Ash Composition Research Articles

The Effect of Fly Ash Mixture on Concrete Compressive Strength

Fly ash is a waste from the steam power plant industry that can be used as added material in making concrete. This is because the chemical compounds in fly ash are almost the same as cement. The purpose of this study was to determine the compressive strength of concrete with partial replacement of cement with fly ash. The composition of partial replacement of cement with fly ash is 0%, 20%, 25%, 30%, and 35%. The planned concrete quality is 30 MPa and tested at the age of 7 days and 28 days. The test results show the average compressive strength of the concrete for all variations of both 7-day and 28-day replacement is less than 30 MPa. The greater composition of fly ash used, the smaller the compressive strength value of the concrete. This is caused by the slow hydration process because fly ash is pozzolans which delay the hydration process. In addition, the reduction of cement content will also result in a decrease in compressive strength, this is because the bonding capacity of the aggregate decreases. However, when viewed based on the density of the concrete, the fine fly ash grains can make the concrete denser.

Density, load and fly ash effect on stabilization of high plasticity soil with lime

The reuse recycling materials or industrial waste materials with aims to reduce pollution and environmental pollution, strongly supports concept of green building. Fly Ash is result of combustion pulverized system coal at the PLTU Tenayan, is no longer included in the B3 waste category. The usage of Fly Ash usage as building material, mine restoration, roads in this decade, is to replace cement or lime. The fly ash composition is mixed with lime for sub-base, will applied on high plasticity soils. A fix-mixture of soil and lime 5%, mixed with fly ash up to 30% of the mixture. The samples test was made at Optimum Moisture Content, with density values around Maximum Dry Density i.e. under compacted (under MDD) and over compacted (above MDD). Consolidated testing was performed with and without curing. Changes of load are represented by load increment ratio (LIR). The selected LIR value is 1.0; 1,5; and 2.0. The results showed that the higher of density, the volume of void is lower. The soil compression index value is the same for all density values, if the soil structure has not destroyed. or fatigue yet. In samples with crushed/broken soil structures, the value of the compressibility index decreased sharply. Curing successfully decreased the void ratio and compressibility of the soil. The strength of fly ash will decrease when reacting with water, so if soil burdened, the void ratio decreases drastically. The formation of strong molecular bonds between Fly ash and lime takes time. So, the compressibility value of the sample by curing 28 days is better than without curing. The composition levels between fly ash and lime also affects the compressibility index of the mixture. The optimum combination occurs in samples with a fly ash content of 25%.

Influence of the chemical content of sawdust on the levels of important macronutrients and ash composition in Pearl oyster mushroom (Pleurotus ostreatus).

Influence of chemical composition of sawdust on the nutritional profile of oyster mushrooms (Pleurotus ostreatus) has yet to receive significant research attention. This information will help mushroom growers to select specific sawdust for the production of mushroom with desired dietary preferences. This study assessed the influence of the chemical composition of sawdust on the macronutrients and ash content of the pearl oyster mushrooms. The American Standard for Testing Materials and other widely accepted protocols were used to determine the C-N ratio, pH, lignin, hemicellulose and cellulose contents of mixed sawdust from tropical wood species. The study evaluated the fat, crude fibre, crude protein, carbohydrate, and ash content of the oyster mushroom cultivated on the sawdust. Cellulose constituted the largest component of the sawdust (47.82%), followed by lignin (33.29%). The yield of the mushroom (on 0.05 kg of sawdust) ranged from 490.1 to 540.9 g (biological efficiency: 44-50%); the average carbohydrates constituent in the mushroom was 56.28%. pH of the sawdust influenced the crude protein, carbohydrate, fat and ash content of oyster mushrooms (p<0.05) most significantly. The hemicelluloses also had a significant effect (p<0.05) on the mushroom's minerals, fat and crude fiber content. The study revealed that the mushroom producers would likely obtain high protein content using sawdust with low pH (slightly acidic to slightly basic) in the oyster mushroom. Mushrooms grown on substrates, rich in hemicelluloses, had low fat and high crude fiber content.

