Initial Biomass Research Articles

Clams on stilts: a phytoplankton bioassay investigating effects of wastewater effluent amendments and Corbicula fluminea grazing

Shallow-water habitats are being restored in the Sacramento-San Joaquin River Delta with the goal of enhancing phytoplankton production and food availability for higher trophic levels. However, elevated grazing pressure from the non-native freshwater clam Corbicula fluminea and localized depletions of dissolved inorganic nitrogen may limit phytoplankton biomass accumulation in restored habitats. To evaluate interactions between nutrients and grazing on phytoplankton productivity and biomass accumulation, Sacramento River water high or low in phytoplankton biomass was amended with wastewater effluent, presence of C. fluminea, or both, in 48 h in situ incubations. We measured changes in chl a concentration, phytoplankton community composition, and photosynthetic efficiency as well as carbon and nitrogen uptake rates as indicators of phytoplankton responses. Diatoms dominated phytoplankton communities before and after incubation. Chl a concentrations increased 0.7 and 7.4 times in the high and low phytoplankton biomass controls, respectively, and 4.5 and 14 times in the high and low phytoplankton biomass effluent-added treatments, respectively. In the clam treatments, chl a accumulation was suppressed to near zero regardless of effluent additions or initial phytoplankton biomass. In treatments with clams and effluent combined, phytoplankton photosynthetic efficiency was nearly 50% lower than in the effluent-only treatments, suggesting phytoplankton were stressed in the presence of clams. This experiment demonstrated that the presence of clams can prevent the accumulation of phytoplankton biomass, both directly by clam filtering and indirectly by depressing phytoplankton photosynthetic efficiency and rate of growth. We recommend that future wetland restoration projects promoting increased phytoplankton biomass assess clam settlement likelihood as well as nutrient availability.

Environmental friendly approach on biosorption of Ag nanoparticles using Aspergillus terreus BIOS PTK 6 biomass: Optimization, kinetics and characterization studies

The present study focused on the biosorption of Aspergillus terreus dead biomass for the removal of silver nanoparticles (AgNPs) from aqueous solution. For the better removal of AgNPs, pH, temperature, incubation time, initial biomass concentration and agitation speed were optimized and AgNPs treated as well as control biosorbents were characterized using Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray spectroscopy (EDX) analyses. In our study, the optimum conditions of pH, temperature, incubation time, initial biomass concentration and agitation speed for the maximum removal of AgNPs was found to be 4, 30 °C, 200 min, 1 mg/mL and 125 rpm, respectively. Interestingly, in our study, Langmuir isotherm model was best correlated with the highest regression coefficient (R2) of 0.992 and the maximum biosorption was found to be 740.63 μg/mL. FTIR results showed that carboxyl, carbonyl and secondary amine groups were involved in the biosorption of AgNPs. FESEM images of AgNPs treated biosorbent depicted rough surface and the presence of AgNPs on the surface of biosorbent was clearly observed. EDX spectrum showed Ag peak, which confirmed the successful uptake of AgNPs by A. terreus dead biomass. Thus, our study shows that A. terreus could be used as a cost-effective eco-friendly biosorbent for AgNPs removal from aqueous solution. Therefore, exploiting the same fungus for both synthesis and removal of AgNPs could be a novel approach in the context of mycoremediation practices.

Variability in the phytoplankton response to upwelling across an iron limitation mosaic within the California current system

AbstractCoastal upwelling currents such as the California Current System (CCS) comprise some of the most productive biological systems on the planet. Diatoms dominate these upwelling events in part due to their rapid response to nutrient entrainment. In this region, they may also be limited by the micronutrient iron (Fe), an important trace element primarily involved in photosynthesis and nitrogen assimilation. The mechanisms behind how diatoms physiologically acclimate to the different stages of the upwelling conveyor belt cycle remain largely uncharacterized. Here, we explore their physiological and metatranscriptomic response to the upwelling cycle with respect to the Fe limitation mosaic that exists in the CCS. Subsurface, natural plankton assemblages that would potentially seed surface blooms were examined over wide and narrow shelf regions. The initial biomass and physiological state of the phytoplankton community had a large impact on the overall response to simulated upwelling. Following on‐deck incubations under varying Fe physiological states, our results suggest that diatoms quickly dominated the blooms by “frontloading” nitrogen assimilation genes prior to upwelling. However, diatoms subjected to induced Fe limitation exhibited reductions in carbon and nitrogen uptake and decreasing biomass accumulation. Simultaneously, they exhibited a distinct gene expression response which included increased expression of Fe‐starvation induced proteins and decreased expression of nitrogen assimilation and photosynthesis genes. These findings may have significant implications for upwelling events in future oceans, where changes in ocean conditions are projected to amplify the gradient of Fe limitation in coastal upwelling regions.

