Biodegradable Substrate Research Articles

Enhancing cellulose acetate biodegradability in cigarette filters: an in-depth analysis of thermal alkaline pretreatment, microbial dynamics, and breakdown pathway prediction

BackgroundThe demand for bioplastics has increased exponentially as they have emerged as alternatives to petrochemical plastics. However, there is a substantial lack of knowledge regarding bioplastic degradation. This study developed a novel pretreatment method to improve the accessibility of a bioplastic substrate for biodegradation. In this study, cellulose acetate, a bioplastic found in the world’s most littered waste, e.g. cigarette filters, was selected as a potential substrate. Before anaerobic digestion, three thermal alkaline pretreatments: TA 30 °C, TA 90 °C, and TA 121 °C, were used to evaluate their effects on the chemical alterations of cellulose acetate.ResultThe ester groups in cellulose acetate were significantly reduced by the TA 30 °C pretreatment, as seen by a decrease in C = O stretching vibrations and shortening of C − O stretches (1,270 ∼ 1,210 cm− 1), indicating effective removal of acetyl groups. This pretreatment significantly enhanced cellulose acetate biodegradability to a maximum of 91%, surpassing the previously reported cellulose acetate degradation. Methane production increased to 695.0 ± 4 mL/g of volatile solid after TA 30 °C pretreatment, indicating enhanced cellulose acetate accessibility to microorganisms, which resulted in superior biogas production compared to the control (306.0 ± 10 mL/g of volatile solid). Diverse microbes in the anaerobic digestion system included hydrolytic (AB240379_g, Acetomicrobium, FN436103_g, etc.), fermentative, and volatile fatty acids degrading bacteria (JF417922_g, AB274492_g, Coprothermobacter, etc.), with Methanobacterium and Methanothermobacter being the sole hydrogenotrophic methanogens in the anaerobic digestion system. Additionally, an attempt to predict the pathway for the effective degradation of cellulose acetate from the microbial community in different pretreatment conditions.ConclusionsTo the best of our knowledge, this is the first study to estimate the maximum cellulose acetate degradation rate, with a simple and cost-effective pretreatment procedure. This approach holds promise for mitigating the environmental impact of cellulose acetate of cigarette filters and presents a sustainable and economically viable waste management strategy.

Degradable cellulose acetate-based waterborne polyurethane sand-fixing agents for sand control in desert regions

In hot and arid desert regions, degradable chemical sand-fixing agents are efficient in dealing with problems caused by wind-blown sand movement without damaging the environment. This study aimed to develop a set of biodegradable sand-stabilizing substances, cellulose acetate (CA)-based waterborne polyurethane (WPU), utilizing CA as a partial hydroxyl provision through an acetone-based technique. The findings demonstrate that all the CA/WPU sand-fixing agents had unique, evenly spherical particles and were fully capable of degradation. The CA/WPU-2 sand-fixing agent contained 20 % polypropylene glycol (PPG) of CA. It showed strong viscosity, thermal stability, and water resistance. Furthermore, seed germination will be hindered by the CA/WPU-2 sand-fixing agent due to its superior sand-fixing capability compared to pure WPU. Consequently, it is suitable for application in arid regions where plant survival is difficult. CA/WPU-6 contained 120%PPG of CA. it showed outstanding O2 permeability and hydrophilicity due to its significant use of cellulose acetate. In addition, it demonstrated higher wind-blown sand resistance compared to popular commercial sand-fixation production. Furthermore, it sustained a consolidation strength lower than the highest penetration capability for herbaceous plant seeds. Therefore, CA/WPU-6 is a suitable option for establishing vegetation in dry situations. The results of this study address the demand for sustainable production and cost reduction, offering significant potential for industrial applications.

Injectable biodegradable microcarriers for iPSC expansion and cardiomyocyte differentiation.

