Pure Wheat Straw Research Articles

Morphology and phosphate distribution in bottom ash particles from fixed-bed co-combustion of sewage sludge and two agricultural residues

The purpose of this study was to provide detailed knowledge of the morphological properties of ash particles, including the volumetric fractions and 3D distributions of phosphates that lay within them. The ash particles came from digested sewage sludge co-combusted with K- and Si-rich wheat straw or K-rich sunflower husks. X-ray micro-tomography were combined with elemental composition and crystalline phase information to analyse the ash particles in 3D.Analyses of differences in the X-ray attenuation enabled calculation of 3D phosphate distributions that showed high heterogeneity in the slag particles. This is underscored by a distinct absence of phosphates in iron-rich and silicon-rich parts. The slag from silicate-based wheat straw mixtures had lower average attenuation than that from sunflower husks mixtures, which contained more calcium. Calculated shares of phosphates between 7 and 17 vol% were obtained, where the highest value for a single assigned phosphate was observed in hard slag from wheat straw with 10 % sewage sludge. The porosity was notably higher for particles from pure wheat straw combustion (62 vol%), compared to the other samples (15–35 vol%). A high open pore volume fraction (60–97 vol%) indicates that a large part of the pores can be accessed by the surroundings. For all samples, more than 60 % of the discrete (closed) pores had an equivalent diameter < 30 μm, while the largest volume fraction consisted of pores with an equivalent diameter > 75 μm. Slag from sunflower husk mixtures had larger pore volumes and a greater relative number of discrete pores >75 µm compared to wheat straw mixtures.

Volatile-char interactions during biomass pyrolysis: Effects of AAEMs removal and KOH addition in char

The effects of Alkali/alkaline earth metals (AAEMs) removal and KOH addition in char on formation and distribution of wheat straw pyrolysis products during volatile-char interactions were studied in a fixed-bed reactor. The results showed that after AAEMs removal from char, significant interactions between volatiles and char still existed, as its non-condensable gas yield greatly increased with less detectable organics observed in bio-oil compared to pure wheat straw pyrolysis. XPS results indicated that more aromatic carbon structures (C-Cprimary) were exposed on char surface after AAEMs removal, which might act as active sites during the interactions. KOH addition in char exhibited much bigger cracking performance than its interior K in char, resulting in a significant reduction in bio-oil yield and a great increase in non-condensable gas yield. KOH addition in char might promote decarboxylation, decarbonylation and sugar-ring opening reactions, leading to the decrease of linear acids and carbonyls and anhydrosugars and the increase of phenols and other aromatics in bio-oil. The cracking/decomposition of furans, cyclopentenones, and phenols and other aromatics would also be largely enhanced with the increasing amount of KOH addition. In addition, KOH in char could act as a catalyst for the char self-reforming by volatiles during the interactions.

HS-GC-IMS identification of volatile aromatic compounds of freshly-cooked rice packaged with different disposable lunchboxes

The rapid development of online-to-offline food delivery service has necessitated the replacement of plastic lunchbox using biodegradable ones. In current study, a total number of fourteen panelists were firstly recruited and trained to investigate how different commercial disposable lunchboxes affect the freshly cooked rice sensory properties during heat preservation (60 °C, 60 min). The lunchboxes were made of pure polypropylene (PP), polypropylene-starch (PP-S), pure wheat-straw and sugarcane-straw (WS & SS) and Paper. The discrepancy of volatile aromatic substances was then analyzed using headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) to study the possible mechanism beneath the variations of the influences of different lunchboxes on the aromatic properties of rice. Results showed that, compared with the textural attributes, the aroma was significantly and positively correlated with panelist’s acceptability, among which, the aroma of starchy, sulfur and smoky are the most important ones. The moisture absorption plays an important role in affecting the aromatic characteristics of the packaged rice. While all lunchboxes have inhibitory effects on the production of volatile flavor substances including 2,6-Dimethylpyrazine, 2-Acetylpyrazine and γ-Octalactone, pure PP and PP-S lunchboxes generated undesirable flavor substances including 2-Ethyl-1-hexanl and Camphene, and thus reduced panelist’s preferences. It was also found that the panelist liked the rice packaged by Paper lunchbox the best because of its better performance in maintaining the aroma of starchy and sulfur, the two substances that are associated with the higher concentration of ethereal and fruity volatile flavor substances. This study provides important information for manufacturers to understand how different disposable lunchboxes may impact the textural and aromatic properties of packaged foods.

