Mercury Control Research Articles

Characteristics of a biomass-based sorbent trap and its application to coal-fired flue gas mercury emission monitoring

A novel sorbent trap based on rice husk char (RHC) was developed. Scanning electron microscopy and Brunauer–Emmett–Teller analysis revealed that the raw RHC possesses a developed pore structure and has potential for mercury adsorption after brominated impregnation (RHC-HBr). The performance of both the raw and impregnated sorbents for Hg capture was investigated in a fixed bed system and compared with the performance of commercial activated carbon (AC). RHC-HBr showed a remarkable Hg adsorption capacity (57.84μg/g) comparable with commercial AC. The RHC-HBr sorbent passed the analytical bias test for mercury detection when spiked by Hg0 and HgCl2 under both the lower and upper concentration levels. Field verification test of the biomass-based sorbent traps was performed in a 6 kWth fluidized-bed combustion (FBC) system. The Ontario Hydra Method (OHM) was applied as the reference method for evaluating HgT(g) measured by the sorbent traps. The field verification test showed that RHC-HBr sorbent traps perform with almost the same accuracy as AC-based sorbent traps, with 97.5±2.9% field recovery rate, 3.2% breakthrough rate, and 0.6% relative deviation. HgT(g) field sampling based on the biomass-based traps was performed in a utility 660MW coal-fired unit in parallel with the OHM under two different operational loads (100% and 75%). Mercury migration and the removal characteristics of the existing air pollution control devices (APCDs) were evaluated using the biomass-based sorbent traps. The final Hg emissions from the stack were determined to be 0.65 and 1.54μg/Nm3 for 100% and 75% operational loads, respectively, indicating that a high load operation condition could be beneficial for mercury control by existing APCDs.

Study on the Leaching of Mercuric Oxide with Thiosulfate Solutions

Mercury is receiving more concern due to its high mobility and high toxicity to human health and the environment. Restrictive legislations and world-wide efforts have been made on mercury control, especially the release and disposal of mercury-contaminated wastes. This paper describes a novel technology for detoxifying mercury-containing solid wastes with thiosulfate salts. Various parameters which may potentially influence mercury extraction from mercuric oxide with the thiosulfate leaching system—including reagent concentration, solution pH, and temperature—have been examined. The experimental results show that virtually all mercuric oxide can rapidly dissolve into the thiosulfate leaching system under optimized experimental conditions, indicating that thiosulfate is an effective lixivant for recovering mercury from mercury-containing solid waste.

Current and Potential Future Bromide Loads from Coal-Fired Power Plants in the Allegheny River Basin and Their Effects on Downstream Concentrations.

The presence of bromide in rivers does not affect ecosystems or present a human health risk; however, elevated concentrations of bromide in drinking water sources can lead to difficulty meeting drinking water disinfection byproduct (DBP) regulations. Recent attention has focused on oil and gas wastewater and coal-fired power plant wet flue gas desulfurization (FGD) wastewater bromide discharges. Bromide can be added to coal to enhance mercury removal, and increased use of bromide at some power plants is expected. Evaluation of potential increases in bromide concentrations from bromide addition for mercury control is lacking. The present work utilizes bromide monitoring data in the Allegheny River and a mass-balance approach to elucidate bromide contributions from anthropogenic and natural sources under current and future scenarios. For the Allegheny River, the current bromide is associated approximately 49% with oil- and gas-produced water discharges and 33% with coal-fired power plants operating wet FGD, with 18% derived from natural sources during mean flow conditions in August. Median wet FGD bromide loads could increase 3-fold from 610 to 1900 kg/day if all plants implement bromide addition for mercury control. Median bromide concentrations in the lower Allegheny River in August would rise to 410, 200, and 180 μg/L under low-, mean-, and high-flow conditions, respectively, for the bromide-addition scenario.

Evaluating the effectiveness of the Minamata Convention on Mercury: Principles and recommendations for next steps

The Minamata Convention on Mercury is a multilateral environmental agreement that obligates Parties to reduce or control sources of mercury pollution in order to protect human health and the environment. The Convention includes provisions on providing technical assistance and capacity building, particularly for developing countries and countries with economies in transition, to promote its effective implementation. Evaluating the effectiveness of the Convention (as required by Article 22) is a crucial component to ensure that it meets this objective. We describe an approach to measure effectiveness, which includes a suite of short-, medium-, and long-term metrics related to five major mercury control Articles in the Convention, as well as metrics derived from monitoring of mercury in the environment using select bioindicators, including people. The use of existing biotic Hg data will define spatial gradients (e.g., biological mercury hotspots), baselines to develop relevant temporal trends, and an ability to assess risk to taxa and human communities of greatest concern. We also recommend the development of a technical document that describes monitoring options for the Conference of Parties, to provide science-based standardized guidelines for collecting relevant monitoring information, as guided by Article 19.

