Evaluation of Ozone Pretreatment on Flux Parameters of Reverse Osmosis for Surface Water Treatment

This research details the effects of ozone pretreatment on flux of a reverse osmosis membrane. Initial tests were conducted to determine the effects of ozonation on solids removal, turbidity, and chemical oxygen demand concentrations using various doses on a simulated surface water. These initial tests showed that the best reduction of solids in the 2–5 microns range was at 0.30 mg/L of ozone. Next, a series of bench scale tests was run for 62.5 hours using a standard reverse osmosis system under constant pressure with three pre-ozonation doses and a no ozone baseline dose. Temporal models were developed using the flux data from these tests to determine the effects of operating hours and ozone dosage on flux. It was found that the laboratory data were not linear and followed power law models. Statistical analysis was used to determine the significance of each ozone dose on the four developed models. The change in flux over the 62.5 operating hours with an ozone dosage of 0.30 mg/L showed the lowest flux change. Last, the models were tested using Hermia's filtration models and resistance versus time data to determine the type of membrane fouling that existed. It was concluded that the major fouling was pore blockage. This work demonstrated that ozone pretreatment is effective prior to use with reverse osmosis since it shows a better solid and organic removal rate as well as decreased flux and resistance changes over time.     

Uses of Ozone in a Three-Phase System for Water Treatment: Ozone Adsorption

A new technique of using ozone for water treatment is presented. This new technique consists of using a three-step-process composed firstly of ozone adsorption on an appropriate adsorbent, secondly water treatment, and thirdly regeneration of the adsorbent. Results regarding ozone adsorption (the first step) are presented in this paper. Different types of silica gel and a type of TiO₂ have been tested for ozone adsorption. It was found that the physical characteristics of the silica gel affect its capacity for ozone. Titanium dioxide has shown ozone decomposition instead of adsorption as it contains Lewis acid sites. An exponential decrease of the silica gel capacity with its moisture content has been found. Linear isotherms in the range of ozone concentrations less than 100?g/m³ NTP have been found. A particle diffusion model with linear equilibrium isotherm has been used to model the breakthrough curves in fixed bed columns.     

Development of a Process to Measure Ozone Concentration in Processing Water at the Point of Product Application

Ozone is an effective sanitizing agent against a broad spectrum of pathogenic and spoilage organisms. Optimization of treatment applications of ozonated water is needed for increased use in the food industry. An experimental apparatus and process has been developed to digitally measure ozone concentrations in processing water at the point of product application. Two application methods were evaluated. Effects of locally available water quality and water temperature on the ozone concentrations produced were determined. Rapid measurement of ozone concentration at the product application will facilitate the investigation of improved product quality in shrimp.     

Applications of Ozone in Japan for Water and Wastewater Treatment

In Japan, ozone is used for potable water treatment, night soil and industrial wastewater treatment, and for offensive gas treatment at sewage and night soil treatment plants. This paper describes its implementation, and presents experimental findings of the combined ozone and ultraviolet radiation as a new ozone utilization technology.     

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.     

Start-Up and Optimization of the Ozone Disinfection Process At the Sebago Lake Water Treatment Facility

The purpose of the ozone process at the Sebago Lake Water Treatment Facility (SLWTF) is to meet the disinfection requirements of the Surface Water Treatment Rule with ozone and without filtration. The start-up experience is presented including initial operating strategies to meet disinfection requirements. An ozone system performance test conducted during the first month of plant operation is described and the results are reviewed. The initial and proposed activities of an ozone optimization project are discussed.     

Improvement of a Measurement System for Surface Loss Rate of Ozone

Ozone molecules present in high-purity oxygen as a feed gas interact with surfaces and oxygen molecules in an enclosed container. Therefore, some of the ozone molecules are destroyed and the density of ozone decreases with time. An experimental system has been constructed to monitor the temporal decrease in ozone density in a container based on the HgI 254 nm photoabsorption method. Our investigation is focused on the dependence of the effective lifetime of ozone on the wall material at various gas pressures. During the experiments, distortion of the measured decay curves often caused by instabilities in the mercury lamp intensity. We thus attempted to build a simple setup that eliminates the effect of long-term intensity drift. This setup is based on light source intensity monitoring by a separate photodetector and data correction software. This article describes the setup of the experimental apparatus, the results including some preliminary experiments and the temporal variation of the surface loss rate of ozone by repeated measurement along with inspections of the wall surface by Auger electron spectroscopy.     

