Effects Of Different Mixing Ratios Research Articles

Effects of the fermentation quality and microbial community of waxy maize mixed with fodder soybean silage.

Waxy maize (Zea mays L. sinensis Kulesh) is highly regarded for its high nutritional content and unique taste. Although the stalks and leaves contain high carbohydrate levels after ear harvesting, inadequate crude protein (CP) limits the utilization and promotion of waxy maize silage in animal husbandry. In this study, waxy maize and fodder soybeans were mixed for sowing in different proportions [1:0 (CK), 1:1 (A1), 1:2 (A2), 1:3 (A3), and 1:4 (A4)] to investigate the effects of different mixing ratios on the growth of the waxy maize, the chemical indices, fermentation quality, and the microbial community of the mixed silage after ear harvesting. The mixed planting of waxy maize and fodder soybeans in different proportions had no effect on the yield and quality of the waxy maize ears and increased the aboveground biomass after ear harvesting. After ear harvesting, the neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents significantly decreased, and the CP content and relative feeding value (RFV) gradually increased in the mixed silage. The pH of the treatments was lower than 4.2 except for A4, and the lowest ammonia nitrogen (AN) concentration was observed in A3. With increasing proportions of fodder soybeans, the abundance of beneficial bacteria increased and that of harmful bacteria decreased; Firmicutes and Lactobacillus were the dominant phylum and genus, respectively, and both increased gradually. Redundancy analysis (RDA) revealed that the fermentation indices affecting the microbial community composition in the silage were inconsistent among the different mixed sowing combinations. The Mantel test showed that the composition of the microbial communities in the treatments was significantly correlated with the ADF, water-soluble carbohydrate (WSC), and propionic acid (PA) contents. Comprehensive analysis revealed that the optimal mixed sowing ratio of waxy maize to fodder soybeans was 1:3, and waxy maize and fodder soybeans silage can increase the utilization of aboveground biomass and improve the fermentation quality and feeding quality of silage by changing the microbial community. These findings lay a certain theoretical foundation for improving the utilization of waxy maize.

Optimizing the Mixing Ratios of Source-Separated Organic Waste and Thickened Waste Activated Sludge in Anaerobic Co-Digestion: A New Approach

Anaerobic co-digestion (AnCoD) presents several advantages over conventional mono-digestion. Various factors can impact the efficiency of the co-digestion process, including the mixing ratio of the feedstocks. This study primarily investigates the effects of different mixing ratios on methane production during the co-digestion of source-separated municipal organic waste (SSO) with thickened waste activated sludge (TWAS). While the C/N or COD/N ratio has generally been used for optimizing the mixing ratios of co-digested feedstocks, a new approach is introduced in this study to evaluate the effects of the lipid, protein, and carbohydrate (L:P:C) ratios on the efficiency of AnCoD with respect to methane production, kinetics, and synergism at mixing ratios of TWAS:SSO of 10:90, 30:70, 50:50, 70:30, and 10:90. AnCoD improved methane production and kinetics relative to TWAS at all mixing ratios, the highest of which was at the 10:90 ratio, corresponding to a methane yield, maximum methane production rate, and an L:P:C ratio of 353 mL CH4/g COD, 25 mL CH4/g COD/d, and 8:1:18, respectively. Improvements in methane yields and kinetics due to synergy were evident at all mixing ratios, with improvements in methane yields ranging from 11 to 23% and improvements in kinetics ranging from 18 to 58%. Improvements in methane yields and kinetics were insensitive to the feedstock composition beyond the 50:50 mixing ratio.

The Effect of Scrap Tires and Reclaimed Asphalt Pavement on the Behavior of Stone Columns

The objective of this investigation is to understand how to use waste tires to surround stone pillars and mix gravel with recycled asphalt pavement (RAP) and stone pillars to provide an environmentally friendly and cost-effective weak layer improvement method. To study the behavior of such stone columns, experiments were conducted in units consisting of a single stone column with recycled asphalt pavement as filling material and a single stone column covered with old tires. To test the effect of different mixing ratios, rapeseed content was selected from 0% to 100%. Elasticity tests were conducted on cladded and nonclad stone column samples. Furthermore, direct shear tests were conducted on samples with different ratios of gravel and rapeseed mixtures. The results of the load-bearing capacity test show that the cover of the stone columns with old tires can significantly increase the load-bearing capacity. Replacing 25% of natural stone column aggregates with RAP increases the load capacity. But as the percentage of RAP in the mixture increases from 25% to 100%, the loading capacity decreases. Another advantage is the reinforced stone column. From the point of view of ecology, an advantage is the use of recyclable materials.

