Biomass Support Research Articles

Enhancing the production and immobilization of cell‐bound lipase from yeast‐like fungus Magnusiomyces capitatusA4C for sustainable biodiesel production in a packed bed reactor

AbstractMagnusiomyces capitatus A4C, a mycelium‐forming and lipase‐producing yeast‐like fungus, was employed in a five‐level factorial design to optimize the collective and interactive influences of carbon, nitrogen and emulsifying sources and their possible effects on cell‐bound lipase (CBL) and cell biomass production. The cell culture of M. capitatus A4C was incubated along with biomass support particles (BSPs) to immobilize the enzyme while anchoring CBL on their surfaces. Among the BSPs tested, CBL immobilized on loofah sponge under optimized conditions showed a substantial hydrolytic activity of 12.7 U mL−1 and a cell‐loading capacity of 0.61 g g−1 of BSPs. Immobilized CBL was applied for biodiesel production via transesterification and esterification. The conversion percentage of triacylglycerides was approximately 100% at 24 h with the addition of water at 1:1 (v/v). The conversion of oleic acid into biodiesel via esterification was 100% at 48 h in the presence of 15% (v/v) isooctane. Further, biodiesel production was scaled up using a packed bed reactor. The batch production of biodiesel in a packed bed reactor through transesterification was 96.2%, with a circulation flow rate of 5.5 mL min−1 for 18 h. On the other hand, oleic acid conversion into biodiesel via esterification was 99.5%, with a circulation flow rate of 5.5 mL min−1 for 24 h. Further investigation revealed that the immobilized biocatalyst exhibited higher stability with esterification (85.3% fatty acid methyl ester) after ten repeated cycles.

Co-bioaugmentation with microalgae and probiotic bacteria: Sustainable solutions for upcycling of aquaculture wastewater and agricultural residues into microbial-rice bran complexes

Aquaculture farming generates a significant amount of wastewater, which has prompted the development of creative bioprocesses to improve wastewater treatment and bioresource recovery. One promising method of achieving these aims is to directly recycle pollutants into microbe-rice bran complexes, which is an economical and efficient technique for wastewater treatment that uses synergetic interactions between algae and bacteria. This study explores novel bioaugmentation as a promising strategy for efficiently forming microbial-rice bran complexes in unsterilized aquaculture wastewater enriched with agricultural residues (molasses and rice bran). Results found that rice bran serves a dual role, acting as both an alternative nutrient source and a biomass support for microalgae and bacteria. Co-bioaugmentation, involving the addition of probiotic bacteria (Bacillus syntrophic consortia) and microalgae consortiums (Tetradesmus dimorphus and Chlorella sp.) to an existing microbial community, led to a remarkable 5-fold increase in microbial-rice bran complex yields compared to the non-bioaugmentation approach. This method provided the most compact biofloc structure (0.50 g/L) and a large particle diameter (404 μm). Co-bioaugmentation significantly boosts the synthesis of extracellular polymeric substances, comprising proteins at 6.5 g/L and polysaccharides at 0.28 g/L. Chlorophyta, comprising 80% of the total algal phylum, and Proteobacteria, comprising 51% of the total bacterial phylum, are emerging as dominant species. These microorganisms play a crucial role in waste and wastewater treatment, as well as in the formation of microbial-rice bran complexes that could serve as an alternative aquaculture feed. This approach prompted changes in both microbial community structure and nutrient cycling processes, as well as water quality. These findings provide valuable insights into the transformative effects of bioaugmentation on the development of microbial-rice bran complexes, offering potential applications in bioprocesses for waste and wastewater management.

Preparation and Compositional Analysis of Lignocellulosic Plant Biomass as a Precursor for Food Production During Food Crises.

