An Ozone-based Advanced Oxidation Process for an Integrated Air Pollution Control System

Six case studies of fires or explosions involving air pollution control (APC) systems are reviewed in this paper. These case studies have been generalized from actual accident investigations performed by the authors.The case studies cover the APC technologies of thermal oxidation, catalytic oxidation, gas scrubbers, adsorption, and condensation. Each of the technologies was used to control emissions of volatile organic compounds (VOCs). The accidents encompass a broad range of industries, ignition sources, and circumstances. The causal factors for these accidents are compared with applicable safety guidelines and standards to show how safeguards could have prevented or mitigated these accidents.The common theme that emerges from these accident investigations is that APC systems should not be specified and installed strictly by intuition or experience, but rather through careful engineering design. The key findings of this study are: Characterize the waste stream to be treated. Conduct a process hazard analysis for each APC system, with particular emphasis on fire and explosion hazards. Design the APC system using good engineering practices. Operate the APC system within its design specifications. Periodically verify that the APC system performance satisfies its technical and regulatory objectives. Perform maintenance activities in accordance with manufacturer's recommendations. Each of the accidents was the direct result of the omission of one or more of these basic tenets. © 2005 American Institute of Chemical Engineers Process Saf Prog, 2005

The characteristics of air pollution control (APC) residues are influenced by the furnace type, APC system, and waste composition. In this study, the characteristics of APC residues from nine municipal solid waste incineration plants (the compositions of incinerated solid waste are similar) with different furnace types and APC systems were compared.APC residues contain a great amount of Ca and Cl, and the contents of Al, Si, and Fe in the APC residues from fluidized bed incinerators are higher. The mineral compositions of APC residues are not influenced by the flue gas treatment process, but their contents vary. The contents of Cd, Pb, and Zn in the APC residues from fluidized bed incinerators are lower, while those of Cr, Ba, Cu, and Ni are greatly influenced by the APC systems, with the "grate+dry scrubber" APC residues having the lowest values. The differences in the heavy metal contents in the APC residues from two incinerators before and after the upgrading of the APC systems are not significant. The leaching toxicity of Pb in the APC residues from grate incinerators is higher than that from fluidized bed incinerators, while some elements with low contents in fluidized bed APC residues can be leached more in acetic acid buffer solution. The acid neutralization capacity of the APC residues is related to Ca content. The leaching concentrations of most heavy metals are significantly increased under strong acidity (Cd, Ni, and Zn:leachate pH < 8; Pb, Cu, and Cr:leachate pH < 4). The maximum leaching concentrations of As, Ba, Cu, Ni, and Pb in the APC residues from grate incinerators are mainly controlled by their total content. The leaching concentrations of As, Ba, Cu, Ni, and Pb in the APC residues from fluidized bed incinerators are lower than those from grate incinerators with similar metal contents, which may be due to their different chemical speciation influenced by furnace types and the complexation with Al and Fe compounds.

Control of air pollutant emissions is a mean to protect air quality. In most cases, this is realized by the imposition of specific emission standards, which usually are based on national and international experience. However, in areas with intense and dense polluting activities (e.g. industrial sites, trafficked roads) these horizontal measures will most probably fail to sustain local air quality. This is mainly because they do not consider the local transport mechanisms of pollutants from the source to the receptor. High local concentration levels might be the result of specific meteorological conditions, amplification owe to neighbour sources and deficient design of the air pollution control (APC) systems. Present work describes a conceptual and holistic approach based on the downwind optimisation, which takes into consideration also the transfer mechanisms that induce the ground level concentration of pollutants. This method can be used to design efficiently and dynamically control both the APC systems and the plant processes. Thus, local air quality can be sustained and protected in all cases and also achieve a significant reduction in capital and operational costs. Nevertheless, no cost-benefit analysis has been conducted here. The approach is also demonstrated in a comprehensive case study.

This paper gives results of the measurements and evaluation of emissions from seven Swedish incineration plants. The investigated incinerators ranged from 12 to 80 MW, and include Martin grate, Von Roll grate, Overthrust (W+E) grate, Vereinige Kesselwerke (V+K) grate, travelling grate, vibration grate and circulating fluidized bed (CFB) types. The analytical techniques used include online carbon monoxide (CO), nitrogen oxides (NOX), sulfur dioxide (SO2), particulate matter (PM), carbon dioxide (CO2), combustion and flue gas temperatures, gas chromatography and mass spectrometry (GC/MS), using Tenax as adsorbent. A number of volatile organic compounds (VOCs) were identified and quantified. The effects of waste compositions, size of incinerators, air pollution control systems on the VOCs in flue gas were investigated. Overall combustion characteristics such as waste compositions, carbon monoxide incinerator output have been related to the emissions of total volatile organic compounds (TVOCs). The results show that these large‐scale incinerators have low VOC emissions, ranging from 0.07 to 0.90 mg/nm after the flue‐gas cleaning systems. The efficiency of air pollution control (APC) systems in reducing VOCs ranged from 26.1 to 90.4 %. High efficiency was found in the new systems with lime reactors and textile filters. Results from two incinerators showed that electrostatic precipitators had no effect on reducing VOCs. High TVOC emissions occurred in two plants when the moisture and plastic contents of the refuse were high. The relationship between CO and TVOC was also indicated, although incinerators, combustion conditions, flue gas cleaning systems and fuels are all confounding factors.

