Batch-mode System Research Articles

Removal of Cu(II) and Cd(II) From Aqueous Solutions by Polyaniline on Sawdust

The present work deals with the removal of Cu(II) and Cd(II) ions from aqueous solutions in a batch mode system using polyaniline doped sawdust (PANI/SD). The effects of various experimental conditions such as pH, initial metal ion concentration, time, and temperature were studied. The sorption system follows a second-order kinetic model, and adsorption equilibrium was achieved within 40 min. The maximum adsorption capacities obtained from the Langmuir isotherm model are 208.77 mg/g and 136.05 mg/g for Cu(II) and Cd(II), respectively, at pH 5.0 and a temperature of 293 K. Thermodynamic parameters such as ΔH°, ΔS°, and ΔG° were evaluated for the adsorption process, and the results show that the adsorption of Cu(II) and Cd(II) is spontaneous and endothermic. Desorption of metal ions and regeneration of adsorbent is achieved in 2 M hydrochloric solution. It is therefore reasonable that PANI/SD could be used for the removal of Cu(II) and Cd(II) ions from waste water.

Use of solar energy in the treatment of water contaminated with phenol by photochemical processes

The solar driven photo-Fenton process for treating water containing phenol as a contaminant has been evaluated by means of pilot-scale experiments with a parabolic trough solar reactor (PTR). The effects of Fe(II) (0.04-1.0 mmol L-1), H2O2 (7-270 mmol L-1), initial phenol concentration (100 and 500 mg C L-1), solar radiation, and operation mode (batch and fed-batch) on the process efficiency were investigated. More than 90% of the dissolved organic carbon (DOC) was removed within 3 hours of irradiation or less, a performance equivalent to that of artificially-irradiated reactors, indicating that solar light can be used either as an effective complementary or as an alternative source of photons for the photo-Fenton degradation process. A non-linear multivariable model based on a neural network was fit to the experimental results of batch-mode experiments in order to evaluate the relative importance of the process variables considered on the DOC removal over the reaction time. This included solar radiation, which is not a controlled variable. The observed behavior of the system in batch-mode was compared with fed-batch experiments carried out under similar conditions. The main contribution of the study consists of the results from experiments under different conditions and the discussion of the system behavior. Both constitute important information for the design and scale-up of solar radiation-based photodegradation processes.

Removal of cadmium (II) from aqueous solutions by adsorption on agricultural waste biomass

This paper reports the feasibility of using various agricultural residues viz. sugarcane bagasse (SCB), maize corncob (MCC) and Jatropha oil cake (JOC) for the removal of Cd(II) from aqueous solution under different experimental conditions. Effect of various process parameters, viz., initial metal ion concentration, pH, and adsorbent dose has been studied for the removal of cadmium. Batch experiments were carried out at various pH (2–7), adsorbent dose (250–2000 mg), Cd(II) concentration (5–500 mgl −1) for a contact time of 60 min. The maximum cadmium removal capacity was shown by JOC (99.5%). The applicability of Langmuir and Freundlich isotherm suggests the formation of monolayer of Cd(II) ions onto the outer surface of the adsorbents. Maximum metal removal was observed at pH 6.0 with a contact time of 60 min at stirring speed of 250 rpm with an adsorbent dose of 20 g l −1 of the test solution. The maximum adsorption of cadmium (II) metal ions was observed at pH 6 for all the adsorbents viz; 99.5%, 99% and 85% for JOC, MCC, and SCB, respectively. Order of Cd(II) removal by various biosorbents was JOC > MCC > SCB. JOC may be an alternative biosorbent for the removal of Cd(II) ions from the aqueous solution. FT-IR spectra of the adsorbents (before use and after exhaustion) were recorded to explore number and position of the functional groups available for the binding of Cd(II) ions on to studied adsorbents. These results can be helpful in designing a batch mode system for the removal of cadmium from dilute wastewaters.

