Cumulative Yield Research Articles

Super diluted mixture alkali (SDMA) pretreatment for cornstalk anaerobic Digestion: A green strategy for High-Solid biogas production

Biogas production from lignocellulose by anaerobic digestion has made significant progress lately. However, the bioconversion of lignocellulose is still hindered by its recalcitrant and heterogeneous structure. To overcome this challenge, a novel method of super diluted mixture alkali (SDMA) pretreatment was developed to enhance the biogas production from cornstalk in high-solid anaerobic digestion. The cornstalks treated with 2 g/L NH3 and 1 g/L NaOH achieved a cumulative methane yield of 241.50 mL/g VS, which was 184.65 % and 55.6 % higher than that of the untreated and 2 % NaOH treated cornstalks, respectively. The system stability was verified by a scale-up experiment in a 10 L bioreactor. Remarkably, the entire process does not generate any wastewater or chemical pollution. Moreover, the resultant biogas slurry could be directly applied as a concentrated bio-fertilizer. The findings are potentially beneficial for the development of the second-generation biogas industry from lignocellulosic biomass, which can provide both clean and economical bioenergy.

Metabolic mechanism of thermal pretreatment combined with ethanol pre-fermentation to enhance anaerobic digestion of food waste: A comprehensive analysis of key enzyme-encoding genes

Ethanol pre-fermentation (EP) can enhance methanogenic efficiency and facilitate food waste (FW) hydrolysis, while ensuring anaerobic digestion (AD) system stability. FW contains high-water content, and thermal pretreatment (TP) can significantly enhance solids and soluble organic matter content. The study focused on investigating the mechanism of TP combined with EP (TP-EP) on the AD of FW. The results showed that TP-EP enriched hydrolyzing and acid-producing bacteria, as well as the methanogens Methanosarcina, and Methanothrix. Consequently, the degradation rates of soluble chemical oxygen demand, volatile fatty acids, and cumulative methane yield exhibited an increase of 9.54%, 5.94%, and 20.42%, respectively, in comparison to the control. EP promoted carbohydrate metabolism, while TP promoted amino acid metabolism and enhanced energy metabolism by enriching F-type ATPase and NADHase. When combined as TP-EP, the processes integrated the advantages and promoted substrate hydrolysis and energy metabolism while enhancing methanogenic metabolism.

Exploitation and Utilization of Generated Oil and Gas by Pyrolysis Simulation Modeling of Shale Source Rocks under the Condition of In Situ Conversion

Previous studies have mainly focused on the source rocks of the 7th Member of Yanchang Formation (Chang 7 Member) in the Ordos Basin, with very few studies focusing on the extracts from the source rocks. These extracts have important guiding significance for studying the in situ conversion process of shale oil. Taking the shale source rock of the Chang 7 Member as an example, this paper selected the extract of shale source rock (i.e., retained oil), which has been less studied previously, as the sample to carry out the hydrocarbon-generating pyrolysis simulation experiment of a semi-open–semi-closed system. Seven groups of parallel simulation experiments were designed with a pressure of 20 MPa. The generated oil and gas were collected and quantified, and their geochemical characteristics were researched. In addition, the generated oil and gas were investigated from aspects of cumulative yield and net increased yield, and the chromatographic and mass spectral characteristics of the generated oil were also researched. Based on this, an inductive hydrocarbon generation model of retained oil in shale source rocks was established: slow hydrocarbon generation stage (300–320 °C), rapid hydrocarbon generation stage (320–360 °C), and residual oil pyrolysis stage (0.79%Ro–1.47%Ro). This study is of important significance to guide the research on the in situ conversion process of shale source rock.