Comparison of Waste Biomass from Pine, Eucalyptus, and Acacia and the Biochar Elaborated Using Pyrolysis in a Simple Double Chamber Biomass Reactor

Using waste biomass is considered one of the ways to reduce climate change. Arboreal waste biomass from pine, eucalyptus, and particularly invasive plants (Acacias) would make it possible to transform this natural resource, but needs to be adjusted to current and innovative technologies. The production of high fixed carbon biochar with this biomass would improve not only environmental aspects, but also the use of currently not susceptible materials for other types of exploitation. The objective of this study is to develop biochar from three different waste biomass materials and compare their parameters with those of the original biomass. Thermochemical conversion processes were used in a simple double chamber reactor developed for this study. Temperatures between 400 and 500 °C during 280 min were achieved and allowed to transform the initial biomass in a biochar with a high content of fixed carbon. By comparing the original biomass with the final biochar through tests of humidity, density, calorific values, fixed carbon, and cationic and elemental analysis, an increase in the parameters was confirmed. Fixed carbon of 70%, 77%, and 71% with pine, acacia, and eucalyptus biomass have been obtained, respectively, with yields between 30% and 40%. The results are favorable, particularly with acacia invasive plants, and could help in their difficult silviculture management.

Geographic variation in projected US forest aboveground carbon responses to climate change and atmospheric deposition

Forest composition and ecosystem services are sensitive to anthropogenic pressures like climate change and atmospheric deposition of nitrogen (N) and sulfur (S). Here we extend recent forest projections for the current cohort of trees in the contiguous US, characterizing potential changes in aboveground tree carbon at the county level in response to varying mean annual temperature, precipitation, and N and S deposition. We found that relative to a scenario with N and S deposition reduction and no climate change, greater climate change led generally to decreasing aboveground carbon (mean −7.5% under RCP4.5, −16% under RCP8.5). Keeping climate constant, reduced N deposition tended to lessen aboveground carbon (mean −7%), whereas reduced S deposition tended to increase aboveground carbon (+3%) by 2100. Through mid-century (2050), deposition was more important for predicting carbon responses except under the extreme climate scenarios (RCP8.5); but, by 2100, climate drivers generally outweighed deposition. While more than 70% of counties showed reductions in aboveground carbon relative to the reference scenario, these were not evenly distributed across the US. Counties in the Northwest and Northern Great Plains, and the northern parts of New England and the Midwest, primarily showed positive responses, while counties in the Southeast showed negative responses. Counties with greater initial biomass showed less negative responses to climate change while those which exhibited the greatest change in composition (>15%) had a 95% chance of losing carbon relative to a no-climate change scenario. This analysis highlights that declines in forest growth and survival due to increases in mean temperature and reductions in atmospheric N deposition are likely to outweigh positive impacts of reduced S deposition and potential increases in precipitation. These effects vary at the regional and county level, however, so forest managers must consider local rather than national dynamics to maximize forest carbon sinks in the future.

Carbon Dioxide Methanation Enabled by Biochar-Nanocatalyst Composite Materials: A Mini-Review

Due to ever-increasing global warming, the scientific community is concerned with finding immediate solutions to reduce or utilize carbon dioxide (CO2) and convert it in useful compounds. In this context, the reductive process of CO2 methanation has been well-investigated and found to be attractive due to its simplicity. However, it requires the development of highly active catalysts. In this mini-review, the focus is on biochar-immobilized nanocatalysts for CO2 methanation. We summarize the recent literature on the topic, reporting strategies for designing biochar with immobilized nanocatalysts and their performance in CO2 methanation. We review the thermochemical transformation of biomass into biochar and its decoration with CO2 methanation catalysts. We also tackle direct methods of obtaining biochar nanocatalysts, in one pot, from nanocatalyst precursor-impregnated biomass. We review the effect of the initial biomass nature, as well as the conditions that permit tuning the performances of the composite catalysts. Finally, we discuss the CO2 methanation performance and how it could be improved, keeping in mind low operation costs and sustainability.

Colonial Microcystis' biomass affects its shift to diatom aggregates under aeration mixing.

