Addition Of Wheat Straw Research Articles

Does higher ratio of wheat straw addition decrease PAHs degradation in PAHs-contaminated paddy soils and PAHs concentrations in rice?

There are considerable studies focusing on impacts of straw returning on PAHs degradation and bioavailability in PAHs-contaminated upland soils, while similar research in paddy soils is limited. Incubation experiments and pot trials were conducted to study effects of straw returning on PAHs degradation in paddy soils and PAHs accumulation in rice, respectively. There are threshold effects of straw returning on PAHs degradation in PAHs-contaminated paddy soils. The inflection point of PAHs degrading was recorded under 0.8 % wheat straw treatment (conventional (CS) and pretreated wheat straw (PS)), which increased PAHs degradation by 18.13–32.36 %. The lowest PAHs concentrations in rice were recorded under 1 % straw (CS and PS) treatment, which was attributed to the highest PAHs degradation in rhizosphere soils. Compared to CS treatment, PS treatment significantly (p < 0.05) increased PAHs degradation by 7.93–10.28 % and PAHs concentrations in rice by 12.38–45.87 % due to that increasing dissolved organic carbon (DOC) enhanced PAHs concentrations in porewater of rhizosphere soils. Higher diversity enhanced the metabolic pathways and function genes to degrade PAHs by improving bacterial phenotypes and biochemical processes under 1 % wheat straw and PS treatment. The present study firstly demonstrated that the effects of straw returning on PAHs degradation in PAHs-contaminated paddy soils and PAHs concentrations in rice depended on amount and methods of straw returning.

Properties of biochars derived from different straw at 500℃ pyrolytic temperature: Implications for their use to improving acidic soil water retention

Climate change cause extreme weather effects with temperature increases and drops in humidity, such as drought and heatwaves, which will lead to more evaporation in arid and semi-arid lands. The application of biochar made from crop straw without burning to farmland can effectively improve the water retention capacity of soil. A testing program has been carried out in a climate simulation laboratory to study the effects of different straw biochars on the cracking and evaporation of soils due to drying. Biochar from wheat straw (WS), corn straw (CS) and rice straw (RS) is produced at a pyrolysis temperature of 500℃. Thermogravimetric analysis and elemental analysis are carried out to obtain the properties of the biochar. Five percent of WS, CS and RS biochar by weight is added to acidic soil. Digital camera and digital image processing technology are used to analyze the crack morphology of the samples during evaporation. The results indicate that the RS biochar has the highest ash content (32.5 %), CS biochar has the highest content of volatile solid (25.36 %) and WS biochar has the highest content of fixed carbon (55.38 %). Biochar can effectively improve the water retention capacity of soil. The final water contents of the WS, CS and RS biochar soil samples are 132.3 %, 101.0 %, and 20.7 % respectively higher than that of the soil without biochar. Moreover, biochar can effectively reduce the degree of soil cracking. The addition of WS, CS and RS biochar can reduce soil cracking by 9.21 %, 16.57 %, and 7.46 %, respectively. WS contains more total cellulose than CS and RS, so WS biochar is the best choice to improve soil water retention ability. Therefore, biochar technology helps to optimize soil water retention while avoiding environmental pollution from straw burning.

Inhibition of microbially mediated total organic carbon decomposition in different types of cadmium contaminated soils with wheat straw addition