Cell therapy is a potential novel treatment for cardiac regeneration and numerous studies have attempted to transplant cells to regenerate the myocardium lost during myocardial infarction. To date, only minimal improvements to cardiac function have been reported. This is likely to be the result of low cell retention and survival following transplantation. This study aimed to improve the delivery and engraftment of viable cells by using an injectable microcarrier that provides an implantable, biodegradable substrate for attachment and growth of cardiomyocytes derived from induced pluripotent stem cells (iPSC). We describe the fabrication and characterisation of Thermally Induced Phase Separation (TIPS) microcarriers and their surface modification to enable iPSC-derived cardiomyocyte attachment in xeno-free conditions is described. The selected formulation resulted in iPSC attachment, expansion, and retention of pluripotent phenotype. Differentiation of iPSC into cardiomyocytes on the microcarriers is investigated in comparison with culture on 2D tissue culture plastic surfaces. Microcarrier culture is shown to support culture of a mature cardiomyocyte phenotype, be compatible with injectable delivery, and reduce anoikis. The findings from this study demonstrate that TIPS microcarriers provide a supporting matrix for culturing iPSC and iPSC-derived cardiomyocytes in vitro and are suitable as an injectable cell-substrate for cardiac regeneration.

A Trimode Self-Cleaning Composite Membrane with an Eco-friendly Substrate for Energy-Saving Wastewater Recycling

A separation membrane with low or clean energy costs is urgently required for energy-saving and long-term service since electric energy generated from burning non-renewable resources will gradually cause a burden to the environment. At present, the conventional membrane being used in one mode is critical for a variety of scenarios in real life, which suffers from a trade-off effect, short service life, being difficult to recycle after damage. Herein, we report a trimode purification membrane composed of an eco-friendly polycaprolactone (PCL) substrate and functional graphene dioxide/polyaniline (GO/PANI) particles. Due to the photothermal transfer and photocatalytic properties of GO/PANI blend, the composite membrane can absorb 97.44% solar energy to handle natural seawater or mixed wastewater, which achieves a high evaporation rate of 1.47 kg m−2 h−1 in solar-driven evaporation mode. For the photocatalytic adsorption–degradation mode, 93.22% of organic dyes can be adsorbed and degraded after 12 h irradiation under 1 kW m−2. Moreover, electric-driven cross-flow filtration mode as a supplement also shows effective rejection over 99% for organic dyes with a high flux over 40 L m−2 h−1 bar−1. The combination of solar-driven evaporation, photocatalytic adsorption–degradation, and electric-driven cross-flow filtration demonstrates a prospective and sustainable strategy to generating clean water from sewages.Graphical A trimode self-cleaning composite membrane of bio-degradable substrate PCL and functional particles GO/PANI were successfully fabricated, which can purify natural seawater or mixed wastewater stably in solar-driven evaporation mode, handle organic dyes by reduction–oxidation chemical transformation in photothermal adsorption–degradation mode, and be applied in cross-flow filtration mode driven by electric as a supplement for rainy, cloudy days, or at night.

Modified zero-valent iron nanoparticles enhanced remediation of PCBs-contaminated soil

The high toxicity and persistence of polychlorinated biphenyls (PCBs) in the environment require effective remediation of PCBs-contaminated soil. This study used polylactic acid (PLA) and polyethylene glycol 4000 (PEG-4000) to modify zero-valent iron nanoparticles (nZVI) and conducted characterization analysis. It was found that when the addition amount of PLA was 2 %, the dispersion of modified nZVI was better. The initial pH and water to soil ratio were subjected to single factor experiments and fitted using RSM response surface methodology. The optimal reaction conditions were obtained as follows: the addition amount was 84 g·kg−1, the initial pH was 5.41, and the optimal removal rate was 74 % when the ratio of water to soil was 1.8:1. PLA and PEG-4000 were biodegradable substances that played crucial roles in enhancing the effectiveness of nZVI for PCBs-contaminated soil. By encapsulating nZVI with PLA, we significantly reduced its oxidation when exposed to air. Additionally, the inclusion of PEG-4000 helped prevent the particles from clumping together. The synergistic effect of them increased the effective reaction of nZVI and PCBs and ultimately leading to more efficient remediation. This study offered a new pathway for the efficient green remediation of PCBs-contaminated soil.