A new type of mixed vegetable insulating oil with better kinematic viscosity and oxidation stability

• The molecular dynamics model of mixed vegetable insulating oil with different proportion was established. • The effects of different mixing ratios on the kinematic viscosity of mixed oil were studied by molecular dynamics. • The difference of oxidation stability between palm fatty acid ester and rapeseed oil was studied by First-Principle. • A mixing ratio with good kinematic viscosity and oxidation stability was obtained. Natural ester is a new type of environment-friendly energy, and the research on its performance is crucial in order to be widely popularized and applied in electrical equipment. The mixing of different natural esters can ameliorate the performance handicap of natural esters. Therefore, two widely applied natural esters, rapeseed oil and palm fatty acid ester (PFAE) were selected in this paper. The kinematic viscosity and oxidation stability of mixed oil were analyzed on the basis of the establishment of the mixture of two oils with different mixing proportion by simulation. Results indicate that the kinematic viscosity of the mixed oil decreased with the addition of PFAE. The kinematic viscosity of the mixed oil decreased by 51.3% when the mixing ratio was 80% rapeseed oil and 20% PFAE. The addition of short chain oil molecules increases the mean square displacement, mean-square radius of gyration and free volume of the mixed oil. The oil molecules in the mixed system have fewer tangles and reduced internal friction between them. DFT calculation shows that numerous electron traps in PFAE provide a channel for the transition of valence electrons. The methyl group in PFAE has strong positive electrostatic potential and strong electron affinity, which makes the oxidation stability of PFAE lower than that of rapeseed oil. Therefore, 80% rapeseed oil and 20% PFAE are the best mixing ratio in this study. This ratio has the best improvement on the kinematic viscosity of the mixed oil and the least influence on the oxidation stability.

Effects of different Bacillus licheniformis and Bacillus subtilis ratios on nutrient digestibility, fecal microflora, and gas emissions of growing pigs.

The objective of this study was to evaluate the effects of different mixing ratios of Bacillus licheniformis and Bacillus subtilis in diets on nutrient digestibility, fecal microflora, and odor gas emissions of growing pigs. A total of four crossbred ([Landrace × Yorkshire] × Duroc) barrows with average body weight (BW) of 41.2 ± 0.7 kg were randomly allotted four diets over four periods in a 4 × 4 Latin square design. Treatments were as follows: Control (CON, basal diet), CON + 0.2% probiotic complex (L4S6, B. licheniformis and B. subtilis at a 4:6 ratio), CON + 0.2% probiotic complex (L5S5, B. licheniformis and B. subtilis at a 5:5 ratio), CON + 0.2% probiotic complex (L6S4, B. licheniformis and B. subtilis at a 6:4 ratio). Dietary probiotic supplementation showed higher crude protein (CP) digestibility values and lower Escherichia coli counts in fecal samples than the CON group (p < 0.05). There was no significant difference in NH3 or H2S emission until day 3. The positive effect of H2S and NH3 emissions was detected earlier with the L4S6 and L5S5 compared to the L6S4, which had a lower ratio of B. subtilis. Both the L4S6 and L5S5 probiotic complexes significantly decreased the fecal H2S and NH3 emission in days 4 and 6 (p < 0.05). On day 7, all probiotic complexes decreased (p < 0.05) H2S and NH3 emissions than the CON group. Our results agreed that the dietary supplementation of Bacillus licheniformis and Bacillus subtilis complexes in growing pigs can significantly improve CP digestibility and reduce fecal E. coli counts, NH3 and H2S emissions. Notably, the higher mixing ratio of Bacillus subtilis in probiotic supplementation is more effective in reducing the odor of manure.