Hydrodynamic Evaluation of a Turbine Ozone Contactor

Detailed tracer and ozone profile evaluations in a full-scale turbine ozone contactor were conducted to support the development of a hydrodynamic model. The tracer results combined with ozone concentration profiles suggested that the flow through the contactor is very complex and cannot be described as a single CSTR as stipulated by current regulations. A multistage mathematical flow model was developed and calibrated. Cocurrent flow of water and gas in a central part of the reactor was postulated to explain significant ozone concentration gradients. The developed model was suitable for use as a framework for calculations of ozone mass transfer and residual concentrations.     

Development of a Practical Method for Using Ozone Gas as a Virus Decontaminating Agent

Our objective was to develop a practical method of utilizing the known anti-viral properties of ozone in a mobile apparatus that could be used to decontaminate rooms in health care facilities, hotels and other buildings. Maximum anti-viral efficacy required a short period of high humidity (>90% relative humidity) after the attainment of peak ozone gas concentration (20–25 ppm). All 12 viruses tested, on different hard and porous surfaces, and in the presence of biological fluids, could be inactivated by at least 3 log_10, in the laboratory and in simulated field trials. The ozone was subsequently removed by a built-in catalytic converter.     

Ozone Treatment of Cooling Water: Results of a Full-Scale Performance Evaluation

This paper is the first technical status report of a continuing evaluation of ozone treatment for cooling tower water. Data will be presented that illustrate the results of ozone treatment in a 3,400-ton air-conditioning cooling system at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee, which is operated by Martin Marietta Energy Systems, Inc., for the U.S. Department of Energy. Heat transfer data and equipment inspections confirm that a threshold surface temperature exists, below which heat exchange surfaces remain free of mineral scale. Heat exchange surfaces that exceed the temperature threshold experience calcium carbonate scaling. The temperature threshold effect may explain why ozone treatment has been reported as a successful treatment for air conditioning cooling towers, but has not been successful in higher temperature process cooling systems. Plans for future ozone investigations will be discussed.     

The Utilization of Ozone for Treating Vegetable Processing Lines

Adoption of ozone technologies as Food Safety treatments in the Agri-Food Industries today is still being approached with great caution. This paper reviews selected successes in using ozone UV and advanced oxidation to enhance food safety and reduce energy costs in the Agri-Food industry. Included is a preliminary case study of utilizing ozone and chlorination in a FTNON vegetable washing system. Vegetable flotation washing systems such as the FTNON equipment produced by Noord-Oost in the Netherlands have the potential to vigorously wash sand as well as floating particulate from vegetables and fruits. With minor modifications these machines can be adapted to utilize combinations of ozone, UV and chlorination. Preliminary trials indicate plate counts are lowered with the combination treatment. Future data will need to be collected to determine the levels of chlorination required to ensure residual microbial protection without detracting from product taste and quality. When developed, these systems have the potential to enhance food safety, reduce water use and wastewater discharge amounts, reduce electrical demand and increase product shelf life.     

Ozone Versus Ozone/Peroxide Induced Particle Destabilization And Aggregation: A Pilot Study

This research compares the role of ozone and the conjunctive use of ozone plus hydrogen peroxide in particle destabilization and particle aggregation, and improvement in filtered water quality. Particle destabilization was observed at all doses of ozone and ozone/peroxide studied, whereas aggregation was observed with ozone only at lower doses (> 2 mg/L) and in conjunction with ozone/peroxide (all doses studied). As compared to alum alone, the ozone-plus-alum and ozone/peroxide-plus-alum treatments provided improved flocculation and better filtered water quality. In addition, each of these preoxidations significantly reduced alum requirements. Overall, in terms of particle destabilization and aggregation; i.e., effectiveness as a coagulation aid, Ozone/peroxide performed better than ozone.     

An Antibiofouling Ozone System for Cooling Water Circuits. I - Application to Fresh Water Circuits -

A new antibiofouling ozone system with an intermittent injection of high-concentration ozone has been developed. The system was demonstrated to be effective for preventing biofouling on surfaces in fresh water stream. The application of the system reduces remarkably both the capital and the running costs compared to adopting conventional ozonation method.     

An Assessment of the Benefits Afforded by the Continuous Versus Intermittent Operation of Ozone for Drinking Water Treatment

Stricter regulation by OFWAT has encouraged water companies to optimize all stages of the water treatment process. This work reviews the ozonation process, in order to evaluate the benefits and disadvantages of continuous versus intermittent ozone operation. Two Advanced Water Treatment Works (AWTW) were surveyed, Farmoor AWTW, Which involves traditional (chemical) treatment processes, and Kempton Park AWTW, which incorporates slow sand filter sandwich? beds. Both reviews indicated that continuous ozone operation would result in an optimized solution based on dependability of ozone plant, reliability of water quality and cost efficiency.     