In the event of a sunlight-blocking, temperature-lowering global catastrophe, such as a global nuclear war, super-volcano eruption or large asteroid strike, normal agricultural practices would be severely disrupted with a devastating impact on the global food supply. Despite the improbability of such an occurrence, it is prudent to consider how to sustain the surviving population following a global catastrophe until normal weather and climate patterns resume. Additionally, the ongoing challenges posed by climate change, droughts, flooding, soil salinization, and famine highlight the importance of developing food systems with resilient inputs such as lignocellulosic biomass. With its high proportion of cellulose, the abundant lignocellulosic biomass found across the Earth's land surfaces could be a source of energy and nutrition, but it would first need to be converted into foods. To understand the potential of lignocellulosic biomass to provide energy and nutrition to humans in post-catastrophic and other food crisis scenarios, compositional analyses should be completed to gauge the amount of energy (soluble sugars) and other macronutrients (protein and lipids) that might be available and the level of difficulty in extracting them. Suitable preparation of the lignocellulosic biomass is critical to achieve consistent and comparable results from these analyses. Here we describe a compilation of protocols to prepare lignocellulosic biomass and analyze its composition to understand its potential as a precursor to produce post-catastrophic foods which are those that could be foraged, grown, or produced under the new climate conditions to supplement reduced availability of traditional foods. These foods have sometimes been referred to in the literature as emergency, alternate, or resilient foods. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Convection oven drying (1 to 2 days) Alternate Protocol 1: Air-drying (2 to 3 days) Alternate Protocol 2: Lyophilization (1 to 4 days) Support Protocol 1: Milling plant biomass Support Protocol 2: Measuring moisture content Basic Protocol 2: Cellulose determination Basic Protocol 3: Lignin determination Basic Protocol 4: Crude protein content by total nitrogen Basic Protocol 5: Crude fat determination via soxtec extraction system Basic Protocol 6: Sugars by HPLC Basic Protocol 7: Ash content.

Determinants of public preferences on low-carbon energy sources: Evidence from the United Kingdom

We empirically derive the determinants of British public preferences for different low-carbon energy sources using machine learning algorithm-based variable selection methods (ridge, lasso, and elastic net regression models). We seek to understand the drivers of support for solar, wind, biomass, and nuclear energy, which are the largest low-carbon energy sources and together account for the majority of UK power generation. Explanatory variables examined include those related to demographics, knowledge, perceptions of climate change, and government policy. We carry out a comparative study by synthesising the results of our independent analyses for each energy source and find that the preferred energy sources vary with respondents’ views on anticipated climate change impacts. Those who believe that potential effects of climate change will be catastrophic tend to prefer renewable energy sources whereas those less concerned about climate change tend to prefer nuclear power. The public also prefers energy sources about which they are more familiar or knowledgeable. Energy transition policies should be adjusted to better consider the factors that drive public acceptance of low-carbon energy sources, including exploring ways to secure policy support that considers energy source-specific characteristics and expanding public awareness of climate change and individual technologies, particularly among certain demographics.

Predicting partner fitness based on spatial structuring in a light-driven microbial community.

Microbial communities have vital roles in systems essential to human health and agriculture, such as gut and soil microbiomes, and there is growing interest in engineering designer consortia for applications in biotechnology (e.g., personalized probiotics, bioproduction of high-value products, biosensing). The capacity to monitor and model metabolite exchange in dynamic microbial consortia can provide foundational information important to understand the community level behaviors that emerge, a requirement for building novel consortia. Where experimental approaches for monitoring metabolic exchange are technologically challenging, computational tools can enable greater access to the fate of both chemicals and microbes within a consortium. In this study, we developed an in-silico model of a synthetic microbial consortia of sucrose-secreting Synechococcus elongatus PCC 7942 and Escherichia coli W. Our model was built on the NUFEB framework for Individual-based Modeling (IbM) and optimized for biological accuracy using experimental data. We showed that the relative level of sucrose secretion regulates not only the steady-state support for heterotrophic biomass, but also the temporal dynamics of consortia growth. In order to determine the importance of spatial organization within the consortium, we fit a regression model to spatial data and used it to accurately predict colony fitness. We found that some of the critical parameters for fitness prediction were inter-colony distance, initial biomass, induction level, and distance from the center of the simulation volume. We anticipate that the synergy between experimental and computational approaches will improve our ability to design consortia with novel function.