The effect of hydrodynamic mixing on controlling Microcystis blooms or changing the algal community to diatom dominance has been widely studied; however, the effects of colonial Microcystis biomass on the development of the algal community are poorly known. Here, in order to study the changes in Microcystis blooms under continuous aeration mixing, an experiment was carried out in a greenhouse with factors of varying biomass of Microcystis and inorganic nitrogen and phosphorus enrichment in summer. There were three chlorophyll a (Chl-a) levels in six treatments: low Chl-a level of 68.4μgL-1 (treatments L, L-E), medium Chl-a level of 468.7μgL-1 (treatments M, M-E), and high Chl-a level of 924.1μgL-1 (treatments H, H-E). Treatments L-E, M-E and H-E were enriched with the same inorganic nitrogen and phosphorus nutrients. During the experiment of 30days, the concentration of Microcystis and Chl-a decreased, and diatom Nitzschia palea cells appeared in all the treatments, which became dominant in treatments M, M-E, H and H-E, with the highest biomass of 9.41 ± 1.96mgL-1 Nitzschia in treatment H-E on day 30. The rank order of the biomass of Nitzschia from low to high was (L = L-E) < (M = M-E) < H < H-E (P < 0.05). In addition, Nitzschia cells were aggregates attached to Microcystis colonies in all the treatments. The results showed that the initial biomass of colonial Microcystis affected the algal shift from Microcystis dominance to Nitzschia dominance. However, the enriched inorganic nitrogen and phosphorus was beneficial for the Nitzschia increase in the high biomass treatment alone. The shift from Microcystis dominance to diatom dominance under continuous aeration mixing may be caused by low light conditions as well as the nutrients released from Microcystis decay. Moreover, the aerobic condition caused by aeration mixing maintained the colonial mucilaginous sheath to support the growth of Nitzschia cells in aggregation. This study found for the first time that Microcystis blooms could shift to diatom Nitzschia dominance in aggregates. It provided a method to control and manipulate Microcystis blooms to diatom dominance through continuous aeration mixing to proper biomass of Microcystis colonies. The shift to diatoms dominance would provide more high quality food organisms for aquaculture and be beneficial to the materialcycling and energy flowing in food web dynamics.

Selective method for invasive plant removal enhances restoration

Effective and sustainable restoration of habitats invaded by non‐native plant species requires both invader removal and recovery of native species. However, efficacy of removal methods and native species responses commonly depend on site conditions, spatial scale, and time, indicating invader removal and restoration approaches must consider environmental context. To better understand how selectivity of invader control methods and site conditions determine invader removal efficacy and resident community responses, we conducted an experiment with a widespread plant invader in the southeast United States (cogongrass, Imperata cylindrica) and co‐occurring resident species across nine sites that varied widely in environmental context. We found that three applications of the commonly used broad‐spectrum herbicide glyphosate reduced invader cover by 97%, on average, across the sites over 2 years. Fluazifop‐P‐butyl, a selective grass‐specific herbicide was equally effective (95% reduction in cover) in removing the invader when only two additional treatments were applied (five treatments total over 2 years) but it also helped preserve or allow for recovery of resident plant cover. Furthermore, removal efficacy was similar across sites regardless of differences in environmental conditions. Higher resource availability, as estimated by initial invader biomass at the sites, resulted in greater resident species recovery, but only under the grass‐specific herbicide treatment. Our results suggest that refocusing invasive plant management efforts from removal alone to community‐wide native species preservation and recovery, in part by using more selective invader removal strategies, has higher initial management costs but could simultaneously ease invader impacts and enhance ecosystem restoration.

Uranium removal in groundwater by Priestia sp. isolated from uranium-contaminated mining soil

Priestia sp. WW1 was isolated from a uranium-contaminated mining soil and identified. The uranium removal characteristics and mechanism of Priestia sp. WW1 were investigated. The results showed that the removal efficiency of uranium decreased with the increase of initial uranium concentration. When the uranium initial concentration was 5 mg/L, the uranium removal efficiency achieved 92.1%. The increase of temperature could promote the uranium removal. Carbon source could affect the removal rate of uranium, which was the fastest when the methanol was used as carbon source. The solution pH had significant effect on the uranium removal efficiency, which reached the maximum under solution pH 5.0. The experimental results and FTIR as well as XPS demonstrated that Priestia sp. WW1 could remove uranium via both adsorption and reduction. The common chloride ions, sulfate ions, Mn(II) and Cu(II) enhanced the uranium removal, while Fe(III) depressed the uranium removal. The Priestia sp. WW1 could effectively remove the uranium in the actual mining groundwater, and the increase of initial biomass could improve the removal efficiency of uranium in the actual mining groundwater. This study provided a promising bacterium for uranium remediation in the groundwater.

