Filter Fly Ash Research Articles

Effect of pore characteristics on permeability of sintered diatomite filter for microfiltration

Diatomite, because it is inherently porous and irregular, presents an interesting opportunity to investigate how the processing conditions of green bodies and the incorporation of spherical pores affect the final properties of a sintered ceramic filter. The water flux of a diatomite filter sintered at 1200°C was 6·3×104 L m−2 h−1 bar−1, which is higher than the water fluxes of typical ceramic filters such as spherical fly ash (1·6×104 L m−2 h−1 bar−1), γ-alumina (∼1·0×103 L m−2 h−1 bar−1) and zirconia (1·6×103 L m−2 h−1 bar−1) filters. The results obtained in this study show that the pressure applied during the processing of green bodies and the incorporation of spherical pores directly affect pore characteristics and accordingly determine the permeability of the sintered diatomite filters.

Treatment of wood leachate with high polyphenols content by peat and carbon-containing fly ash filters

In the present study, two combinations of filter materials in filter/columns were examined for removal of total organic carbon (TOC) and polyphenols (PP) found in storm water runoff from wood storage areas in a wooden floor industry. One filter/column was packed with peat mixed with carbon-containing fly ash, while another filter/column contained only peat (without ash). The mixture of peat and ash has shown faster and higher removal capacity for TOC and faster removal with the same final removal capacity for PP (in grams of pollutant per kg of sorbent) at the saturation point. The superiority observed for the peat and ash filter is presumably due to the unique characteristics of peat and ash, which enhanced the treatment efficiency when used together in a mixture. Based on the observed results, filters formed by peat and carbon-containing ashes proved to be a potentially low-cost option for the treatment of storm water generated at storage areas of wood materials such as logs, sawdust and wood chips.

Performance and Hydration of Blended Cements with Fly Ash and Sugar Filter Mud

Thermal insulation material with flexural strength 0.597 MPa, compressive strength 1.1111 MPa and porosity 46.71% shows that its density of the materials decreases down to 0.5466 g/cm3 using sugar filter mud as raw material. The closed porosity and dense structure of sample has been observed by photograph and the main crystalline phases of the sample using XRD techniques are tricalcium silicate and ettringite. These mineral reacting with water will occur the hydration reaction and is contribute to improve the strength of the body.

Study on Emission Control of Dioxins by Thermal Decomposition

In this paper, we present the data regarding the thermal decomposition of PCDD/Fs during the manufacturing process of ceramisite from MSWI fly ash, and the efficiency of bag filter with activated carbon injection technology to reduce the gas emission of PCDD/Fs. The distribution of seventeen 2,3,7,8-chlorinated dioxins and furans in MSWI fly ash, ceramisite product, bag filter ash and emission gases were analyzed, and the international toxic equivalents (I-TEQ as 2,3,7,8-tetraCDD) values were calculated by using international-toxicity equivalency factor (I-TEF). The total I-TEQ value of PCDD/Fs in MSWI fly ash reached up to 904.944 ng/kg. After high temperature calcining, only 1.250 ng I-TEQ/kg of PCDD/Fs is left in the ceramisite product. The concentrations of PCDD/Fs in two kinds of bag filter ashes, with activated carbon injection (AC) and without activated carbon injection (NAC), were 324.723 ng I-TEQ/kg and 217.066 ng I-TEQ/kg, respectively. The distribution patterns of seventeen 2,3,7,8-chlorinated dioxins and furans in MSWI fly ash, ceramisite product and bag filter ashes are alike, which suggested that the secondary formation of PCDD/Fs did not significantly occur during the thermal process of manufacturing ceramisite from MSWI fly ash. When no activated carbon was injected, the gas emission of PCDD/Fs was 0.373 ng I-TEQ/Nm3, but 100 mg/Nm3 of activated carbon injection, the gas emission of PCDD/Fs was declined to 0.081 ng I-TEQ/Nm3, which is lower than the gas emission limit established by the European Union Directive of 0.1 ng I-TEQ/Nm3. Therefor, we can recommend that the manufacturing ceramisite from MSWI fly ash using the developed rotary kiln system is an effective measure to safely dispose the MSWI fly ash on the aspect of dioxin emission control.

