Biogenic sunflower oil-chitosan decorated fly ash nanocomposite film using white shrimp shell waste: Antibacterial and immunomodulatory potential.

A new sunflower oil-chitosan decorated fly ash (sunflower oil/FA-CSNPs) bionanocomposite film was synthesized using the extract of Litopenaeus vannamei (White shrimp) and evaluated as an antibacterial and immunomodulatory agent. Fly ash-chitosan nanoparticles were produced by using chitosan (CS) isolated from white shrimp extract, glacial acetic acid and sodium tripolyphosphate solution as cross-linkage. The ultrafine polymeric sunflower oil-CS film was fabricated by treating fly ash-chitosan nanoparticles with sunflower oil in glacial acetic acid under continuous stirring for 24 h. The nanostructure of the fabricated polymeric film was confirmed and characterized by different microscopic and spectroscopic approaches. The surface morphology of pre-synthesized bionanocomposite film was found to be homogenous, even and without cracks and pores. The crystallinity of formed bionanocomposite film was noticed at angles (2θ) at 12.65°, 15.21°, 19.04°, 23.26°, 34.82°, and 37.23° in the XRD spectrum. The fabricated film displayed excellent stability up to 380 °C. The formed sunflower oil/FA-CSNPs bionanocomposite film showed promising antibacterial towards Bacillus subtilis with highest zone of inhibition of 34 mm and Pseudomonas aeruginosa with zone of inhibition of 28 nm. The as-synthesized bionanocomposite film exhibited highest cell viability effect (98.95%), followed by FA-CSNPs (83.25%) at 200 µg mL-1 concentrations. The bionanocomposite film exerted notable immunomodulatory effect by promoting phagocytosis and enhancing the production of cytokines (NO, IL-6, IL-1ß, and TNF-α) in macrophage-derived RAW264.7 cell line.

Investigation of mineral commodity residues based on alkalinity, solubility and other physicochemical aspects aiming the management of amazonian acidic soils.

The large amounts of mineral residues generated by the bauxite-alumina industries in the Amazon - with a production scale in the same order of magnitude as their source commodities - have been seen as new sources of raw materials (secondary mines) and/or an inseparable part of a sustainable production system, i.e., a source for the generation of co-products within a circular economy system. In the present study, two alkaline residues from this mining-metallurgical industry were assessed for their potential to amend productive acidic Amazonian soils, namely, (1) insoluble solid residue from the Bayer process (bauxite residue, BR) and (2) ash from energy production from coal (coal combustion residues, CCRs: fly ash, FA, and bottom ash, BA). A physicochemical investigation was performed to evaluate the possible benefits that these residues can offer to the soil‒plant system. The alkalinity of the residues was adjusted "to a value of pH 8-10" by leaching with H3PO4 using a central composite experimental design. The chemical analyses indicated high levels (total and soluble) of essential elements such as Ca and S in the CCRs. All residues showed a high cation exchange capacity (CEC). Regarding the water holding capacity (WHC), FA showed a higher value than the other residues (68.6%). After pH adjustment, available P increased significantly for all residues, and the Ca and S contents remained high for the CCRs, while in BR, there was a decrease in available Na, and aluminum (Al3+) was not available because the potential acidity (H + Al) < 0.6. Finally, complementary analyses showed that with respect to mineralogy, BR is composed mainly of iron oxyhydroxides and aluminosilicate phases, while carbonate, sulfide and silicate phases dominate the CCRs. The neutralizing character, the presence of nutrients in the CCRs and the unavailability of Al3+ in BR are positive physicochemical characteristics for the management of Amazonian acid soils; the use of this residues would add to the circular economy and sustainability of the Amazon.

Application of aluminum oxide nanoparticles in asphalt cement toward non-polluted green environment using linear regression.