High water levels and low light co-inhibit colonization of fragments from the clonal invader Alternanthera philoxeroides

Natural disturbances and human activities frequently fragment aquatic plants. Vegetative fragments of invasive clonal plants have a high capacity for colonization and regrowth, which results in rapid spreading of these plants. A case study was conducted to explore the effects of the water level and light on the colonization and regrowth of a clonal invasive plant – Alternanthera philoxeroides. In the study, the growth of 10-cm-long fragments of A. philoxeroides was followed in three water levels (0, 2, and 10 cm) and two light conditions (10% and 80% of natural light). Results showed that total biomass of A. philoxeroides under all treatments except 10% of natural light and 10 cm of water level was higher than the initial biomass, which suggested that fragments of A. philoxeroides can regrow under most conditions. However, treatments of high water levels and low light inhibited regrowth, clonal expansion, and vegetative propagation of clonal fragments by reducing their total biomass, number of nodes and storage root biomass. Creating habitats of high water levels and low light, for example, by planting native emergent aquatic plants, can hamper the spread of this clonal invader. Our study contributes a new perspective to controlling the spread of invasive clonal plants by creating habitats that inhibit the colonization of invasive plant propagules.

Factors driving carbon accumulation in forest biomass and soil organic carbon across natural forests and planted forests in China

IntroductionForests play a pivotal role within the global carbon cycle. However, how to enhance carbon storage in existing forests remains unclear.MethodsIn this study, we conduct a comprehensive analysis of data from 2,948 forest sites across China. Utilizing structural equation modeling (SEM), we investigate the intricate relationship between climate, tree species diversity, stand structure, function traits, initial biomass carbon stocks (BCi), soil organic carbon stocks (Soil C content), and carbon accumulation in biomass (ΔBC) and soil organic carbon stocks (ΔSOC) within both natural forests (NF, n = 1,910) and planted forests (PF, n = 1,038).ResultsOur findings underscore the critical influence of tree species diversity and stand structure drivers of both direct and indirect carbon accumulation, with distinct drivers emerging based on the carbon pools in NF and PF. Specifically, increasing tree species diversity from its minimum to maximum value through management-results in a 14.798 tC/ha reduction in BC and 0.686 tC/ha in SOC in NF. Conversely, amplifies BC and SOC in PF by 0.338 tC/ha and 0.065 tC/ha, respectively. Enhancing stand structure-such as stand density-results in a 231.727 tC/ha reduction in BC and SOC in NF, and a 10.668 tC/ha in BC and 64.008 tC/ha increment in SOC in PF.DiscussionOverall, our results indicate that higher tree species diversity, stand density and age-group limits further carbon accumulation in BC and SOC in current NF. In contrast, low tree species diversity and stand density limits the development of carbon storage potential in planted forests. To enhance carbon sequestration capacity, China should change its current policy of completely banning logging of natural forests. Natural forests need thinning and reduced tree species diversity, while planted forests should increase tree species diversity and stand density.

Sequential Extraction of Carbohydrates and Lipids from Chlorella vulgaris Using Combined Physical and Chemical Pre-Treatments

A key focus of microalgae-based fuels/chemicals research and development has been on the lipids that many strains generate, but recent studies show that solely recovering these lipids may not be cost competitive with fossil-derived processes. However, if the carbohydrates can also be recovered and ultimately converted into useful chemical intermediates, this may improve the economics for microalgae-based sustainable product technologies. In the present work, physical and chemical pre-treatments were performed on the Chlorella vulgaris microalgae strain to recover the carbohydrates from the biomass primarily in the form of glucose and galactose. The effects of temperature, acid concentration, microalgae solid-to-liquid loading, and hydrolysis time on carbohydrate hydrolysis and recovery was explored to identify optimum conditions. The highest recovery of total carbohydrates, 90 ± 1.1 wt% at 95% confidence which represents 40 wt% of the initial biomass, was obtained using temperature-assisted weak-acid extraction. Sequential extraction of carbohydrates and lipids was then explored. The highest recovery of total lipids was 71 ± 1.8 wt%, which represents 22 ± 0.9 wt% of the initial biomass. The sequential extraction of carbohydrates followed by lipids resulted in an overall recovery of 60 ± 1.6 wt% of the initial biomass, which is higher than current single product recovery strategies. These results suggest that adding carbohydrate recovery may be a viable strategy for overcoming a major economic hurdle to microalgae-derived chemical and fuel production by significantly increasing the yield of usable materials from microalgae biomass.