A Green Biocomposite Produced by Passive Cell Immobilization onto Waste Biomass Support for Biodecolorization of Reactive Dye Contamination

AbstractThe waste biomass of grape pomace was utilized for the immobilization of model fungal cells (Thamnidium elegans) providing a green, innovative, and practical biocomposite for efficient biodecolorization of a model reactive dye (Reactive Yellow 2). Appreciable decolorization capacity at optimized conditions was observed as qmax=151.0 mg g‐1 with the suggested biocomposite (TECWGP). During the batch process, the biocomposite exhibited the highest dye removal of 98.57 % in the RY2‐contaminated solutions. The biosorptive decolorization process was the best predicted by the Langmuir isotherm and the pseudo‐second‐order kinetic models. The possible interactions between RY2 and TECWGP were also examined. Synthetic wastewater treatment experiments indicated that TECWGP has a good decolorization potential. Overall, the findings indicated that TECWGP could be a good alternative to synthetic materials for the treatment of reactive dye‐contaminated aqueous phase. Furthermore, the utilization of agro‐industrial waste to support fungal cells contributes to the growth of a solid circular bio‐based economy.

Solutions for Optimizing Processes of Biological Treatment of Wastewater from the Textile Industry

Abstract In the present paper, the main concerns regarding the purification processes of wastewater from the textile industry containing nitrogen-type dyes are reviewed, and a method for the biological purification of these waters is developed. After consulting the results of the research in this field of wastewater treatment worldwide, a series of effective methods, described in the first chapter of this paper can be taken as positive examples. Following that, some methods of biological treatment of textile and leather industry wastewater are proposed, such as the inclusion of a biological treatment step using a fixed bed reactor. At the conclusion of this paper, recommendations are made for textile fabric operative industry, which are useful in biological contact processes. Biomass support panels, with limited flexibility and substantial surface expansion, with or without frames, form a variety of biomass support elements (textile fabric or otherwise), which can contain biological purification processes through the biomass panels.

A Review Study of Immobilized Microbial-Nanoparticles: Techniques and Biotechnology Applications

Immobilization of microbial cells on nanomaterials opens up broad prospects in biotechnology applications including environmental pollution control and enhancement of biofuel production. Cell-immobilization contributes to improved microbial performance, protection of microbes, and further biomass degradation. Moreover, nanoparticles as biomass support is an advanced strategy in bioremediation. Nanoparticles are interesting for immobilizing microbes due to their unique physicochemical properties. This review throws some light on the recent advances in immobilization of microbial cells techniques onto nanoparticles as a carrier where they are subsequently used as an nano-bio-stimulator in bioprocessing. The benefits and drawbacks of immobilization techniques are included. The biotechnology applications of nano-biocatalyst in bioprocessing are covered including biosorption of pollutants from wastewater and stimulants in biofuel production processes for a green energy generation. The use of nano-bio-catalysts in bioprocesses is an effective strategy for achieving economic feasibility in many processes. Furthermore, future prospects for microbial cell immobilization techniques are discussed.

Enhanced biological nitrogen and phosphorus removal from sewage driven by fermented glycerol: comparative assessment between sequencing batch- and continuously fed-structured fixed bed reactor.

The nutrient biological removal from sewage, especially from anaerobic reactor effluents, still represents a major challenge in conventional sewage treatment plants. In this work, the nitrogen and phosphorus removal from anaerobic pre-treated domestic sewage in an up-flow anaerobic sludge blanket (UASB) reactor was assessed in a structured fixed bed reactor (SFBR) operated in a continuous and in a batch mode using polyurethane foam as material support for biomass and fermented glycerol as the exogenous carbon source. The SFBR was operated as a sequencing batch reactor with cycles of 90, 120, and 150min under anaerobic, oxic, and anoxic conditions, respectively, reaching average efficiencies for total nitrogen and phosphorus removal of 88% and 56%, respectively. Fermented glycerol was added during the non-aerated periods. Under continuous feeding, the SFBR was operated with aeration/non-aeration periods of 2/1 (h) and 3/1 (h), hydraulic retention time of 12h, and a recirculation ratio of 3. Without fermented glycerol addition, the maximum removal of total nitrogen (TN) reached 42%, while adding glycerol in the non-aerated period improved TN removal to 64.9% (2/1h) and 69.5% (3/1h). During continuous operation, no phosphorus removal was observed, which was released during the non-aerated period, remaining in the effluent. Optical microscopy analyses confirmed the presence of polyphosphate granules and of the phosphorus accumulating organisms in the reactor biofilm. It was concluded that the batch feeding method was determinant for phosphorus removal. The structured fixed bed reactor with polyurethane foam proved to be feasible in the removal of organic matter and nutrients remaining in the UASB reactor effluent.