In order to decrease the greenhouse gas emissions generated by regular Portland cement (OPC), additional cementitious ingredients have been frequently employed, even while building road bases. OPC's susceptibility to moisture and lack of flexibility make it ineffective for stabilizing road bases. This research used alkali-activated materials (AAM) with fly ash to investigate the mechanical properties of cold asphalt binder (freeze-thaw cycles) including the compressive, flexural strength, workability and porosity of cement. Dry specimens and specimens in distilled water have both been used in the experiments to study these temperature correlations. One sample was tested at 20 °C, and the other was frozen and thawed five times at a temperature of -5 °C (cold region environment). The resulting mixtures' morphologies and microstructures were analyzed via SEM images. During the 7 to 28-day curing period, the mixture's growth ratio rose. The combination registered both the greatest and lowest robust elastic modulus. The total compressive strength of the material decreased as the water-to-cement ratio increased due to the greater amount of free water accessible with a higher cationic asphalt emulsion (CAE) content. The moderate loss of flexural strength with increasing CAE concentration after 7 and 28 days of curing was seen. There is not a major impact on flexural strength in the materials by looking at the very modest gaps in flexural strength between 7 and 28 days curing periods. Due to the particle shape and size of this precursor, FA's inclusion allowed for a lower water to binder rate while maintaining a similar level of workability. The porosity and water absorption values rose with FA substitutions. Further studies might clarify the lower flexural strength observed in this study by adding other hybrids plus fly ash such as lime or nanoparticles.

Effect of alkaline washing treatment on leaching behavior of municipal solid waste incineration bottom ash.

This study aimed to find an effective, inexpensive, and safe washing treatment for municipal solid waste incineration bottom ash (MSWIBA) in order to reduce its potential harmful effects in disposal and recycling. The washing solutions, namely tap water (TW), saturated lime water (SLW), and wastewater from concrete batching plant (WW) were used to wash MSWIBA at different liquid-solid (L/S) ratios and for different durations. Leaching behavior of some heavy metals, chloride, and sulfate from MSWIBA was tested and evaluated. From the TCLP leaching test, when the L/S ratio was above 5, WW was the most effective solution in reducing As, Cd, Se, and Sb emissions from MSWIBA. The calcium and iron ions present in the WW were essential for controlling the leaching of As, Cd, and Sb from MSWIBA due to the formation of stable crystalline pharmacosiderite, cadmium hydroxide sulfate, and hydromeite during the washing process. Using WW showed the best effect in removing sulfate from MSWIBA. At a L/S ratio of 10, about 83% of the sulfate could be removed from MSWIBA after 20 min of washing. The L/S ratio was most influential in removing chloride from MSWIBA. The three washing treatments chosen were effective in reducing the chloride level in MSWIBA to below the level of hazardous waste. Nevertheless, there were still substantial amounts of chloride remaining in the treated MSWIBA. Under the Dutch Building Materials Decree, the treated MSWIBA may be used as a building material in parts which allow isolation, control, and monitoring (ICM).

Transformation of hazardous sacred incense sticks ash waste into less toxic product by sequential approach prior to their disposal into the water bodies.

Incense sticks ash is one of the most unexplored by-products generated at religious places and houses obtained after the combustion of incense sticks. Every year, tonnes of incense sticks ash is produced at religious places in India which are disposed of into the rivers and water bodies. The presence of heavy metals and high content of alkali metals challenges a potential threat to the living organism after the disposal in the river. The leaching of heavy metals and alkali metals may lead to water pollution. Besides this, incense sticks also have a high amount of calcium, silica, alumina, and ferrous along with traces of rutile and other oxides either in crystalline or amorphous phases. The incense sticks ash, heavy metals, and alkali metals can be extracted by water, mineral acids, and alkali. Ferrous can be extracted by magnetic separation, while calcium by HCl, alumina by sulfuric acid treatment, and silica by strong hydroxides like NaOH. The recovery of such elements by using acids and bases will eliminate their toxic heavy metals at the same time recovering major value-added minerals from it. Here, in the present research work, the effect on the elemental composition, morphology, crystallinity, and size of incense sticks ash particles was observed by extracting ferrous, followed by extraction of calcium by HCl and alumina by H2SO4 at 90-95 °C for 90 min. The final residue was treated with 4 M NaOH, in order to extract leachable silica at 90 °C for 90 min along with continuous stirring. The transformation of various minerals phases and microstructures of incense sticks ash (ISA) and other residues during ferrous, extraction, calcium, and alumina and silica extraction was studied using Fourier transform infrared (FTIR), dynamic light scattering (DLS), X-ray fluorescence (XRF), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and inductively coupled plasma-optical emission spectroscopy (ICP-OES). DLS was used for analyzing the size during the experiments while FTIR helped in the confirmation of the formation of new products during the treatments. From the various instrumental analyses, it was found that the toxic metals present in the initial incense sticks ash got eliminated. Besides this, the major alkali metals, i.e., Ca and Mg, got reduced during these successive treatments. Initially, there were mainly irregular shaped, micron-sized particles that were dominant in the incense sticks ash particles. Besides this, there were plenty of carbon particles left unburned during combustion. In the final residue, nanosized flowers shaped along with cuboidal micron-sized particles were dominant. present in If, such sequential techniques will be applied by the industries based on recycling of incense sticks ash, then not only the solid waste pollution will be reduced but also numerous value-added minerals like ferrous, silica, alumina calcium oxides and carbonates can be recovered from such waste. The value-added minerals could act as an economical and sustainable source of adsorbent for wastewater treatment in future.