Lightweight Artificial Aggregate Based on Fly Ash for New Rehabilitation Materials

During rehabilitation work are often strict requirements on the use of high quality lightweight materials, including aggregate. Due the constantly increasing social pressure on the optimal use of secondary raw materials is therefore most appropriate to exploit the potential of fly ash as mineral residue from the combustion of ground coal in power plants. Especially filter fly ash has proven to be an adequate substitute for traditional materials in the past. This article deals with the evaluation of physical and mechanical properties of cold-consolidated pellets based on conventional and fluidized fly ash with various cement addition.

Impact of Variable Hydraulic Conductivity on Bioretention Cell Performance and Implications for Construction Standards

Bioretention cells have become an accepted technology for storm-water management due to their potential benefits in runoff volume reduction and water quality improvement. Over the years, a considerable amount of research has been done to improve performance, whether by improved functionality or by introducing engineered filter media to target specific contaminants. The design for a full-scale demonstration project carried out in Oklahoma incorporated a sand and fly ash filter for enhanced phosphorus adsorption and surface sand plugs for improved infiltration. Samples taken from the filter media during construction exhibited heterogeneity in fly ash content, and therefore, hydraulic conductivity due to the pozzolanic property of fly ash. Maximizing contaminant attenuation will require achieving uniform flow through the cell to ensure use of the entire filter volume. Thus, it is important to understand how the small-scale filter heterogeneity and the large-scale sand plugs impact performance of this design. To do this, a three-dimensional finite element model was developed in a software tool to simulate saturated flow through a bioretention cell. Three general configurations were modeled for three different scenarios. A filter-only configuration was evaluated to assess the effect of filter media hydraulic conductivity heterogeneity on flow through the cell. The second configuration added a top soil and sand plug layer with six sand plugs measuring 1.5 m by 1.5 m, which was similar to the constructed cells. The final configuration evaluated a top soil and sand plug layer with 14 smaller sand plugs only 1 m by 1 m. Three different scenarios were evaluated for each configuration that varied by size and distribution of the filter media heterogeneity. The first scenario used the measured scale and range variability, while the second used the same scale with double the variation, and the third used the same variability, but increased the scale volume by a factor of 27. Model results indicate that variability in fly ash content creates complex flow through the filter medium, but does not result in significant preferential flow. Sand plugs create some flow concentration but do not dominate flow within the cell, and the number of sand plugs is not significant provided that their total area is appropriate to maintain the desired drainage rate.

Speciation of Trace and Major Elements from Coal Combustion Products of Serbian Power Plants (II)—Obilic Power Plant

Six composite filter fly, bottom, and dump ash samples, each taken from Obilic power plant, were subjected to the sequential extraction procedure comprised of five phases. Iron silicates, alumosilicates not containing iron and silicates not containing iron nor aluminum, as well as a form of aluminum not containing silicon, are established as substrates dissolved in the fifth phase of extraction. Alumosilicates and mixed oxides of iron and manganese are dissolved in the third phase of extraction. Association patterns and distribution of trace and major elements with substrates as well as environmental consequences of such distribution were established and discussed.

English

The removal of Cr(VI) from aqueous solution by batch adsorption experiments using fly ash (FA) and composite filter material made of fly ash (FACFM) as adsorbents were investigated. The influence of pH, contact time on the selectivity and sensitivity of the removal process were investigated. The effect factors such as adsorbent dosage level, initial Cr(VI) concentration and temperature were studied throughorthogonal experiment to investigate their degree of influence on the Cr(VI) adsorption process. Results show that FA and FACFM can be considered as efficient sorbents for the removal of Cr(VI) from aqueous solutions. It was also shown that increase in the adsorbent dosage level led to increase in Cr(VI) adsorption due to the increased number of adsorption sites, the adsorption process was highly pH dependent and the optimum pH was less than 3. Both adsorption rate and the removal ratio of FA were larger than that of FACFM because of its larger contact area and its powdery form, but concerning the intensity and ease of separation from aqueous solution, FACFM was more practical and can be used for wastewater treatment. Key words: Cr (VI), fly ash (FA), fly ash composite filter material (FACFM), adsorption, orthogonal experiment.