Fruitlet Thinning Reduces Biennial Bearing in Seven High-tannin Cider Apple Cultivars

Many European apple (Malus ×domestica Borkh.) cultivars used for making alcoholic cider have a highly biennial bearing habit. To determine target crop load recommendations, seven cider cultivars grown in a high-density orchard were hand-thinned to crop densities of 0, 3, 6, and 9 fruit/cm2 trunk cross-sectional area (TCSA) or left unthinned as a control for 3 consecutive years (2016–18). Treatments were imposed on the same trees for all 3 years. Greater year-to-year yield variability, as measured by the biennial bearing index (BBI), correlated negatively with cumulative yields both within and among cultivars. Greater crop density had a negative correlation with the amount of return bloom in all years, but reducing crop density had a negligible effect on return bloom in the “off” year. When trees were left unthinned in the high-crop “on” years there was little to no return bloom in the following year. Partial budget analysis found that manually reducing crop density would result in a positive net change in 3-year profitability for Dabinett, but not the other cultivars. Over 4 years, under conservative assumptions about fruit set, chemical thinning to 9 fruit/cm2 TCSA would likely result in increased cumulative profitability in all seven cultivars. Hand-thinning was projected to be less profitable than chemical thinning but would still result in increased net profitability over 4 years, for five of the seven cultivars. These findings highlight the horticultural and economic benefits of crop load management for cider apple orchards. Further, many high-tannin cider cultivars can sustain a higher crop density than what is recommended for fresh-market apple production and still have adequate return bloom and cumulative yields.

The effect of nitrogen and phosphorus fertiliser application rate and strategy on herbage production and nitrogen response in spring

Maximising herbage yield while reducing nitrogen (N) fertiliser input, particularly in spring, is essential to ensure environmental and economic sustainability on grassland farms. A plot experiment was conducted over 2 yr, comparing three different spring N application rates of 30 (30N), 60 (60N) and 90 (90N) kg N/ha using three different spring application strategies: 0:100 (S1), 50:50 (S2) or a 33:66 (S3) split across February and March, respectively. Half of the plots also received phosphorus (P) fertiliser with the first application of N at a rate of 13 kg P/ha. Nitrogen fertiliser application for the remainder of the year (April–September) was the same for all plots (23 kg N/ha/application). Both spring and cumulative herbage yields were significantly affected (P < 0.05) by N application rate; 90N had the greatest spring and cumulative herbage yield compared to 30N and 60N (10,925, 9,834 and 10,499 kg DM/ha, respectively); however, N response reduced as N application rate increased. Nitrogen application strategy had a significant effect (P < 0.05) on spring herbage yield, with S1 significantly lower than S2 and S3. Applying 13 kg P/ha in spring increased herbage yield at defoliations 2 (23 April) and 3 (15 May) (+133 and 56 kg DM/ha, respectively), relative to no application of P fertiliser, as well as increasing cumulative herbage yield (+241 kg DM/ha). The results of the current study indicate that N should be applied in early February and the strategic application of N and P during spring can increase spring and cumulative herbage yield.

Association of magnetic-flyash in anaerobic co-digestion for biomethane optimization: Promoting biofilm formation

The application of low-cost magnetic industrial wastes as accelerants can significantly improve the performance of anaerobic co-digestion (AcoD), thereby enhancing the biogas yield. In this work, varying concentrations (1.0–4.0 wt.%) of magnetic flyash (MFA) were applied to the AcoD of cow manure (CM) and aloe peel waste (APW). All AcoD systems were operated under mesophilic condition (37 ᴼC) with a 5 mT magnetic field. The AcoD system with 2.0 wt.% of MFA showed the highest cumulative biogas yield (487 mL/g VS), methane content (65.17%), COD, TS and VS removal rates (36.45, 45.49 and 52.10%, respectively), and fertility (3.4%). However, the 1.0 wt.% of NMFA also showed higher cumulative biogas yield (432 mL/g VS), methane content (60.23%), COD, TS and VS (27.69, 18.24 and 43.64%, respectively), and fertility (3.31%) than other NMFA concentrations (1.5 & 2.0 wt.%). Kinetic models verified that MFA coupled with a magnetic field could increase biogas potential and production rate. A strategy for determining the role of MFA in microbial biofilm formation and improving biodegradation, which increases the biogas yield, is also suggested. This work demonstrates a cost-effective application of MFA in bioenergy production systems by improving the AD process.