Co-pelletization of fungi and microalgae for efficient tetracycline and nutrient removal

The potential harm to environmental and human health caused by antibiotic abuse has attracted widespread concern. In this study, the effects of the initial biomass ratio of Chlorella vulgaris and Ganoderma lucidum on the basic properties (sphericity, diameter, and color), growth, and photosynthetic performance of microalgae-fungi symbionts were analyzed. The effect and mechanism of tetracycline hydrochloride (TC) removal were investigated. Optimal removal was obtained at a 10:1 ratio (microalgae/fungi) with a 5 mm diameter symbiont. Under these conditions, the chlorophyll a concentration was 186.49 ± 17.81 μg L−1, and maximum removal efficiencies for total phosphorus, total nitrogen, chemical oxygen demand, and TC in wastewater were 84.68% ± 8.13%, 82.96% ± 8.12%, 81.77% ± 7.68%, and 94.57% ± 5.14%, respectively. These results provide important theoretical guidance for treatment applications for antibiotic-containing wastewater.

Effects of initial vegetation heterogeneity on competition of submersed and floating macrophytes

&lt;p&gt;Non-spatial models of competition between floating aquatic vegetation (FAV) and submersed aquatic vegetation (SAV) predict a stable state of pure SAV at low total available limiting nutrient level, &lt;italic&gt;N&lt;/italic&gt;, a stable state of only FAV for high &lt;italic&gt;N&lt;/italic&gt;, and alternative stable states for intermediate &lt;italic&gt;N&lt;/italic&gt;, as described by an S-shaped bifurcation curve. Spatial models that include physical heterogeneity of the waterbody show that the sharp transitions between these states become smooth. We examined the effects of heterogeneous initial conditions of the vegetation types. We used a spatially explicit model to describe the competition between the vegetation types. In the model, the FAV, duckweed (&lt;italic&gt;L. gibba&lt;/italic&gt;), competed with the SAV, Nuttall's waterweed (&lt;italic&gt;Elodea nuttallii&lt;/italic&gt;). Differences in the initial establishment of the two macrophytes affected the possible stable equilibria. When initial biomasses of SAV and FAV differed but each had the same initial biomass in each spatial cell, the S-shaped bifurcation resulted, but the critical transitions on the &lt;italic&gt;N&lt;/italic&gt;-axis are shifted, depending on FAV:SAV biomass ratio. When the initial biomasses of SAV and FAV were randomly heterogeneously distributed among cells, the vegetation pattern of the competing species self-organized spatially, such that many different stable states were possible in the intermediate &lt;italic&gt;N&lt;/italic&gt; region. If &lt;italic&gt;N&lt;/italic&gt; was gradually increased or decreased through time from a stable state, the abrupt transitions of non-spatial models were changed into smoother transitions through a series of stable states, which resembles the Busse balloon observed in other systems.&lt;/p&gt;

The predictability of near‐term forest biomass change in boreal North America

AbstractClimate change is driving substantial changes in North American boreal forests, including changes in productivity, mortality, recruitment, and biomass. Despite the importance for carbon budgets and informing management decisions, there is a lack of near‐term (5–30 year) forecasts of expected changes in aboveground biomass (AGB). In this study, we forecast AGB changes across the North American boreal forest using machine learning, repeat measurements from 25,000 forest inventory sites, and gridded geospatial datasets. We find that AGB change can be predicted up to 30 years into the future, and that training on sites across the entire domain allows accurate predictions even in regions with only a small amount of existing field data. While predicting AGB loss is less skillful than gains, using a multi‐model ensemble can improve the accuracy in detecting change direction to &gt;90% for observed increases, and up to 70% for observed losses. Higher stem density, winter temperatures, and the presence of temperate tree species in forest plots were positively associated with AGB change, whereas greater initial biomass, continentality (difference between mean summer and winter temperatures), prevalence of black spruce (Picea mariana), summer precipitation, and early warning metrics from long‐term remote sensing time series were negatively associated with AGB change. Across the domain, we predict nondisturbance‐induced declines in AGB at 23% of sites by 2030. The approach developed here can be used to estimate near‐future forest biomass in boreal North America and inform relevant management decisions. Our study also highlights the power of machine learning multi‐model ensembles when trained on a large volume of forest inventory plots, which could be applied to other regions with adequate plot density and spatial coverage.