Cooperative Agreement DE-FC26-06NT42726 was established in January 2006, and is current through Amendment 2, April 2006. The current reporting period, April 1, 2008 through June 30, 2008, is the eighth progress-reporting period for the project. However, this report will be the final report (instead of a quarterly report) because this project is being terminated. Efforts to bring this project to a close over the past several months focused on internal project discussions, and subsequent communications with NETL, regarding the inherent difficulty with completing this project as originally scoped, and the option of performing an engineering study to accomplish some of the chief project objectives. However, NETL decided that the engineering study did indeed constitute a significant scope deviation from the original concepts, and that pursuit of this option was not recommended. These discussions are summarized in the Results and Discussion, and the Conclusion sections. The objective of this project by a team lead by URS Group was to demonstrate the use of regenerative heat exchange to reduce flue gas temperature and minimize evaporative water consumption in wet flue gas desulphurization (FGD) systems on coal-fired boilers. Furthermore, the project intended to demonstrate that regenerative heat exchange to cool flue gas upstreammore » of the electrostatic precipitator (ESP) and reheat flue gas downstream of the FGD system would result in the following benefits to air pollution control (APC) systems on coal-fired power plants: (1) Improve ESP performance due to reduced gas volume and improved ash resistivity characteristics, (2) Control SO3 emissions through condensation on the fly ash, and (3) Avoid the need to install wet stacks or to provide flue gas reheat. Finally, operation at cooler flue gas temperatures offered the potential benefit of increasing mercury (Hg) removal across the ESP and FGD systems. This project planned to conduct pilot-scale tests of regenerative heat exchange to determine the reduction in FGD water consumption that can be achieved and assess the resulting impact on APC systems. An analysis of the improvement in the performance of the APC systems and the resulting reduction in capital and operating costs were going to be conducted. The tests were intended to determine the impact of operation of cooling flue gas temperatures on FGD water consumption, ESP particulate removal, SO{sub 3} removal, and Hg removal, and to assess the potential negative impact of excessive corrosion rates in the regenerative heat exchanger. Testing was going to be conducted on Columbian coal (with properties similar to low-sulfur Eastern bituminous coal) and SO{sub 3} will be spiked onto the flue gas to simulate operation with higher SO{sub 3} concentrations resulting from firing a higher sulfur coal, or operating with a selective catalytic reduction (SCR) unit. The project was also going to include associate planning, laboratory analytical support, reporting, and management activities. The URS project team finalized a conceptual alternative approach to demonstrate, via an engineering study, the use of regenerative heat exchange to reduce flue gas temperature and minimize evaporative water consumption. This idea was presented in summary format to NETL for consideration. NETL determined that this alternative approach deviated from the original project objectives, and that it would be in the best interest of all parties involved to cancel the project.« less

The subject matter of the article is an air pollution control process. The aim is development of proposals for the synthesis of the air pollution control system based on hyperconvergent infrastructures. The objectives are: the development of a mathematical model for constructing pollutants concentration fields; substantiation and development of a conceptual model of the geoinformation system for air pollution control, justification and selection of the basic infrastructure of the control system. The methods used are: system analysis of risks, cause-and-effect analysis, statistical methods. The following results are obtained: The basic influencing on character of dispersion and distribution of harmful substances factors in atmosphere are allocated. A multifactorial mathematical model has been developed for constructing fields of concentration of pollutants, which is based on two types of distribution-the normal and S L -distribution of Johnson. The geoinformation technology (GIT) structure components are determined. A program for determining the stability class of the atmosphere has been developed. A model of the process under investigation on a cartographic basis was developed with the presentation of the results in the form of a concentration isotype. The structure of the database of the parameters of sources and characteristics of sources of air pollution, which is part of the serving hyperconvergent infrastructure, has been developed. Conclusion . The synthesized air pollution control system will allow to solve such tasks: collection of primary information, its systematization, analysis and formation of a data bank; processing and presentation of data in the form of thematic pollution maps; Assessment of the current state of the environment and forecast; analysis of the causes of observed and probable changes in the state; prompt provision of necessary information to all stakeholders.