Biogas Production from the Co- and Tri-digestion of Pineapple Wastes with Food Wastes and Pig Manure

Biogas Production from the Co- and Tri-digestion of Pineapple Wastes with Food Wastes and Pig Manure

Performance of single slope solar stills: A comparative study of conventional and modified stills with nanofluid and reflectors

Nature has naturally desalinated water for centuries through the process of solar heating, where oceanic water transforms into vapor and then returns to Earth as freshwater precipitation. Freshwater is vital for sustaining life, but growing populations, industrial expansion, and increased agricultural production have created a rising demand for it. Desalination has emerged as a potential solution to address water scarcity. Existing desalination technologies fall into two categories: single-phase processes like reverse osmosis and electro-dialysis, and phase-change processes such as distillation and solar stills. While single phase processes provide freshwater, some rely on non-renewable fossil fuels for energy, indirectly contributing to greenhouse gas emissions. Solar distillation, in contrast uses renewable energy from the sun, offers a promising and sustainable alternative for freshwater production. Solar stills employ shallow water basins within enclosed structures, as moisture collects on the interior surface of the glass cover, cooled by natural airflow. In this study, two 250 X 250 mm2 single slope solar stills were designed, one conventional and the other modified with nanofluids and reflectors. The experiment assessed their performance in Hyderabad’s typical climate, with a glass cover slope of 17.45°. Both stills operated with a 1 cm water depth (500 ml) to observe the water distillate output. Readings were recorded for two different nanofluid concentrations (considering 0.08% and 0.1% of Cerium Oxide nanoparticles by volume mixed with water) allowing for a comparison of their cumulative hourly yields and effectiveness in increasing freshwater output.

Co-digestion potential of different industrial sludge sources and impact on energy recovery

Co-digestion potential of the wastewater treatment sludges produced at two industries with different characteristics was investigated in anaerobic batch reactors operated at mesophilic (35±2 °C) condition. The sludge sources selected were from a food industry producing edible oil and from a textile industry producing woven fabric. Reactor performance was evaluated by the conventional parameters as well as by monitoring the biogas production during co-digestion of both industrial sludges at equal mixing proportions. Results indicated that both of these sludge sources had substantial biogas production potential with a cumulative biogas yield more than 425 mL/g-VSSfed whereas it was about 5-fold lower only for the food sludge. On the other hand, chemical oxygen demand (COD) removal reached to about 90% during co-digestion with a well recovery of pH value and alkalinity concentration for sufficient buffering at the end of incubation. Therefore, by the combination of different industrial sludges through co-digestion; higher digestion performance and improved methane yield could be achieved due to better balanced substrate and nutrients. Regarding the initial heavy metals in the supernatant phase of the mixed sludge; iron (Fe), zinc (Zn), nickel (Ni), aluminum (Al), and manganese (Mn) could be removed from 56% to 80% while no apparent removals were observed in cadmium (Cd) and lead (Pb) at the end of operation. Hence, these potential toxic pollutants in the digestate should be taken into consideration while deciding the most appropriate resource recovery and ultimate disposal methods.

Enhanced biomethane production from waste activated sludge anaerobic digestion by ceramsite and amended Fe2O3 ceramsite

Wastes recycling and reutilization technique could simultaneously fulfill waste control and energy recovery sustainably, which has attracted increasing attention. This work proposed a novel waste reuse technology utilizing ceramsite and amended Fe2O3-ceramsite made from waste activated sludge (WAS) as additives to promote the yield of methane from WAS anaerobic digestion (AD). Experimental results demonstrated that compared to the control (85.05 ± 0.2 mL CH4/g-VS), the cumulative methane yield was effectively enhanced by 14% and 40% when ceramsite and Fe2O3-ceramsite were added. Further investigation revealed that ceramsite, especially the Fe2O3-ceramsite, enriched the populations of key anaerobes involved in hydrolysis, acidification, and methanogenesis. Meanwhile, potential syntrophic metabolisms between syntrophic bacteria and methanogens were confirmed in the Fe2O3-ceramsite AD system. Mechanisms studies exhibited that ceramsite and Fe2O3-ceramsite reinforced intermediate processes for methane production. The favorable pore structure, enhanced Fe (III) reduction capacity and conductivity also contributed a lot to the AD process.