Comparative study on the effects of wood dust and rice husk on wheat straw gasification process: Ash fusion characteristics and gasification reactivity

The ash fusion characteristics and gasification reactivity of wheat straw (WS) blended with rice husk (RH) and wood dust (WD) were investigated, respectively. Furthermore, the transformation of minerals and synergy behaviour of gasification reactivity were explored. Results demonstrated that both RH and WD could enhance the ash fusion characteristic temperatures of WS, which were due to the increasing contents of higher melting-point compounds (quartz and tridymite in WS/RH mixtures, and Ca-silicates in WS/WD mixtures) and the decreasing contents of lower melting-point K-based compounds. Compared to pure WS, the deformation temperature of WS/RH mixture increased from 780 °C to 1233 °C at an RH ash ratio of 60%, and that of WS/WD mixture increased to 1065 °C at a WD ash ratio of 20%. Based on the appropriate ratio of WS, the gasification reactivity of WS increased with increasing WD ratios, whereas that of WS decreased with increasing RH ratios. Besides, the presence of synergistic effect and the reduction of activation energy were observed in two co-gasification processes.

Phenotyping of Different Italian Durum Wheat Varieties in Early Growth Stage With the Addition of Pure or Digestate-Activated Biochars.

This study aims to highlight the major effects of biochar incorporation into potting soil substrate on plant growth and performance in early growth stages of five elite Italian varieties of durum wheat (Triticum durum). The biochars used were obtained from two contrasting feedstocks, namely wood chips and wheat straw, by gasification under high temperature conditions, and were applied in a greenhouse experiment either as pure or as nutrient-activated biochar obtained by incubation with digestate. The results of the experiment showed that specific genotypes as well as different treatments with biochar have significant effects on plant response when looking at shoot traits related to growth. The evaluated genotypes could be clustered in two main distinct groups presenting, respectively, significantly increasing (Duilio, Iride, and Saragolla varieties) and decreasing (Marco Aurelio and Grecale varieties) values of projected shoot system area (PSSA), fresh weight (FW), dry weight (DW), and plant water loss by evapotranspiration (ET). All these traits were correlated with Pearson correlation coefficients ranging from 0.74 to 0.98. Concerning the treatment effect, a significant alteration of the mentioned plant traits was observed when applying biochar from wheat straw, characterized by very high electrical conductivity (EC), resulting in a reduction of 34.6% PSSA, 43.2% FW, 66.9% DW, and 36.0% ET, when compared to the control. Interestingly, the application of the same biochar after nutrient spiking with digestate determined about a 15–30% relief from the abovementioned reduction induced by the application of the sole pure wheat straw biochar. Our results reinforce the current basic knowledge available on biological soil amendments as biochar and digestate.

Morphological characterisation of ash particles from co-combustion of sewage sludge and wheat straw with X-ray microtomography.