Bulking agent in dry anaerobic digestion as a key factor for the enhancement of biogas production

Dry anaerobic digestion (dry-AD) is an attractive process for solid wastes such as agri-food waste. However, some limitations mainly associated to lack of effective mixing, can hinder the methane production capacity of the systems. Bulking agent (BA) has been proposed as a solution to the compaction issues in systems without mechanical agitation, such as leaching bed reactors. However, effects of BA are still not clear, and, thus, the factors to consider for its dose has not been optimized yet. This work studies the effect of BA in dry-AD. Two substrates with different characteristics were proposed as models, bean peel as a lignocellulosic substrate and a mixture of food waste as a readily biodegradable substrate. Inert plastic rings were used as BA at different BA:S ratios. Assessed BA:S ratio did not affect the performance of methane production for the lignocellulosic waste, but it did significantly affect to the easily biodegradable substrate, showing up to a 28% of methane production increase. This result could be due to the presence of lignocellulosic compounds in the bean peel, behaving like a natural BA. In assays with an increased bed height, the compaction of the system was more severe, resulting in the rapid acidification of the processes. At these conditions, the positive effect of BA addition was more marked, allowing methane production and no acidification of the system. Thus, the addition of BA is a suitable strategy for improving methane production or stability in dry-AD systems without requiring the stirring of the systems.

Agricultural and industrial wastes applied on the high performance energy storage devices

Driven by population growth, the destruction of the environment and the energy demand continue to increase dramatically. This study uses garlic skin and carbon fiber from agricultural and industrial wastes to prepare energy storage devices. Carbon quantum dots (CQDs) were obtained from garlic skin using high-temperature pyrolysis. The specific capacitance of the gel electrolyte could be effectively increased with a small number of CQDs doping. A methylcellulose-based carbon fiber-electrode was prepared by grinding and depositing the industrial recycled carbon fiber onto a biodegradable methylcellulose substrate. The methylcellulose-based recycled carbon fiber-electrode has the highest specific capacitance, energy density, and power density, which are 155 F/g, 10 Wh/kg, and 4047 W/kg, respectively, at a scan rate of 0.02 V/s, and demonstrates excellent performance, such like high specific capacitance, low internal resistance as well as rapid charge and discharge characteristics, which may have potential to replace the expensive carbon nanotubes and graphenes. The electrodes were made from recycled carbon fiber, the gel electrolyte with garlic CQDs, and a separator assembled into a sandwich structure to form supercapacitors. The capacity retention rate of the supercapacitor still retained 96 % of its initial value after 2000 cycles of charge and discharge testing at a constant current of 0.20 mA. This demonstrates the supercapacitor prepared in this study with competitive power density, energy density, high rate capability, and excellent life cycle stability by combining the garlic skin and carbon fiber from agricultural and industrial wastes, highlighting the enormous potential of agricultural and industrial wastes for energy storage applications.

Sustainable adsorbent frameworks based on bio-resourced materials and biodegradable polymers in selective phosphate removal for waste-water remediation.

Phosphorus to an optimum extent is an essential nutrient for all living organisms and its scarcity may cause food security, and environmental preservation issues vis-à-vis agroeconomic hurdles. Undesirably excess phosphorus intensifies the eutrophication problem in non-marine water bodies and disrupts the natural nutrient balance of the ecosystem. To overcome such dichotomy, biodegradable polymer-based adsorbents have emerged as a cost-effective and implementable approach in striking a "desired optimum-undesired excess" balance pertaining to phosphate in a sustainable manner. So far, the reports on adopting such adsorbent-approach for wastewater remediation remained largely scattered, unstructured, and poorly correlated. In this background, the contextual review comprehensively discusses the current state-of-the-art in utilizing biodegradable polymeric frameworks as an adsorbent system for phosphate removal and its efficient recovery from the aquatic ecosystem, while highlighting their characteristics-specific functional efficiency vis-à-vis easiness of synthetic and commercial viability. The overview further delves into the sources and environmental ramifications of excessive phosphorus in water bodies and associated mechanistic pathways of phosphorus removal via adsorption, precipitation, and membrane filtration enabled by biodegradable (natural and synthetic) polymeric substrates. Finally, functionality optimization, degradability tuning, and adsorption selectivity of biodegradable polymers are highlighted, while aiming to strike a balance in "removal-recovery-reuse" dynamics of phosphate. Thus, the current review not only paves the way for future exploration of biodegradable polymers in sustainable cost-effective adsorbents for phosphorus removal but also can serve as a guide for researchers dealing with this critical issue.