Dual roles in interspecies electron transfer of carbon-based materials for accelerating anaerobic digestion of food waste

Food waste is tremendously generated and leads to serious environmental pollution if it is improperly disposed. Anaerobic digestion is recognized as an effective biotechnology to treat food waste. In order to improve the conversion efficiency, the effect of carbon-based materials on anaerobic digestion of food waste was investigated, and the microbial communities and electron transport pathways were also analyzed. The results showed that adding biochar improved the performance of anaerobic digestion of food waste, but adding graphite had no significant effect. The maximum daily methane yield of 67.79 ± 6.37 and 72.78 ± 6.17 mL/g VS·d were obtained with 1.250 (BC10) and 1.875 (BC15) g biochar/g VS raw material added, increased by 13.27% and 21.61% in comparison with the control system. Meanwhile, the systems reached 80% of cumulative methane yield on day 10, and the increase of 13.50% (423.66 ± 13.74 mL/g VS) and 13.57% (423.96 ± 20.33 mL/g VS) were obtained for the methane yield. Adding biochar selectively increased the relative abundance of Syntrophomonas, Clostridium sensu stricto, Petrimonas, Clostridium XlVb, Comamonas, Acinetobacter, Methanothrix and Methanobacterium. The interaction between Methanobacterium and Syntrophomonas was also promoted due to biochar acted as an electron carrier. Therefore, biochar had complex regulation on electron transport pathway of anaerobic digestion and promoted the conversion efficiency of food waste.

Investigation into the hydrogen production performance of a novel 5-kW hybrid-system composed of a solar steam generator directly connected with conventional solid oxide electrolysis cells

Coupling solar energy with solid oxide electrolysis cell has the potential to reduce electricity consumption and improve energy conversion efficiency. This study introduces a pioneering 5 kW direct-connected hybrid system that couples a solar steam generator with solid oxide electrolysis cells utilizing conventional electrical energy for the electrolysis process. The successful demonstration of hydrogen production showcases promising results. When the solar irradiation power is 2.26 kW, the inlet water flow rate is 1.23 kg/h under operations at 700 °C, the hydrogen production efficiency of the system reaches 95.2 %, and the steam conversion ratio approaches 92 %, giving a cumulative hydrogen production yield of 5,840 NL in 6.3 h. The solid oxide electrolysis system is further tested under different operating conditions of the stack and solar irradiation. The experimental results show that a greater operating temperature is conducive to more efficient hydrogen production, while more water vapor at the cathode leads to a larger steam conversion ratio. The results indicate that increasing the irradiation power is beneficial to hydrogen production while decreasing the irradiation power will lead to fluctuations of hydrogen yield. In addition, the system efficiency (45.3 %) is higher than that of a photovoltaic alkaline water electrolysis (12.6 %) or photovoltaic proton exchange membrane electrolysis (14.76 %) system at the same irradiation power. Under the same electrolysis power and cathode inlet temperature, the total power consumption of a traditional solid oxide electrolysis system is significantly greater than that of the proposed hybrid system. The comparison shows that the saved electricity of the proposed hybrid system can account for about 30 %. Therefore, the proposed hybrid system has significant efficiency and power savings advantages.

Co-pretreatment (calcium peroxide + freeze) to improve anaerobic fermentation of waste activated sludge: Method optimization and mechanism insights