The Application of Ozone for Water Treatment In The United Kingdom — Current Practive and Recent Research

Only two water works in the UK apply ozone at present as part of their treatment, onefor taste and odor control and theother forcolor removal. Forthetwo applicationus ozone was the most economical option at thetime theplants were installed andozone has been successful for the purpose for which it was designed.     

Ozone in the United States of America -- State-Of-The-Art

Applications for ozone in the United States have evolved through a lengthy maturation process, which began with drinking water treatment (taste/odor/color removal) in the early 1900s, and grew slowly until acceleration began in the mid-1980s. Although deodorization became a stable market in the 1960s-1970s, these applications were small, for the most part. One of the largest uses for ozone is oxidation of process chemicals in the chemical industry, which began in the USA about the 1940s, and subsequently has spread worldwide. Today, thanks primarily to environmental regulatory pressures which began to impact ozone in the mid-1980s, ozone now is used increasingly in the USA for drinking water treatment and for some municipal and industrial wastewater applications. The U.S. Environmental Protection Agency (EPA) has recognized the growing importance of ozone (> 200 drinking water plants use ozone today), and has appointed IOA representatives to two of its regulatory development committees as stakeholders. Several U.S. cities have installed or are installing wastewater treatment processes for potable reuse purposes, which include the use of ozone. Three full-scale U.S. pulp bleaching plants use tons/day quantities of ozone. Smaller applications for ozone include water treatment for cooling tower waters (biofouling control), swimming pools and spas, marine aquaria, bottled water disinfection and maintenance of high purity waters in the pharmaceuticals and electronics industries. A new application for ozone is in commercial laundries to reduce energy costs and replace chemicals. In mid-1997, a public declaration was made by an expert panel that ozone is Generally Recognized As Safe (GRAS) for contact with foods. This declaration opens the door for ozone to be used in U.S. food processing industries. U.S. research scientists and engineers are at the forefront in studies which define the technical aspects of ozone technologies in a variety of applications employing advanced oxidation, including the treatment of hazardous wastes, groundwater remediation, and process water recovery and reuse in the semi-conductor industry.     

The Ozone Laundry Handbook: A Comprehensive Guide for the Proper Application of Ozone in the Commercial Laundry Industry

Applications of ozone in commercial laundry systems began in the late 1980s–early 1990s. Early installations showed promise for ozone to save considerable energy over conventional (thermal) systems. However, inconsistent performances of ozone equipment of that period coupled with a lack of in-depth understanding of how ozone was performing hindered commercial acceptance of ozone. With continued study and testing, these early misunderstandings about ozone have been overcome, and today many thousands of commercial laundry systems are using ozone successfully in many parts of the world. For example, more than 2,000 ozone laundry systems are operating in commercial laundry systems in the USA and another 2,000 commercial ozone laundry systems in the United Kingdom alone! Based on proven performance data obtained from many of these successful applications of ozone in commercial laundry systems, the authors have developed an Ozone Laundry Handbook, intended to be a summation of current knowledge and a guide to the laundry owner/operator considering the use of ozone. The Handbook contains 10 chapters, including discussions of the economic, environmental and microbiological benefits of ozone in commercial laundries, a discussion of ozone technologies as they apply to laundry systems, a comparison of traditional vs ozone laundry formulations, methods of applying ozone for laundering, operator training and ozone safety, a discussion on facts and fallacies about ozone for laundering, and finally a chapter on the future of ozone for laundering. The Handbook also contains a Glossary of Ozone Terms, Indices, and an Index.     

—Review Paper—Application Of Ozone for Treatment of Swimming Pool Water in the Federal Republic of Germany

In the fields of application of ozone plants produced by the German ozone industry, the treatment of pool water is foremost. Especially the precursors of the chlorine-nitrogen compounds (combined chlorine) and the chlorine-carbon compounds (haloforms) which, for reasons of health, are reckoned among the undesirable substances in pool water, can be considerably reduced through the use of ozone during pool water treatment. The efficiency of the treatment processes depends substantially on the reaction period of the ozone with the pool water contaminants, as is shown by tests with new processes having long ozone contact periods.     

Disinfection of Seawater: Application of UV and Ozone

Ozone and ultraviolet technologies are proposed as potential disinfecting agents for seawater. Ozone doses were applied in the range 0.38 to 4.89 mg O₃ L^?1. They permit to observe a complete disinfection as well as UV doses superior to 320 J L^?1. Impacts of both processes on organic matter were also studied. UV absorbances were reduced in both cases but in higher proportion using ozone (up to 50% removal). Total organic carbon was slightly reduced by UV radiation, and ozonation achieves up to 10% mineralization. Ozone reaction proceeds with biochemical oxygen demand increase. Seawater ozonation, in addition, leads to the formation of residual oxidants that show an inhibitory effect on autochthonous microorganisms.