Speciation of Trace and Major Elements from Coal Combustion Products of Serbian Power Plants (I)—“Kostolac A” Power Plant

In order to examine association patterns and pollution potential of trace and major elements from coal ash, six composite samples of fresh, filter fly, and aged dump coal ash from “Kostolac A” power plant located 100 km from Belgrade, the Serbian capital, were subjected to the sequential extraction procedure. Five extractants were applied (in the following order): distilled water, 1 M ammonium acetate, 0.2 M ammonium oxalate/0.2 M oxalic acid, an acidic solution of H2O2, and 6 M HCl. Obtained concentrations were statistically analyzed and associations of trace and major elements were established.

Characterization of fly ash from a hazardous waste incinerator in Medellin, Colombia

Bag filter (BF) fly ash from a hazardous waste incinerator located in Medellín, Colombia was characterized. Particle size distribution, chemical composition, metal loading, surface area, morphology, and chemical environment were assessed before and after fly ash extraction with toluene. Fly ash consists of low surface area platelets of SiO 2 smaller than 0.5 μm agglomerated in spheres between 20 and 100 μm. High concentration of sodium chloride, carbon, and heavy metals such as Cu, Fe, Pb, Hg, Cd, Co and Mn are deposited over the fly ash surface. The carbon is oxidized and forms different structures such as amorphous carbon black, nano balls and more crystalline fullerenes like nano onions. The high concentration of dioxins, furans and dioxin-like PCBs (superior to 185 ng WHO-TEQ/g) is favored by oxidized carbon, chlorine and metals such as Cu and Fe on the shell of the particles. Before and after toluene extraction, fly ash samples presented similar morphology. However, after extraction their particle size increased while their surface area decreased by 35% and the carbon and metal contents decreased by 35% and 50%, respectively.

Trapping behavior of gaseous cesium by fly ash filters

The high volatility of a gaseous form and its high chemical reactivity make a cesium emission control very difficult work. In this study, fly ash filters were tested for the removal of gaseous cesium from a hot flue gas under air and hydrogen conditions at 700–1000 °C. Tests were performed by using a simulated gaseous cesium volatilized from Cs 2SiO 3 in a two-zone furnace. Fly ash filter was found to be the most promising filter for trapping the gaseous cesium. The results of the trapping tests are presented, along with the effects of the temperature, superficial gas velocity, and carrier gas on the cesium trapping quantity.

Submerged membrane bioreactor using fly ash filters: trials with distillery wastewater

This work presents preliminary results for distillery wastewater treatment in a MBR equipped with filters prepared from waste fly ash. The system was fabricated locally and employed submerged membranes in the 2-8 microm pore-size range. Distillery wastewater, after anaerobic digestion, was used as the feed and the bioreactor was inoculated with sludge obtained from a local distillery unit. The MBR was operated for around 250 days. The wastewater quality was monitored in terms of COD (chemical oxygen demand), colour, phenol, and MLSS (mixed liquor suspended solids) concentration. An average COD and phenol removal of 36% and 60% respectively was obtained. The maximum suspended solids retention by the ash filter was as high as 98%. The results were encouraging and further trials are currently underway to improve the performance.

A New Approach to Minimize Pyroprocessing Waste Salts Through a Series of Fission Product Removal Process

In this work, a new approach to remove fission products including decay heat elements was proposed. This study aims at providing a new way to minimize the amount of waste salt for a repository, while removing the high decay heat fission products [Cs, Sr, Ba, and Y including other rare earth (RE) elements] from the waste salts generated during a chloride pyroprocessing procedure. These elements were removed in consecutive order from the pyroprocessing units. First, Cs could be released in the form of an oxide gas during voloxidation of UO2 and captured by a fly-ash filter. Then, Sr was recovered in the form of carbonate precipitates from the LiCl waste salt generated during the course of an electoreduction process, by using Li2CO3. Finally, RE elements plus yttrium in the spent LiCl-KCl waste salt generated during electrorefining were removed in the form of oxides (or oxychlorides) by using an oxygen sparging method. It was confirmed that the removal yields of each element were ~90% for Cs at ~1473 K, >99% for Sr at a molar ratio of [Li2CO3/SrCl2 = 3], and >99% for the RE elements plus yttrium. Using these successes as a basis, a reference flow sheet for removing the high decay heat elements from pyroprocessing units is presented in this work. Also, a salt regeneration system to minimize the amount of waste salt is proposed in this study.