The reduction, harmlessness, and recycling of waste-activated sludge (WAS) can be accomplished by anaerobic fermentation, where sludge disintegration is the key speed-limiting process. Co-pretreatment, as a derivative of pretreatment, has attracted more and more attention. However, obtaining optimal co-pretreatment conditions is difficult. Response surface methodology (RSM) can combine statistical analysis with mathematics to optimize the parameters. Therefore, in the current work, RSM optimization for CaO2-freezing co-pretreatment conditions to improve the production of short-chain fatty acids (SCFAs) from WAS was carried out using the Box-Behnken Design based on Design Expert software. We obtained the optimal values of three pretreatment parameters: −18 °C freezing temperature, 48.6 h freezing time, and 0.19 g CaO2/g VSS addition. After 5 days of fermentation, the maximum cumulative yield of SCFAs was 162.34 mg COD/g VSS. CaO2-freezing co-pretreatment promoted the solubilization and release of organic matter in WAS during anaerobic fermentation, which not only provided more organic matter for the subsequent production of SCFAs but also improved the methane production capacity in the anaerobic digestion stage. 16S rRNA genes sequencing revealed that the abundance of SCFAs-producing bacteria (i.e., Macellibacteroides and Proteiniclasticum) was significantly enriched in the fermentation tank after CaO2-freezing co-pretreatment. All in all, this study successfully optimized the co-pretreatment conditions based on RSM, providing new insights and effective solutions for the environmentally friendly and efficient realization of solid waste recycling.

Effects of different tillage and residue management systems on soil organic carbon stock and grain yield of rice–wheat double cropping system

Of late, intensive agricultural practices are often associated with many negative implications for soil systems, such as decline in soil organic matter and biological diversity, and increase in the risk of soil erosion, and degradation of soil physical quality. However, conservation agriculture (CA) offers minimum soil disturbance, improving and creating more efficient use of natural resources, enhancing use efficiency of external inputs and increasing soil functioning, organic matter content, and biodiversity. However, CA practices need to be redefined at the specific field level or growing conditions to promote sustainable production system without deteriorating soil health, and to manage profitability. Therefore, a fixed-site field experiment was conducted to evaluate the effects of different tillage and residue management practices; CT0 (puddled transplanted rice followed by conventional tilled wheat sown with residue removal); CTR (puddled transplanted rice followed by conventional tilled wheat sown with residue retention); NT0 (direct seeded rice followed by zero-tilled wheat sown with residue removal); NTR (direct seeded rice followed by zero-tilled wheat sown with residue retention) on soil organic carbon (SOC) stock and grain yield of rice–wheat double cropping system. The results showed that the mean SOC stock increased by 31%, 21.9% and 15.3% and by 35.2%, 22% and 17% under NTR, CTR, and NT0 compared with CT0. Furthermore, the SOC sequestration rate in NTR was significantly higher than other treatments. Particulate organic carbon (POC) concentration was 58.4% higher in 0–15 cm than 15–30 cm soil layer, and the maximum concentration was recorded under NTR and minimum was under CT0. The highest average rice grain yield was recorded under CTR, which was 5.5%, 16.2% and 24.3% higher than CT0, NTR and NT0, respectively. Both NTR and CTR produced more average wheat yield, which was 8.4% and 8.5% higher than CT0 and NT0, respectively. Principal component analysis (PCA) also showed that cumulative cropping system yield and SOC were increased under CTR, NTR as compared to other treatments. Therefore, it can be drawn that residue retention could be a useful management practice to increase SOC stock and grain yield under both tillage practices in the rice–wheat cropping system.

Growth, fruit bearing behaviour, yield and quality of some apple cultivars

Apple is a temperate climate fruit species grown almost worldwide. Research and past experiences have shown that apples have different growth and fruiting behaviours. Knowing the growth and fruiting behaviours of apples, determining the training system, how to prune, will shed light on the cultural practices that need to be done in order to obtain quality and early high yield. In light of the above, the study aimed to determine the growth and fruiting behaviours of different apple. In the experiment, eight apple cultivars, ‘Jeromine’, ‘Fuji Zehn Astec’, ‘Granny Smith Challenger’, ‘Buckeye Gala’, ‘Rosy Glow’, ‘Golden Reinder’, ‘Ginger Gold’ and ‘Amasya’, grafted on M9 rootstock were used. The growth and fruiting behaviours of the cultivars were determined by phenological observations, canopy dimensions, tree dimensions, canopy volume, tree volume, number and size of annual shoots on the leader, number of spurs, internode distance, distribution of flowers on the tree and similar measurements and evaluations. In addition, yield and some quality characteristics of fruits were also recorded. It was determined that ‘Rosy Glow’ and ‘GS Challenger’ cultivars showed the best performance in terms of growth, and ‘Fuji Zehn Astec’, ‘Rosy Glow’, ‘Buckeye Gala’, ‘GS Challenger’ cultivars in terms of cumulative yield. Additionally, this study found that there was a positive relationship between yield and branch angles in the first two years. Considering all the years, it was determined that ‘Fuji Zehn Astec’ and ‘Granny Smith Challenger’ cultivars produced larger fruits than the others. In conclusion, it was revealed that the growth and fruiting behaviours of apple cultivars cannot be classified very clearly, and it would be more accurate to group them as spur, semi-spur, standard and tip bearer in general. It was claimed that the number of flowers in the cluster is not a characteristic of apples. Besides, ‘Fuji Zehn Astec’, ‘Rosy Glow’, ‘GS Challenger’ was suggested for high yield in the new training systems.