Some Studies on Cutting Force Generation in Machining of Mg-Ca1.0 Alloy

Magnesium alloy has qualities that are similar to those of bone, it is now commonly acknowledged as a biodegradable material. Mg-Ca1.0 is a recently developed biodegradable substance that doesn’t cause any harmful substances to be produced in the body. It is frequently utilized in fixation screws and supporting plates for bone implants. To far, very little research has been published on the machining of biodegradable Magnesium Calcium alloy. This investigation’s goal is to evaluate the cutting forces produced during a face milling procedure. The experimental work used a one-factor-at-a-time strategy to assess how process factors affect performance attributes. The current study uses a CVD diamond-coated insert to examine how the depth of cut, feed rate, and cutting speed affect the radial (Fx), tangential (Fy), and axial (Fz) cutting forces during face milling in a dry machining environment.

Physicochemical properties of native Jack bean (Canavalia ensiformis) starch: An underutilised legume

Legumes are a cost-effective source of proteins and abundant starch, a biodegradable substance, providing human nutrition and serving various food sectors globally. Some of the neglected (underutilised) legumes can also be used as the cheapest source of starch. Therefore, the present study was conducted to determine the physicochemical characteristics of jack bean (Canavalia ensiformis) starch - a legume not widely known so underutilised. The starch was isolated from the bean by standard method to study its various properties. One-way analysis of variance was employed to verify a significant difference at the 5% significance level. The jack bean yielded 30.98% of starch. The starch’s moisture, ash, fat, protein, fiber, and carbohydrate content were 9.67%, 0.19%, 0.27%, 0.56%, 0.27%, and 89.28% respectively. The physicochemical properties were also determined. The apparent and total amylose contents were 43.82% and 47.78%, respectively, with 7.66% of amylose leaching at 95°C. The water and oil absorption capacities were 2.31 and 2.56 g/g, respectively, while emulsion capacity and stability were 62.30 and 71.38 %, respectively. The solubility and swelling power of jack bean starch increased with temperature from 55 to 95°C. The effect of starch concentrations (6, 8, and 10%) on freeze-thaw stability revealed that water expelled decreased as starch content increased. Nevertheless, a comprehensive investigation has not been conducted into the distinct functional characteristics and other attributes of jack bean starch. This study could provide new opportunities for conventional starch industries that rely on starch from sources like cereals, tubers, and rhizomes.

Biogas from wastewater’s sludge as potential resource for transportation. Experimental approach.

Considering growing energy requirements and the quest for self-sufficiency in energy sources, the utilization of waste-derived materials has surged in various fields of research in recent years. Within this framework, waste waters, sludge, or slurries, biodegradable substances, second-generation effluents, and the resulting by-products have emerged as crucial substrates of interest to produce biogas through anaerobic digestion (AD). The objective is to employ these materials as the foundation for generating renewable energy, ultimately establishing them as the primary energy source for households or industries. This paper endeavours to assess, both physically and chemically, the waste industrial and urban wastewaters sourced from west Banat region as a foundational substrate material for co-fermentation alongside residual biomass from cereals. The results obtained are presented.

Shared and more specific genetic determinants and pathways underlying yeast tolerance to acetic, butyric, and octanoic acids