Wheat straw returning is a common agronomic measure in the farmland. Understanding organic carbon transformation is of great significance for carbon budget under the premise of widespread distribution of cadmium (Cd) contaminated soils. An incubation experiment was conducted to assess the influence of Cd contamination on the decomposition and accumulation of total organic carbon (TOC) as well as the composition and abundance of bacterial communities in eight soil types with wheat straw addition. The results showed that inhibition of Cd contamination on microbially mediated organic carbon decomposition was affected by soil types. The lower cumulative C mineralization and higher TOC content could be observed in the acidic soils relative to that in the alkaline soils. The content of Cd in soil exhibits different effects on the inhibition in decomposition of TOC. The high dosage level of Cd had stronger inhibitory impact due to its high toxicity. The decomposition of TOC was restricted by a reduction in soil bacterial abundance and weakening of bacterial activities. Redundancy analysis (RDA) indicated that Proteobacteria and Gemmatimonadetes were abundant in alkaline Cd-contaminated soils with wheat straw addition, while Bacteroidetes dominated cumulative C mineralization in acidic Cd-contamination soils. Moreover, the abundance of predicted functional bacteria indicated that high-dose Cd-contamination and acid environment all inhibited the decomposition of TOC. The present study suggested that pH played an important role on carbon dynamics in the Cd-contaminated soils with wheat straw addition.

Co-pyrolysis of chrome-tanned leather shavings with wheat straw: Thermal behavior, kinetics and pyrolysis products

The thermal behavior and kinetics of chrome-tanned leather shavings (CLS)/wheat straw (WS) blends at different mass ratios during co-pyrolysis were investigated, and the pyrolysis products were characterized. Model-free isoconversional and master-plots methods were applied to determine kinetic triplet of the pyrolysis/co-pyrolysis of CLS, WS and their blends based on thermogravimetric (TG) analysis. Results showed that the activation energy for CLS pyrolysis was reduced by the addition of WS, and a synergistic promoting effect predominated across the majority of temperature ranges and feedstock compositions during the co-pyrolysis process. TG-Fourier transform infrared spectrometry-Mass spectrometry analysis showed the changes in evolution profiles of H2O, CO, CO2, HNCO and pyrrole during pyrolysis. The pyrolysis solid residues were characterized and results indicated that the addition of WS to CLS can increase solid residue yield and potentially inhibit the formation of hexavalent chromium during pyrolysis. This study helps to foster a promising solution for the valorization and safe disposal of chromium-containing solid wastes from leather industry.

Mechanical and Tribological Characterization of Green Composite Fabricated by Wheat Flour and Wheat Straw

The excessive use of traditional plastic polymers has elevated environmental concerns. These polymers are extremely difficult to dispose off. It takes a long time for plastics to disintegrate. These plastics enter into river water through several channels, and for a considerable amount of time, it flow with the stream. Numerous marine creatures get sick after ingesting the trash and animals on the ground. Therefore, an effort is made for such a green composite which do not harm the creatures and animals. A green composite material was fabricated by compression molding using wheat flour (WF) as a matrix and wheat straw (WS) as a reinforcement. Both materials are natural and digestible for living beings. WS was lighter than WF, so the addition of WS made the composite lighter. A poly-lactic acid (PLA) coating was done over the surface of the WF-WS composite to make it water resistant and wear resistant. The pin on disc wear test was performed to get the specific wear rate of the composite. The air jet erosion was also carried out to know the erosion value of the composite. The thermo-gravimetric analysis was performed to investigate the thermal stability of the composite in order to ensure the use of the composite up to 200° C. It was found that the addition of WS fibers in the composite increased thermal stability. The scratch test was conducted to find out the strength of the 1 mm thickness coating. The WF-WS composite with PLA coating can be used in non-load bearing components and light weight applications. It can also be used for eco-friendly food packaging materials.

Migration of Melamine and Its Derivatives from Melamine/Bamboo/Wheat Straw-Made Tableware Purchased from Internet Markets or Retail Shops in China.