대형배출원에서의 수은 측정방법 비교 및 배출계수 개발에 관한 연구

Abstract Recently, studies on reducing mercury have been actively conducted worldwide, which include the current status of mercury emissions and mercury control technology. Among the control technology, Sorbent Trap measurement method has been aggressively developed due to its reliability, easiness in measurement and analysis.The purpose of this study is to evaluate the applicability of the new international measurement method; Sorbent Trap. For this, the study compared the Sorbent trap method (US EPA Method 30B) and the Korean Standard Method for Examination of Air(ES 01408.1) to evaluate their reliability, and developed mercury emission factors.As the result, the relative standard deviations(% RSD) of the two methods were 3.5~13.4% at Coal-fired Power Plants(CPP), 4.0~18.4% at Cement Kilns(CK), and 3.0~11.3% at Medical Waste Incinerators(MWI). The emis-sions factors were developed as 14.50kg/ton at CPP, 45.10kg/ton at CK, and 1,290.2kg/ton at MWI. Key words : Mercury measurement, Sorbent trap, % RSD, Emission factor

Development of a Green Technology for Mercury Recycling from Spent Compact Fluorescent Lamps Using Iron Oxides Nanoparticles and Electrochemistry

The widespread use of energy efficient mercury containing lamps and impending regulations on the control of mercury emissions has necessitated the development of green mercury control technologies such as nanosorbent capture and electrolysis regeneration. Herein we describe a two-step green technique to remove and recycle mercury from spent compact fluorescent lamps (CFLs). The first element included the assessment of capture efficiencies of mercury vapor on magnetite (Fe3O4) and maghemite (γ-Fe2O3), naturally abundant and ubiquitous components of atmospheric dust particles. Around 60 μg of mercury vapor can be removed up to 90% by 1.0 g of magnetite nanoparticles, within a time scale of minutes. The second step included the development of an electrochemical system for the mercury recycling and regeneration of used nanoparticles. Under optimized conditions, up to 85% of mercury was recovered as elemental mercury. Postelectrolysis regenerated iron oxide nanoparticles were used in several sorption–electroly...

Mercury mass flow in iron and steel production process and its implications for mercury emission control

The iron and steel production process is one of the predominant anthropogenic sources of atmospheric mercury emissions worldwide. In this study, field tests were conducted to study mercury emission characteristics and mass flows at two iron and steel plants in China. It was found that low-sulfur flue gas from sintering machines could contribute up to 41% of the total atmospheric mercury emissions, and desulfurization devices could remarkably help reduce the emissions. Coal gas burning accounted for 17%–49% of the total mercury emissions, and therefore the mercury control of coal gas burning, specifically for the power plant burning coal gas to generate electricity, was significantly important. The emissions from limestone and dolomite production and electric furnaces can contribute 29.3% and 4.2% of the total mercury emissions from iron and steel production. More attention should be paid to mercury emissions from these two processes. Blast furnace dust accounted for 27%–36% of the total mercury output for the whole iron and steel production process. The recycling of blast furnace dust could greatly increase the atmospheric mercury emissions and should not be conducted. The mercury emission factors for the coke oven, sintering machine and blast furnace were 0.039–0.047gHg/ton steel, and for the electric furnace it was 0.021gHg/ton steel. The predominant emission species was oxidized mercury, accounting for 59%–73% of total mercury emissions to air.

Effect of HBr formation on mercury oxidation via CaBr2 addition to coal during combustion

Adding CaBr2 to coal to enhance elemental mercury (Hg0) oxidation during combustion has been an effective mercury control technology, but the added CaBr2 may increase levels of noxious Br2 or HBr gases in flue gas.

Benefits of mercury controls for the United States.