BackgroundThe improvement of yeast tolerance to acetic, butyric, and octanoic acids is an important step for the implementation of economically and technologically sustainable bioprocesses for the bioconversion of renewable biomass resources and wastes. To guide genome engineering of promising yeast cell factories toward highly robust superior strains, it is instrumental to identify molecular targets and understand the mechanisms underlying tolerance to those monocarboxylic fatty acids. A chemogenomic analysis was performed, complemented with physiological studies, to unveil genetic tolerance determinants in the model yeast and cell factory Saccharomyces cerevisiae exposed to equivalent moderate inhibitory concentrations of acetic, butyric, or octanoic acids.ResultsResults indicate the existence of multiple shared genetic determinants and pathways underlying tolerance to these short- and medium-chain fatty acids, such as vacuolar acidification, intracellular trafficking, autophagy, and protein synthesis. The number of tolerance genes identified increased with the linear chain length and the datasets for butyric and octanoic acids include the highest number of genes in common suggesting the existence of more similar toxicity and tolerance mechanisms. Results of this analysis, at the systems level, point to a more marked deleterious effect of an equivalent inhibitory concentration of the more lipophilic octanoic acid, followed by butyric acid, on the cell envelope and on cellular membranes function and lipid remodeling. The importance of mitochondrial genome maintenance and functional mitochondria to obtain ATP for energy-dependent detoxification processes also emerged from this chemogenomic analysis, especially for octanoic acid.ConclusionsThis study provides new biological knowledge of interest to gain further mechanistic insights into toxicity and tolerance to linear-chain monocarboxylic acids of increasing liposolubility and reports the first lists of tolerance genes, at the genome scale, for butyric and octanoic acids. These genes and biological functions are potential targets for synthetic biology approaches applied to promising yeast cell factories, toward more robust superior strains, a highly desirable phenotype to increase the economic viability of bioprocesses based on mixtures of volatiles/medium-chain fatty acids derived from low-cost biodegradable substrates or lignocellulose hydrolysates.

Enhancing ecological complexity in soft‐bottom coastal ecosystems: the impact of introducing hard substrates

Coastal ecosystems globally face pressures, with natural coastal habitats being replaced by engineered structures. While hard structures for navigation‐purposes and coastal defense can negatively impact native communities, they can also be applied in ecological restoration as artificial reefs. This way substrates may facilitate establishment of biogenic (shellfish) reefs and provide habitat heterogeneity in soft‐sediment ecosystems. In a 1.5‐year experiment, we introduced six different types of natural or biodegradable hard substrates in a subtidal soft‐sediment system. We compared the substrates with surrounding soft sediment and evaluated differences among substrate types using biodiversity indices, community composition analyses, and food web indicators. This offers a comprehensive understanding of how the introduced hard substrates affect ecosystem complexity. Overall ecological complexity indicators were higher in the second year of the experiment. We found a significant increase in species richness, community composition, and link density (number of feeding interactions per species) on hard substrates compared to the surrounding sediment. However, Shannon diversity index and food web connectance (measure of food web saturation) did not differ between substrates and the surrounding sediment. Although differences among types of hard substrates were small, certain species were uniquely associated with specific substrates with wood and granite performing best. While there was no establishment of epibenthic shellfish reefs within 1.5 years, we conclude that introducing hard substrates effectively enhances ecological complexity in soft‐bottom coastal ecosystems within that timeframe. We recommend the use of substrates with a historical ecological relevance in the system for scaling up introduction of substrates for ecological restoration.

Enhancement of medium-chain fatty acids production from sludge anaerobic fermentation liquid under moderate sulfate reduction

In recent years, there has been a marked increase in the production of excess sludge. Chain-elongation (CE) fermentation presents a promising approach for carbon resource recovery from sludge, enabling the transformation of carbon into medium-chain fatty acids (MCFAs). However, the impact of sulfate, commonly presents in sludge, on the CE process remains largely unexplored. In this study, batch tests for CE process of sludge anaerobic fermentation liquid (SAFL) under different SCOD/SO42− ratios were performed. The moderate sulfate reduction under the optimum SCOD/SO42− of 20:1 enhanced the n-caproate production, giving the maximum n-caproate concentration, selectivity and production rate of 5.49 g COD/L, 21.4% and 4.87 g COD/L/d, respectively. The excessive sulfate reduction under SCOD/SO42− ≤ 5 completely inhibited the CE process, resulting in almost no n-caproate generation. The variations in n-caproate production under different conditions of SCOD/SO42− were all well fitted with the modified Gompertz kinetic model. Alcaligenes and Ruminococcaceae_UCG-014 were the dominant genus-level biomarkers under moderate sulfate reduction (SCOD/SO42− = 20), which enhanced the n-caproate production by increasing the generation of acetyl-CoA and the hydrolysis of difficult biodegradable substances in SAFL. The findings presented in this work elucidate a strategy and provide a theoretical framework for the further enhancement of MCFAs production from excess sludge.