Predicting the extent of andic soils across western Haleakalā, Maui

AbstractMaui is one of five Hawaiian Islands affected by orographic climate effect, exhibiting a massive precipitation gradient across western Haleakalā. However, high variability of volcanic ash deposits as a parent material across the study area complicates the ability to isolate the influence of climate on soil formation. Little is documented about the spatial extent of ash deposition, frequency and intensity of volcanic ejecta events, and composition of ash. Therefore, andic soils, which contain short range order (SRO) aluminosilicates and iron oxides that result in unique soil chemical and physical properties, are challenging to map. Using environmental and andic property data from 16 pedons sampled in the study area—bulk density, phosphate retention, and aluminum plus ½ iron extracted by ammonium oxalate—we applied multiple linear regression to create spatial prediction models of these three soil properties. Predicted soil properties were then used to classify andic soils. The mean prediction for an independent set of pedons showed a soil classification accuracy of 50% in the study area for Andisols (data to 60 cm), andic intergrades (data to 75 cm), and non‐andic soils. Soil property predictions using depth‐weighted average data to 1 m increased soil classification user accuracy of Andisols to 87.5%, andic‐intergrades to 100%, and non‐andic soils to 83.3%. Whether a soil exhibits andic soil properties within 60 or 75 cm is irrelevant when considering prior or current presence of ash in a soil. Accounting for all available pedon data with depth proves most important when attempting to predict andic properties and classes.

Chemical characteristics of wildfire ash across the globe and their environmental and socio-economic implications

The mobilisation of potentially harmful chemical constituents in wildfire ash can be a major consequence of wildfires, posing widespread societal risks. Knowledge of wildfire ash chemical composition is crucial to anticipate and mitigate these risks.Here we present a comprehensive dataset on the chemical characteristics of a wide range of wildfire ashes (42 types and a total of 148 samples) from wildfires across the globe and examine their potential societal and environmental implications. An extensive review of studies analysing chemical composition in ash was also performed to complement and compare our ash dataset.Most ashes in our dataset had an alkaline reaction (mean pH 8.8, ranging between 6 and 11.2). Important constituents of wildfire ash were organic carbon (mean: 204 g kg−1), calcium, aluminium, and iron (mean: 47.9, 17.9 and 17.1 g kg−1). Mean nitrogen and phosphorus ranged between 1 and 25 g kg−1, and between 0.2 and 9.9 g kg−1, respectively. The largest concentrations of metals of concern for human and ecosystem health were observed for manganese (mean: 1488 mg kg−1; three ecosystems > 1000 mg kg−1), zinc (mean: 181 mg kg−1; two ecosystems > 500 mg kg−1) and lead (mean: 66.9 mg kg−1; two ecosystems > 200 mg kg−1). Burn severity and sampling timing were key factors influencing ash chemical characteristics like pH, carbon and nitrogen concentrations. The highest readily dissolvable fractions (as a % of ash dry weight) in water were observed for sodium (18 %) and magnesium (11.4 %). Although concentrations of elements of concern were very close to, or exceeded international contamination standards in some ashes, the actual effect of ash will depend on factors like ash loads and the dilution into environmental matrices such as water, soil and sediment. Our approach can serve as an initial methodological standardisation of wildfire ash sampling and chemical analysis protocols.

Valorising Wood Ash as an Effective Green Alternative Pulping Agent for Achieving a High Yield of Banana Micro-Lignocellulose Fibres of Enhanced Crystallinity

AbstractThis study aims to explore the use of wood ash, a common waste, as an alternative and eco-friendly pulping agent. The first and most important singularity of the study is that wood ash solution, though mild in nature, has proven to be an effective pulping agent (in comparison with the common pulping solution, sodium hydroxide): comparable lignin (45%) and hemicellulose (50%) removal, high crystallinity (72–77%) and high pulp yield (70%) were obtained. Another particularity of this study is that the reported advanced aspects of pulped banana fibres, notably the chemical functionality, crystallinity and crystallite size have been correlated with the chemical composition of the wood ash used: calcium pectinate was formed on the pulped fibre surface. It apparently played a role in enhancing the fibre crystallinity. Moreover, another specialness of this study is that non-conventional factors, which would have significant bearing during industrial scale processing, such as liquor ratio, fibre input size and duration have been investigated—the latter has shown that to attain maximum delignification, small fibre input size at a high liquor ratio of 40 for an extended period of 2 h are necessary. Finally, the pulped banana fibres (which were intended to be used for membrane fabrication for use in water purification system) have depicted their applicability in the fabrication of ultrafiltration membranes by virtue of their aspect ratio, semi-hydrophilicity (due to presence of residual lignin) and projected high mechanical strength (due to high crystallinity and low crystallite size). Graphical Abstract Graphical abstract showing outcomes when pulping with wood ash solution.