Coupled microwave hydrothermal dechlorination and geopolymer preparation for the solidification/stabilization of heavy metals and chlorine in municipal solid waste incineration fly ash.

To improve the degradation efficiency of persistent organic pollutants (POPs) in municipal solid waste incineration fly ash (MSWIFA), as well as to overcome the difficulties of subsequent hydrothermal liquid and hydrothermal slag treatment, a two-step treatment strategy of microwave hydrothermal degradation coupled with geopolymer immobilization was proposed. Results showed that the optimal process parameters for microwave hydrothermal dechlorination were a temperature of 220 °C, a time of 1 h, and NaOH addition of 10 wt%. Microwaves accelerated the OH- mediated hydrolysis reactions and promoted the breaking of CCl bonds, leading to dechlorination. The compressive strength of the 20 % MSWIFA-based geopolymers reached 75.79 MPa, and the immobilization rate of the heavy metals (HMs) and Cl- surpassed 90 %. Alkaline environment provided by microwave hydrothermal promoted the formation of Ca(OH)2, which subsequently formed Friedel's salt (3CaO•Al2O3•CaCl2•10H2O) with Cl- in the geopolymer. The charge density difference and density of states (DOS) of Friedel's salt were analyzed by first-principles calculations, confirming that the existence of strong interactions between Ca-s, Al-p, O-p, and Cl-p states was the chemical mechanism of Cl- immobilization. The Friedel's salt and HMs were encapsulated by geopolymers with dense silica-alumina tetrahedral frameworks, achieving the solidification/stabilization (S/S) of HMs and Cl-. This work provided a new approach for the environmentally sound and resourceful treatment of MSWIFA.

Co-incineration effect of sewage sludge and municipal solid waste on the behavior of heavy metals by phosphorus.

The effects of sewage sludge phosphorus (P) content on heavy metal behavior during co-incineration of sewage sludge and municipal solid waste (MSW) were evaluated. Thermogravimetric differential thermal analysis revealed that MSW incineration was mainly caused by organic matter and fixed carbon, while sewage sludge incineration was caused by volatile matter. During co-incineration, the peak weight loss at 460 °C shifted to slightly higher temperatures and the sludge ratio increased, indicating that interaction effects during co-incineration delayed pyrolysis and polymer/fixed carbon incineration. The residual heavy metal ratios after mono-incineration of sewage sludge were higher than those after MSW mono-incineration. The Cl content of MSW (0.757%) was much higher than that of sewage sludge (0.068%), which resulted in the conversion of heavy metals into metal chlorides and then volatilized during MSW mono-incineration. A synergistic effect of co-incineration was evident for Cu, but not for lead (Pb) or cadmium (Cd). X-ray absorption fine structure (XAFS) measurement revealed that Cu in MSW ash was in the form of CuO(s), but was Cu3(PO4)2 in sewage sludge and co-incineration ashes. CuO(s) is relatively unstable and may be transformed to CuO(g) or CuCl(s) before volatilizing at high temperature or in the presence of Cl. Phosphorus has the effect of stabilizing Cu in sewage sludge during co-incineration.

Efficient Activation of Coal Fly Ash for Silica and Alumina Leaches and the Dependence of Pb(II) Removal Capacity on the Crystallization Conditions of Al-MCM-41.

In this study, four different coal fly ashes (CFAs) were used as raw materials of silica and alumina for the preparation of the alumina-containing Mobil Composition of Matter No. 41 (Al-MCM-41) and the exploration of an activation strategy that is efficient and universal for various CFAs. Alkaline hydrothermal and alkaline fusion activations proceeded at different temperatures to determine the best treatment parameters. We controlled the pore structure and surface hydroxyl density of the CFA-derived Al-MCM-41 by changing the crystallization temperature and aging time. The products were characterized by small-angle X-ray diffraction, nitrogen isotherms, Fourier-transform infrared spectroscopy, 29Si silica magic-angle spinning nuclear magnetic resonance, and transmission electron microscopy, and they were then grafted with thiol groups to remove Pb(II) from aqueous solutions. This paper innovatively evaluates the CFA activation strategies using energy consumption analysis and determines the optimal activation methodology and parameters. This paper also unveils the effect of the crystallization condition of Al-MCM-41 on its subsequent Pb(II) removal capacity. The results show that the appropriate selection of crystallization parameters can considerably increase the removal capacity over Pb(II), providing a new path to tackle the ever-increasing concern of aquic heavy-metal pollution.