Seasonal dynamic modeling and simulation of solar thermal membrane desalination system for sustainable freshwater production: a case study of Tanta, Egypt

AbstractMembrane distillation (MD) is an effective process for desalinating seawater, combining the merits of both thermal and membrane distillation. In this context, the sizing methodologies and optimization strategies are developed from the balance of the system’s energy demand. Therefore, accurate numerical modeling of the heat transfer and thermodynamic behavior of the MD systems is crucial for the optimal design of solar-based MD systems. The interest in utilizing solar thermal heating techniques for feed water heating in MD systems is increasing worldwide for sustainable freshwater production and lowering energy consumption. Hence, in this research, a coupled analytical modeling based on heat transfer, mass transport, and thermodynamic analysis is created to dynamically simulate a solar direct contact membrane distillation system (SDCMDS) driven by vacuumed tubes solar collectors (VTSCs) to analyze its performance, under real weather of Tanta, Egypt. The influences of the solar collecting area on the performances of the proposed SDCMDS for augmenting the freshwater production of the SDCMDS are studied. Four cases of the proposed SDCMDS are investigated: two identical VTSCs of 1.80 m2 each unit in summer (Case I), two identical VTSCs in winter (Case II), four identical VTSCs in summer (Case III), and four identical VTSCs in winter (Case IV). The results show that the utilization of four VTSCs connected in series significantly improved the feed seawater temperature range from 30.0 to 70.5 °C compared to a feed temperature range of 30.0–49.5 was achievable by utilizing only two VTSCs. Moreover, the daily averaged permeate flux were 2.21, 1.29, 3.41, and 2.07 L/day per m2 of solar harvesting area with daily cumulative distilled water yield of 7.48, 4.60, 23.04, and 14.78 L/day for Cases I, II, III, and IV, respectively, at a saline flowrate of 0.20 kg/s. The daily average total efficiency of the SDCMDS was obtained to be 14.70%, 12.50%, 24.95%, and 22.50% for Cases I, II, III, and IV, respectively.

Effect of pretreatment with efficient microorganisms on anaerobic digestion of rice drying residue

Rice drying generates large amounts of impurities which has been previously studied for biogas production with unfavorable results due to its high lignocellulosic content. This research aimed to assess the effect of the pretreatment and bioaugmentation with efficient microorganisms on the anaerobic digestion of rice drying residue, and the kinetics of methane production. For the study, rice drying residues were pretreated for 48 hours with efficient microorganisms diluted 1:100, in a relation of 18 mL gVS-1 of substrate; while for bioaugmentation microorganisms were added directly to the reactors. The kinetic behavior of the digestion process was described through four models of first and second order. The highest methane yield was obtained with pretreated residues (363.7 LN kgVS-1), being 9.9% higher than that of the substrate without pretreatment. Bioaugmentation did not show significant differences. All the models fitted well with the experimental cumulative methane yield data, but the Hill modified model had the best fit in all cases. The study shows that the use of efficient microorganisms is an attractive option to increase waste degradation in anaerobic digestion processes.