Mercury pollution poses risks for both human and ecosystem health. As a consequence, controlling mercury pollution has become a policy goal on both global and national scales. We developed an assessment method linking global-scale atmospheric chemical transport modeling to regional-scale economic modeling to consistently evaluate the potential benefits to the United States of global (UN Minamata Convention on Mercury) and domestic [Mercury and Air Toxics Standards (MATS)] policies, framed as economic gains from avoiding mercury-related adverse health endpoints. This method attempts to trace the policies-to-impacts path while taking into account uncertainties and knowledge gaps with policy-appropriate bounding assumptions. We project that cumulative lifetime benefits from the Minamata Convention for individuals affected by 2050 are $339 billion (2005 USD), with a range from $1.4 billion to $575 billion in our sensitivity scenarios. Cumulative economy-wide benefits to the United States, realized by 2050, are $104 billion, with a range from $6 million to $171 billion. Projected Minamata benefits are more than twice those projected from the domestic policy. This relative benefit is robust to several uncertainties and variabilities, with the ratio of benefits (Minamata/MATS) ranging from ≈1.4 to 3. However, we find that for those consuming locally caught freshwater fish from the United States, rather than marine and estuarine fish from the global market, benefits are larger from US than global action, suggesting domestic policies are important for protecting these populations. Per megagram of prevented emissions, our domestic policy scenario results in US benefits about an order of magnitude higher than from our global scenario, further highlighting the importance of domestic action.

Meeting Minamata: Cost-effective compliance options for atmospheric mercury control in Chinese coal-fired power plants

A new international treaty, Minamata Convention, identifies mercury (Hg) as a global threat to human health and seeks to control its releases and emissions. Coal-fired power plants are a major source of mercury pollution worldwide and are expected to be the first key sector to be addressed in China under Minamata Convention. A best available technique (BAT) adoption model was developed in the form of a decision tree and cost-effectiveness for each technological option. Co-benefit control technologies and their enhancement with coal blending/switching and halogen injection (HI) can provide early measures to help China meet the Minamata Convention obligations. We project future energy and policy scenarios to simulate potential national mercury reduction goals for China and estimate costs of the control measures for each scenario. The “Minamata Medium” scenario, equivalent to the goal of the US Mercury and Air Toxics Standards (MATS) rule, requires the application of activated carbon injection (ACI) and HI on 30% and 20% of power plants, respectively. The corresponding total costs would be $2.5 billion, approximately one-fourth the costs in the US. An emission limit of 3µg/m3 in 2030 was identified as a feasible policy option for China to comply with Minamata Convention.

Characterization of the Modes of Occurrence of Mercury and Their Thermal Stability in Coal Gangues

The utilization of coal gangue in a power plant has attracted wide interest in China; however, coal gangue represents a new anthropogenic source of mercury pollution due to its high mercury content. Understanding the modes of occurrence of mercury in coal gangue is crucial for developing the mercury control technology used during coal gangue combustion. In this study, the mercury in four typical coal gangues in China was characterized by a sequential extraction procedure (SEP) coupled with a temperature-programmed decomposition (TPD) method. The method is proved to be an effective approach in studying the modes of occurrence of mercury as well as the thermal stability of coal gangues by distinguishing the characteristic release temperature during the thermal decomposition process. The iron–manganese oxide-bound Hg releases at a temperature range of 200–600 °C, while the carbonate-bound Hg releases at a temperature range of 250–300 °C. The organic-bound Hg, sulfide-bound Hg, and silicate-bound Hg release a...

Mechanisms and roles of fly ash compositions on the adsorption and oxidation of mercury in flue gas from coal combustion

Coal combustion is a predominant anthropogenic source of atmospheric mercury emissions. The oxidation and adsorption on the surface of fly ashes are crucial to mercury control. In this study, we discussed the mercury adsorption/oxidation mechanisms on the surface of fly ashes and different roles of organic and inorganic compositions based on the experimental results of a fixed-bed reactor and temperature programmed decomposition technique (TPDT). The results indicated that the fly ashes played significant roles in mercury oxidation and adsorption. The residual Cl element on the surface of fly ashes after pretreatment at 650°C contributed to the oxidation and adsorption of mercury. The heterogeneous oxidation process in this study has been confirmed to follow an Eley–Rideal mechanism. Unburned carbon (UBC) is important for mercury oxidation and adsorption on fly ashes. O2 promoted mercury adsorption, but not oxidation. The adsorption capacity was greatly increased in a simulated flue gas, and the oxidation rate was 60%. Al2O3, Fe2O3 and TiO2 were capable of adsorbing mercury. Among these compounds, Al2O3 displayed the largest adsorption capacity. Mercury adsorption did not occur on the surface of CaO and MgO. The flue gas compositions exhibited no influences on the adsorption capacity for the above five metallic oxides. No metallic oxides catalyzed the mercury oxidation regardless of the flue gas composition.

SCR atmosphere induced reduction of oxidized mercury over CuO-CeO2/TiO2 catalyst.