Continuous determination of hydrogen peroxide formed in advanced oxidation and electrochemical processes

The Miami-Dade 3,000 tpd Refused-Derived Fuel (RDF) facility is located in Miami-Dade County, FL and is operated by Montenay Power, a Veolia Environmental Services Company. A team composed of plant staff and outside experts underwent a thorough equipment-by-equipment review of the Air Pollution Control (APC) system and identified a series of low cost design and operational improvements to the lime slakers, the spray dryers and the baghouses. These improvements were implemented over the course of several months and resulted in a drop in lime consumption, in the economy of one and a half air compressor units, and in reduced APC related plant downtime and maintenance costs. This paper describes several key improvement projects (including the upgrade of the spray nozzles, the change in slaking water quality and the fly ash fluidization project), detailing the initial problem, the chosen solution, the difficulties encountered during implementation and the achieved benefits.

The task force has comprehensively reviewed efforts for air pollution prevention and control, the acute health effects of fine particles (PM2.5), and the health benefits of air pollution prevention and control in China. It has been found that the overall prevention and control of ambient PM2.5 pollution in China has made remarkable progress in recent years. However, it still remains at a relatively high level. Short-term exposure to ambient PM2.5 significantly increases the mortality and morbidity risk of Chinese residents, resulting in changes to levels of relevant biological markers. Prolonged PM2.5 heavily polluted weather greatly increases the risk of cardiovascular disease morbidity and mortality. Among chemical composition of PM2.5, carbon-containing components, some inorganic salts, and heavy metals are linked with the health impacts. The health risks of PM2.5 pollution are higher for children, the elderly, and patients with cardiovascular or respiratory diseases than for the general population because the former groups are vulnerable subpopulations. The implementation of air pollution prevention and control policies has significantly improved human health. The implementation of personal protective equipment can significantly reduce the health damage caused by short-term exposure to ambient PM2.5 pollution. Based on scientific evidence of PM2.5 pollution and acute health risks in China, the following three recommendations are proposed. 1) The policy recommendations for the prevention and control of ambient PM2.5 pollution include the following: to continuously strengthen the widespread use and efficient development of clean energy; to further promote industrial upgrading; to focus on the control of transportation pollution; to keep improving the modernization system of air pollution control; to formulate and refine relevant standards for air quality gradually; and to estimate the effects and health benefits after the implementation of clean air actions, and relevant policies. 2) Prevention of ambient PM2.5 pollution and protection of public health recommendations include the following: to strengthen the release of air pollution monitoring and relevant information; to strengthen awareness of air pollution hazards; to clarify the guidance and recommendations for protecting population health from air pollution; and to strengthen the health protection of population vulnerable to ambient air pollution. 3) Recommendations for research on health risks of air pollution include the following: to strengthen research on air pollutant monitoring technology and monitoring system based on the promotion of accurate exposure assessment; to systematically carry out full-spectrum identification and correlation studies of air pollutants and health effects; to conduct studies on key toxic components and early biomarker inventory of air pollution health effects; to discover the toxicity mechanisms of the key toxic components of air pollutants; to carry out research on population health risk assessment and early warning of combined exposure to air pollutants; and to execute comprehensive studies on the health and economic benefits of pollution and carbon reduction under the national strategies of carbon neutrality and beautiful China.

With the increasing severity of global water pollution, traditional wastewater treatment methods have gradually revealed limitations in dealing with complex and refractory pollutants. Advanced oxidation processes (AOPs) have emerged as a promising alternative due to their ability to generate highly reactive radicals (such as hydroxyl and sulfate radicals) that can effectively degrade a wide range of pollutants. This review provides a detailed overview of various AOP technologies, including Fenton processes, ozone-based AOPs, persulfate-based AOPs, photocatalytic AOPs, electrochemical AOPs, and sonochemical AOPs, focusing on their fundamental principles, reaction mechanisms, catalyst design, and application performance in treating different types of wastewater. The research results show that the improved Fenton process can achieve a chemical oxygen demand (COD) removal rate of up to 85% when treating pharmaceutical wastewater. Photocatalytic AOP technology demonstrates higher degradation efficiency when treating industrial wastewater containing refractory pollutants. In addition to effectively degrading refractory pollutants and reducing dependence on traditional biological treatment methods, these advanced oxidation processes can also significantly reduce secondary pollution generated during the treatment process. Moreover, by optimizing AOP technologies, the deep mineralization of harmful substances in wastewater can be achieved, reducing the potential pollution risks to groundwater and soil while also lowering energy consumption during the treatment process. Additionally, this review discusses the challenges faced by AOPs in practical applications, such as high energy consumption, insufficient catalyst stability, and secondary pollution. This review summarizes the research progress and application trends of catalytically driven AOPs in the field of wastewater treatment over the past five years. It aims to provide a comprehensive reference for researchers and engineering professionals on the application of AOPs in wastewater treatment, promoting the further development and practical implementation of these technologies.