The Potential Application of Natural Clinoptilolite-Rich Zeolite as Support for Bacterial Community Formation for Wastewater Treatment.

The aim of this study was to investigate the use of natural zeolite as support for microbial community formation during wastewater treatment. Scanning electron microscopy (SEM), thermal decomposition and differential thermogravimetric curves (TGA/DGT) techniques were used for the physicochemical and structural characterization of zeolites. The chemical characterization of wastewater was performed before and after treatment, after 30 days of using stationary zeolite as support. The chemical composition of wastewater was evaluated in terms of the products of nitrification/denitrification processes. The greatest ammonium (NH4+) adsorption was obtained for wastewater contaminated with different concentrations of ammonium, nitrate and nitrite. The wastewater quality index (WWQI) was determined to assess the effluent quality and the efficiency of the treatment plant used, showing a maximum of 71% quality improvement, thus suggesting that the treated wastewater could be discharged into aquatic environments. After 30 days, NH4+ demonstrated a high removal efficiency (higher than 98%), while NO3+ and NO2+ had a removal efficiency of 70% and 54%, respectively. The removal efficiency for metals was observed as follows (%): Mn > Cd > Cr > Zn > Fe > Ni > Co > Cu > Ba > Pb > Sr. Analysis of the microbial diversity in the zeolite samples indicated that the bacteria are formed due to the existence of nutrients in wastewater which favor their formation. In addition, the zeolite was characterized by SEM and the results indicated that the zeolite acts as an adsorbent for the pollutants and, moreover, as a support material for microbial community formation under optimal conditions. Comparing the two studied zeolites, NZ1 (particle size 1–3 mm) was found to be more suitable for wastewater treatment. Overall, the natural zeolite demonstrated high potential for pollutant removal and biomass support for bacteria community growth in wastewater treatment.

Growth kinetic of Rhizopus sp. immobilised on loofah sponge for whole-cell biocatalyst in different cultivation media

Immobilisation of filamentous fungi such as Rhizopus sp. onto biomass support particles (BSP) surface was studied as whole-cell biocatalyst. The function was to aid fermentation process. By using the microbial immobilisation process, the complex procedures of isolation, purification and immobilisation of extracellular enzyme can be avoided. Loofa sponge was selected as the BSP to aid in the immobilisation of the cells. In this study, the growth of immobilised Rhizopus sp. on loofa sponge was compared in four different cultivation media and the attachment of Rhizopus sp. on loofa sponge was investigated using scanning electron microscopy (SEM). The media used in this study were hydrolysed cassava starch, cassava dextrose, potato dextrose, and soy dextrose. The process condition and other parameters which were temperature, pH, inoculum dilution, and weight of loofa sponge, fixed at 30 °C, 7, 20 mL, and 2 g, respectively. The highest and lowest of maximum growth (ymax) of the immobilised cells were determined from potato dextrose and soy powder mixed with dextrose media, respectively at 1.5281 g/g and 1.0370 g/g. Whilst, the highest and lowest observed rate constant (k) were obtained from cassava starch mixed with dextrose and soy powder mixed with dextrose, which respectively at 2.9403 day−1 and −0.8763 day−1. SEM images showed the presence of mycelia attached to the loofah sponge after immobilisation process. In conclusion, Rhizopus sp. has been successfully immobilised on loofah sponge as a whole-cell biocatalyst.