Effects of One-Step Abrupt Temperature Change on Anaerobic Co-Digestion of Kitchen Waste with Dewatered Sludge

The operating temperature of anaerobic digesters should be adjusted to adapt to seasonal variations in environmental temperature and the composition of organic solid waste. This study investigated the effects of one-step abrupt temperature changes (from mesophilic to thermophilic temperature, M–T, and from thermophilic to mesophilic temperature, T–M) and the inoculation ratio on methane yield and microbial diversity during the anaerobic co-digestion of kitchen waste with dewatered sludge. The results showed that the cumulative methane yield (CMY) level resulting from thermophilic control and the M–T digesters was greater than that resulting from mesophilic control and the T–M digesters. The CMF of M–T digesters increased, whereas the CMY of T–M digesters gradually decreased with an increase in the inoculation ratio. The maximal CMY was 385.1 mL/g-VSSadded, which corresponded to an M–T digester with a 5% inoculation ratio. In the later stage of anaerobic digestion, the bacterial community of T–M was more diverse than that of M–T, but the archaeal community of M–T was more diverse than that of T–M. The one-step temperature change from thermophilic to mesophilic temperature was more stable than that from mesophilic to thermophilic temperature.

Early rootstock selection under ‘tahiti’ acid lime crown in Capitão Poço, Pará State, Brazil

Citrus represents one of the main fruit crops grown in the world, highlighting the ‘Tahiti’ acid lime tree. The objective was to compare rootstock varieties combined with this scion to identify those with the best agronomic performance and precocity of production, in addition to Phytophthora gummosis resistance. The experiment was carried out in Capitão Poço, northeast region of Pará, and the following seven rootstock genotypes were evaluated: ‘Sunki Tropical’, ‘BRS O S Passos’, ‘BRS Bravo’, ‘BRS Donadio’, ‘Citrandarin Indio’, ‘BRS Matta’, and ‘LVK x LCR-038’. A randomized block experimental design was used, with three replications and 10 plants per plot. The evaluated characteristics were: plant height (m); crown volume (m3); number of ripe fruit per plant; total yield of ripened fruit per plant (kg plant-1); cumulative fruit yield (fruit kg plant-1); and average productive efficiency (fruit kg m-3 of crown). The average productive efficiency was high. For early selection, the best rootstocks in terms of yield, stability and adaptability were Sunki Tropical, BRS O S Passos, and Cintradarin Indio. The fruit number had the greatest direct effect on fruit yield, and crown pruning was directly harmful. Further studies to understand the complex interaction of G x E for BRS Donadio and Sunki Tropical should be carried out.

Process mechanisms of nanobubble technology enhanced hydrolytic acidification of anaerobic digestion of lignocellulosic biomass

This study explored the efficiency of CO2-, N2-, and H2- nanobubble treatment in anaerobic digestion (AD) of rice straw, with a focus on the processes and metabolic pathways of hydrolytic acidification, and revealed the underlying mechanisms. Mechanistic investigations revealed that nanobubbles, particularly CO2 nanobubbles, significantly increased the degradation of amorphous cellulose, resulting in higher levels of soluble carbohydrates (6.27 % – 11.13 %), VFAs (4.39 % – 24.50 %), and a remarkable cumulative H2 yield (74 – 94 times) Microbial community analysis indicated that the CO2 nanobubble promoted the growth of acidifying bacterial communities, such as Mobilitalea, unclassified_f_Lachnospiraceae, and Bacteroides. This indicates that the introduction of CO2 nanobubbles improved the total abundance of predicted functional enzymes were increased by 14 %, resulting in the production of more easily degradable intermediates. Based on the analysis of total methane production and kinetic analysis, it can be concluded that nanobubble addition enhanced methane production levels of 4.22 %−7.79 % with lower lag time (λ) (0.88–1.06 day) compared to the control group (1.09 day). The results also elucidated changes in relative enzymatic activities involved in the bioconversion of cellulose and hemicellulose during the hydrolysis stage with nanobubble treatment. This work is more beneficial for understanding the promoting effect and mechanism of nanobubbles on AD, facilitating the more precise application of nanobubble technology in the field of renewable energy.