The ecofriendly and sustainable concept of bamboo- and wheat straw-made tableware has gained attention in recent years. However, it is necessary to note that these kinds of tableware are composed of melamine (MEL)-formaldehyde resin with the addition of bamboo fibers or wheat straw. This study aims to explore the potential migration of MEL and its derivatives from the tableware and conduct a risk assessment. The study involved 46 bowls or cups purchased from Internet markets or retail shops in China, whose raw materials included MEL, bamboo, and wheat straw. There were four pieces of glass- or ceramic-made tableware used as the control group. Migration testing was performed according to the test conditions selected from the European Union Reference Laboratory for Food Contact Materials. Considering the realistic worst-case scenario, we measured the concentrations of MEL and its derivatives in food simulants using ultra-performance liquid chromatography-tandem mass spectrometry and estimated the exposure risks for adults and 1-year-old infants. MEL and its derivatives could migrate from MEL-, bamboo-, and wheat straw-made tableware with varying concentrations. The total migration was ranked as follows: bamboo-made tableware > MEL-made tableware > wheat straw-made tableware > glass- or ceramic-made tableware (p < 0.001). The primary contributor to the total concentration for MEL- and bamboo-made tableware was MEL, whereas cyanuric acid (CYA) was the main contributor for wheat straw-made tableware. Based on the total concentration of MEL and its derivatives and the strictest TDI value, the proportions of the calculated hazard quotient ≥1 for MEL-, bamboo-, and wheat straw-made tableware in adults were 53.50%, 92.30%, and 1.90%; and the proportions in 1-year-old infants increased to 86.00%, 100.00%, and 7.40%. The utilization of MEL-, bamboo-, and wheat straw-made tableware could be regarded as a significant source of human exposure to MEL and its derivatives. It is advisable for both adults and infants to refrain from using tableware manufactured with MEL and bamboo fiber, as it may increase the susceptibility to MEL-related diseases.

Impact of organic amendments addition to sandy clay loam soil and sandy loam soil on leaching process of chlorantraniliprole insecticide and bispyribac-sodium herbicide

The leaching of two pesticides, cholantraniliprole (CAP) and bispyribac-sodium (BPS) in sandy clay loam soil (soil A) and sandy loam soil (soil B) were examined, by soil columns under laboratory conditions. In addition, the effect of adding 5% biochar and wheat straw to the soils on the leaching of CAP and BPS was studied. It is clear from the results that BPS is more leachable than CAP in all soil columns, and more leached to soil B. It was found that the addition of biochar and wheat straw has a significant effect on the movements of these pesticides and can be used to reduce the environmental impact. For CAP, 71 to 97% and 84 to 97% were recovered from the soil A columns and soil B columns, respectively, while for BPS, 94 to 99% were recovered from columns of soil A and soil B.

Inoculation with Bacillus alters nitrogen uptake and metabolism in roots of Diospyros lotus under wheat straw addition in soil

Inoculation with Bacillus alters nitrogen uptake and metabolism in roots of Diospyros lotus under wheat straw addition in soil

Simulation of dissolved-oxygen distribution in matrix particles during the aerobic composting process of sewage sludge with two-region model

The anaerobic cores of compost particles generate and emit harmful off-gases during composting, and the air-immobile region is a significant factor contributing to an anaerobic environment. However, existing research methods cannot predict the aerobic/anaerobic region distribution of compost particles in air-mobile and air-immobile regions under different flow conditions on the compost pile. Therefore, this study obtained the characteristic parameters of the air-immobile region during composting with different bulking agents using a two-region model (TRM). Furthermore, a fitted equation coupled model was developed to numerically simulate the relationship between the surface oxygen concentration (CO2,S) and aerobic/anaerobic layer thickness (LA/LANA). The results showed that adding peanut shells and wheat straw significantly decreased the proportions of air-immobile regions by 0.02 and 0.07, respectively in the curing phase compared with rice bran treatment (increased by 0.06), although there was no significant change in the early stages of composting. And, the addition of peanut shells and wheat straw enhanced the mass transfer of porous gases between the air-mobile and air-immobile regions of the compost piles during the thermophilic phase (rice bran treatment increased by 0, both peanut shell and wheat straw treatments increased by 0.001); however, there were no observable differences in initial-material, temperature-increasing, and curing phases. The O2 concentrations in the air-mobile and air-immobile regions decreased, and the LANA gradually increased as the composting process progressed and the height of the compost pile increased. The fitted equation coupled model simulates the actual situation well and can support the accurate regulation of harmful gas production in composting systems.