CuO-CeO2/TiO2 (CuCeTi) catalyst synthesized by a sol-gel method was employed to investigate mercury conversion under a selective catalytic reduction (SCR) atmosphere (NO, NH3 plus O2). Neither NO nor NH3 individually exhibited an inhibitive effect on elemental mercury (Hg(0)) conversion in the presence of O2. However, Hg(0) conversion over the CuCeTi catalyst was greatly inhibited under SCR atmosphere. Systematic experiments were designed to investigate the inconsistency and explore the in-depth mechanisms. The results show that the copresence of NO and NH3 induced reduction of oxidized mercury (Hg(2+), HgO in this study), which offset the effect of catalytic Hg(0) oxidation, and hence resulted in deactivation of Hg(0) conversion. High NO and NH3 concentrations with a NO/NH3 ratio of 1.0 facilitated Hg(2+) reduction and therefore lowered Hg(0) conversion. Hg(2+) reduction over the CuCeTi catalyst was proposed to follow two possible mechanisms: (1) direct reaction, in which NO and NH3 react directly with HgO to form N2 and Hg(0); (2) indirect reaction, in which the SCR reaction consumed active surface oxygen on the CuCeTi catalyst, and reduced species on the CuCeTi catalyst surface such as Cu2O and Ce2O3 robbed oxygen from adjacent HgO. Different from the conventionally considered mechanisms, that is, competitive adsorption responsible for deactivation of Hg(0) conversion, this study reveals that oxidized mercury can transform into Hg(0) under SCR atmosphere. Such knowledge is of fundamental importance in developing efficient and economical mercury control technologies for coal-fired power plants.

Potentials of whole process control of heavy metals emissions from coal-fired power plants in China

Recently, more and more poisoning accidents associated with toxic heavy metals have been reported throughout China, coal-fired power plants (CFPPs) sector is regarded as one of the most important source categories of anthropogenic atmospheric releases of heavy metals due to tremendous annual coal consumption (about 1785.3 Mt in 2012). In this paper, with the concept of whole process control, the co-benefit or synergistic removal efficiencies of different control measures used in CFPPs of China are evaluated, the combination of coal washing before burning plus post combustion cleaning of selective catalytic reduction (SCR) + electrostatic precipitator/fabric filters (ESP/FFs) + wet flue gas desulfurization (WFGD) configuration is identified to be the best available control technology for heavy metals abatement of CFPPs at present and in the near future. However, the widely application of special mercury control (SMC) technologies in Chinese CFPPs in future is greatly needed. Furthermore, three energy scenarios and three control scenarios were assumed to forecast the future trend of heavy metals emissions. Under the same control scenario, the change of the energy saving and energy structure will give rise to about 24.1% and 24.6% of abatement potential for heavy metals in 2020 and 2030, respectively. Whereas, under the current energy consumption pattern and air pollution control policies, the installation of SCR + SMC + ESP/FFs + WFGD will result in about 21.0–44.1% and 36.3–67.5% of reduction for heavy metals emissions in 2020 and 2030, respectively. Finally, integrated control suggestions are proposed to minimize the final toxic heavy metals discharges.

Economic analysis of atmospheric mercury emission control for coal-fired power plants in China

Coal combustion and mercury pollution are closely linked, and this relationship is particularly relevant in China, the world's largest coal consumer. This paper begins with a summary of recent China-specific studies on mercury removal by air pollution control technologies and then provides an economic analysis of mercury abatement from these emission control technologies at coal-fired power plants in China. This includes a cost-effectiveness analysis at the enterprise and sector level in China using 2010 as a baseline and projecting out to 2020 and 2030. Of the control technologies evaluated, the most cost-effective is a fabric filter installed upstream of the wet flue gas desulfurization system (FF+WFGD). Halogen injection (HI) is also a cost-effective mercury-specific control strategy, although it has not yet reached commercial maturity. The sector-level analysis shows that 193tons of mercury was removed in 2010 in China's coal-fired power sector, with annualized mercury emission control costs of 2.7 billion Chinese Yuan. Under a projected 2030 Emission Control (EC) scenario with stringent mercury limits compared to Business As Usual (BAU) scenario, the increase of selective catalytic reduction systems (SCR) and the use of HI could contribute to 39tons of mercury removal at a cost of 3.8 billion CNY. The economic analysis presented in this paper offers insights on air pollution control technologies and practices for enhancing atmospheric mercury control that can aid decision-making in policy design and private-sector investments.

