Ozone and Nitrogen Oxides Generation in Gas Flow Enhanced Hollow Needle to Plate Discharge In Air

Siemens made the first ozone generation system by corona discharge about hundred and fifty years ago. At present mainly two types of atmospheric pressure electrical discharges - corona discharge and dielectric barrier discharge are used for production of ozone. Another type of discharge, which can be used for this purpose, is multineedle to plate electrical discharge enhanced by the gas flow. Contrary to the conventional arrangement when the gas is flowing around the needles we studied the discharge in which the gas was pumped through the needles. Results of studies of ozone and nitrogen oxides production by DC electrical discharge in air at atmospheric pressure with a single hollow needle to plate electrode configuration enhanced by the flow of air through the needle for both polarities of the needle, different airflow rates and currents are presented in this paper.     

环境空气二氧化硫采样及分析中的质量控制

为提高环境空气中二氧化硫测定结果的准确性,对二氧化硫的采样及分析过程中可能影响到其测定结果的诸多因素加以简要论述。结合工作实际,从导气管、采样温度、试剂、显色反应和比色管的影响等方面提出了一些可操作性强的技术建议。     

Ozone Generation from Oxygen and Air: Discharge Physics and Reaction Mechanisms

Industrial ozone generation uses a special high pressure, low temperature electrical discharge which is referred to as the dielectric barrier discharge or silent discharge. The filamentary structure of this discharge and the properties of individual microdischarges are discussed. The main reaction paths for the excited atomic and molecular species in oxygen and air are identified. Possible approaches to obtain high power densities, high ozone generating efficiencies or high ozone concentrations are discussed.     

The Benefits of Small Quantities of Nitrogen in the Oxygen Feed to Ozone Generators

This paper reports the ozone generation in pulsed multichannel dielectric barrier discharge. The influence of nitrogen addition (0.1%–10%) on ozone concentration and ozone generation efficiency in nitrogen–oxygen gas mixtures is studied. Results show that adding 0.1% N₂ would not seriously increase the ozone production. Meanwhile, 1% N₂ content exhibits the highest ozone production efficiency in low SIE (J/L, defined as the ratio of power to gas flow rate) region (0–200 J/L) while adding 0.3% N₂ would lead to the highest ozone generation efficiency in high SIE region (300–800 J/L). The increase of ozone production induced by N₂ addition is more significant in low SIE region compared with that in high SIE region. At 100 J/L, ozone production efficiency increases 26.9% to 201.6 g/kWh with 1% N₂ addition when compared with that in oxygen. At 18 J/L, the observed maximum ozone generation efficiency reaches 252 g/kWh at 1.3 g/Nm³ with 1% N₂ addition. An increase of ozone production can be obtained with 0.3%–2% N₂ addition in all explored SIE ranges.     

Effect of Application of Ozone and Ozone Combined with Hydrogen Peroxide and Titanium Dioxide in the Removal of Pesticides From Water

The aim of this research work is to study the influence of hydrogen peroxide and titanium dioxide in the ozone-based treatment to degrade 44 organic pesticides present in natural water, which are systematically detected in the Ebro River Basin (Spain). The studied pesticides are: alachlor, aldrin, ametryn, atrazine, chlorfenvinfos, chlorpyrifos, pp'-DDD, op'-DDE, op'-DDT. pp'-DDT, desethylatrazine, 3,4-dichloroaniline, 4,4'-dichlorobenzophenone, dicofol, dieldrin, dimethoate, diuron, α-endosulphan, endosulphan-sulphate, endrin, α-HCH, β-HCH, γ-HCH, δ-HCH, heptachlor, heptachlor epoxide A, heptachlor epoxide B, hexachlorobenzene, isodrin, 4-isopropylaniline, isoproturon, metholachlor, methoxychlor, molinate, parathion methyl, parathion ethyl, prometon, prometryn, propazine, simazine, terbuthylazine, terbutryn, tetradifon and trifluralin. The ozonation using 3 mg O₃ L^?1 produces a pesticides removal close to 23%, whereas the application of O₃/H₂O₂ and O₃/TiO₂ treatments achieves average degradation yields lower than the ozonation. However, the application of O₃/H₂O₂ /TiO₂ process improves considerably the pesticides degradation and an average degradation yield of 36% is obtained.     