A divided flow aerobic-anoxic baffled reactor for simultaneous nitrification-denitrification of domestic wastewater

A novel aerobic-anoxic baffled reactor is designed for the effective denitrification of real domestic wastewater without an external carbon source. The flow is divided between two inlets at the beginning of each zone to provide a carbon source for the denitrifying bacteria. The effects of operating parameters such as the ratio of chemical oxygen demand to nitrogen (COD/N), flow division ratio, and hydraulic retention time (HRT) on the nitrogen removal were investigated. The optimum values of COD/N and HRT were estimated using response surface methodology (RSM) coupled with a central composite experimental design. The addition of porous biomass support media considerably improved the denitrification and removal of COD. Furthermore, the aerobic-anoxic system showed high stability against sudden HRT and COD/N ratio changes. The microbial analysis showed that Alcaligenes, Achromobacter, and Bordetella were the dominant denitrifying bacteria in the anoxic zone, whereas other species coexisted in the aerobic zone.

Elucidating the removal of organic micropollutants on biological ion exchange resins

Biological ion exchange (BIEX) refers to operating ion exchange (IX) filters with infrequent regeneration to favor the microbial growth on resin surface and thereby contribute to the removal of organic matter through biodegradation. However, the extent of biodegradation on BIEX resins is still debatable due to the difficulty in discriminating between biodegradation and IX. The objective of the present study was to evaluate the performance of BIEX resins for the removal of organic micropollutants and thereby validate the occurrence of biodegradation. The removals of biodegradable micropollutants (neutral: caffeine and estradiol; negative: ibuprofen and naproxen) and nonbiodegradable micropollutants with different charges (neutral: atrazine and thiamethoxam; negative: PFOA and PFOS) were respectively monitored during batch tests with biotic and abiotic BIEX resins. Results demonstrated that biodegradation contributed to the removal of caffeine, estradiol, and ibuprofen, confirming that biodegradation occurred on the BIEX resins. Furthermore, biodegradation contributed to a lower extent to the removal of naproxen probably due to the absence of an adapted bacterial community (Biotic: 49% vs Abiotic: 38% after 24 h batch test). The removal of naproxen, PFOS, and PFOA were attributable to ion exchange with previously retained natural organic matter on BIEX resins. Nonbiodegradable and neutral micropollutants (atrazine and thiamethoxam) were minimally (6%–10%) removed during the batch tests. Overall, the present study corroborates that biomass found on BIEX resins contribute to the removal of micropollutants through biodegradation and ion exchange resins can be used as biomass support for biofiltration.

Palm Oil Decanter Cake Wastes as Alternative Nutrient Sources and Biomass Support Particles for Production of Fungal Whole-Cell Lipase and Application as Low-Cost Biocatalyst for Biodiesel Production

This is the first report on the possible use of decanter cake waste (DCW) from palm oil industry as alternative nutrient sources and biomass support particles for whole-cell lipase production under solid-state fermentation (SSF) by newly isolated fungal Aspergillus sp. MS15 and their application as a low-cost and environment-friendly biocatalyst for biodiesel production. The results found that DCW supplemented with 0.1% K2HPO4, 0.05% MgSO4·7H2O, 1% peptone and 2% urea and pH adjusted to 6.0 was optimal for whole-cell lipase production. The optimal moisture content and fermentation temperature was 60% and 37.5 °C, respectively. Environmentally friendly biodiesel production, through either esterification or transesterification using whole-cell lipase immobilized on DCW as a biocatalyst, was optimized. The optimal reaction temperature for both reactions was 37 °C. The whole-cell lipase effectively esterified oleic acid into >95% biodiesel yield through esterification under optimal water activity at 0.71 and an optimal methanol to oleic acid molar ratio of 2:1, and also effectively transesterified palm oil under optimal water activity at 0.81 and an optimal methanol to oil molar ratio of 3:1. The fuel properties of produced biodiesel are close to the international biodiesel standards. These results have shown the circular utilization of palm oil mill waste for the low-cost production of an effective biocatalyst, and may contribute greatly to the sustainability of renewable bioenergy production.