Transformation behavior of potassium-containing minerals during co-gasification of petroleum coke and biomass

Interactions between alkali metals in biomass and silicon and aluminum minerals in petroleum coke (PC) are closely related to the gasification reactivity and the deactivation of active K-catalyst during co-gasification. This study comprehensively investigated the evolution of K-containing minerals and their impact on the gasification reactivity and ash fusion characteristics during the co-gasification of PC and wheat straw (WS). The results showed that the addition of WS improved the gasification reactivity of PC, but only up to a certain point due to the K-containing mineral evolutions at high temperatures. Adding WS below 20 wt% resulted in the deactivation of K and the formation of inert kaliophilite and nepheline. However, when WS addition exceeded 20 wt%, a substantial amount of K acted as an active K-catalyst, significantly increasing gasification reactivity. The shrinking core model was found to be more appropriate than the homogeneous model when considering gasification kinetics during co-gasification.

Effect of Wheat Straw Addition on Organic Carbon Mineralisation and Bacterial Community in Orchard Soil

Crop straw returning can stimulate organic carbon mineralisation and C sequestration simultaneously, which affects soil fertility. However, the effects of crop straw on organic carbon mineralisation and soil bacterial community in orchards are not fully understood. A 90-day incubation experiment was performed to investigate the effects of wheat straw (0, 1, 4, 6, 8, and 10 t·ha−1) on organic carbon mineralisation and bacterial community in orchard soil. Wheat straw addition enhanced the CO2 efflux rate and cumulative organic carbon mineralisation (Cmin), especially high level. The trend of CO2 efflux rate was increased sharply, especially during the early incubation stage (the first 13 days), and then decreased in the later phase. Furthermore, soil bacterial community structure displayed distinct changes in response to straw addition. Available nitrogen, potassium, organic carbon, β-glucosidase, and pH were the key factors driving soil bacterial community changes. The bacterial taxa in networks were significantly related to Cmin. The Proteobacteria, Actinobacteria, and Chloroflexi were positively related to Cmin; while Planctomycetes, Patescibacteria, and Gemmatimonadetes showed a negative relationship with Cmin by correlation and redundancy analyses. Co-occurrence network analysis showed a discrete bacterial network in 10 t·ha−1 of straw, while cohesive networks in others. Straw addition promoted organic carbon mineralisation by improving the soil biochemical properties, including enzymes activities, and nutrient contents, and regulating bacterial community composition. On the whole, 4 t·ha−1 of straw could be considered an economical level for improving soil organic carbon and bacterial community stability in orchards.

Assessing the efficacy of water management and wheat straw addition in mitigating methane emissions from rice paddy fields

AbstractTo improve the quality of soil, agriculture typically uses organic additions like wheat straw (WS). Water management (WM) methods such as alternative wetness and dryness irrigation (AWDI) in paddy rice farming can increase water use efficiency and reduce greenhouse gas (GHG) emissions. In this study, a randomized complete block design (RCBD) pot greenhouse experiment was conducted to assess the effects of WM (CFI (continued flooding irrigation) and AWDI), WS (15.0 and 30.0 ton ha−1), and their interaction (WS*WM) on CH4 emissions and rice yield in a paddy calcareous soil cultivated with rice. The largest CH4 emission occurred 30 and 70 days following rice planting. Single applications of WS at 15.0 and 30.0 ton ha−1 significantly increased CH4 emissions by 19.60% and 68.70% (P &lt; 0.01), respectively, compared to the Control. Compared to CFI, the AWDI reduced CH4 emissions by 31.20% (P &lt; 0.01). The correlations between AWDI and CH4 emissions in days after rice planting were significantly negative at the 0.01 level based on Pearson correlation. Adding WS in the AWDI significantly decreased CH4 emissions by 27.70 and 25.64% in 15.0 and 30.0 ton ha−1 added WS (P &lt; 0.05), respectively, compared to sole WS. Both rates of WS resulted in a considerable increase in biomass and rice grain compared to the Control, while the AWDI had no significant effect on biomass and grain yield. Our data showed significant interaction between AWDI and WS on biomass. Our study shows that the AWDI saved 18.50% water compared to the CFI.