Mixing of arsenic-rich groundwater and surface water in drinking water distribution systems: Implications for contaminants, disinfection byproducts and organic components

The utilization of groundwaters containing high levels of arsenic (As) for drinking water purposes presents major health and economic challenges for water utilities. One low-cost approach is to mix arsenic-rich groundwater (GW) with arsenic-free surface waters (SW) to achieve acceptable As levels. In this study we investigated the effect of different mixing ratios on water quality in an eastern Croatian water distribution system (WDS). To investigate the effects of mixing on drinking water quality, we measured the organic matter (OM) composition, disinfection byproduct (DBP) and metal concentrations in differently mixed ratios of GW and SW within the WDS. Fluorescence analysis revealed that the GW and SW had similar OM composition, with an almost equal ratio of humic- and protein-like OM throughout the WDS despite fluorescence indices revealing slightly different OM sources between the two water types. The tyrosine-like OM component was more variable, increasing during warmer months and towards the end of the WDS, most likely due to enhanced biofilm formation. Arsenic concentrations decreased to below 10 μg/L in the second half of the sampling campaign. Acceptable water quality was achieved after a period of destabilization and solubilization of loose deposits within the WDS resulting in their mobilization caused by water quality changes. Principal component and classification analysis, regression models and Spearman correlation coefficients revealed an association between As, OM and DBP concentrations with these correlations suggestive of their role in As mobilization in the WDS. Changing source waters, with different OM content and characteristics, corresponded to variable As release within the WDS.

Enhanced Conductivity in Highly Stretchable Silver and Polymer Nanocomposite Conductors.

In stretchable conductors, there is a trade-off relationship between the stretchability and conductivity which makes it difficult to increase both properties simultaneously. From a practical point of view, however, high conductivity is a more important parameter for real-world applications of wearable and mobile electronics. To obtain a highly conductive stretchable conductor, we developed a stretchable conductor composed of silver (Ag) flat-type microparticles, Ag nanoparticles and a polyester binder. The printed stretchable conductor was then sintered using the intense pulse light sintering technique. The effects of different mixing ratios of Ag flat-type particles and nanoparticles on dispersibility, printability, surface properties, conductivity, and stretchability were examined. Increasing the content of Ag-flat type particles in the composite improved dispersibility, printability, and conductivity. The stretchable conductor exhibited the outstanding conductivity of 5.5×106 S/m. Increasing the Ag nanoparticles content increased the stretchability of the conductor. As the nanoparticle content increased to 30%, the stretchable conductor showed the excellent stretchability of 210%, and withstood 2,600 repeated stretching cycles at a fixed tensile strain of 50%. The conductors also exhibited superb foldability during 10,000 repeated folding tests, up to a radius of 1 mm, without any failures.

Effects of Carbonization on the Co-Activation of Sludge and Biomass to Produce Activated Coke

Abstract Activated coke was prepared by mixing sewage sludge and waste poplar bark biomass from furniture manufacturing. The physical activation method of these feedstocks with steam for 1 h at 850 °C was implemented. The elemental composition, pore distribution, microstructure, and surface functional groups of the activated coke products were analyzed by proximate analysis, ultimate analysis, N2 adsorption, scanning electron microscopy, and Fourier transform infrared spectroscopy, respectively. The effects of different mixing ratios of sludge and biomass, preactivation carbonization temperature, and activation method on the activated coke were investigated. When the proportion of biomass was two-thirds of the total feedstock mass and the carbonization temperature was 300 °C, the produced activated coke had the highest specific surface area and the most extended micropore structure. Water vapor (steam) activation was found to be beneficial to the formation of oxygen-containing functional groups. This study established that steam is beneficial to pore expansion and promotes pore development. It was found that the carbonaceous feedstocks acquired initial porosity through carbonization in nitrogen, which proved to be instrumental in the ensuing activation process. After sequential carbonization and activation, the produced active coke acquired a higher specific surface area and microporosity, compared with the active coke produced by activation alone.