Trace elements in sediments and plankton from two high-altitude lakes in a volcanic area from North Patagonia, Argentina.

This study analyzes the distribution of nine potentially toxic trace elements (arsenic, antimony, bromine, cobalt, chromium, mercury, rubidium, selenium, and zinc) in sediments and plankton from two small mesotrophic lakes in a non-industrialized area impacted by the Caviahue-Copahue volcanic complex (CCVC). The two lakes have different plankton community structures and received different amounts of pyroclastic material after the last CCVC eruption. Trace element concentrations of surface sediments differed between lakes, according to the composition of the volcanic ashes deposited in the lakes. The size of organisms was the principal factor influencing the accumulation of most trace elements in plankton within each lake, being trace element concentrations generally higher in the microplankton than in the mesozooplankton. The planktonic biomass in the shallower lake was dominated by small algae and copepods, while mixotrophic ciliates and different-sized cladocerans dominated the deeper lake. These differences in the community structure and species composition influenced the trace element bioaccumulation, especially in microplankton, while habitat use and feeding strategies seem more relevant in mesozooplankton bioaccumulation. This work contributes to the scarce records of trace elements and their dynamics in plankton from freshwater ecosystems impacted by volcanic activity.

Physical properties, chemical composition, and toxicity leaching of incineration fly ash by multistage water washing.

Incineration fly ash contains a large amount of chloride, which limits the scope of its resource utilization. Water washing effectively removes chlorides and soluble substances, increasing the ability to dispose of them. The properties of incineration fly ash after multi-level water washing have been studied, providing theoretical guidance for the safe disposal of water-washed ash at all levels. Taking a practical project as an example, this paper analyzed the impact of three-stage countercurrent water washing on the physicochemical properties and toxicity leaching of incineration fly ash with different washing grades by XRD, BET, XRF, SEM, and ICP-MS. The results showed that with the improvement of washing grade, the removal rate of chloride ions was more than 86.96%. However, due to the removal of soluble substances, dioxins enriched from 98ng-TEQ/kg of raw ash to 359ng-TEQ/kg of tertiary washed incineration fly ash. Cr, Cu, and Zn also increased from 40.35mg/L, 356.55mg/L, and 3290.58mg/L of raw ash to 136.30mg/L, 685.75mg/L, and 5157.88mg/L, respectively. Pozzolanic activity had increased from 40.56% of the raw ash to 74.12% of the tertiary-washed incineration fly ash. There was no risk of excessive heavy metal leaching, and the dioxin content was lower than the raw ash in the primary washed incineration fly ash. After multi-stage water washing, incineration fly ash accumulated heavy metals, so more attention must be paid to the issue of heavy metal content in the safe disposal process.

PHYSICAL PROPERTIES OF GEOPOLYMERS MADE FROM MINERAL WASTE

Geopolymer is an alumino-silicon gel consisting of tetrahedral SiO 4 and AlO 4 sections, polycondensed in a spatial structure as a result of the reaction between aluminosilicates and an alkaline activator.The report is a part of the complex research plan for geopolymers, in which information is given about the experimental results in the preparation of geopolymers from natural and man-made mineral components characteristic of Latvia (clay, sand, wood ash, brick waste).The aim of the study was to find out the dependence of the geopolymer formation process on the composition of the reacting components at constant exposure factors. Sodium alkali solution and sodium silicate was used in the experiments. The raw materials used are red and gray clay, sand, wood ash.The composition of the clay, ash and sand composition was changed with an interval of twenty percent. The obtained geopolymer samples were subjected to physical and technical tests. The compositions that are perspective in terms of properties in the studied modes of exposure have been determined.