산업폐기물 소각시설에서 폐기물 유형에 따른 입자상물질의 배출특성

The emissions characteristics of particulate matters(PM) according to the types of wastes from industrial waste incinerator of 800 kg/hr treatment capacity were investigated. For this study, the incinerate waste are as follows; waste resin, waste wood, waste urethane, waste gunny, and waste paper. The particulate samples were collected to be emitted in stack and air pollution control(both cyclone and bag filter). In stack, the concentrations of PM were in the range of 2.61 to <TEX>$26.51 mg/Sm^3$</TEX> and the major chemical species were C, Si, Cl, K, Na, Ca in all the wastes. In cyclone fly ash, the mean content of heavy metal were in the order of Fe > Zn > Pb > Cu > Mn > Cr > Ni > Cd > As > Hg and the heavy metal content of waste resin were Zn 34,197.5 mg/kg, Fe 27,587.6 mg/kg, Pb 6,055.8 mg/kg, respectively. In bag filter fly ash, the mean content of heavy metal were in the order of Zn > Pb > Fe > Cu > Mn > Cd > Cr > Ni > As > Hg and the heavy metal content of waste wood were Pb 36,405.2 mg/kg, Fe 15,762.9 mg/kg, Cu 9,989.5 mg/kg, Cd 2,230.1 mg/kg, respectively. Comparing the heavy metal content of both cyclone and bag filter, in cyclone, the Cr, Fe, Ni content were higher than in bag filter and the Cd, Cu, Hg content were lower than in bag filter.

Assessment of surface and depth filters by filter quality

This paper reviews the concept of filter quality ( q F) for dust filtration media composed of different structures: metal fiber beds (MFB), fabric filters (BF), and fly ash filters (FAF). Filter quality is a useful index of the filtration performance, which incorporates both pressure drop and filtration efficiency. Major parameters affecting the filter quality are filtration velocity in the range of 0.06–0.19 m/s, dust loading, porosity of the medium in the range of 75–93%, and internal structure of the medium. The experimental observation showed that filter quality decreased with increasing filtration velocity or dust concentration. A unique increase in filter quality during the initial stage of filtration appeared with the FAF as a result of the predominately surface filtration with less pore clogging. Nevertheless, the filter quality cannot be taken as an absolute indicator of filter performance, but rather it should be used just as a reference parameter depending on operating conditions. The results of this work show that fly ash filters are capable of providing more stable performance, particularly during the initial stage of filtration, and thereafter of a certain time filter quality initiates to decline as other filters.

Fate of mercury and chlorine during SRF co-combustion

Abstract Within the scope of the European Demonstration project RECOFUEL the behaviour and fate of chlorine and mercury during co-combustion of Solid Recovered Fuel (SRF) was investigated in detail, focusing on the environmental compatibility, and based on a lab-scale approach. In this context the term co-combustion describes the thermal utilisation of pre-treated waste-derived fuels such as SRF in industrial furnaces or power plants as a supplemental fuel. Following the definitions of the European initiative on SRF standardisation CEN/TC 343, these kind of fuels have to be produced from non-hazardous bio-residues, mixed- and mono waste streams. It is one of the key aspects of the production process to reduce the content of waste-borne pollutants such as chlorine or heavy metals. Nonetheless, the efficiency of the production process is limited and the residual pollutant concentrations may exceed those of coal to a certain extent. The experiments, focusing both on chlorine and mercury, indicated that the co-combustion process increases the flue gas concentration of gaseous chlorine species, primarily hydrogen chloride, as a result of waste-borne chlorine. Furthermore, significant differences were observed for ash-bound chlorine, which cannot be explained with the increased chlorine concentration in the gas phase alone. Considering the trace element mercury, increased chlorine inputs did not necessarily lead to increased ionic mercury shares. Furthermore, no or only insignificant amounts of gaseous elemental mercury Hg0(g) could be determined downstream the fly ash filter system, while residual HgCl2(g) concentrations do not differ significantly.

