The operation of these water treatment systems has shown that safe and high quality pool water is obtained reliably and economically. One pool (Main Pool) is of Olympic size, the other (Learner pool) is designed especially for use by children. Both pools utilize a full corona discharge ozone water treatment system. They were the first ozone systems in the U.S. to be built for public pools using the process of ozonation, flocculation, filtration, ozone removal and residual chlorination.
An extensive testing program was initiated in cooperation with the Wisconsin Department of Health. The bacteriological water quality from these swimming pools was in compliance with Wisconsin State Health Regulations and the German DIN Standard 19,643.
The first year of operation of the Peck Aquatic Center has shown that the corona discharge ozone pool water treatment process can:
1) Operate reliably in a public swimming pool environment without the need for highly or special operator qualifications.
2) Produce continuously bacteria- and virus-free pool water without the harmful and unpleasant effects of chlorine.
3) Creates a user constituency group praising and promoting the use of “minimal chlorine swimming” in the community. 相似文献
It has been indicated that the removal of the five species of aromatic nitro compounds by ozonation can well be expressed mathematically by first order reaction equations. Besides, the reaction constants and half-life periods for various species of the tested nitro compounds were calculated at different temperatures and pH.
An ozonation effect index (OI) was developed in the study to express the degree of degradation of substrates by ozonation, by means of which the five aromatic nitro hydrocarbons were compared with each other and finally ranked in the following order from greatest to smallest degrees of degradation:
p-nitroaniline > nitrobenzene > p-dinitrobenzene > p-nitrotoluene > m-dinitrobenzene
It has also found that the CODm/M ratio increases with ozone doses. This means that some easily degradable intermediates are produced, and increase in concentration with increase of ozone dose in the ozonation process.
The mechanisms of removing the five aromatic nitro hydrocarbons are discussed from the viewpoint of orienting effects of substituent groups on the aromatic rings. 相似文献
Introduction of new technological achievements and development in the field of flame retardancy (FR)
Review of the current state of science and technology in FR
Review of applications and markets for FR products
Presentation of recent developments in local and global standardization and in testing technology
Discussion of toxicity and environmental issues
Provision of a unique opportunity for newcomers to FR research technology and marketing to become acquainted with the FR field in all its aspects
Discussion of halogen-based and non-halogen-based flame retardant chemicals, syngergism, intumescence, FR mechanisms, modeling, flame parameters, inherently FR polymers, and polymer blends 相似文献
1. Surface irregularities caused by melt flow phenomena
2. Crystallization behavior
3. Melt drawing phenomena in certain types of polyethylene 相似文献
The study of the interactions between those reactants has been made according to the following main topics :
As for THM formation, experiments conducted on simple organic compounds or on natural fulvic acids show important decreases in THM or TCAA formation after ozonation. It may be noticed, however, that the ozonation of surface waters may induce the formation of haloform precursors, usually with a low level of reactivity.
In water supplies containing bromide ions, oxidation of the latter through hypobromous acid may take place during the ozonation stage. Failing preozonation treatment, hypobromous acid is generated very rapidly during chlorination, thus inducing the formation of chloro- brominated organic compounds.
During the ozonation of fulvic acid solutions, the presence of small amounts of bicarbonate was found to improve precursor removal significantly.
It can be concluded that the partial analogy of the action of ozone or chlorine on aromatic structures, whether simple or complex (such as humic and fulvic acids), seems to indicate that the consequence of preozonation is the destruction, at least in part, of the most reactive sites for THM production, thus leading to a decrease of the volatile organochlorinated compounds formed during the post-chlorination. However, some ozonation products of natural waters are THM precursors, though of low reactivity. Then, in the presence of bromide ions, the formation of volatile organobrominated compounds may be observed during ozonation. 相似文献
Further developments are expected in the field of lamp construction and also improvement of reactor geometry. A better knowledge of the aging of the lamps is required, as well as of the photochemical reactions of oxygen in the technologies applied.
Systems presently available are most promising for application on small scale or in areas of public water distribution which have no developed structure.
Ozonated water was produced using a contact system specifically designed for these tests by Ozotech Ltd. Ozone residual concentrations in the order of 0.1 mg/L were found to be capable of removing 80-99% of the biofilm in single applications. However, effectiveness of ozone was dependent on morphology, thickness and age of the biofilms. Intermittent application of ozone, using residual concentrations < 0.1 mg/L, was found to be capable of weakening the biofilm, but a minimum period of 3-h was required for effective control.