Comparison of the new Cl2/O3/UV process with different ozone- and UV-based AOPs for wastewater treatment at pilot scale: Removal of pharmaceuticals and changes in fluorescing organic matter

The principal sources of chlorine in the MSW feed to WTE power plants are food wastes (e.g., wheat, green vegetables, melon, pineapple), yard wastes (leaves, grass, etc.), salt (NaCl), and chlorinated plastics (mostly polyvinyl chloride). Chlorine has important impacts on the WTE operation in terms of higher corrosion rate than in coal-fired power plants, formation of hydrochloric gas that must be controlled in the stack gas to less than the U.S. EPA standard (29 ppm by volume), and potential for formation of dioxins and furans. Past Columbia studies have shown that the chlorine content in MSW is in the order of 0.5%. In comparison, chlorine concentration in coal is about 0.1%; this results in much lower HCl concentration in the combustion gases and allows coal-fired power plants to be operated at higher superheater tube temperatures and thus higher thermal efficiencies. Most of the chlorine output from a WTE is in the fly ash collected in the fabric filter baghouse of the Air Pollution Control system. This study examined in detail the sources and sinks of chlorine in a WTE unit. It is concluded that on the average MSW contains about 0.5% chlorine, which results in hydrogen chloride concentration in the WTE combustion gases of up to 600 parts per million by volume. About 45% of the chlorine content in MSW derives from chlorinated plastics, mainly polyvinyl chloride (PVC), and 55% from salt (NaCl) and chlorine-containing food and yard wastes. An estimated 97–98% of the chlorine input is converted to calcium chloride in the dry scrubber of the Air Pollution Control (APC) system and captured in the fly ash collected in the baghouse; the remainder is in the stack gas at a concentration that is one half of the U.S. EPA standard. Reducing the input of PVC in the MSW stream would have no effect on dioxin formation but would reduce the corrosion rate in the WTE boiler.

Wastes from dry air pollution control (APC) systems may not be less problematic to transport and landfill than wastes from wet APC Units, particularly the thixotropic flue gas desulfurization (FGD) sludge. FGD sludge can be converted to a soil-like, disposable material by forced oxidation, fly ash blending, or lime fixation. Dry APC wastes require dust-suppression. Dry APC wastes contain 15-23.7 weight percent of Ca(OH)/sub 2/ and CaCO/sub 3/ as compared to 3.6 mole % of CaCO/sub 3/ for wet material. Higher reagent stoichiometries have been reported for dry APC (1.3-1.5), as compared to wet systems (1.05); thus contributing greater dry waste generation rates. For a 1% sulfur, 10% ash, 10,000 Btu/lb coal, 0.14 ton of dry waste is generated per ton of coal. Oxidized FGD sludge yields 0.036 ton waste/ton coal while blended and fixated wastes contribute 0.113 and 0.12 ton of waste per ton of coal, respectively. Dry APC waste exhibited compacted density of 40 lb/CF; wet wastes reflect densities ranging from 80-90 lb/CF; (oxidized), 75-90 lb/CF (blended), and 95-105 lb/CF (fixated). Higher waste rates and lower compacted densities require more area for dry APC waste disposal than for wet.

A two-year comprehensive advanced oxidation processes (AOPs) pilot test was completed for a Singapore waterworks in 2011–2013. This study focused on oxidative removal of spiked organic contaminants with ozone and ozone-based AOPs (ozone application together with hydrogen peroxide, which is necessary for AOPs). The ‘optimized H2O2 dosage’ test philosophy was verified during the test period – keeping the residual ozone at 0.3 mg/L in the water for disinfection purpose by minimizing the H2O2 dosage. This study also monitored the bromate concentration in both ozone- and AOP-treated water, and all the samples reported below the laboratory detection limit (&amp;lt;5 µg/L), which is also lower than the WHO Guidelines for Drinking Water Quality (&amp;lt;10 µg/L). For comparison, a low pressure UV-based AOP test was conducted in the final stage of the study. The electrical energy per order (EEO) value is compared with ozone- and UV-based AOPs as well. The results indicated that ozone-based AOP with an optimized hydrogen peroxide dosage could be the most energy efficient option for this specific water matrix in terms of most selected compounds.

Air pollution control systems in WtE units: An overview