Co-pyrolysis of biosolids with lignocellulosic biomass: Effect of feedstock on product yield and composition

Co-pyrolysis technology is an effective method to reduce heavy metal concentration in biochar produced from biosolids. In the current study, the effect of co-pyrolysis feedstock on product yield and properties was studied by mixing Biosolids (BS) with Wheat Straw (WS) and Canola Straw (CS) in a 3:1 mass ratio and carrying out thermal decomposition at 700 °C in a fluid bed reactor. This study found that the feedstock ash content and the volatile matter had a significant effect on biochar, oil, and gas yields from co-pyrolysis. The results also indicated that the addition of WS and CS feedstock notably reduced As, Cd, Cr, Cu, Ni, Pb, Se, and Zn concentrations in the biochar, due to the net effect of dilution and synergistic effects. BS-WS and BS-CS co-pyrolysis reduced Cu concentration in biochar by 61.6% and 63.3%, respectively, and Zn concentration by 66.4% and 64.4%, respectively. Lignocellulosic biomass addition also reduced biochar yield and improved C, H, and N content, along with the calorific value and the thermal stability of biochar. C content was increased by 36.9% in BS: WS biochar and 43.3% in BS: CS biochar compared to solely biosolids’ biochar. The calorific value of biochar was increased by 43.5% and 52.9% in BS-WS biochar and BS-CS biochar compared to biosolids’ biochar. During co-pyrolysis, CS addition produced oil with the lowest mole percentage of nitrogenated compounds. However, the addition of WS and CS increased co-pyrolysis oil acidity. Biosolids co-pyrolysis with WS and CS also increased the gas yield and the heating value compared to biosolids pyrolysis. Furthermore, the synergistic effect between biosolids and co-feedstocks resulted in increased gas yields and decreased oil and biochar yields.

The impact of heavy metal contamination on soil quality and plant nutrition. Sustainable management of moderate contaminated agricultural and urban soils, using low cost materials and promoting circular economy

A three-year experiment was conducted over six different soils, from northern and central Greece. The soils samples derived from both rural and urban environments, and they were moderately contaminated with heavy metals (Cu, Cd, Pb, Zn). Experiments were carried out by adding crop residues of wheat straw, cultivated in the plain of Thessaly, in the soil samples. Preliminary experiments were carried out to find the optimal mixing ratio of straw with soils, as well as the cut size, the temperature and humidity of the straw before its incorporation. The addition of wheat straw caused significant changes in the visual, physical, chemical, nutritional and microbiological quality indices of the soils studied. The indices related to the fertility and nutritional capacity of the soil samples were, in most cases, significantly improved, enhancing the soil health. Furthermore, the use of the straw reduced the availability of toxic metals, increasing, on the other hand, the availability of trace elements. Although the use of straw for improving soil properties has been known since ancient times, its use for polluted soil remediation is a matter of concern. A significant number of environmental and economic problems could be addressed if the principles of the circular economy were taken into account by decision-makers. Wheat straw, could be a key factor for soil health improvement, increasing its fertility and limiting the risks of toxic pollutants.

Effect of natural biomass fillers on the stability, degradability, and elasticity of crop straws liquefied polyols‐based polyurethane foams

AbstractOilseed rape straw (OS), rice straw (RS), wheat straw (WS), and corn stover (CS) particles were used to reinforce bio‐polyols based polyurethane (PU) foams. The influence of crop straws (XS) fillers on the stability in water, degradability in soil, thermal stability, and elasticity of foams were investigated. The incorporation of OS and CS particles in the PU matrix increased the stability of reinforced foams in water, while the addition of WS and RS particles made foams lower stability in water. PU foams reinforced by XS particles displayed mass reductions up to 53.8% after burying in soil for 250 days. The reinforced foams were more stable under heating but the enhancement of thermal stability trended to disappear after water immersion or soil burying. The reinforced foams showed better elasticity that incorporations of OS and CS made PU foams higher height recovery percentage, while RS and WS made the recovery percentage decline firstly and then enhance during three times compressions. All these four XS particles are suitable to modify bio‐based PU foams, especially OS and CS particles appear to be more outstanding in preparing foams with higher stability in water, degradability in soil, thermal stability, and elasticity than RS and WS particles.