EFFECT OF ACTIVATION TEMPERATURE AND ZnCl2 CONCENTRATION FOR MERCURY ADSORPTION IN NATURAL GAS BY ACTIVATED COCONUT CARBONS

Elemental mercury from natural gas has increasingly become an environmental concern due to its high volatility and toxicity. Activated carbon adsorption is an effective mercury control method. Mercury content in natural gas should be removed to avoid equipment damage in the gas processing plant or the pipeline transmission system. This research describes the process of mercury removal from natural gas by coconut active carbon impregnated with ZnCl2. Activation temperature and ZnCl2 solution concentration are significant affect the mercury adsorption capacity. Charcoal was prepared from coconut shell and activated at 500, 700 and 900oC in constant fl ow of nitrogen. The effect of activation temperature and ZnCl2 concentration for mercury adsorption on adsorbent show that the adsorption ability of adsorbent is affected by increasing activation temperature up to an optimum temperature of 700oC. Ability of adsorption increases with increasing ZnCl2 concentration and mercury adsorption was optimum at 7% concentration of ZnCl2. The results indicated that the adsorption capacity of mercury in natural gas by activated carbon-impregnated chlor is very signifi cant. The conclusion of this paper is that optimum activation temperature 700oC and 7% ZnCl2 impregnated on adsorbent can improve the mercury adsorption in natural gas.

Impacts of the Minamata convention on mercury emissions and global deposition from coal-fired power generation in Asia.

We explore implications of the United Nations Minamata Convention on Mercury for emissions from Asian coal-fired power generation, and resulting changes to deposition worldwide by 2050. We use engineering analysis, document analysis, and interviews to construct plausible technology scenarios consistent with the Convention. We translate these scenarios into emissions projections for 2050, and use the GEOS-Chem model to calculate global mercury deposition. Where technology requirements in the Convention are flexibly defined, under a global energy and development scenario that relies heavily on coal, we project ∼90 and 150 Mg·y(-1) of avoided power sector emissions for China and India, respectively, in 2050, compared to a scenario in which only current technologies are used. Benefits of this avoided emissions growth are primarily captured regionally, with projected changes in annual average gross deposition over China and India ∼2 and 13 μg·m(-2) lower, respectively, than the current technology case. Stricter, but technologically feasible, mercury control requirements in both countries could lead to a combined additional 170 Mg·y(-1) avoided emissions. Assuming only current technologies but a global transition away from coal avoids 6% and 36% more emissions than this strict technology scenario under heavy coal use for China and India, respectively.

The Mercury Emission of Flue Gas from Cement Kiln Control Technology Research

Mercury emissions from cement plants has attracted the attention of the world, the United States and the European Union and other developed countries have already made strictly limitations of mercury emission from cement plants,China has also been developed to limitation of mercury emission from cement plants. Mercury of cement plants comes mainly from coal and raw materials.,and mercury from flue gas can be removed by removal equipment, so you can use mercury control technology to remove mercury in flue gas. Depending on the different size and raw materials, of the plants, and mercury emissions under different conditions is not the same, so there is no mature mercury removal technology can be applied directly.1 Overview

Atmospheric mercury footprints of nations.

The Minamata Convention was established to protect humans and the natural environment from the adverse effects of mercury emissions. A cogent assessment of mercury emissions is required to help implement the Minamata Convention. Here, we use an environmentally extended multi-regional input-output model to calculate atmospheric mercury footprints of nations based on upstream production (meaning direct emissions from the production activities of a nation), downstream production (meaning both direct and indirect emissions caused by the production activities of a nation), and consumption (meaning both direct and indirect emissions caused by final consumption of goods and services in a nation). Results show that nations function differently within global supply chains. Developed nations usually have larger consumption-based emissions than up- and downstream production-based emissions. India, South Korea, and Taiwan have larger downstream production-based emissions than their upstream production- and consumption-based emissions. Developed nations (e.g., United States, Japan, and Germany) are in part responsible for mercury emissions of developing nations (e.g., China, India, and Indonesia). Our findings indicate that global mercury abatement should focus on multiple stages of global supply chains. We propose three initiatives for global mercury abatement, comprising the establishment of mercury control technologies of upstream producers, productivity improvement of downstream producers, and behavior optimization of final consumers.

Novel Sorbents and their Sorptive Properties for Mercury Emissions Control of Coal-Fired Flue Gas

Mercury is a striking pollutant and mercury emissions from coal-fired power plants are under environmental regulation. The primary objective of mercury abatement in coal-fired power plants is to remove elemental mercury. Sorbent injection is one of the major commercially available technologies for mercury control from coal fired power plants and activated carbon is the most commonly employed sorbent. Modified activated carbons have been found to exhibit high mercury emission reduction efficiency. Noble metal and metal oxides also showed excellent mercury adsorption capacity. Fly ash, a waste product from coal-fired solid wastes, may be an excellent adsorbent owing to its low cost and abundance. There is no consistent evidence for the adsorption mechanism of mercury on modified activated carbon; a popular view is that the sorption mechanism is combination of physisorption and chemisorption.