Combustion of phosphorus-rich residual streams can produce nutrient-rich ashes and these can be used either in further processing or as materials for direct nutrient recycling. The latter requires knowledge on morphological parameters of such ash particles that may impact plant growth, nutrient availability, and soil physical properties. The present work aims to determine the porosity, pore size, and specific surface area of ash particles, and discuss these properties in light of literature concerning interaction with soil water and plant roots. Bottom ash particles from combustion of sewage sludge and wheat straw and their co-combustion were analysed with X-ray microtomography. Image analysis provided information on morphology, specific surface area, porosity, and pore structure on a micrometre scale resolution. Co-combusting sewage sludge with wheat straw resulted in differences in ash particles' porosity and pore structure compared to combustion of pure fuels. Pure wheat straw ash displayed 62vol% porosity while there was no apparent difference between 10wt% or 30wt% mixtures of sewage sludge, with a porosity of 29-31vol%. Open pore volume comprise the largest part of the porosity (72-99vol%) enabling interaction between surrounding pore water and nutrients. Overall, the ash particles display large open volume fractions and thin particle walls which may lead to rapid weathering and extensive interaction with soil water. The particles generally contained pore openings over 200µm towards the surroundings, which provide opportunities for interaction with microbes and roots from a variety of plant species in addition to nutrient transport by soil water.

Effect of compacted dose of pure straw and blends of straw with calcium carbonate or cassava starch on pelletising process and pellet quality

In this study, changes in the nature of particle size distribution (PSD) of wheat straw (WS) were analysed after the addition of calcium carbonate (CC) additives or cassava starch (CS) with 2 and 6% wt/wt ratios, respectively. Pelletising was conducted for materials with moisture contents of 20% w.b. at a temperature of 78 °C, in a die with an open compaction chamber with a height of 80 mm, using single doses of 50, 100, and 150 mg. The straw blend with 6% wt/wt CC exhibited the most even PSD and the lowest particle size geometric mean of 0.71 mm. These features positively influenced the mechanism of bonds among the particles, compaction effect, and quality of the pellets. Based on mathematical models, it was observed that under optimal conditions, agglomeration of the blend with 4% wt/wt CC using the 100 mg dose aided in achieving the maximum single pellet density of 850 kg m−3. This required a specific compaction work of 36 kJ kg−1 followed by a pellet shift of 0.63 mm in the die, by using a piston realising a specific work of 10.92 kJ kg−1. The produced pellets were characterised by a superior elasticity modulus of 6.15 MPa and high compression strength; for their deformation until cracking, a specific compaction work of 5.52 mJ mm−2 was required. Furthermore, the water absorption capacity of the crushed pellets was 4.00 g H2O g–1 DM (dry matter), which was higher than those of pure WS, the blend with CS, and uncrushed pellets.

Pelletising pure wheat straw and blends of straw with calcium carbonate or cassava starch at different moisture, temperature, and die height values: Modelling and optimisation

This study aimed to identify the optimal conditions for pelletising wheat straw (WS) and blends with cassava starch (CS) or calcium carbonate (CC) at a 2–10% wt/wt additive ratio. The process was investigated in a die with an open chamber having an opening diameter of 8 mm and heights of 66, 76, and 86 mm. The moisture and temperature of the material were 10–30% w.b. and 78–108 °C, respectively. The piston displacement at maximum agglomeration pressure, pellet shift in the die, specific compaction work, specific work for pellet shifting, and additional single pellet density were suitable characterising features of the pelletising process. Regression models were developed for the prediction of the features; these models were optimised by determining the most favourable control variables and target function values. The optimal single pellet density was achieved at 4% wt/wt additive ratio, 23% w.b. moisture content, 78 mm die height, and 80 °C material temperature. Under these conditions, the piston displacement, specific compaction work, and specific work for pellet shifting in the die were 27, 43, and 34% lower than their respective maximum values, while the pellet shift was higher by 29% because of the minimum target function. Adding CC was more favourable than adding CS because the single pellet density of the WS blend with CC (853 kg m−3) was 20% higher than that of the blend with CS as the additive. Optimal conditions for pellet forming are an important indication for their use in actual industrial production.