The impact of wheat bran and molasses addition to caramba mix silage on feed value and in vitro organic matter digestibility

BackgroundThe fermentation process in silage is an inherently uncontrolled process that results in significant nutritional losses. Supplementing silage with different additives may boost nutrient and energy recovery during fermentation, which in turn can boost animal productivity. However, the impact of wheat bran and molasses addition on feed value of caramba mix silage is unknown. MethodsThis study determined the impact of molasses and wheat straw addition on fermentation and in vitro organic matter digestibility of caramba mix silage. Caramba was cut at harvest maturity and subjected to five different treatments, i.e., control, addition of 5% and 10% molasses, and addition of 5% and 10% wheat bran. Caramba mix and additives were mixed and ensiled into laboratory type 1 L glass containers. Silage fermentation, chemical and microbiological composition, and in vitro metabolic energy content in silages were determined 60 days after the initiation of treatments. ResultsDifferent chemical and microbial properties of silage were significantly altered by the addition of molasses and wheat bran. The addition of 10% molasses resulted in the highest values of all measured traits of Caramba mix silage. The dry matter was 27.00%, 28.44%, 33.93%, 32.67%, and 30.61% in control, 5% molasses, 10% molasses, 5% wheat bran and 10% wheat bran, respectively. Similarly, pH was 5.32, 4.89, 4.56, 4.62, and 4.39 in control, 5% molasses, 10% molasses, 5% wheat bran and 10% wheat bran, respectively. Likewise, crude protein was 14.58%, 13.03%, 16.23%, 14.75%, and 16.42% in control, 5% molasses, 10% molasses, 5% wheat bran and 10% wheat bran, respectively. ConclusionIt is concluded that addition of molasses and wheat bran to the caramba mix silage increased the chemical, and microbiological qualities. Particularly molasses improved the digestibility of silage. Therefore, it is recommended that 10% molasses should be added during the fermentation of the silage to improve chemical, and microbiological properties of Caramba mix silage.

Sound absorption, structure and mechanical behavior of konjac glucomannan-based aerogels with addition of gelatin and wheat straw

• KGM, gelatin and wheat straw were used to prepare aerogels for sound absorption. • Addition of gelatin contributes to formation of more small open pores. • Multi-cavity structure of wheat straw is beneficial to sound absorption. • Mechanical strength is improved with finer pores, thicker walls and nest structure. • Gelatin and wheat straw addition is considered in modeling of compressive behavior. Environment-friendly konjac glucomannan (KGM)-based aerogels with addition of gelatin and wheat straw are produced by freeze-drying method to have promising sound absorption performance, thermal stability and mechanical property. Results show that gelatin addition can significantly improve sound absorption performance at medium and high frequencies, as well as mechanical strength, because of the positive effect on increase of small open pores. Appropriate little addition of wheat straw can improve the sound absorption property due to the dissipation effect of sound energy by the unique multi-cavity structure. Better sound absorption performance is achieved than melamine foam, while the best result is obtained with a noise reduction coefficient of 0.38, and the coefficient reaches 0.88 at 4500 Hz. Wheat straw addition leads to strength reduction firstly but enhancement when the addition is more than 1.00%, where fine wheat straw bars form nest structures for strengthening. For potential loading capacity evaluation, a mechanical model is proposed and confirmed to be effective in predicting compressive stress – strain relationship of KGM-based aerogels with consideration of gelatin and wheat straw addition.