The Effect of Relative Humidity on Ozone Production by Corona Discharge in Oxygen or Air – A Numerical Simulation – Part II : Air

The simulation of the temporal evolution of the various neutral gaseous species studied (O, O₃, H, OH, HO₂, H₂O₂, N, NO, NO₂, NO₃, N₂O, N₂O₅, HNO₂, and HNO₃) use corona effects. The physical conditions of the discharge were used. The reactions take place in dry or humid air, after the dissociation of O₂, N₂, and H₂O by an electronic pulse. When water vapor is present, there is a probability of production of H₂O₂, HNO₂, and HNO₃ in air. Temperature and humidity have cumulative effects. With multiple pulses, the O₃ maximal concentration is obtained for a limited number of pulses.     

水环境中细菌学监测的质量控制

水环境中细菌学监测的质量控制是保证细菌学监测准确性和科学性的基础。对细菌学监测的质量控制方法及质控考核未知样的研制做了一些探讨。     

橡胶膜密封干式气柜组装工艺和质量控制

介绍了橡胶膜密封干式气柜的组装工艺和质量控制 ,旨在充分肯定橡胶膜密封干式气柜的优越性和取代水密封湿式气柜及稀油密封干式气柜的必要性     

Urban and Background Ozone Trend in 1984-1999 at Subtropical Hong Kong,South China

There has been a growing concern for the impact of increasing Asian pollutant emissions on climate, atmospheric chemistry and air quality of the downwind region. In this study, we examined the long-term records of surface ozone (O₃) and its precursors (NO and NO₂) measured in Hong Kong from the early 1980s to 2000. The urban O₃ concentration has shown more than two-fold increase since the early 1980s and the increase was especially apparent after the late 1980s. The O₃ increases led to frequent O₃ pollution episodes and caused deterioration of local air quality. Such increases were not accompanied by local NO and NO₂ concentration changes in Hong Kong but coincided with the increase of NO_x emissions from Asia. We derived the background O₃ concentration for the South China region using the early morning (1:00–5:00 a.m. local standard time) data and linked the transport of Asian emissions and background O₃ change using back air trajectory and local meteorology. The derived background O₃ concentration shows an increase rate of 1.5% per year over the 15-year period from 1984 to 1999, which is close to that in the midlatitudes of East Asia at Japan. The sharp O₃ increase is related to the regional O₃ built-up in South China and the East Asia region due to the increases in the pollutant emissions as a result of rapid urban and industrial development in the region.     

The Role of Ozone in Improving Drinking Water Quality in London and Oxford

In recent years, drinking water quality has become a major subject for public and political debate, with the issue of pesticides in drinking water receiving much attention. The EC Drinking Water Directive included a limit of 0.1?µg/1 for individual pesticides, a standard far more stringent than health-based minimum levels set by such bodies as the World Health Organizations and the US EPA. With traditional treatment processes such as chemical coagulation, flocculation, filtration and slow sand filtration unable to meet the stricter pesticide standard, an additional method of treatment was required. Consequently, ozone and granular activated carbon (GAC) have been installed at all the major water treatment works (WTWs) in London and Oxford treating river Thames water. Groundwater WTWs, deemed to be at risk from pesticides, have GAC filters only. Computational Fluid Dynamics (CFD) was investigated as a tool for optimizing the design of ozone contractors. The aim was to distribute ozone flow uniformly so that maximum contact would be made between the water and gas. However, the application of ozone in water treatment processes remains expensive when compared to conventional treatment. Consequently, a cost benefit analysis of continuous versus intermittent ozone operation was carried out. Operational data was obtained and compared for two Thames Water UK and Ireland (TWUKI) surface water treatment works (one conventional (chemical) works and the second based on biological processes).     

New Restaurant Concept Relies on Ozone,UV Radiation,Ultrasound and Modified Air Packaging