Characterization of PCDD/Fs and heavy metals from MSW incineration plant in Harbin

The characterization of PCDD/Fs and heavy metals in the flue gas and fly ash of Harbin municipal solid waste (MSW) incineration plant, located in the northeast of China, was investigated in this study. The MSW was treated in a twin internal fluidized (TIF) bed incinerator. The results indicate that the emission of PCDD/Fs into the environment is 0.02 ng I-TEQ/m 3 and the level of PCDD/Fs in the fabric filter fly ash is 0.7982 ng I-TEQ/g. The leachability levels of Pb, Cd and Hg in the fly ash are below the limits of environmental protection standard in China. However, the contents of Cu, Zn, and Hg are high in the fly ash. This suggests that the fly ash is a hazardous waste that requires special treatment and disposal. The practice of more than four years of operation shows that the TIF bed incinerator is very suitable and practical for China.

Radioactivity of coal and ashes from Figueira coal power plant in Brazil

The Figueira coal-fired power plant (CFPP) is among the Brazilian CFPP which presents higher uranium concentration. Gamma-ray spectrometry was used to determine 238U, 226Ra, 210Pb, 232 Th and 40K contents in pulverized coal, furnace bottom ash and fly ash samples. The natural radionuclide concentrations in pulverized coal ranged from 813 to 2609 Bq . kg-1 for U series and from 22 to 40 Bq . kg-1 for 232 Th. The fly ash fraction gave concentrations ranging from 1442 to 14641 Bq . kg-1, for uranium series. The same enrichment factor was observed for 238U, 226Ra and 232 Th. Only 210Pb and stable Pb presented a high enrichment factor for the last stage filter fly ash. The concentration of the uranium series found in the ashes is close to the limit adopted by the Brazilian guideline (CNEN-NN-4.01).22 Therefore, it is advisable to evaluate the environmental impact of the installation.

Remediação de drenagem ácida de mina usando zeólitas sintetizadas a partir de cinzas leves de carvão

Zeolitic material was synthesized from coal fly ashes (baghouse filter fly ash and cyclone filter fly ash) by hydrothermal alkaline activation. The potential application of the zeolitic product for decontamination of waters from acid mine drainage was evaluated. The results showed that a dose of 30 g L-1 of zeolitic material allowed the water to reach acceptable quality levels after treatment. Both precipitation and cation-exchange processes accounted for the reduction in the pollutant concentration in the treated waters.

Emissions of Polycyclic Aromatic Hydrocarbons from Batch Hot Mix Asphalt Plants

This study was set out to assess the characteristics of polycyclic aromatic hydrocarbon (PAH) emissions from batch hot mix asphalt (HMA) plants and PAH removal efficiencies associated with their installed air pollution control devices. Field samplings were conducted on six randomly selected batch HMA plants. For each selected plant, stack flue gas samples were collected from both stacks of the batch mixer (n = 5) and the preheating boiler (n = 5), respectively. PAH samples were also collected from the field to assess PAHs that were directly emitted from the discharging chute (n = 3). To assess PAH removal efficiencies of the installed air pollution control devices, PAH contents in both cyclone fly ash (n=3) and bag filter fly ash (n = 3) were analyzed. Results show that the total PAH concentration (mean; RSD) in the stack flue gas of the batch mixer (354 microg/Nm3; 78.5%) was higher than that emitted from the discharging chute (107 microg/Nm3; 70.1%) and that in the stack flue gas of the preheating boiler (83.7 microg/Nm3; 77.6%). But the total BaPeq concentration of that emitted from the discharging chute (0.950 microg/Nm3; 84.4%) was higher than contained in the stack flue gas of the batch mixer (0.629 microg/Nm3; 86.8%) and the stack flue gas of the preheating boiler (= 0.112 microg/Nm3; 80.3%). The mean total PAH emission factor for all selected batch mix plants (= 139 mg/ton x product) was much higher than that reported by U.S. EPA for the drum mix asphalt plant (range = 11.8-79.0 mg/ton x product). We found the overall removal efficiency of the installed air pollution control devices (i.e., cyclone + bag filter) on total PAHs and total BaPeq were 22.1% and 93.7%, respectively. This implies that the installed air pollution control devices, although they have a very limited effect on the removal of total PAHs, do significantly reduce the carcinogenic potencies associated with PAH emissions from batch HMA plants.