Cross Flow Microfiltration System in Separating Fermented Nixtamal Corn for Preparation of Natural Folic Acid

A purification process of biomass of nixtamal yellow corn fermented by Rhizopus oligosporus strain C1 (FNC-A) and Rhizopus sp (FNC-B) was performed using a microfiltration (MF) membrane with pore size 0.15 µm installed in a crossflow microfiltration (CFMF) system to obtain retentate and permeate fractions as natural folic acid preparations. CFMF process was conducted at room temperature with a pump motor frequency (PMF) of 10 Hz (flow rate of 3.5 L/min) and a transmembrane pressure (TMP) of 4 bar for 0, 15, 30, 45, 60, 75, and 90 minutes. Based on optimum folic acid, the results showed that the best treatments of FNC-B and FNC-B were achieved at 90 min, resulting in a folic acid increase in retentate of FNC-A and FNC- B of 72.61 and 95.26%, reducing sugar of 20.41 and 170.93% (1.7-folds), total sugars of 155.51% (1.55-folds) and 426.76% (4.27-folds), and dissolved protein of 55.33 and 39.20%, and decrease in total solids of 88.91 and 91.64%, respectively, compared to initial biomass of FNC-A and FNC-B. The MFCF system effectively separated folic acid in retentates of FNC-A (33.77%) and FNC-B (95.27%) at the optimal condition. Folic acid monomers predominated the characteristics of FNC-A and FNC-B in optimum conditions with molecular weights of 442.10 and 442.18 Dalton, the average particle size of 38.31 μm and 37.97 μm, and distribution of particles at 10, 50, and 90% from the particle size 10.31, 26.32 and 81.55 μm, and 10.37, 28.04 and 76.09 μm, respectively.

Cross Flow Microfiltration System in Separating Fermented Nixtamal Corn for Preparation of Natural Folic Acid

A purification process of biomass of nixtamal yellow corn fermented by Rhizopus oligosporus strain C1 (FNC-A) and Rhizopus sp (FNC-B) was performed using a microfiltration (MF) membrane with pore size 0.15 µm installed in a crossflow microfiltration (CFMF) system to obtain retentate and permeate fractions as natural folic acid preparations. CFMF process was conducted at room temperature with a pump motor frequency (PMF) of 10 Hz (flow rate of 3.5 L/min) and a transmembrane pressure (TMP) of 4 bar for 0, 15, 30, 45, 60, 75, and 90 minutes. Based on optimum folic acid, the results showed that the best treatments of FNC-B and FNC-B were achieved at 90 min, resulting in a folic acid increase in retentate of FNC-A and FNC- B of 72.61 and 95.26%, reducing sugar of 20.41 and 170.93% (1.7-folds), total sugars of 155.51% (1.55-folds) and 426.76% (4.27-folds), and dissolved protein of 55.33 and 39.20%, and decrease in total solids of 88.91 and 91.64%, respectively, compared to initial biomass of FNC-A and FNC-B. The MFCF system effectively separated folic acid in retentates of FNC-A (33.77%) and FNC-B (95.27%) at the optimal condition. Folic acid monomers predominated the characteristics of FNC-A and FNC-B in optimum conditions with molecular weights of 442.10 and 442.18 Dalton, the average particle size of 38.31 μm and 37.97 μm, and distribution of particles at 10, 50, and 90% from the particle size 10.31, 26.32 and 81.55 μm, and 10.37, 28.04 and 76.09 μm, respectively.