With the development of the new Swiss Ventafresh technology (Steffen, 2007 Steffen, H.P. April 2-4 2007. Presentation of the VENTAFRESH Disinfection and Packing Technology in Several Food Processing Applications, April 2-4, Fresno, CA: Proc. Intl. Water Technology Conference and OZONE V. Session D, paper 4 [Google Scholar]; Steffen et al., 2007a,b) that produces edible, packaged foods having much longer shelf-lives than are available by current technologies, new vistas in food service and restaurant service have become available. About 170 km outside of Madrid is a new food processing and packaging plant. Raw foodstuffs (spices, fruits, meats, vegetables, rice, potatoes, pasta, salads, etc.) are delivered to this plant where they are washed (in ozone-containing water), peeled, sliced, etc. Microwaveable packing trays are filled with ingredients of a complete meal and then sealed with a microwaveable plastic film (sometimes with modified atmospheres). Both the packing trays and the sealing film are disinfected using combinations of ozone and UV radiation. Individual meals are prepared and packaged, but are not precooked, then are delivered to five (currently) Crono Chef restaurants strategically located throughout Madrid (www.crono.tv). There are only waiters/waitresses. A customer entering a Crono Chef restaurant is seated, offered the usual libations, and given a menu of the meals stocked?–?in refrigerators, not frozen. The customer's selection is cooked fresh in one of many microwave ovens on the premises. Cheese and/or desserts follow, along with the usual after-dinner drinks, if desired. This new concept in food delivery can be extended to food service for large institutions, e.g., military installations, sporting events, hospitals, elder care facilities, schools, prisons, highway restaurants, and is available for franchising.     

Impact of Ozone and Biological Filtration on Water Quality Parameters in Arlington,Texas

The City of Arlington began experiencing atypical water quality problems beginning in 1999 after ozonation and biofiltration were added to the existing conventional treatment processes. These problems included high chloramine residual decay rates, system nitrification and elevated manganese levels in the finished water. This study reviewed literature, existing plant and system data and collected additional data to determine if modifications to the plant and system processes would resolve these water quality problems. Results demonstrated that chloramine stability is improved with increased free chlorine contact time at a pH near 8.3. Improved biofiltration by nurturing the biomass in the filters also improves chloramine stability as well as eliminating the breakthrough of manganese at the filters. Careful monitoring and minimizing water age in the distribution system can also reduce water quality issues.     

Combined Use of Ozone and Granular Activated Carbon (GAC) in Potable Water Treatment; Effects on GAC Quality After Reactivation

Common processes in potable water treatment regarding dissolved organics removal (natural organic matter, NOM, and organic micropollutants, OMP) include oxidation techniques – like ozonation -and adsorption onto granular activated carbon (GAC). This paper deals with combined ozonation and GAC filtration. Effects on water quality are discussed: partial oxidation of dissolved organics by ozone, leading to changing adsorption behavior and enhanced biodegradation in GAC columns. Special emphasis is laid on long term effects of ozone on GAC quality after several thermal reactivations. Long term experience indicates that ozonation prior to GAC filtration, leading to moderate ozone concentrations in the GAC influent, does not influence GAC quality negatively, even after more than ten reactivation cycles.     

Comparison of Aqueous Ozone and Chlorine as Sanitizers in the Food Processing Industry: Impact on Fresh Agricultural Produce Quality

The effects of ozone treatment on fresh strawberry and shredded lettuce food quality were tested by varying applied ozone concentration, contact time, pH and temperature to assess ozone a potential food sanitizer. The produce quality was assessed by comparing the changes in texture firmness, browning and decolorization, oxygen consumption and carbon dioxide respiration after the post-treatment storage from 0 to 21 days. The effectiveness of ozonation on natural microfloras including mesophiles, psychotrophes, yeasts and molds, was also evaluated for the improvement in produce shelf-life. As compared to chlorine treatments, ozone treatments slightly increased the lettuce browning but substantially retarded its respiration rates and firmness deterioration even after 21 days of storage. For strawberry, no significant difference in food quality was observed between ozone and chlorine treatments. Finally, ozone treatments at the doses below 10 mg/L were found not effective in killing natural microfloras grown on the produce surfaces.     

Chemical Changes of Canola Oil During Frying Under Atmospheric Condition and Combination of Nitrogen and Carbon Dioxide Gases in the Presence of Air

The effects of different frying methods; frying under atmospheric condition and frying in the presence of different ratios of nitrogen and carbon dioxide gases; were investigated on chemical changes of canola oil. The tests were conducted four times per day during four consecutive days. The chemical changes of oil samples were determined by analyzing peroxide value (PV), p-anisidine value (p-AV), totox value (TV) and acid value (AV). Irrespective of the test methods, PV increase was observed on the first day followed by significant (p < 0.05) reduction in the subsequent days. On the first day, the highest p-AV and TV was observed in oil fried under atmospheric condition and the lowest p-AV and TV for those fried under gases. However, from the second day, the p-AV and TV in frying under different ratios of nitrogen and carbon dioxide gases were significantly (p < 0.05) higher than the frying under atmospheric condition. Additionally, hydrolysis and oxidation of oil during frying resulted in continuous AV increase that among them atmospheric frying had the highest AV. In conclusion, atmospheric frying accelerates the rate of oil deterioration and application of nitrogen and carbon dioxide gases in the fryer could reduce the rate of oil disintegration.     