Accreting neutron stars: composition of the upper layers of the inner crust

Abstract We model the nuclear evolution of an accreted matter as it sinks toward the stellar center, in order to find its composition and equation of state. To this aim, we developed a simplified reaction network that allows for redistribution of free neutrons in the inner crust to satisfy the recently suggested neutron hydrostatic and diffusion equilibrium condition. We analyse the main reaction pathways for the three representative thermonuclear ash compositions: Superburst, Kepler, and Extreme rp. In contrast to the previous results, which neglect redistribution of free (unbound) neutrons in the inner crust, the most significant reactions in our calculations are neutron captures and electron emissions. The pycnonuclear fusion plays some role only for Kepler ashes. For the direct application of our results in astrophysical codes we present profiles of the average charge, 〈Z〉, impurity parameter, Qimp and equation of state for a set of models, parametrized by the pressure at the outer-inner crust interface. Typically, for Superburst ashes Qimp ≈ 1 − 4, while for Kepler ashes Qimp decreases from ≈23 at the outer-inner crust interface to ≈5 at the end of our simulation (the corresponding density equals ρdc ≈ 2 × 1012 g cm−3). At the same time, for Extreme rp ashes Qimp remains large ≈30 − 35 in the considered inner crust region. Our results are important for modeling the thermal relaxation of transiently accreting neutron stars after the end of the outburst.

Physico-Chemical Study of the Possibility of Utilization of Coal Ash by Processing as Secondary Raw Materials to Obtain a Composite Cement Clinker

A significant amount of energy waste has accumulated in the world, in particular, large-tonnage fine ash from central heating stations (coal ash), which can negatively affect the natural environment and the health of the population. However, at the same time, due to its chemical composition, this waste can be disposed of by complex processing as a secondary mineral component, thus reducing the anthropogenic load on the natural environment. This article presents a physico-chemical study of coal ash for its further use as a secondary mineral component, in particular, a component of a raw mixture with limestone to produce a composite Portland cement clinker. Coal ash and limestone were subjected to granulometric, chemical, differential thermal, scanning electron microscopy, elemental chemical and X-ray structural analyses, as well as modeling to assess the possibility of optimizing the raw material and mineralogical composition of the composite Portland cement clinker. During the research, the chemical and elemental compositions of the coal ash and limestone were determined and SEM images of the coal ash were obtained; it was found that 68.04% of the coal ash was represented by the fraction with granules &lt;0.16 mm. Using X-ray diffraction analysis, the main limestone minerals were identified, which were represented by calcite and silica. Based on the results of mathematical modeling of the utilization of coal ash from a thermal power plant by processing with limestone, a two-component raw material mixture containing 23.66% fly ash and 76.34% limestone was optimized and the optimal mineralogical composition of the composite Portland cement clinker was determined. Utilization of coal ash by processing as a secondary raw material can be carried out at almost any ash storage facility anywhere in the world, taking into account the chemical composition of the processed ash. It was found that the replacement of natural raw materials with man-made raw materials in the form of coal ash contributed to a reduction in fuel consumption for firing (kg of conventional fuel) by 13.76% and a decrease in the thermal effect of clinker formation by 5.063%.

Characteristic of phosphorus rich compounds in the incinerated sewage sludge ashes: a case for sustainable waste management

Growing concern over mineral resources supply forces us to search for alternative sources of Phosphorus. The possibility to recover phosphorus from incinerated sewage sludge ashes appears to be an important aspect in anthropogenic phosphorus cycle and sustainable economy. To make phosphorus recovery efficient it is important to learn the chemical and mineral composition of ash and phosphorus speciation. The phosphorus content in the ash was over 7%, what corresponds to medium rich phosphorus ores. The main phosphorus rich mineral phases were phosphate minerals. The most widespread was tri-calcium phosphate Whitlockite with various Fe, Mg and Ca proportions. In minority Fe–PO4 and Mg–PO4 were detected. Whitlockite commonly overgrown with hematite, influences negatively mineral solubility and thus recovery potential and indicates low bioavailability of phosphorus. Considerable amount of phosphorus was found in the low crystalline matrix where phosphorus content was around 10 wt% however low crystallinity and dispersed phosphorus also does not strengthen the potential to recover this element.

