LAI and mean temperature contribute significantly for construction of the model. In this case the performance criteria are satisfactory. The determination coefficient (R²), Nash-Sutcliffe efficiency and the Relative Mean-Squared Error (RMSE) are respectively: 0.92, 0. 92 and 0.75 mm/day.


Removal of Anionic Dye in Acid Solution by Self Crosslinked Insoluble Dendronized Chitosan

Kishor Sarkar, Sovan Lal Banerjee and PP Kundu

Insoluble Dendronized Chitosan (DCTS) was prepared to improve the adsorption capacity of chitosan (CTS) as well as to lower its solubility at lower pH for efficient removal of acid dye, Acid Blue 9 (AB 9) from aqueous solutions. Dendronized chitosan was prepared by grafting ‘dendrimer-like’ Polyamidoamine (PAMAM) onto CTS surface using Michael addition reaction followed by amidation reaction. The obtained CTS derivative became insoluble at any pH medium due to self inter- and intra-molecular cross linking during the reaction without any external crosslinker. The adsorption capacity of the CTS derivative was studied using batch method with respect to various parameters like, initial pH of the dye solution, initial dye concentration, adsorption temperature and adsorption time. The batch study showed that the adsorption capacity of CTS derivative increased many times than that of chitosan. From the adsorption kinetic study, it was found that the adsorption of dye molecule on the adsorbent surface obeyed pseudosecond- order kinetic instead of generally reported pseudo-first-order kinetic. Dsorbent surface obeyed pseudo-second-order kinetic instead of generally reported pseudo-first-order kinetic. The adsorption equilibrium showed that the Langmuir equation represented best fit of the experimental data than that of Freundlich equation. The desorbed DCTS could be reused for the adsorption of the acid dyes. The results in this study showed that DCTS may be an attractive candidate for removing anionic dyes from the wastewater.


Method Validation for the Trace Analysis of Geosmin and 2-Methylisoborneol in Water by “Salt-Free” Purge-and-Trap Sampling/GC-MS, Using the Eclipse 4660 Sample Concentrator

Thavrin Manickum and Wilson John

The Eclipse 4660 purge-and trap sample concentrator, coupled to a gas chromatograph-mass spectrometer, was fully validated for trace analysis of the taste-odorants geosmin (GSM) and 2-methylisoborneol (2-MIB) in the absence of salt or methanol. The procedure involved purging a 25 mL sample volume, at 80°C, for 11 min. Quantitation was done by separation on an HP 5-MS capillary column (30 m × 0.25 mm × 0.25 μm), followed by mass spectrometric detection in the selected ion monitoring (SIM) mode. The method was found to be linear (r2 ≥ 0.995) over the calibration range 0-100 ng/L for both target analytes. The overall accuracy, determined by recovery, was 104.21% ± 19.46 (mean ± SD, range = 65.29-143.13%) for 2-MIB, and 85.24% ± 8.28 (mean ± SD, range = 68.66-101.82%) for GSM. The within-day precision averaged 7.97% for 2-MIB, and 8.77% for GSM. The day-to-day precision was 20.96% for 2-MIB, and 7.52% for GSM. The limit of quantitation (LOQ) was 6 ng/L and 5 ng/L for 2-MIB and GSM; the limit of detection (LOD) was 5 ng/L and 4 ng/L for 2-MIB and GSM respectively. Earlier findings regarding the dehydration of 2-MIB to 2-methyl-2-bornene (2-M-2-B) were confirmed. The average amount of 2-M-2-B formed was 27% (range: 15-50%), with RSD = 33.26%. There is evidence of dehydration of 2-MIB to 2-M-2-B at sample purge temperature of 40°C and higher. The poor day-to-day precision for 2-MIB has been proposed to be due to the inconsistent amount of 2-M-2-B formed. A minimum sample purge temperature of 40°C is required to purge 2-MIB and GSM from water, which can be detected by GC/MS under the purge-and-trap conditions at a concentration of 100 ng/L. The developed method was found to be sensitive, accurate, precise and reproducible for trace analysis of geosmin in water matrices.


The Future of Free and Open Source Software (FOSS) for Hydrology and Water Resources Management

Amos T. Kabo-bah, Xie Yuebo and Justice Odoi

Free and Open Source Software (FOSS) is rapidly growing in recent times and has changed the way in which licensing costs, sharing and distributions of software programs are managed globally. To a large extent, FOSS offers the cheapest and most effective solutions for technology transfer in software programs towards researchers and students worldwide. FOSS offers software free of charge online, including source code and all the information needed to allow easy adaptability to specific user needs. The research examines the benefits of transforming proprietary, public domain and free modelling codes and software for better river management and development. In order to achieve this goal, a conceptual framework called Hydrological Software Forum (HSF) is developed. The role of the HSF to ensure effective sharing and knowledge transfer among students and researchers has also been identified. It is hope that the adoption of HSF can help bring a new revolution to the development and use of modelling codes and software for river applications.


Regression Models for Determining the Fate of BOD5 under Biological Treatment Method in Polluted Rivers

Amos T. Kabo-bah, Xie Yuebo and Song Yajing

The estimation and prediction of BOD5 is an important criterion for wastewater management and biological treatment of polluted rivers. The biological treatment method has been identified as the most optimal and technologically efficient technology to treat polluted urban rivers and streams. This practice has seen tremendous acceptability and applicability in most parts of China. However, the high cost of measurements, laboratory tests and sampling uncertainties associated with water quality variables make monitoring and prediction of desired water quality variables during biological treatment campaigns difficult. This paper has developed empirical models to predict the fate of BOD5 during a biological treatment method. The developed ten models were evaluated using ten-stratified cross validation technique. The results indicate high R2 relationships between observed and computed values. Prediction accuracy of the models were also assessed and showed errors in the range of ± 26% ~ ± 37%. These errors seem acceptable according to previous work on BOD5 measurements and forecasting. It is presumed that the unexplained nature for empirical formulae to integrate all the natural processes underpinning BOD5 processes might have been the cause. This notwithstanding, the results show plausible application for prediction and management of biological treatment projects and replicable for wastewater treatment systems.


Polyvinyl Alcohol-Cellulose Acetate Composite Reverses Osmosis Membranes: I. Synthesis and Characterization

Amera Muhammed, El-Hashash, Mekewi, Guirguis, Ramadan and Hassanien

To overcome the high salinity water resources problem, reverse osmosis (RO) process is considered one of the most required techniques due to its high portable water quality produced. Optimization of membranes quality and function is still pursued and considered as of an important added value to the RO processes. In the present study, thin film PVA/CA+PEG membranes were prepared and the PVA layer was crosslinked by a varying maleic acid concentration at different reaction periods. The polymer composite is to be employed for the reverse osmosis process of brackish, saline and sea water purification. Optimization of reaction conditions and parameters such as salt rejection and water flux that affect on the membrane efficiency were verified. Structural and functional characterization of the PVA/CA composite membranes through Fourier Transform Infrared (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction pattern, scanning electron microscopy (SEM), swelling behavior and membrane mechanical properties were monitored.



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