Immobilization of liposomes on hydrophobically modified polymer gel particles in batch mode interaction

Immobilization of liposomal phospholipids onto Sephacryl S-1000 gels that were chemically conjugated with hydrophobic alkyl moieties, octyl, dodecyl and hexadecyl, was examined in batch mode interaction. Compared with the octyl gel, the dodecyl and the hexadecyl gels were found to immobilize the three to four times more phospholipids with the less hydrophobic moieties. The encapsulation of a water-soluble marker, with other evidences, suggests that the majority of the immobilized phospholipids maintained liposomal morphology. As the lipid of the interacting liposomes, egg yolk phosphatidylcholine (eggPC), 1,2-dimyristoylphosphatidylcholine (DMPC) and a mixture of DMPC and 1,2-dimyristamido-1,2-deoxyphosphatidylcholine were examined. At 22°C, DMPC liposomes showed higher extent of immobilization than at 37°C but not eggPC liposomes, suggesting that the phase of liposomal membrane could have influence on the immobilization. Exchange between the immobilized liposomes and free ones was found to be small, less than 3%. The gel that had been first interacted with liposomes to apparent saturation could further immobilize the newly added liposomes. The rate of this second immobilization was similar to that of the slow adsorption process; the both could be based on the same mechanism, possibly involving rearrangement of the immobilized liposomes on the gel as proposed by Lundahl. As had been observed in the flow mode, the immobilization had preference for smaller liposomes. In application of the system in batch mode, the size distributions of the immobilized liposomes and of those left in the supernatant may differ from that of the originally added liposomes.

Nitrogen removal during leachate treatment: comparison of simple and sophisticated systems

Membrane bioreactors (MBR) have become common in treating municipal wastewaters. Applied to leachates treatment MBR were also successful with pilot scale experiments and full-scale facilities as well. We succeeded previously in designing an efficient nitrification-denitrification process with an ethylene glycol byproduct as carbon source for denitrification. Moreover, an unexpectedly high inert COD removal efficiency was also observed in the full-scale MBR facility thereby making it possible to increase the operating time of the final GAC (Granulated Activated Carbon) adsorber. Since MBR are very sophisticated systems. Simpler and "lower" cost systems can also be considered. For example it is possible to nitrify leachates from sanitary landfill using a simple infiltration-percolation technique with a low energy cost. To validate previously published laboratory experiments, a semi industrial-scale pilot installation was installed at the Montzen landfill site (Belgium). The process is based on infiltration-percolation through a granular bed. This well known process was modified to increase the load, notably by changing the support medium, adding an electric fan that is run intermittently and maintaining temperatures greater than 15 degrees C. The new material is a type of granular calcium carbonate with a large specific surface area. These technical improvements enabled the system to nitrify up to 0.4 kg NH4+-N/m3 of reactor bed per day at a hydraulic load of 0.35 m.d(-1), with an ammonia removal rate in the range of 80 to 95%. Despite the high ammonia nitrogen inlet concentrations, this system exhibits remarkable nitrification efficiency. Moreover, these performances are achieved in a batch mode system without recirculation or dilution processes. If complete nitrification is needed, it can be obtained in a second in series of bioreactors. The system can be classified as a low cost process. An international patent is pending. Possible performances of those systems were compared with the usual methods for leachates treatment.

Enhancement of the specificity of an enzyme-based biosensor for L-tryptophan.

A new selective amperometric biosensor for reagentless L-tryptophan determination has been developed using immobilized tryptophan-2-monooxygenase (TMO, EC 1.13.12.3). This enzyme-based biosensor provides a rapid-response detection system for concentrations of L-tryptophan between 25 and 1,000 microM in a batch mode system and between 100 and 50,000 microM in a flow-injection mode. The response time was 30 seconds, and the total analysis time was less than 3 minutes. The biosensor retained catalytic activity and fidelity of phenylalanine and tryptophan response for greater than 4 months with repeated usage. The biosensor selectivity to L-tryptophan was dramatically increased relative to phenylalanine when a competitive inhibitor of TMO, indole acetamide (IA), was included. The biosensor was successfully used for L-tryptophan determination in nutrition broth, giving values identical to those determined by HPLC analysis.