Characterization of teff straw from selected teff varieties from Ethiopia

Utilization of biomass is important both for economic and environmental projection purposes. To use biomass for industrial applications as well as to reduce its pollution load on environment, it is important to characterize and determine the compositions of the biomass. In this work, the proximate and chemical analyses of straws of four (Dagim, Filagot, Kora and Kuncho) Teff (Eragrostis tef) varieties were investigated with three replications. The thermographic and FTIR of the teff straws and the ashes were also studied. The volatile matter contents of the teff straws were 78.80, 77.00, 80.20 and 80.60% for the Dagim, Kuncho, Kora and Filagot varieties, respectively. The ash contents of the straws were 6.34% for Dagim, Kuncho and Kora while the value is 6.00% for Filagot. The fixed carbon contents of the straws were 14.86, 16.67, 13.47 and 13.40% for Dagim, Kuncho, Kora and Filagot varieties, respectively. The silica contents of the teff straw for the Filagot, Kora, Dagim, and Kuncho varieties are 5.92, 5.66, 4.94, and 4.70%, respectively. This corresponds to 92.21, 91.59, 77.19 and 87.20% silica contents in the ashes produced from Filagot, Kora, Dagim, and Kuncho varieties, respectively. The results show that the proximate and chemical composition of ash produced from teff straws show slight differences. Moreover, the silica content of the teff straw is comparable with the values reported for rice husk and wheat straw. Thus, teff straw can be used for the production of silica.

Geopolymer fly ash composites modified with cotton fibre

The work’s primary goal is to assess the influence of the cotton fibres addition and their proportion on the strength properties and thermal conductivity of foamed geopolymer composites based on fly ash.Fly ash from a thermal power plant was used as the foundation material to create the geopolymer composites in this study. Volcanic silica was used as an additional source of silicon. As an additive, the recycled cotton flock was used in amounts of 0.5%, 1% and 2% by weight of dry ingredients. The density, compressive, and three-point bending strength of the created geopolymers were measured. Moreover, the thermal conductivity measurements for three temperature ranges: 0–20C, 20–40C, and 30–50C for all investigated geopolymers were conducted. The structure of tested materials was observed using a scanning electron microscope (SEM).It was demonstrated within the context of the study that the addition of cotton fibres to foamed fly ash-based geopolymers aids in slightly reducing their density. Cotton fibres can be used to boost the strength of the examined geopolymers; for samples with 1% cotton fibres added, compressive strength rose by around 22% and flexural strength by about 67%. Additionally, it is feasible to lower their thermal conductivity coefficient by incorporating cotton fibres into foamed fly ash-based geopolymers.The results obtained highlight the potential of fly ash-based geopolymer composites with the addition of cotton flocks for application as insulating materials in the building industry.The novelty of this work is the demonstration of the possibility of producing foamed geopolymers based on fly ash with the addition of recycled cotton fibres, with properties that make them suitable for use as building insulation materials.

Comparative analysis of the antioxidant capacity of milk from different breeds of cow in Nigeria

Milk is an essential component of human and animal diets, and cattle are a major source of milk for human consumption. Environmental, nutritional, genetic, and physiological factors can affect animal milk composition. This study was aimed at evaluating the antioxidant properties of milk samples from four cattle breeds, namely: White Fulani (WF), Sokoto Gudali (SG), Red Bororo (RB), and the exotic Holstein Friesian (HF) in Sokoto, Nigeria. Fatty acid, amino acid profile, antioxidant vitamins, antioxidant minerals, and antioxidant enzymes activities of the samples were assessed using standard methods. The results of the analysis indicated that milk of SG had the highest values for moisture (85.57%), Vit C (79.24mg/dl), DPPH scavenging activity (80.04%), and FRAP (1083.33mgTE/100g of FW). Milk of RB had the highest ash (4.52%), protein (3.63%), copper (0.19 ppm), zinc (0.16 ppm), iron (3.47 ppm), and antioxidant amino acid composition. The milk of HF had the highest lipid (5.89%), oleic acid (1.17 mg/ml), total polyphenol content (TPC) (0.26 mgTE/100g of FW) and selenium (103.10 ppm) levels. WF had the highest carbohydrate (15.07%), palmitic acid (98.39 mg/ml), stearic acid (35.46 mg/ml), Vit A (55.38 mg/dl), Vit E (52.18 mg/dl) content, catalase (0.02 U/L) and superoxide dismutase (3.00 U/mL) activities. These results show that milk from the WF has better antioxidants and therefore antioxidant capacities than the other breeds. Overall, the study indicates that cow milk is a good source of antioxidants, whose levels vary between the different breeds of cattle. These nutritional differences can be explored during milk sourcing based on nutritional requirements.