Influence of inoculating microbes on municipal sewage sludge composting

The influence of Ilkompost and Micromix bacterial consortium inoculation during sewage sludge (SS) with wheat straw (WS) composting was assessed. The effect of inoculation on compost quality parameters such as pH, temperature, nutrient contents and C/N, bacterial and fungal population were determined. Compared to the control treatment, the temperature of piles and population of microorganism increased after inoculated bacterial consortiums at the beginning of compost. But, WS addition did not effect on compost quality parameters and microbial population. Fungal and bacterial population, the peak temperature, or heating rate, of Micromix bacterial consortium based on Streptomyces pratensis, Bacillus mesentericus, Azotobacter chroococcum inoculated treatments was clearly higher than that of Ilkompost bacterial consortium based on Pediococcus pentosaceus, Streptomyces sindenensis, Bacillus megaterium inoculated treatments

Annual Nitrogen Removal Efficiency and Change in Abundance of Nitrogen Cycling Microorganisms in Swine Wastewater Treated by Crop Straw Materials

Based on previous research, using straw material to treat swine wastewater can effectively reduce the concentration of nitrogen (N); however, the annual N-removal efficiency and change in the abundance of N-cycling functional genes remain unclear. In this study, four treatments (wheat straw, rice straw, corn stalk, and CK) were set up, with the aim of studying the annual N-removal efficiency and change in the abundance of functional genes. Our results showed that:① the total nitrogen (TN) removal and NH4+-N removal efficiency were the best in the first six months and were significantly reduced in the following six months. In addition, the TN removal and NH4+-N efficiency in straw and wheat straw were better than those in corn straw. The TN-removal efficiency in straw and wheat straw were 32.81%±11.34% and 32.99%±9.60%, respectively. The NH4+-N removal efficiency in straw and wheat straw were 35.3%±13.23% and 34.97%±12.00%, respectively. ② The abundance of N-cycling functional genes significantly increased by the addition of straw materials, compared with that of the CK (P<0.05). The average abundances of nirK, nirS, and hzsB were 6.45×109 copies·L-1, 6.18×109 copies·L-1, and 2.31×109 copies·L-1, respectively. The average abundances of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) were 6.12×1010 copies·L-1 and 4.93×109 copies·L-1, respectively. The average hzsB gene abundance was 2.31×109 copies·L-1. The average abundance of 16S rRNA in the treatment was 8.90×1010 copies·L-1. The abundances of hzsB and nirS genes in the straw and wheat straw were higher than those in the other treatment, indicating that the activities of anaerobic ammonia oxidation and denitrifying microorganisms were significantly increased by the addition of straw and wheat straw (P<0.05). In addition, the abundance of AOA and AOB genes were increased in wheat straw, suggesting that wheat straw could promote nitrification. The results provided data supporting the molecular mechanism of nitrogen removal in swine wastewater treatment with straw materials.

Effects of Straw Biochar on Heavy Metal Cu in Soil Under Different Conditions

ABSTRACT Biochar has been widely deemed as a soil conditioner to modify the physicochemical and biological properties of soil. In this research, the influence of different biochar application conditions on the effect of heavy metal Cu in soil was detected. In batch experiments, the combinations could definitely enhance the adsorption abilities, and under the combination ratio of 4 wt % biochar, 3 wt % wheat straw, and 5 wt % cow manure compost in the soil, the adsorption rate would be more than 97% in 60 mins. The adsorption kinetics showed the adsorption processes were multiphase diffusion processes and the conversion of activation energy in soil surface was obvious, while the isotherms analysis suggested the adsorption of Cu by the soil under various amendments was mainly monolayer adsorption as well as some other complex reactions. However, in the eluviation experiments, more and more Cu was lost in the leaching solutions when wheat straw and compost were added into the soil as well as biochar. pH values changes indicated that the connections among Cu and solids may be mostly related to the precipitation reaction in the eluviation experiments. FTIR analysis implied that the addition of wheat straw and compost in the biochar could indeed enhance the reaction between heavy metal Cu and soil, however, the reactions were rather complicated, and under the eluviation condition, there was not enough time to form the stable bonds, so more Cu was dissolved into the leaching water.