Polyurethane foam as biomass support for removal of thiosalts from flotation process water

Water recycling is a common practice in sulphide ore processing plants by flotation. Inherent thiosalts accumulation in process water often causes efficiency drop and environmental issues for wastewater discharging. Passive and active depuration methods have been applied for thiosalts removal and bio-oxidation in packed bed bioreactors can be considered the most promising option.In this work, polyurethane foam is for first time used as biomass support material in continuous bio-oxidation of thiosalts. Two columns, 15 and 197 cm in height and 8.4 cm in diameter, packed with 1 cm in edge length cubic particles were trialled. A new and fast start-up procedure was performed allowing to effectively operate them in less than seven days. Complete removal of thiosalts in real liquors were achieved with bio-oxidation rates close to 0.45 kg/hm3 and residence time lower than 7 h. Stability, robustness and versatility showed by the bioreactors allows to affirm that polyurethane foam is a suitable material as biomass support in continuous packed bed bioreactors for thiosalts bio-oxidation.

Immobilization of Zymomonas mobilis In situ in Flexible Polyurethane and Potential for Bioconversion in Sodium Maltobionate

Maltobionic acid and its salts are produced by the action of the periplasmic enzymatic complex glucose-fructose oxidoreductase (GFOR), and glicono-δ-lactonase (GL) from Zymomonas mobilis and, for such, cell immobilization is outstanding. Thus, the objective of this work was to immobilize, in situ, Z. mobilis cells containing GFOR/GL in flexible polyurethane foam (PU) in order to produce maltobionic acid. In the immobilization, concentrations of polyurethane and biomass support constituents varied, and the visual aspect of the material immobilized was assessed, its enzymatic activity, immobilization yield, and operational stability. In the maximized immobilization condition, morphological analysis of the support and bioconversion runs were performed. The scanning electron microscopy analysis showed that the microorganism was trapped in the PU (7 g of polyol; 3.5 g of isocyanate; 0.02 g of silicone, and 7 g of biomass). The immobilized material maximum enzymatic activity against glucose was 19.40 U g-1dry cell, with an immobilization yield of 60.29% and 15 reuses. In bioconversion, 491.42 mmol L-1 of sodium maltobionate were produced in 47.56 h, with a conversion factor of 0.88 and mass productivity, specific productivity, and specific product formation speed of 2.58 mmol h-1; 1.81 mmol g-1 h-1 and 6.25 mmol g-1 h-1, respectively. This study's results contribute to the production of aldonic acids because it uses scarce information in the area and application potentials.

Statistical modeling and optimization of tannery wastewater treatment in a fluidized bed bioreactor with low density biomass support

Treatment of tannery industry effluent is a serious challenge due to the presence of toxic pollutants including dyes and heavy metals. This work is focused on the optimization of bed height and air flow rate for tannery industry wastewater treatment in a fluidized bed reactor with low density biomass support. Response surface methodology was adopted for the optimization of process parameters viz air flow rate, bed height and wastewater dilution ratio and the best operating conditions were identified. The optimum values for the maximum chemical oxygen demand (COD) removal are: air flow rate—233 LPH, Bed height—82 cm and wastewater dilution ratio—1:2. The results from the IFBR showed that a maximum of 90.2% of COD reduction obtained at an airflow rate of 233 LPH and initial bed height of 82 cm. In this research, a maximum colour removal of 83.4% was achieved. A high correlation coefficient (R2) value of more than 0.94 for all the three models indicates that the RSM based models predict the data well. The relative effect of variables on COD removal, colour removal and air hold up were depicted in perturbation plots.

Utilizing palm oil mill effluent (POME) for the immobilization of Aspergillus oryzae whole‐cell lipase strains for biodiesel synthesis