A tool for developing interactive configuration applications

Knowledge-based techniques have been proven to be well suited for configuration tasks and several, often successful, systems have been developed. The goal of these knowledge-based techniques has in general been to produce “black box” configuration systems, i.e., batch-mode systems that take a set of requirements as input and produce configurations as output. This has resulted in rather complex systems that have been time-consuming to develop and in which the choices of components, which are often subjective, are hidden from the user. In this paper we present a less complex and more interactive approach to configuration that we label interactive configuration by selection (ICS). The idea is that a configuration system could be more of a tool, assisting in the task of configuration, than a “black box” automatically producing configurations directly from requirements. To support the approach we have developed OBELICS. OBELICS is a prototype of a tool, implemented in SICStus Objects, that integrates both a problem-solving method for ICS and a tool for domain knowledge modeling. With OBELICS we hope to demonstrate that such a tool can make it feasible and profitable to develop configuration applications, even for small scale applications.

A program system for efficient multispectral classification

Pixelwise multispectral classification is an important tool for analyzing remotely sensed imagery data. The computing time for performing this analysis becomes significantly large when large, multilayer images are analyzed. In the classical implementation of the supervised multispectral classification assuming gaussian-shaped multidimensional class-clusters, the computing time is furthermore approximately proportional to the square of the number of image layers. This leads to very appreciable CPU-times when large numbers of multispectral channels are used and/or temporal classification is performed. In order to decrease computer time, a classification program system has been implemented which has the following characteristics: (1) a simple one-dimensional box classifier, (2) a multidimensional box classifier, (3) a class-pivotal “canonical” classifier utilizing full maximum likelihood and making full use of within-class and between-class statistical characteristics, (4) a hybrid classifier (2 and 3 combined), and (5) a local neighbourhood filtering algorithm producing generalized classification results. The heart of the classifier is the class-pivotal canonical classifier. This algorithm is based upon an idea of Dye suggesting the use of linear transformations making possible a simultaneous evaluation of a measure of the pixel being likely not to belong to the candidate class as well as computing its full maximum likelihood ratio. In case it is more likely to be misclassified the full maximum likelihood evaluation can be truncated almost immediately, i.e. the candidate class can often be rejected using only one or two of the available transformed spectral features. The result of this is a classifier with CPU-time which is empirically shown to be linearly dependent upon the number of image layers. The use of the hybrid classifier lowers the CPU-time with another factor of 3–4. Furthermore, for certain problems like classifying water-non water a single spectral band is often sufficient for making decisions and for such cases the simple one-dimensional box is used. The program constitutes a very efficient and flexible tool for multispectral classification. In many cases, the result from the pixelwise classifier is only the first step in the analysis procedure and often one wants a generalized classified image. The CLEANUP-routine (5) is a tool for achieving this by comparing the class-assignment for a particular pixel with those of the surrounding pixels. This scheme for supervised classification has been implemented and incorporated in several program systems for multilayer image processing and analysis like the batch-mode system on IBM 370 (TGLIB), the dialog system for batch-job summission on IBM 370 (PICCOLA) both in Stockholm as well as the dialog system on DEC 10 PILIP (PIXLIB) and its interactive supplement on PDP 11 34 (PIXLIB) at FOA 3 in Linköping. This work was partly financed by, and PICCOLA is now administered under, DFR (Swedish Board for Space Activity).

An economic analysis of an automated system for interpreting electrocardiograms

For the past year routine electrocardiograms (ECGs) from the Heart Station at U.S. Naval Hospital, San Diego, California have been automatically interpreted using the Smith/Mayo computer program with an IBM 360/65 at the Naval Electronics Laboratory Center, San Diego, California. The ECGs are batch processed. In the near future, an on-line, automated ECG interpretation system will be centralized in the Heart Station and have the capability to process ECGs for all U.S. Navy medical facilities in Southern California. This paper discusses the economic implications of such a system and compares its costs with those of a manual system, the existing batch mode system and commercial ECG service bureaus for similar ECG workload volumes. Finally, an evaluation of the accuracy of the Smith/Mayo program's interpretation of 4,628 normal and abnormal ECGs is presented.