Migration and emission behavior of arsenic and selenium in a circulating fluidized bed power plant burning arsenic/selenium-enriched coal.

Arsenic (As) and selenium (Se) pollution caused by coal combustion is receiving increasing concerns. The environmental impacts of As/Se are determined not only by stack emission but also by leaching process from combustion byproducts. For a better control of As/Se emission from As/Se-enriched coal combustion, this study investigated the migration and emission behavior of As/Se in a circulating fluidized bed (CFB) power plant equipped with fabric filter (FF) and wet flue gas desulfurization (WFGD) system. The results demonstrated that arsenic was both enriched in bottom ash (41.4-47.6%) and fly ash (52.4-58.6%), while selenium was mainly captured by fly ash (73.9-83.4%). Limestone injection into furnace promoted As/Se retention in ash residues. Arsenic was mainly converted into arsenate in high-temperature regions and partly trapped in bottom ash as arsenite. In contrast, selenium capture mainly occurred in low-temperature flue gas by the formation of selenite, because of the poor thermal stability of most selenite. Triplet-tank method can totally remove arsenic in WFGD wastewater. And 18.4-58.7% of selenium was removed, resulting from the precipitation of Se4+ anions with highly soluble Se6+ anions remaining in wastewater. The concentrations of As and Se in the stack emission were 0.25-1.02 and 0.96-2.24 µg/m3, receptively. The CFB boiler equipped with FF + WFGD was shown to provide good control of the As/Se emission into the atmosphere. Leaching tests suggested that more attention should be paid to As leachability from fly ash/gypsum, and Se leachability from gypsum/sludge.

Treatment of environmental contamination using sepiolite: current approaches and future potential.

To evaluate the potential of sepiolite-based materials to resolve environmental pollution problems, a study is needed which looks at the whole life cycle of material application, including the residual value of material classified as waste from the exploitation of sepiolite deposits in the region or from its processing and purification. This would also maximize value from the exploitation process and provide new potential for local waste management. We review the geographical distribution of sepiolite, its application in the treatment of potentially toxic elements in soil and across the wider landscape, an assessment of modification and compositional variation of sepiolite-based applications within site remediation and wastewater treatment. The potential of sepiolite-based technologies is widespread and a number of processes utilize sepiolite-derived materials. Along with its intrinsic characteristics, both the long-term durability and the cost-effectiveness of the application need to be considered, making it possible to design ready-to-use products with good market acceptance. From a critical analysis of the literature, the most frequently associated terms associated with sepiolite powder are the use of lime and bentonite, while fly ash ranked in the top ten of the most frequently used material with sepiolite. These add improved performance for the inclusion as a soil or wastewater treatment options, alone or applied in combination with other treatment methods. This approach needs an integrated assessment to establish economic viability and environmental performance. Applications are not commonly evaluated from a cost-benefit perspective, in particular in relation to case studies within geographical regions hosting primary sepiolite deposits and wastes that have the potential for beneficial reuse.

Inhibition of polychlorinated dibenzo-p-dioxins and dibenzofurans by phosphorus-containing compounds in model fly ash.

Waste incineration is a preferred method in China to dispose the municipal solid waste, but controlling the production of highly toxic polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans effectively during incineration is both challenging and imperative. In this study, the suppression of PCDD/Fs by various phosphorus-containing compounds was explored, and the mechanisms responsible for the inhibition were studied in detail. The experiments took place in a lab-scale vertical tubular reactor at 350 °C under a simulated flue gas (12 vol% O2 in N2 flow), and both the off-gases and residues were collected for PCDD/Fs analysis. The scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to characterize the reaction residues. The experimental results revealed that NH4H2PO4 and (NH4)2·HPO4 showed the highest inhibitory effect (57.2% and 57.3%, respectively) on the PCDD/Fs formation, followed by CaHPO4 with inhibition efficiency of 39.1%. In contrast, KH2PO4 and K2HPO4 barely inhibited the generation of the PCDD/Fs. The inhibitory effect of NH4H2PO4 and (NH4)2·HPO4 was similar to that of nitrogen-based inhibitors. At the same time, it was proven that the inhibitory activity of CaHPO4 might be due to the reaction of it with Cu2+ forming stable compounds.