CHEMICAL PROCESSING OF AGRICULTURE WASTES INTO VANILLIN, PULP AND GLUCOSE

Agrotechnical wastes from processing herbaceous plants consist of lignin and polysaccharides, which can be processed into monomers – phenols and carbohydrates. The prospects of chemical processing of several agrotechnical waste types with a high lignin content (flax shives, sunflower seed husks and buckwheat husks) into vanillin, pulp, and glucose by oxidation and acid hydrolysis were studied. It has been shown that despite the distant phylogenetic relationship of the studied plants, their lignins have a similar structure: they contain a similar amount of methoxyl groups (10–13 wt.% per lignin) and give close yields of aromatic aldehydes upon oxidation with nitrobenzene (17–19%) and oxygen (14–16%). In general, the suitability of agrotechnical wastes for oxidation to aromatic aldehydes determines by the lignin content. Among the studied wastes, flax shives are the most promising feedstock for chemical processing into vanillin and glucose. Cellulose-containing solid residues of oxidation process are more easily hydrolyzed compared to the initial lignocellulosic biomass. The inversion of glucose oligomers during the hydrolysis of cellulose with H2SO4 is limited by the hydrolysis of the tetra- and octamers.

Establishing a green biodesulfurization process for iron ore concentrates in stirred tank and leaching column bioreactors using Acidithiobacillus thiooxidans.

The presence of sulfur impurities in complex iron ores represents a significant challenge for the iron mining and steel-making industries as their removal often necessitates the use of hazardous chemicals and energy-intensive processes. Here, we examined the microbial and mineralogical composition of both primary and secondary iron concentrates, identifying the presence of Sulfobacillus spp. and Leptospirillum spp., while sulfur-oxidizing bacteria were absent. We also observed that these concentrates displayed up to 85% exposed pyrrhotite. These observations led us to explore the capacity of Acidithiobacillus thiooxidans to remove pyrrhotite-sulfur impurities from iron concentrates. Employing stirred tank bioreactors operating at 30°C and inoculated with 5·106 (At. thiooxidans cellsmL-1), we achieved 45.6% sulfur removal over 16days. Then, we evaluated packed leaching columns operated at 30°C, where the At. thiooxidans enriched system reached 43.5% desulfurization over 60days. Remarkably, sulfur removal increased to 80% within 21days under potassium limitation. We then compared the At. thiooxidans-mediated desulfurization process, with and without air supply, under potassium limitation, varying the initial biomass concentration in 1-m columns. Aerated systems facilitated approximately 70% sulfur removal across the entire column with minimal iron loss. In contrast, non-aerated leaching columns achieved desulfurization levels of only 6% and 26% in the lower and middle sections of the column, respectively. Collectively, we have developed an efficient, scalable biological sulfur-removal technology for processing complex iron ores, aligning with the burgeoning demand for sustainable practices in the mining industry.

Sweety, salty, sour, and romantic biochar-supported ZnO: highly active composite catalysts for environmental remediation

AbstractThe present work focuses on valorizing the various biochar supports of nano-catalysts and investigates the effect of the type of the initial biomass on the deposition and salient physico-chemical features of the zinc oxide (ZnO) nanoparticles. In this regard, we have used four different biomasses, namely, sugarcane bagasse (Saccharum officinarum), algae (Phaeophyta), mandarin orange peels (Citrus reticulata), and China rose petals (Rosa chinensis) as sources of biochar. Their wet impregnation with zinc acetate was followed by pyrolysis at 500 °C. It led to biochar (nicknamed “sweety,” “salty,” “sour,” and “romantic” biochar, respectively) loaded with very well dispersed, 20–360 nm-sized (mostly) ZnO nanoparticles. Interestingly, depending on the type of biomass used, the size, shape (quartz-like, semi-spherical, spherical, semi-cauliflower, needle or rod-like), and degree of crystallinity of ZnO nanoparticles (hexagonal crystal system) vary, in spite of all other synthesis parameters being similar. Nanoparticle-induced graphitization and crystallization of biochar have been also observed by Raman spectroscopy. The malachite green dye mineralization efficiency in the presence of H2O2 and different biochar-supported ZnO nanocatalysts was 15.1%, 46.3%, 99.9%, 67.9%, and 66.4% for H2O2, china rose petals, algae, mandarin peels, and sugarcane bagasse-supported ZnO catalyst in the presence of H2O2, respectively. Malachite green removal fits in very well with a pseudo-first-order kinetic model with R2 = 0.9701 (at algae biochar-ZnO). 6.6 times enhancement in the mineralization efficiency is observed as compared to just H2O2. The recyclability test of algae biochar impregnated with ZnO after 5 cycles indicates the mineralization efficiency levels up to 81.4%. Beyond these scientific results, this work is based on the principle of biomass waste valorization for sustainable development and circular economy, on the one hand, and addresses the UN Sustainable Development Goals 6, 13, and 14, on the other hand. It is also very clear that biochar is the new romance in the field of materials science and for sustainable future. Graphical Abstract