Enhanced Treatment of Pharmaceutical Wastewater by an Improved A2/O Process with Ozone Mixed Municipal Wastewater

A pilot-scale experiment is carried out for treating mixed wastewater containing pharmaceutical wastewater (PW) and domestic wastewater (DW), by a process that is a combination of hydrolysis acidification-ozone-modified anaerobic–anoxic–aerobic-ozone (A2/O) (pre-ozone) or hydrolysis acidification-modified A2/O-ozone (post-ozone). The effects of different mixing ratios of PW and DW and pre-ozone treatment or post-ozone treatment on the removal of nitrogen and phosphorus and chemical oxygen demand (COD) are compared and studied. The optimal ratio of PW in mixing wastewater is 30%, which has the optimal COD removal efficiency and minimum biotoxicity to biological treatment. The pre-ozone treatment shows more advantages in removing nitrogen and phosphate but the post-ozone treatment shows more advantages in COD removal. Analysis of dissolved organic matter (DOM) demonstrates that post-ozone treatment has a more significant effect on the removal of fulvic acid and humic acid than the effect from the pre-ozone treatment, so the COD removal is better. Overall DOM degradation efficiency by post-ozone treatment is 55%, which is much higher than the pre-ozone treatment efficiency of 38%. Microbial community analysis reveals that the genus Thauera and the genus Parasegetibacter take great responsibility for the degradation of phenolics in this process. All the results show that the post-ozone treatment is more efficient for the mixed wastewater treatment in refractory organics removal.

Development and application of a new similar material for fluid–solid coupling model test

Correct selection of similar materials is key to geomechanical model tests. According to similarity theories, a novel similar material for the fluid–solid coupling model test was developed to solve problems of low similarity and poor stability. A similar material is mixed with calcium carbonate, white cement, paraffin, quartz sand, silicone oil, talc, and iron powder. Quartz sand and talc powder are the main materials; white cement, calcium carbonate, and paraffin are glue; silicone oil and iron powder are regulators. The effects of different mixing ratios on the compressive strength, permeability coefficient, and specific gravity were studied using a single factor analysis method. The main components controlling the material properties were determined through numerous laboratory tests. The experimental results show that the new material strength is controlled by cement, paraffin, and calcium carbonate. Its permeability coefficient can be adjusted by altering the ratio of silicone oil and paraffin. Its specific gravity is mainly affected by iron powder. The new material can simulate low-strength and medium-strength rock materials with different permeabilities, and it can effectively solve the problem that mechanical properties and nonhydrophilic properties cannot be satisfied simultaneously. The material was successfully applied in geological model tests of fault water inrush.

Anaerobic co-digestion of fish processing waste with a liquid fraction of hydrothermal carbonization of bamboo residue

The effect of different mixing ratios of fish processing waste (FPW) with a liquid fraction (LF) of hydrothermal carbonization (HTC) of bamboo residues on biogas and methane yield was investigated. The different mixing ratios (FPW + LF) and HTC temperature (200–280 °C) had significant effects on biogas and methane production. The anaerobic co-digestion of the various mixing ratio of FPW and LF of bamboo residues did not enhance the methane yield compared to the AD of FPW alone. However, a mixture of 75FPW + 25LF(2 2 0) presented a comparable methane production (133 mL/g VS) to that achieved with 100FPW (142 mL/g VS), which represents an increase of only 6.4%. The ratio of 75FPW + 25LF(2 2 0) increased the biogas yield by 81% compared to the control group of 100LF(2 2 0). The mixing ratio of 75 FPW + 25LF(2 2 0) did not require clean water input to dilute FPW for biogas production and can be a practical waste management method.

Simultaneous improvements on nutrient and Mg recoveries of microalgal bioremediation for municipal wastewater and nickel laterite ore wastewater

Effects of different mixing ratios between synthetic municipal wastewater (MW) and magnesium (Mg2+)-enriched nickel laterite ore wastewater (NLOWW) on growth of Chlorella sorokiniana (C. sorokiniana), photosynthetic activities, cellular biocomposition, nutrient and Mg2+ removal were investigated in photobioreactors. In the culture without NLOWW, wrinkled cells were observed with low biomass production. The culture mixed with 0.13% NLOWW obtained 1.89-fold higher biomass yield, 3.77-fold enhanced photosynthetic activity (Fv/Fm value), and improved nutrient removal (nitrogen by 102.2%, phosphorus by 39.3%). However, excessive Mg2+ at 100% NLOWW produced highest reactive oxygen species suppressing microalgal growth. The Mg2+ removal capacity increased with NLOWW loading. Moreover, microalgal assimilation primarily contributed to nutrient removal while absorption was the dominant Mg2+ removal pathway. Carbohydrate content in biomass increased with Mg2+ loading. Finally, the approach for MW/NLOWW treatment was demonstrated as economically feasible with revenue of $75.6 per kilogram biomass through a comprehensive economic model.