Experimental study on gas production optimization of pig manure and wheat straw under different pig manure levels

In order to explore the optimal ratio of pig manure and wheat straw mixed fermentation process, the experiment controlled the temperature of the fermentation control fermentation process to 35 °C, the total mass of the fermentation liquid was 700 g, and the total soild (TS) was 8%. The effect of pig manure content on fermentation. Based on the analysis of the gas production per unit of TS, when the pig manure content is 80%, the unit TS produced has the highest gas yield of 344 ml/g, which is 58.9% higher than that of pure wheat straw fermentation. Fermentation increased by 11.43%. In order to explore the best pig manure content in the fermentation process, regression analysis was performed on the gas production per unit of TS by origin. The result was that when the content of pig manure was 79%, the gas production was the highest, 336.3 ml/g, which was higher than that of wheat straw fermentation. 55.51%, 9.05% higher than pure pig manure fermentation. The methane content was used as the analysis result: when the pig manure content was 75%, the highest average methane content after start-up was 60.33%, which was 15.24% higher than that of wheat straw alone, and 3.4% higher than that of pig manure alone. Therefore, during the fermentation process of pig manure and wheat straw, when the content of pig manure is controlled at about 75%, the biogas production in the fermentation process and the methane content in the biogas can be effectively improved..

Temperature rise and weight loss characteristics of wheat straw under microwave heating

The temperature rise and weight loss characteristics of wheat straw and their mixture under microwave irradiation have been investigated in the laboratory with a fixed bed microwave reactor. The influences of both the microwave power and the additives on the temperature rise and weight loss characteristics of wheat straw are the focuses of this work, which aims to explore a new theoretical foundation for advanced pyrolysis methods. The temperature rise curves show that pure wheat straw had a weak capability to absorb microwave energy, while the mixture of wheat straw and pyrolytic residue had a very strong absorption capability. The ability to absorb microwave energy of the mixture increased with increasing amount of pyrolytic residue. These results are in good agreement with the results of the weight loss curves. Thus, it is feasible to pyrolyze wheat straw in microwave fields by addition of small amounts of pyrolytic residue.

Towards a better understanding of biomass suspension co-firing impacts via investigating a coal flame and a biomass flame in a swirl-stabilized burner flow reactor under same conditions

This paper investigates the combustion characteristics of firing pure coal and firing pure wheat straw in a 150kW swirl-stabilized burner flow reactor under nearly same conditions. The results indicate very different combustion characteristics between the coal flame and straw flame. In the straw flame, the straw particles are little affected by the swirling secondary air jet and travel in a nearly straight line through the oxygen-lean core zones. In the coal flame, most of the coal particles are strongly affected by the secondary air jet and swirled into the oxygen-rich outer radius, which also increases the residence time of coal particles. Both the factors favor a complete burnout of the coal particles. The higher volatile yields of the straw produce more off-gas, requiring more O2 for the fast gas phase combustion and causing the off-gas to proceed to a much larger volume in the reactor prior to mixing with oxidizer. For the pulverized straw particles of a few hundred microns in diameters, the intra-particle conversion is found to be a secondary issue at most in their combustion. The simulations also show that a simple switch of the straw injection mode can not improve the burnout of the straw char.

Study of the characteristics of the ashing process of straw/coal combustion

An experimental study was performed to examine the ashing process during straw/coal co-combustion to determine the effect of the blending ratio on ash products. A total of eleven blending samples with coal contents varying from 5wt.% to 90wt.% along with pure wheat straw and pure coal samples were tested to determine the ash fusion points, oxide contents and mineral contents. Blends with coal contents between 5wt.% and 15wt.% were able to inhibit ash and reduced ash quantity. Blends with coal contents greater than 20wt.% promoted ash and increased ash quantity. Thermal decomposition processes during the combustion and ash pyrolysis of the blends with 10wt.% and 40wt.% and the samples of pure coal and pure wheat straw were simulated using a Thermal Gravity Analyser. The results indicated that the ashing processes of the blends were influenced by the coupling reactions of the minerals in the straw and coal. When using a blend of 10wt.% coal, more potassium (K) was accelerated into gaseous products during the volatile releasing and firing stage, which caused an ash quantity reduction effect. K2O content was lowest in this sample, and a minimum amount of K compounds was detected. With a blend of 40wt.% coal, because the coupling reactions of Ca and Al produced stable minerals of CaAl8Fe4O19 and KSi3AlO8, less CaCO3 and CaSO4 were produced. Thermal decomposition at the ash pyrolysis stage was very weak and resulted in much less gaseous products than what would be expected at high temperatures; therefore, more ash residues remained.