Industrial wastes: Fly ash, steel slag and phosphogypsum- potential candidates to mitigate greenhouse gas emissions from paddy fields.

Waste management and global warming are the two challenging issues of the present global scenario. Increased human population has set the platform for rapid industrialization and modern agriculture. The industries such as energy, steel, and fertilizers play a significant role in improving the social, and economic status of human beings. The industrial production of energy (that involves combustion of coal), production of steel items and diammonium ammonium fertilizer generate a huge amount of wastes such as fly ash (FA), steel slag (SS) and phosphogypsum (PG), respectively. Inappropriate dumping of any kind of waste poses a threat to the environment, therefore, scientific management of waste is required to reduce associated environmental risks. These wastes i.e. SS, FA, and PG being rich sources of oxides of calcium (CaO), silicon (SiO2), iron (FeO), and aluminum (Al2O3), etc. may affect the release of greenhouse gases from the soil. The information associated with the application of FA, SS, and PG onto the paddy fields and their impacts on methane and nitrous oxide emissions are highly fragmented and scarce. The present review extensively and critically explores the available information with respect to the effective utilization of FA, SS, and PG in paddy cultivation, their potential to mitigate greenhouse gases emission and their associated mechanisms. The fine grid assessment of these waste management provides new insight into the next level research and future policy options for industries and farmers.

Development and deployment of integrated air pollution control, CO2 capture and product utilization via a high-gravity process: comprehensive performance evaluation.

In this study, a proposed integrated high-gravity technology for air pollution control, CO2 capture, and alkaline waste utilization was comprehensively evaluated from engineering, environmental, and economic perspectives. After high-gravity technology and coal fly ash (CFA) leaching processes were integrated, flue gas air emissions removal (e.g., sulfate dioxide (SO2), nitrogen oxides (NOx), total suspended particulates (TSP)) and CO2 capture were studied. The CFA, which contains calcium oxide and thus, had high alkalinity, was used as an absorbent in removing air pollution residues. To elucidate the availability of technology for pilot-scale high-gravity processes, the engineering performance, environmental impact, and economic cost were simultaneously investigated. The results indicated that the maximal CO2, SO2, NOx, and TSP removal efficiencies of 96.3 ±â€¯2.1%, 99.4 ±â€¯0.3%, 95.9 ±â€¯2.1%, and 83.4 ±â€¯2.6% were respectively achieved. Moreover, a 112 kWh/t-CO2 energy consumption for a high-gravity process was evaluated, with capture capacities of 510 kg CO2 and 0.468 kg NOx per day. In addition, the fresh, water-treated, acid-treated, and carbonated CFA was utilized as supplementary cementitious materials in the blended cement mortar. The workability, durability, and compressive strength of 5% carbonated CFA blended into cement mortar showed superior performance, i.e., 53 MPa ±2.5 MPa at 56 days. Furthermore, a higher engineering performance with a lower environmental impact and lower economic cost could potentially be evaluated to determine the best available operating condition of the high-gravity process for air pollution reduction, CO2 capture, and waste utilization.

Fly ash and zeolite decrease metal uptake but do not improve rice growth in paddy soils contaminated with Cu and Zn.

Fly ash (FA) and zeolite (Z) are known to reduce bioavailability of metals in soils via immobilization; however, these amendments may not only immobilize metals such as copper (Cu) and zinc (Zn), but also reduce nitrogen (N) and phosphorus (P) availability in the soils via sorption (for N by Z) and precipitation (for P by FA). This study was conducted to evaluate the effects of application of FA and Z (0, 5, and 10% rate) on the availability of nutrients as well as metals in the metal-contaminated soils cultivated with paddy rice (Oryza sativa L.). Both FA and Z reduced Cu and Zn uptake by rice while increasing metal retention in the soils regardless of the application rates. However, reduced uptake of metals did not translate into increase in rice growth, especially at the 10% of amendment rates, due to decreased nutrient uptake as indicated by higher NH4+ and available P concentration in the soils amended with Z and FA, respectively, which inhibited tillering in the early rice growth period and thus reduced biomass accumulation at maturity. Our results suggest that FA and Z may reduce Cu and Zn uptake by rice in the soils contaminated with the metals; however, the availability of N and P is likely to be co-decreased. We suggest that the capacities of FA and Z to immobilize nutrients as well as metals need to be considered prior to using the amendments in metal-contaminated rice paddies.