The fluid velocity was found to affect the rate and amount of biofilm removed. The effects of fluid velocities in the range 0.5-2.5 m/sec were examined. In general, the higher the velocity the greater the initial rate of removal and the percentage of the biofilm removed; this suggested that ozone action was mass transfer dependent.
The effect of ozone on bacterial cell structure was investigated using scanning electron microscopy techniques. Changes in cell structure were revealed after contact with ozone and residuals above 0.4 mg/L were required for 100% kill of bacterial suspensions.
In conclusion, the effectiveness of ozone for full-scale application will vary depending on the morphology of the biofilm, the velocity of the fluid and the ozone dose applied. An ozone dosing regime for commercial application is suggested. 相似文献
A commonly proposed method for controlling .VOC emissions is filtration of the off-gas through adsorption of the stripped organics in the off-gas by granular activated carbon. The high incremental cost of this alternative has produced an interest in alternative control technologies.
One alternative currently available is based on short wavelength ultraviolet (UV) radiation. This technique combines the effects of ozone generation, free radical formation and photolysis of the contaminants to effectively control the VOC emissions. This technique is known as Advanced Photo Oxidation (APO)R.
The cost for APO is $0.27/m3 for a 3.8 m3/hr contaminated water system. A system of this size is adequate for a groundwater decontamination project where a moderate length of time is available for restoration of the site. The cost of a conventional air stripping tower with Granular Activated Carbon (GAC) adsorption emissions control in this size range would be $0.40 to $0.45/m3 (J.M. Montgomery, 1986).
Additional testing will be required to fully develop design guidelines for different contaminants and larger systems. Another area for additional technical documentation is the application of this technique to the liquid phase oxidation of VOCs. 相似文献
Prechlorination was not conducted in the ongoing pilotplant experiment of an advanced water purification process with ozone and granular activated carbon. It is necessary, therefore, to oxidize manganese by the oxidative effect of ozone instead of prechlorination.
It is important for the treatment of manganese to adjust the ozone dosage because manganese is oxidized up to the soluble septavalent state by the surplus ozone. Since ozone does not continue to exist for very long in water, though its disinfecting power is high, final disinfection by chlorine is required. 相似文献
The raw water obtained from 100 different wells will be purified by a water treatment plant of 150,000 m3/day capacity. Considering the high iron content (0.05–0.15 mg/L) and manganese content (0.05–0.2 mg/L), the raw water fails to comply with the requirements of the potable water standard.
Since 1990, over a period of three years, we conducted water purification experiments in several stages. In these, three methods of oxidizing as well as single and double layer open rapid filters were applied to oxidize the manganese (and, to a lesser extent, the water) present in dissolved form, resp., to destroy various living organisms.
In the course of the experiments, it became clear that the chlorine and chlorine + air methods are efficient in case of a small quantity of iron to be oxidized and only 20–25% of the dissolved manganese content could be oxidized.
Neither of the two methods could ensure firm management of microbiological and bacteriological characteristics. The best results were obtained by ozone oxidation, in which case the chemical oxidizing process was almost fully completed and even the chlorine-resistant living organisms could be destroyed.
On the basis of the experiments carried out, the investment program of the water treatment plant was worked out and the conditions of an international tender were compiled whose winner will be commissioned to build up the water works in the time period 1993–1996. One of the main steps of the proposed technology is the ozone treatment. 相似文献
The control strategies investigated and compared are multiloop SISO, 2-way decoupling and l-way decoupling. The control variables are the standard ones, i.e. reflux flow and boilup.
In most of the cases INA has been found to be a useful tool for design of the loops and for comparison of the different control approaches. INA has also been found to be useful for simultaneous tuning of the decouplers and the feedback controllers.
For 2-way decoupling the criterion to minimize interaction at the critical frequency for each primary feedback loop has been found useful in most, but not all, cases. The scheme can be designed by pure gains in the decouplers and there is no reason to introduce dynamics into the decouplers—the systems studied are already sufficiently rich in dynamics.
INA has been found to be a suitable vehicle for the choice between the two possible l-way decoupling schemes.
With the design approach taken, l-way decoupling has been found to provide considerably better control quality than 2-way decoupling in two of the six systems, the differences in control quality being small in the other cases.
The effect of model mismatching on the results, caused e.g. by process nonlinearities, is discussed and simple rules to decrease the parameter sensitivity for 2-way decoupling schemes are given. When model mismatching is considered, the advantage of l-way decoupling over 2-way decoupling seems to increase.