AbstractPalm oil mill effluent (POME) is a palm industrial waste by‐product that is readily available and possesses high quantities of the organic compounds that are necessary for microbial growth. This study investigated the potential of immobilized Aspergillus oryzae whole cells expressing Candida antartica lipase B (r‐CALB) when using a POME‐based medium as a low‐cost carbon source within biomass support particles. The dry cell weight, hydrolytic activity, and remaining protein were measured for a variety of POME (0–2% w/v) and carbon source concentrations (0–2% w/v) with an incubation time of 96 h. Using POME in the culture medium as a carbon source instead of glucose doubled the retention of cell weight from 1.16 ± 0.03 to 2.36 ± 0.02 g within the biomass support particles and improved the hydrolytic activity from 1.61 ± 0.02 to 2.23 ± 0.02 U mg−1 in whole‐cell lipase. This immobilized r‐CALB was used as a catalyst to esterify POME into biodiesel. This synthesis produced an ester content of 97.52 ± 0.21% w/w after 96 h. Immobilized r‐CALB was reusable for more than ten batches, and resulted in an ethyl ester content of more than 90% w/w even after 10 cycles. The present study demonstrated that POME could serve as a sustainable carbon source for industrial microbial culture with the additional incentive of being a treatment that is inexpensive and sustainable. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd

Enhanced surface properties, hydrophobicity, and sorption behavior of ZnO nanoparticle-impregnated biomass support for oil spill treatment.

Metallic nanoparticles (NPs) have gained significant attention in recent years due to their efficiency in the adsorption of water pollutants. Except for magnetic NPs, metallic NPs are rarely used in oil sorption studies, due to the difficulty in recovering the NPs from the treated water. This study reports for the first time the application of ZnONPs for oil spill treatment. The ZnONPs were impregnated onto Musa acuminata peel (MP) support to form a novel material (ZnOMP), which was utilized for the sorption of oil from synthetic oil spills. The as-prepared sorbents were characterized by the SEM, EDS, BET, FTIR, FE-SEM, TGA, and XRD techniques. The presence of 31.32-nm average-sized ZnONPs enhanced the oil uptake characteristics, with clear affinity for the oil phase in comparison to the pristine MP. A maximum sorption capacity of 4.146 g/g and 5.236 g/g was obtained for biosorbents MP and ZnOMP, respectively, which was higher than most reported sorbents. The Freundlich model presented the best fit for the isotherm data, while the pseudo-second-order model was most suited for the kinetics. The presence of competing heavy metal ions in solution did not have any significant effect on the oil sorption capacity onto ZnOMP. The sorption mechanism was attributed to absorption and hydrophobic interactions. ZnONPs impregnated onto the biomass enhanced the spontaneity of oil uptake at higher temperatures. Over 82% desorption of the oil contaminant from the biosorbents was achieved during recovery, using petroleum ether and n-pentane as eluents. Concisely, ZnONPs enhanced the uptake and hydrophobic characteristic of MP biomass and showed good recovery and reusability. Thus, the application of ZnONPs impregnated onto biosorbents in oil spill treatment is highly recommended.

Regime change in a large-floodplain river ecosystem: patterns in body-size and functional biomass indicate a shift in fish communities

Changes in species dominance may drive regime shifts because dominant biotic feedbacks reflect functional traits of a community. Changes in species dominance has been documented by a 25-year fish community dataset encompassing six reaches of the Upper Mississippi and Illinois Rivers. Specifically, common carp (Cyprinus carpio) abundance has declined across all reaches, whereas silver carp (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis) have increased in abundance in the southern three reaches. To test whether signals in the data were consistent with regime transitions, changes in body-size patterns and trends in functional biomass and variance of functional biomass of the fish community were assessed. I further explored biomass thresholds relative to transitions. Shifts in body-size aggregations and trends in functional biomass support hypotheses that transitions from common carp dominance to a more functional diverse community represent alternate regimes. Results indicate such transitions occurred in the early 2000s for the two most northern reaches, and that the third most northern reach is nearing this transition. In the southern reaches, results indicate that transitions from common carp dominance to silver and bighead carp dominance also represent alternate regimes. Regime transitions support biomass thresholds between 8000 and 10,000 g per unit of day electrofishing effort of common carp and between 20 and 2000 g per unit effort in silver and bighead carp. Consistencies across reaches with similar dominance patterns provide support that reinforcing feedbacks, unique to the functional attributes of the dominant species, occur at similar biomass levels. Building knowledge of such feedback mechanisms is imperative to effectively manage for desired regimes.