Preparation and characterization of animal bone powder impregnated fly ash catalyst for transesterification.

The present work reconnoitres the feasibility of utilizing class F fly ash and calcined animal bone powder (CABP) as raw material for the synthesis of heterogeneous solid base catalyst with varying ratios (CABP of 10, 20, and 30 mass%), that is subsequently used for transesterification of mustard oil. Physicochemical characterization of CABP revealed crystalline behavior, signifying one of the components as hydroxyapatite (HAP); when calcined at 900 °C transforms to ß-tricalcium phosphate having a specific surface area of 100 m2 g-1. The synthesized catalyst showed improved catalytic activity when compared to the parental species and the optimal value to achieve the highest conversion of 90.4% would be at CABP loading of 10 mass%, 5.5:1 methanol to oil molar ratio, and 10 mass% catalyst concentration for 6 h. The prepared biodiesel had a calorific value of 36.2 MJ kg-1 with ash content < 0.01 mass%. The catalyst could be reused five times with no loss in its activity. Results indicated that calcium enriched waste materials when impregnated in fly ash might be a potential source of catalyst in biodiesel production.

Uranium speciation in coal bottom ash investigated via X-ray absorption fine structure and X-ray photoelectron spectra.

Similar to chromium contamination, the environmental contamination caused by uranium in radioactive coal bottom ash (CBA) is primarily dependent on the chemical speciation of uranium. However, the relationship between uranium speciation and environmental contamination has not been adequately studied. To determine the relationship between uranium speciation and environmental contamination, X-ray absorption fine structure (XAFS) and X-ray photoelectron spectra (XPS) analyses were performed to determine the uranium speciation in CBA exposed to different chemical environments and simulated natural environments. The leachability of the different forms of uranium in the CBA was studied via a simulated acid rain leaching experiment, and the results showed that 57.0% of the total uranium was leached out as U(VI). The results of a linear combination fit (LCF) of the X-ray absorption near edge structure (XANES) spectrum revealed that in the raw CBA, the uranium mainly occurred as U3O8 (71.8%). However, in the iron-rich particles, the uranium mainly occurred as UO2 (91.9%) after magnetic separation. Magnetite is a ubiquitous ferrous-bearing oxide, and it was effective for the sorption of U(IV). The result of FeSO4 leaching experiment indicated that 96.57% of total uranium was reduced from U(VI) to U(IV) when infiltrated with the FeSO4 solution for 6months. This result clearly demonstrated the changes in chemical valence of uranium in the coal ash and provided a conceptual principle for preventing uranium migration from ash to the surrounding soil and plants.

Effects of coal blending in electrostatic precipitation efficiency-Inner Mongolia, China.

Based on this study, the Al2O3 content of Jungar coal ash is over 45%, and the resistivity of high-Al2O3 ash in Jungar reaches up to 1012 Ω​·cm. These results seriously influenced the electric characteristics of fly ash, and the collection efficiency of electrostatic precipitators (ESPs) evidently decreased. To facilitate the effective collection of fine particle in the flue gas generated before and after coal blending via ESP, the fly ash obtained from a power plant electrostatic precipitation was analyzed in terms of resistivity, size distribution, and cohesive force through a portable dust electrical resistivity test instrument, Bahco centrifuge, and a cohesive force test apparatus invented by the researchers. The mixed ratio of else coal is higher than 50%, the resistivity of the fly ash in the flue gas was lowered to approximately two orders of magnitude, and the size distribution showed an evident decrease in the PM2.5 and PM10 content in fly ash. In addition, the adhesive force and efficiency increase from 95.9 to 99.5% in the electrostatic precipitation. Therefore, the combustion of blending coal is an effective approach to improve the efficiency of ESP used to collect high-Al2O3 fly ash.

Differences in bulk and microscale yttrium speciation in coal combustion fly ash.