Effects of Elevated Carbon Dioxide and Ozone on Foliar Proanthocyanidins in Betula platyphylla, Betula ermanii, and Fagus crenata Seedlings

Proanthocyanidins (PAs) or condensed tannins are a major group of phenolic compounds in the leaves of birch trees and many other woody and herbaceous plants. These compounds constitute a significant allocation of carbon in leaves and are involved in plant responses to environmental stress factors, such as pathogens or herbivores. In some plants, PA concentrations are affected by atmospheric carbon dioxide (CO₂) and ozone (O₃) levels that may influence, for example, species fitness, community structure, or ecosystem nutrient cycling. Therefore, a study on the quantitative response of PAs to elevated concentrations of carbon dioxide (CO₂) and ozone (O₃) was undertaken in seedlings of Betula platyphylla, Betula ermanii, and Fagus crenata. Seedlings were exposed to ambient or elevated O₃ and CO₂ levels during two growing seasons in the Kanto district in Japan. Ten open-top chambers were used for five different treatments with two replicates: filtered air (FA), ambient air (ambient O₃, 43 ppb; ambient CO₂, 377 ppm), elevated O₃ (1.5 × ambient O₃, 66 ppb), elevated CO₂ (1.5 × ambient CO₂, 544 ppm), and elevated O₃ and CO₂ combined. In addition, seedlings growing in natural conditions outside of chambers were studied. Leaf samples were analyzed for total PA concentrations by butanol–HCl assay and for polymeric PA concentrations by normal-phase high-performance liquid chromatography. Total PA concentrations in leaves of all species were similarly affected by different treatments. They were significantly higher in seedlings treated with elevated CO₂ and O₃ combined, and in seedlings growing outside chambers compared with the FA controls. F. crenata contained only traces of polymeric PAs, but significant species × treatment interaction was observed in the polymeric PA concentrations in B. ermanii and B. platyphylla. In B. platyphylla, leaves treated with elevated CO₂ + O₃ differed significantly from all other treatments. It was suggested that the strongest effect of elevated CO₂ and O₃ combined on leaf PA contents resulted from the additive effect of these environmental factors on phenolic biosynthesis.     

The PhytO3 Tech Crop Protection Technology for Microorganism and Insect Control using Ozone,UV, and Dipole-Electrical Air Jet Spray Technologies – Technical Basis and Possible Chemistries Involved

Plants can't walk away when they are attacked by pathogenic microorganisms and insects, or if they are exposed to any form of stress. They do not have a central nervous system that allows them to defend themselves or to ask for help! In the early part of the 20th century, it was discovered that growing plants can be stimulated to respond to stresses by developing a Systemic Acquired Resistance (SAR) to microorganisms and insects. During the last 50 years, and especially during the past decade, significant advances in this agronomical technology have been made. SARs have been proven to result from the application of many types of chemical formulations. Plants respond by generating their own chemicals internally that subsequently prevent attacks by microorganisms and insects. Recently it has been shown that sequential treatment of growing plants with (1) an aqueous spray of high voltage, pulsed negatively charged water, followed immediately with (2) a spray of ozonated water containing 8 mg/L of ozone generated from oxygen, and that followed immediately by (3) high energy UV-C radiation, also causes plants to develop SARs to microorganisms and insects, but without the use of chemicals. The primary advantages of this new ozone-UV-based technology are: (a) there are no harmful effects on the plants, (b) no toxic chemical residues remain on the plants, (c) the technology can be used in rainy weather, when crop protection is most necessary, (d) the technology is environmentally friendly (no chemical residues), and (e) the technology is cheaper for crop growers compared to current chemical approaches.     