Combustion and Emission Reduction Characteristics of GTL-Biodiesel Fuel in a Single-Cylinder Diesel Engine

The purpose of this paper is to investigate the effects of using gas to liquid (GTL)-biodiesel blends as an alternative fuel on the physical properties as well as the combustion and emission reduction characteristics in a diesel engine. In order to assess the influence of the GTL-biodiesel blending ratio, the biodiesel is blended with GTL fuel, which is a test fuel with various blending ratios. The effects of GTL-biodiesel blends on the fuel properties, heat release, and emission characteristics were studied at various fuel injection timing and blending ratios. The test fuels investigated here were GTL, biodiesel, and biodiesel blended GTL fuels. The biodiesel blending ratio was changed from 0%, 20% and 40% by a volume fraction. The GTL-biodiesel fuel properties such as the fuel density, viscosity, lower heating value, and cetane number were analyzed in order to compare the effects of different mixing ratios of the biodiesel fuel. Based on the experimental results, certain meaningful results were derived. The increasing rate of the density and kinematic viscosity of the GTL-biodiesel blended fuels at various temperature conditions was increased with the increase in the biodiesel volumetric fraction. The rate of density changes between biodiesel-GTL and GTL are 2.768% to 10.982%. The combustion pressure of the GTL fuel showed a higher pressure than the biodiesel blended GTL fuels. The biodiesel-GTL fuel resulted in reduced NOx and soot emissions compared to those of the unblended GTL fuel. Based on the experimental results, the ignition delay of the GTL-biodiesel blends increased with the increase of the biodiesel blending ratio because of the low cetane number of biodiesel compared to GTL. As the injection timing is advanced, the NOx emissions were significantly increased, while the effect of the injection timing on the soot emission was small compared to the NOx emissions. In the cases of the HC and CO emissions, the GTL-biodiesel blended fuels resulted in similar low emission trends and, in particular, the HC emissions showed a slight increase at the range of advanced injection timings.

A novel EUS-guided liquid fiducial marker for image-guided radiotherapy in esophageal cancer: The safety and efficacy in vitro and vivo evaluations.

e15573 Background: The true tumor extent of esophageal cancer is hard to visualize on current modalities during radiotherapy. In this study, we evaluated the safety and feasibility of the mixture of N-Butyl Cyanoacrylate and lipiodol to find the most optimal application as the fiducial marker to marking the true tumor extent in esophageal radiotherapy. Methods: Four types of injection matches (1:1-0.1ml, 1:1-0.15ml, 1:3-0.1ml, 1:30.15ml) were injected via syringes in subcutaneous tissue in rats model. Gross histopathological changes, weight, skin score, nodule volume, neutrophil counts and macrophage counts were observed to analyses the effect of different mixing ratios and injection volumes to find the best match. Evaluations following ISO standard criteria are further delivered to test the biocompatibility of the best applicable setting of this fiducial maker. Results: At 7th week, 42 markers (42/48, 87.5%) were still visualized on CT images. No serious adverse events or obvious artifacts were noted through the study. The overall review about the histopathological reaction of the NBCA/Lipiodol was considered to be a combination of acute inflammation, chronic inflammation, granulation tissue, foreign-body reaction and fibrous capsule formation in development. The quantitative analysis showed that when the density of NBCA was low (1:3), lower injection volume (0.1ml) brought the lower weights (p &lt; 0.001). When the injection volume is high (0.15ml), the high NBCA (1:1) caused the lower weight (p &lt; 0.001). At the most time points, the lower injection volume had the lower weights. High injection volume created a 0.079 cm3 increase in nodule size than low volume and high NBCA density also increased the nodule size. As for the inflammatory cells counts, the 3rd week was a key time point, before which the neutrophils decreased sharply and the macrophages keep almost steady, but after that the neutrophils stayed a low level and the macrophages started a rapid growth. On the comparisons of different index (Table), it is showed that the 1:3-0.15ml had an excellent performance as the fiducial marker and final biocompatibility test proved its safety. Conclusions: Overall, our results show that the mixture of NBCA/Lip as the fiducial marker is safe and feasible and the setting of 1:3-0.15ml was most optimal.[Table: see text]