One deficiency of the INA design as used in this paper is that it does not single out the design which is to be preferred on the grounds of robustness. 相似文献
In this paper, examples of field operating problems and their solutions are described. The experiences at specific municipal water and wastewater installations are reviewed in detail. Discussed for each example are : the background and effects of the problem, the problem-solving process, and the eventual resolution of the problem. The examples include simple unit operations to entire processes.
By observing the ozone installation's operation several years after start-up, the design of future ozone systems can be improved and operating problems minimized. 相似文献
The experiments were conducted both on a synthetic water, with or without addition of humic substances, and on raw water from the Moulin-Papon dam. While iron was easily removed by simply increasing the pH measurement from 8.2 to 8.5 without intermediate oxidation, ozonation applied to water with a pH of nearly 8.4 did not enable the manganese to be removed with a low ozone dose (about 1 mg/L) unless a significant amount of bicarbonates (120 to 130 mg/L as CaCO3) were injected prior to the ozonation-filtration stage.
As it removes the manganese from the water, intermediate ozonation also removes the abatement of organics on the filters, and lowers the THM buildup potential. 相似文献
There has been a high degree of proliferation of new products in the form of new polymers, new grades of existing polymers, as well as filled, reinforced, alloyed versions. While this does introduce new degrees of freedom in material selection, it is a source of significant confusion for the design engineers who have to cope with selecting the preferred material from among the many that are available. The choices and data bases are becoming confusing.
Various forms of relatively exotic, aromatic-monomer chemistry are being applied, but the emphasis appears to be on new amorphous polymers.
High-performance requirements exist in virtually all segments of the plastics field; the major end uses are in aerospace, automotive, business machines, electrical/electronics, food packaging, and medical applications.
Foreign presence has strongly increased as European companies have increased imports or have purchased established product lines or business units.
There will be continued pressure on the performance plastics from the lower priced materials which are countering with upgraded, modified, alloyed versions of their own. There is also increased competition between thermoplastics and thermosets as the result of material developments and process refinements. 相似文献
Highlights:
Mathematical model of cascade for separation of multicomponent isotope mixture has been developed.
The model verification has been done.
The isotope transient regularities into cascade during nonstationary processes has been identified. 相似文献
The results obtained in the field confirm the synthesis of some aliphatic carbonyl compounds of low molecular weight. This phenomenon happens preeminently during the ozone disinfection process and, secondarily, during the other disinfection processes.
Experimental results show that, in this last event, chlorine reacts with organic substances, and in a second moment, after organics consumption, if chlorine is still in a sufficient concentration, oxidizing them. 相似文献
Greatly enhanced mass transfer coefficients kL are measured whilst simultaneously maintaining low ozone loss. Comparisons of kL and volumetric coefficient, kL a values, are made with more conventional packed or bubble columns.
Acetic acid, 2-propanol and 4-nitrophenol, representing a wide reactivity range, are used to elucidate the applicability of rotating contactors in effluent treatment. It has been possible to study the effects of surface activity on mass transfer with subsequent reaction and to generate design data for the next generation of rotating contactors. 相似文献
In the paper industry, chemical pulps are washed to recover cooking chemicals and to obtain satisfactory quality for subsequent processing. With the present increased emphasis on pulp mill closure, the industry is attempting to reduce losses from brown stock washing systems. This leads to the need for improved engineering models of the washing operation for either design or control purposes.
Countercurrent washing, either stagewise or continuous, is generally used to obtain good recoveries at relatively low dilution ratios. In the stage-wise mode, rotary vacuum filters are commonly employed with reslurrying of the stock between stages.
The important chemical species in this separation process are sodium and lignin. In addition, other attributes, such as color and BOD5, are of increasing importance with respect to the performance of pulp washing systems. Aggregate characteristics, such as total dissolved solids (TDS) are also of concern.
This paper considers stagewise countercurrent washing of pulp in a cascade of rotary vacuum filters. A model of the multicomponent mass transfer process occurring in the wash zone of each stage is developed and incorporated into the system material balances to produce results useful for either design or performance calculations. 相似文献
- oxido-flocculation, using Fe2+, H2O2
- inter-oxidation, using O3, H2O2 and eventually an heterogeneous catalyst.
- disinfection, using UV, O3 and H2O2 combinations.
Results show that triazines can be removed by all these processes with different efficiencies. At full scale, the O3/H2O2 process presents the best performances from an economical and technical point of view. 相似文献