Ozone in Medicine: Clinical Evaluation and Evidence Classification of the Systemic Ozone Applications,Major Autohemotherapy and Rectal Insufflation,According to the Requirements for Evidence-Based Medicine

Now that indications are clearly defined, applications have mostly become standardized and the active mechanisms have been well confirmed, medical ozone application in the form of the low-dose concept, is established and proven as a complementary medical method in the treatment of chronic inflammations or diseases associated with chronic inflammatory conditions. More than 11,000 systemic ozone treatments in the form of Major Ozone Autohemotherapy (MAH) in 577 patients and ≥ 47,000 Rectal Insufflations (RI) in 716 patients in various clinical studies are subjected to critical clinical assessment and classification according to the criteria of evidence-based medicine (EBM). Statistically significant clinical and/or pharmacological improvements without side-effects or adverse reactions are found in all studies; special attention is drawn to maintaining hygiene when working with blood and to the use of ozone-resistent and biocompatible materials. On summarizing the evidence classification under RCT + CT (Randomized Controlled Trials + Controlled Trials), i.e., Levels Ib and IIa, 12 studies with 657 ozone-treated patients are obtained for MAH and 6 studies with 227 patients for RI. As a result of the evidence here assessed, the two systemic ozone applications, MAH and RI are part of evidence-based medicine. Both applications are effective, safe and economic.     

Water Quality Improvement by Combined UF,RO, and Ozone/Hydrogen Peroxide System (HiPOx) in the Water Reclamation Process

Conventional water reclamation processes, such as membrane bioreactors, are not always effective in removal of pharmaceuticals and personal care products (PPCPs), endocrine disrupting chemicals (EDCs) and/or N-nitrosodimethylamine (NDMA), even with the reverse osmosis (RO) membrane process. A study was conducted, at a NEWater factory in Singapore, to compare a conventional ultrafiltration (UF) membrane /RO treatment process with a treatment train having the HiPOx unit, an advanced oxidation process (AOP), which was installed between the UF and the RO unit operations. By incorporating the HiPOx into the UF/RO treatment process, following results were observed; 1) increased removal of PPCPs, EDCs and NDMA, 2) improvement in ultraviolet transmission (UVT) of the RO permeate, 3) enhanced removal of TOC and color, and increased UVT of the RO brine, 4) suppression of the increase in the RO transmembrane pressure by organic fouling.     

Ozone Reactivity and Free Radical Scavenging Behavior of Phenolic Secondary Metabolites in Lichens Exposed to Chronic Oxidant Air Pollution from Mexico City

Lichen secondary metabolites putatively protect lichens from a variety of environmental stress factors, but it is unknown whether these substances respond to air pollution. To assess such a possibility, the three major phenolics of two epiphytic lichen species with contrasting tolerance to chronic air pollution from Mexico City were studied by combining experimental reactivity data and measured field contents. The antioxidant activity and antiradical power of boninic (BO), 2-O-methylsekikaic (MA), and usnic (US) acids, isolated from the tolerant Ramalina asahinae and salazinic acid (SA), atranorin (AT), and chloroatranorin (CA), from the sensitive Parmotrema stuppeum, were determined in vitro by kinetic experiments with ozone and the free radical diphenyl picryl hidrazyl (DPPH^•), respectively. In addition, the field contents of these phenolics in the lichens, and the potential antioxidant capacity (PAC) they provide, were compared among three forested sites exposed to urban emissions and a similar, relatively clean site. The six phenolics had antioxidant activity and antiradical power according to these trends: CA >> AT > US > SA ≥ BO ≥ MA for O₃; and CA > AT > US > MA > SA = BO for DPPH^•. The three most reactive phenolics are cortical compounds, located in the lichen portion most exposed to the surrounding environment. In contrast, the less reactive SA, BO, and MA are medullary. Such reactivity patterns indicate that some phenolics may provide antioxidative protection at the air–lichen interface. The higher antioxidant power of CA and AT may be due to the reactive hydroxyl groups at positions 2 and 4 of ring A, instead of the less reactive methoxyl at the same positions in both BO and MA. In the field comparisons, total quantified phenolics were significantly higher near Mexico City for both lichens, except for the tolerant R. asahinae at one site. Nevertheless, only the latter species had significantly increased PAC values at all sites near the city. This result is explained by species-dependent changes in individual phenolics. At the polluted sites, R. asahinae had consistently higher contents of its most reactive phenolic, US, with values approximately twice that of the control site. In contrast, P. stuppeum only increased its less reactive SA (26–35%), but this was counteracted by CA and, to a lesser extent, AT degradation. Thus, the substantial increase in US at the polluted sites appears to be associated with the current ecological success of R. asahinae near the city. On the other hand, the inability of P. stuppeum to overcome degradation of its most reactive phenolic (CA) at the same sites seems to partially explain the declining status of this lichen. These results provide evidence for a protective mechanism in lichens against air pollution based on secondary metabolites, which may eventually determine which species survive in forests stressed by oxidative air pollution.