Fabrication of Silicon Carbide from Recycled Silicon Wafer Cutting Sludge and Its Purification

Around the world, silicon carbide (SiC) is used as a raw material in several engineering applications because of its various beneficial properties. Currently, though the Acheson method is one of the most emblematic to manufacture SiC, the direct carbonization of metallic silicon is simple and beneficial. In this reaction, silicon wafer cutting sludge can be used as an alternative silicon source material. The silicon wafer sludge contains silicon, ethylene glycol, cooling water, and a small amount of impurities. In this study, SiC was synthesized using silicon wafer sludge by a carbothermal process. In a typical experiment, the silicon sludge was mixed with carbon at different molar ratios. Then, the mixture was turned into pellets, which were placed in alumina crucibles and heat-treated at a temperature from 1400 °C to 1600 °C to fabricate SiC. To deduce the optimum condition for the synthesis of SiC, an investigation was carried out on the effects of different mixing ratios, temperatures, and heating times. To ensure sufficient carbonization, excess carbon was mixed, and the synthesized SiC was characterized by X-ray diffraction (XRD). Subsequently, purification of the synthesized SiC products by oxidation of excess carbon was performed. The removal of extra carbon could be confirmed by XRD and attenuated total reflectance (ATR) spectroscopy. This process can give basic information for the development of a technology to produce SiC using recycling Si wafer cutting sludge waste.

Adsorption, wetting, foaming, and emulsification properties of mixtures of nonylphenol dodecyl sulfonate based on linear alpha-olefin and heavy alkyl benzene sulfonate

ABSTRACTNonylphenol dodecyl sulfonate (C12NPAS) has been synthesized, and mixed with heavy alkyl benzene sulfonates (HABS) in different proportions. The effects of different mixing ratios on properties such as adsorption, wetting, foaming, and emulsification, of the C12NPAS/HABS surfactant mixtures have been systematically investigated. Experimental results have shown that, after mixing, the wetting and foaming properties of C12NPAS/HABS are improved remarkably. Compared with C12NPAS and HABS alone, the adsorption and emulsifying properties of C12NPAS/HABS are far superior, which we attribute to a synergistic effect between these surfactants.

Interactions between fine and coarse hematite particles in aqueous suspension and their implications for flotation

The interactions between fine and coarse hematite particles were investigated, and their effects on the flotation of the hematite using sodium oleate as a collector were studied through micro-flotation tests, supplemented by optical microscopic analysis, extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) theoretical analysis, and focused beam reflectance measurement (FBRM) particle/aggregate size analysis. The micro-flotation results show that the recovery of hematite from fine-coarse hematite mixtures did not decrease monotonously with increasing the fine hematite mass ratio. The highest recovery was obtained when the fine and coarse hematite were approximately equal in mass ratio, indicating that the interactions between fine and coarse hematite particles could promote the overall flotation recovery. The results of optical microscopy analysis, EDLVO calculation, and FBRM measurements showed that the interaction energies and aggregation tendencies between fine and coarse hematite particles were stronger than that among the fine hematite particles, and the aggregation would weaken when the coarse and fine fractions were mixed in extreme mass ratios, which explained the observed effects of different mixing ratios of fine and coarse hematite particles on their flotation.