Modification of Wheat Straws through Steam Explosion and its Effect on Panel Properties

Particleboards bonded with urea formaldehyde (UF) and a combination of UF and methylene diphenyl diisocyanate (MDI) resins were manufactured using wheat straws modified through different steam explosion treatments. The effect of steam explosion treatment, resin system, and mixing ratios of wood and straw materials on the panel properties was investigated. Generally, with steam explosion treatment of straw fibers, panel properties in bending and internal bond (IB) strength increased, thickness swelling (TS) and water absorption (WA) decreased. The bending properties for the panels made from the straws pretreated with 12 h water-soaking were significantly improved at the UF/MDI content level of 5%/1%. The IB strength dramatically increased, while TS and WA decreased with the use of dual resins. With increased weight ratio of wheat straw to wood particles, the bending properties, IB strength, TS and WA deteriorated. Pure wheat straw boards had the lowest properties. Wood particles in substitution for part of straw materials helped improve the panel properties. The results demonstrated that steam explosion modification and/or its combination with UF/MDI dual resin system can be a feasible approach to improve the bonding strength for wheat straw based particleboards.

Optimisation of wheat straw Triticum drum kraft pulping

This paper explains the problems brought about by the raw material and pulping method used in the Afyon-SEKA Pulp Mill producing bleached pulp from mixed wheat straw ( Triticum drum L.) (65%) and reed ( Phragmites communis) (35%). The use of mixed raw material causes such problems, as heterogeneous pulping, low freeness level, drainage difficulties and wet sheet breaks during the papermaking operations. In addition, silica in raw material results in rather serious difficulties during recovery process. To overcome these problems, first of all, pulping of wheat straw and reed had to be carried out separately. In this case, sulphate pulping characteristics of wheat straw were investigated and optimum parameters were found to be: active alkali charge 14%, sulphidity 20%, maximum temperature 160 °C, time to maximum temperature 55 min, time at maximum temperature 40 min and liquor to straw ratio 4:1. Some properties of wheat straw sulphate pulp produced at optimum cooking conditions were determined to be: screened yield 42%, kappa number 31, SCAN viscosity 1114 ml/g, breaking length 9.8 km, burst index 4.6 kPa m 2/g, tear index 5.1 mN m 2/g and brightness 29 ISO%. Consequently, it was possible to produce bleachable grade pulp from pure wheat straw in a shorter pulping time and lower active alkali than that of Afyon-SEKA Pulp Mill. Thus, this study showed that production capacity of the mill could be increased and freeness level of pulp improved.

Mineral elements in the important cultivated mushrooms Agaricus bisporus and Pleurotus ostreatus

The mineral elements of Agaricus bisporus and Pleurotus ostreatus (separately in the caps and stipes of the fruit body) were analysed. The main conclusions are: 1. 1. The classical (conventional) and the new cultivation methods produce different mineral compositions in champignon. The new method (on pure wheat straw) produced lower B, Ca, Cu, Na, Zn and higher K, Fe, Mg, Ni, P and Ti concentrations. 2. 2. The caps of fruit bodies have, in general, greater concentrations of mineral elements than the stipes in both A. bisporus and P. ostreatus. The exceptions are Ba, Cd, Cr, Li and Sr, whose concentrations are approximately identical in caps and stipes). 3. 3. A. bisporus has higher P, K, Ca but lower trace element concentrations than P. ostreatus, which has higher Mg, B, Cd, Fe and Mn concentrations. 4. 4. Accumulation of heavy metals was not found in the samples examined.