Comparative Study of the Nutritional and Chemical Composition of New Oil Rape, Safflower and Mustard Seed Varieties Developed and Grown in Serbia.

Oilseed crops are widely cultivated and are related to nutrition and human health as valuable nutraceutical sources with valuable biological properties. The growing demand for oil plants used in human and animal nutrition or for the processing industry has contributed to the diversification and development of a new variety of oil crops. Increased oil crop diversity, besides ensuring reduced sensitivity to pests and climate conditions, has also led to improved nutritional values. In order to enable oil crop cultivation to become commercially sustainable, a comprehensive characterization of newly created varieties of oilseeds, including their nutritional and chemical composition, is required. In this study, two varieties of safflower and white and black mustard were investigated as alternative oil species for nutritional parameters, mainly protein, fat, carbohydrate, moisture, ash, polyphenols, flavonoids, chlorophylls contents, acids and mineral composition, and compared with those of two different genotypes of rapeseeds as a traditional oil crop plant. The proximate analysis found that the highest oil content was found in the oil rape NS Svetlana genotype (33.23%), while the lowest was in black mustard (25.37%). The protein content varies from around 26% in safflower samples to 34.63%, determined in white mustard. High content of unsaturated fatty acids and low content of saturated fatty acid was observed in the analyzed samples. In mineral analysis, the dominant elements were phosphorus, potassium, calcium and magnesium, in descending order. The observed oil crops are also good sources of microelements, including iron, copper, manganese and zinc, accompanied by high antioxidant activity due to the presence of significant amounts of polyphenolic and flavonoid compounds.

Cultivation of Pleurotus ostreatus on agricultural wastes and effects on nutritional composition of the fruiting body

ABSTRACT Little interest has been shown in studies related to the effects of cultivating Pleurotus ostreatus on agricultural wastes and their impacts on nutritional value and biological efficiency of the fruiting body. Oil palm fiber, rice husk, sawdust from hardwood, guinea grass, bean pods and rice straw were collected in dried form and used as substrates. Active mycelium of P. ostreatus was used in preparation of spawn, and growth was observed after 30 days following inoculation and fruiting bodies were harvested for analysis. The proximate composition of crude protein, crude fat, crude fiber, ash, moisture, dry matter and carbohydrate composition; antioxidant properties from flavonoids, phenol, lycopene, beta carotene, and ascorbic acid and composition of Na, K, Ca, Mg, Cu, Mn and Zn varied across substrates. All cultivated P. ostreatus on substrates contained high amounts of crude protein, crude fat, crude fiber, ash, moisture, dry matter and carbohydrate, flavonoid, phenol, lycopene, beta carotene, and ascorbic acid, and mineral ions such as Na, K, P, N and Ca. Dry weight and biological efficiency were highest in P. ostreatus cultivated on rice straw, followed by bean pods. Pleurotus ostreatus grown on substrates used contained high amounts of nutrients. Rice straw and bean pods may be used to achieve high nutritional composition and antioxidant contents in P. ostreatus mushrooms.

Effect of preheating Co-firing of biomass and coal on the synergistic reduction of PM and NO source emissions

Co-firing of biomass and coal is a prevalent method in modern thermal power plants to reduce pollutant emissions. This study focuses on the preheating co-firing behavior of coal and biomass to explore the effect of preheating combustion and preheating co-firing on PM (particle matter) and NO source emissions, and different coals were selected to verify the effect of coal rank on this behavior. Coal and biomass were fed into a mixing device through two independent feeders and uniformly mixed before entering the furnace. PM and NO emissions after preheating combustion were measured using an Electrical Low-Pressure Impactor and flue gas analyzer. The results showed that preheating combustion reduced the production of PM1, PM1-10, and NO from coal by 22.30%, 10.75%, and 49.84% respectively, and also reduced the production from biomass by 28.61%, 15.16%, and 53.01% respectively compared to conventional combustion. Preheating co-firing experiments revealed that as the co-firing ratio increases, NO production decreased, but the production of PM1 initially decreased and then increased, reaching a minimum point at a co-firing ratio of 25%. Meanwhile, the lower the rank of the coal, the better the effect of preheating combustion and preheating co-firing, and the ash content and composition of coal also had an impact on the generation of PM1.