Co-Composting of Sewage Sludge with Food Waste Using Bin Composter

Optimization of sludge composting has been analysed by co-composting of sewage sludge with food waste by using a bin composter with regular aeration. Two bin composting experiments were set up to study the effect of different mixing ratios of food waste from the wet market to sewage sludge from Al Hadhbah waste water treatment plant which is located in Tripoli on some physical and chemical characteristics of the resulted compost. The selected ratios were 1:2 (A) and 1:3 (B) of food waste to sewage sludge respectively. Composting was conducted for 100 days and the sampling from the mixtures was performed each five days. Temperature (T), pH, electrical conductivity (EC), total organic carbon contents (TOC %) and total nitrogen contents (TN %) were monitored during the composting. The ratio of C/N, inorganic residual material (ash content) and nutrient changes as represented by potassium (K %) and phosphorus (P %) contents was also determined. The compost produced in this study has a favorable ratio of C/N (13.43 for compost A and 14. 32 for compost B). With significant amount of nutrients (TN %, K%, P%) The results of analysis of variance (ANOVA) revealed a significant effect of elapsed composting time (at the probability level of 0.05) on T, pH, TOC%, K% and P%. The effect of composting ratio was insignificant (at the probability level of 0.05) on T, TOC %, TN %, C/N and P%. The multiple comparison results using Tukey’s test showed significance difference between the mean values of EC and K% among the composting ratio at the confidence level of 95%. Generally, the compost ratio of 1:2 was found to be the most suitable for use as organic fertilizer

Appropriate conditions for applying NaOH-pretreated two-phase olive milling waste for codigestion with food waste to enhance biogas production

The high methane gas production potential of two phase olive milling waste (2POMW) makes its application to biogas plants in business an economical process to increase the productivity of the plants. The objective of this study was to investigate the appropriate conditions for the codigestion of NaOH-pretreated 2POMW with food waste. NaOH pretreatment can increase the methane production by increasing the soluble chemical oxygen demand (sCOD), but it may cause inhibition because of higher levels of alkalinity, sodium ion, volatile fatty acids and long chain fatty acids (LCFAs). Therefore, the first experimental phase of this study aimed to investigate the effect of different mixing ratios of 2POMW to food waste. A continuous stirred tank reactor experiment with different mixing ratios of 3%, 4.3%, 5.7% and 8.3% (2POMW: food waste) was conducted. NaOH pretreatment in the range of 6–20% was used. A mixing ratio up to 4.3%, when 10% NaOH pretreatment was used, caused no inhibition and increased methane production by 445.9mL/g-VS(2POMW). For this mixing ratio an additional experimental phase was conducted with the 20% NaOH pretreatment as the 20% NaOH pretreatment had the highest sCOD. The methane gas production was increased by 503.6mL/g-VS(2POMW). However, pH adjustment was required for applying this concentration of the high alkalinity 20% NaOH-pretreated 2POMW. Therefore, we consider using 10% NaOH pretreatment in a mixing ratio of 4.3% to be more applicable. The increase in methane gas production was correlated to the oleic acid concentration inside the reactors. The high oleic acid concentration of 61.8mg/L for the 8.3% mixing ratio was responsible for the strong inhibition. This study showed that adjusting the appropriate mixing ratio of the NaOH-pretreated 2POMW could increase the electricity production of a reactor that regularly receives food waste.

Greenhouse gas emissions from passive composting of manure and digestate with crop residues and biochar on small-scale livestock farms in Vietnam

This study investigated the effects of different mixing ratios of crop residues and biochar with liquid digestate from anaerobically treated pig manure on CH4, CO2, and N2O emissions over 84 days in a system of passive aeration composting, resembling typical Vietnamese solid manure storage conditions. Two treatments with solid manure were included for comparison. The results showed that C losses through CH4 and CO2 emissions accounted for 0.06–0.28% and 1.9–26.7%, respectively, of initial total C. CH4 losses accounted for just 0.4–4.0% of total C losses. Total N losses accounted for 27.1–40% of initial total N in which N2O emissions corresponded to 0.01–0.57% of initial total N, and hence accounted for only 0.1–1.8% of total N losses. It is assumed that the remainder was either the result of denitrification losses to N2 or ammonia volatilization. The composting of biochar (B) or crop residue with digestate (D) showed significantly lower CH4 and N2O emissions compared with composting manure (M) (p < .05). The composting of digestate with biochar showed significantly lower CO2 and CH4 emissions and significantly higher N2O emissions compared to the composting of digestate with rice straw (RS) (p < .05). The combined composting of digestate with biochar and rice straw (D + B + RS5:0.3:1) showed significantly reduced N2O emissions compared with composting digestate with biochar with alone (p < .05). Composting sugar cane bagasse (SC) with digestate (D + SC) significantly reduced CH4 and N2O emissions compared with the composting of rice straw with digestate (D + RS3.5:1 and D + RS5:1) (p < .05).