Coal combustion ash is a promising alternative source of rare earth elements (REE; herein defined as the 14 stable lanthanides, yttrium, and scandium). Efforts to extract REE from coal ash will depend heavily on the location and speciation of these elements in the ash. This study sought to identify the major chemical forms of yttrium (Y), as a representative REE in coal fly ash samples selected from major coal sources in the United States. Y speciation was evaluated using both bulk scale analyses (sequential extractions, Y K-edge X-ray absorption near-edge spectroscopy - XANES) and complementary analyses at the micron scale (micro-focus X-ray fluorescence and micro-XANES). Sequential selective extractions revealed that the REE were primarily in the residual (unextracted fraction) of coal fly ash samples. Extraction patterns for yttrium resembled those of the lanthanides, indicating that these elements were collectively dispersed throughout the aluminosilicate glass in fly ash. Bulk XANES analysis indicated that Y coordination states resembled a combination of Y-oxides, Y-carbonate, and Y-doped glass, regardless of ash origin. However, in the microprobe analysis, we observed "hotspots" of Y (∼10-50 µm) in some samples that included different Y forms (e.g., Y-phosphate) not observed in bulk measurements. Overall, this study demonstrated that yttrium (and potentially other REEs) are entrained in the glass phase of fly ash and that microscale investigations of individual high-REE regions in fly ash samples do not necessarily capture the dominant speciation.

Design parameters and treatment efficiency of a retrofit bioretention system on runoff nitrogen removal.

Mixed media design is key factor that affects the operation of bioretention systems. In this study, four types of modifiers, namely, water treatment residual (WTR), green zeolite, fly ash, and coconut bran, were mixed with traditional bioretention soil (65% sand + 30% soil + 5% sawdust, by mass). Consequently, four kinds of modified media were obtained. Ten pilot-scale bioretention basins were constructed by setting different configurations. The steady infiltration rates of the modified packing bioretention systems were 3.25~62.78 times that of plant soil, which was 2.88~55.75 m/day. Results showed that the average concentration removal (ACR) of both mixed and layered fly ash and WTR were better than those of the other media, and the effects could reach over 61.92%. In the bioretention basins with WTR as the modifier, the treatment efficiency of nitrogen under the submerged zone height of 150 mm was relatively optimal, and ACR could reach 65.46%. Outflow total nitrogen (TN) load was most influenced by inflow load, and the correlation coefficient was above 0.765. Relative to the change of inflow concentration (IC), the change of recurrence interval (RI) and discharge ratio (DR) was more sensitive to TN load reduction. The reduction rate of TN load decreased by approximately 15% when the recurrence interval increased from 0.5 to 3 years. It decreased by approximately 12% when the discharge ratio increased from 10 to 20. This study will provide additional insights into the treatment performance of retrofit bioretention systems, and thus, can guide media and configuration design, effect evaluation, and related processes.

Phosphorus availability changes in acidic soils amended with biochar, fly ash, and lime determined by diffusive gradients in thin films (DGT) technique.

The lime, biochar, and fly ash are widely used to ameliorate acidic soils. The purpose of our pot experiment was to understand whether these soil amendments affected the availability of phosphorus in soils using diffusive gradients in thin films (DGT) technique. Three soil amendments, biochar (B), fly ash (F), and lime (L), were applied alone or combined to Ultisol and Alfisol at the rate of 40, 40, and 6 g/kg, respectively. The DGT and chemical extraction techniques were used to quantify the soil available (phosphorus) P dynamic in the rice growth period. The addition of amendments can effectively increase the phosphorus content extracted by 0.01 M KCl solution. The biochar amendment showed the best effect on increasing the contents of DGT-P and Olsen-P in the soil. Combined with the DGT-induced fluxes in sediments (DIFS) model, it was found that soil amendments mainly increased the adsorption rate (k) and desorption rate (k-1), and reduced soil reflect time (Tc) of phosphorus released to the pore water. The P contents accumulated in rice grains correlated more closely with the effective P concentration measured by DGT technique, compared with those with soil total P, pore water P, and Olsen-P. These results suggested that the DGT technique had significant advantage over conventional chemical extraction techniques when assessing the bioavailability of phosphorus to rice growth. Application of soil amendments increased the contents of Al-P and Ca-P of both Ultisol and Alfisol, and decreased the content of Fe-P in soils. The addition of amendments could change the affinity of Fe and phosphorus decreasing the phosphorus fixation in soils. The increase of available phosphorus in soil is mainly due to the change of pH value and the direct diffusion of phosphorus in the amendments (biochar and fly ash). In conclusion, soil amendment can affect the availability and adsorption ability of phosphorus in soil, and biochar has the best effect on the availability of soil phosphorus.