Co-firing of coal and woody biomass under conditions of reburning technology with natural gas

It is a continuous imperative to establish the most efficient process of conversion of primary energy from fuel through combustion, which also has the least possible harmful effect on the environment. In this time of expressed demands for decarbonisation, it also means the affirmation of the use of renewable fuels and the indispensable application of appropriate primary measures in the combustion furnace. At the same time, the efficiency of the combustion process depends on several factors, from the type and properties of the fuel to the ambient and technological settings for the process. In this regard, with the aim of determining the static characteristics of combustion, experimental laboratory research was carried out on the combustion of mixtures of brown coal with low heating value and a high ash content with waste woody biomass and different process conditions: temperature, staged combustion air supply (air staging) and in conditions of application of a third or additional fuel (natural gas, reburning technology). Applied experimental methods included the analysis of the combustion process on the basis of input (reactants) - output (products), including the analysis of the composition of flue gases, i.e. the determination of the emission of the key components of flue gases CO2, CO, NOx and SO2, as well as the analysis of the composition of slag, ash and deposits ash, i.e. assessment and evaluation of the behaviour of ash from fuel in that process. Based on the obtained research results, this paper shows the significant positive effects of the application of primary measures in the furnace - compared to conventional combustion: air staging - reduction of net CO2 emissions during co-firing with biomass and reduction of NOx emissions by up to 30%; reburning technology - additional reduction of CO2 and NOx emissions in proportion to the share of natural gas, e.g. at a combustion process temperature of 1350 °C and at a 10% energy share of natural gas during the co-firing of a mixture of brown coal and waste woody biomass, compared to the emission without the use of natural gas, a reduction of NOx emissions by 185 mg/mn3 or by almost 30% was recorded. It was concluded, at the same time, the application of these primary measures in the furnace does not negatively affect the behaviour of ash from the fuel in the given settings of the combustion process.

Phycoremediation and simultaneous production of protein‐rich algal biomass from aquaculture and agriculture wastewaters

AbstractBACKGROUNDMicroalgae cultivation in wastewaters is a potential remediation technology for converting residual nutrients into valuable biomass for biofuels, fertilizers, animal and aquaculture feeds, and bio‐based chemicals. The objective of this study was to determine the potential for microalgae phycoremediation of aquaculture and agriculture wastewaters for sustainable production of nutrient‐rich algal biomass.RESULTSThirty‐seven aquaculture and agriculture wastewaters were evaluated as growth media for two freshwater, chlorophytic microalgae strains (Chlorella sorokiniana SMC14M and Scenedesmus sp. AMDD). Although nutrient levels and physicochemical parameters of the wastewaters varied widely, phycoremediation efficiency of nitrogen and phosphorous was high (&gt; 70%) for a large majority of them, with both microalgae strains. Photobioreactor cultivation (300 L) of C. sorokiniana grown on finfish aquaculture wastewater (CA2) and standard growth medium (SGM) exhibited similar biomass production levels and nutritional compositions of moisture (4.9–5.0%), ash (5.9–6.1%), nitrogen (8.6–8.8%), protein (41.0–42.1%), lipid (8.6–8.8%), carbohydrate (38.3–39.3%) and gross energy (22.2–22.3 MJ⋅kg−1) with highly similar fatty acid and amino acid profiles.CONCLUSIONSThis study demonstrates that the use of freshwater microalgae to remediate various aquaculture and agriculture wastewaters, while producing valuable nutrient‐rich biomass, is feasible. We have found that a particular finfish aquaculture wastewater (CA2) contains all of the nutrients required for rapid microalgae growth, avoiding the need for expensive commercial fertilizers. The biochemical composition of C. sorokiniana grown on CA2 aquaculture wastewater has good potential for use as a nutrient‐rich ingredient for animal and aquaculture feeds, fertilizers products, biofuels and other applications, resulting in remediated water that could be reused. © 2023 National Research Council Canada. Reproduced with the permission of the Minister of Innovation, Science, and Economic Development.