MicroRNA‐encoded peptides inhibit seed germination of the root parasitic plant Orobanche cumana

Societal Impact StatementThe root parasitic plant Orobanche cumana (sunflower broomrape) is one of the major pests of sunflower crops. Despite intense efforts to develop effective agricultural practices and breeding programs, selective control of broomrapes is still rare and ineffective in terms of sustainability. It is thus essential to develop new specific control methods against those pests. miRNA‐encoded peptides (miPEPs) are a new class of peptides regulating the expression of miRNAs and their corresponding target genes. This study demonstrates that certain miPEPs strongly inhibit the germination of broomrape seeds by regulating their miR gene, making them good candidates for use as biocontrol agents against this pathogen.Summary Root parasitic plants of the Orobanchaceae family are a constant and growing threat to agriculture worldwide. Among them, the parasitic weed Orobanche cumana, the sunflower broomrape, causes significant losses to sunflower production in European‐Asian and North African countries. Despite the use of several conventional control methods against this pathogen, none has proved effective or durable, underlining the need to develop innovative strategies. miRNA‐encoded peptides (miPEPs) are regulatory peptides stimulating the expression of their own primary transcript of miRNA, and plant watering with those molecules leads to down‐regulating specifically miRNA target genes and altering plant physiology. Through seed germination assays and qRT‐PCR analysis, we investigated the impact of exogenous treatments of synthetic miPEPs on broomrape seed germination. First, we report that the conserved miRNA repertoire of O. cumana consists of 39 members. Thirty‐nine miPEPs were designed, synthetized, and assayed, 11 of which strongly inhibited O. cumana seed germination. Interestingly, miPEP319a showed the strongest inhibiting effect while miPEP319b did not. Three out of the four corresponding miR319 target genes showed upregulation after treatment with a germination stimulant, which was impaired by treatment with miPEP319a. This downregulation of expression is associated with an increase in the expression of the corresponding pri‐miR319a. We reveal thus that the use of miPEPs can increase our knowledge of key molecular mechanisms underlying a complex parasite interaction and should provide a new phytosanitary method to control broomrape parasitism with highly specific and biodegradable natural substances.

Detection and specific chemical identification of submillimeter plastic fragments in complex matrices such as compost

Research on the plastic contamination of organic fertilizer (compost) has largely concentrated on particles and fragments > 1 mm. Small, submillimeter microplastic particles may be more hazardous to the environment. However, research on their presence in composts has been impeded by the difficulty to univocally identify small plastic particles in such complex matrices. Here a method is proposed for the analysis of particles between 0.01 and 1.0 mm according to number, size, and polymer type in compost. As a first demonstration of its potential, the method is used to determine large and small microplastic in composts from eight municipal compost producing plants: three simple biowaste composters, four plants processing greenery and cuttings and one two-stage biowaste digester-composter. While polyethylene, PE, tends to dominate among fragments > 1 mm, the microplastic fraction contained more polypropylene, PP. Whereas the contamination with PE/PP microplastic was similar over the investigated composts, only composts prepared from biowaste contained microplastic with a signature of biodegradable plastic, namely poly(butylene adipate co-terephthalate), PBAT. Moreover, in these composts PBAT microplastic tended to form the largest fraction. When the bulk of residual PBAT in the composts was analyzed by chloroform extraction, an inverse correlation between the number of particles > 0.01 mm and the total extracted amount was seen, arguing for breakdown into smaller particles, but not necessarily a mass reduction. PBAT oligomers and monomers as possible substrates for subsequent biodegradation were not found. Remaining microplastic will enter the environment with the composts, where its subsequent degradability depends on the local conditions and is to date largely uninvestigated.

Ozonation and Changes in Biodegradable Organic Substances in Drinking Water Treatment: The Future of Green Technology

Studies were carried out to assess changes in biodegradable dissolved organic carbon (BDOC) and assimilable organic carbon (AOC) in groundwater and surface waters after two processes: ozonation and ozonation/UV. The tested water was in contact with O3 firstly for 4 and secondly for 15 min. Three doses of disinfectant were used: 1.6 mg/L, 5.0 mg/L, and 10.0 mg/L. The UV radiation time was 10 and 30 min. The greatest change in AOC and BDOC for groundwater was observed at an O3 dose of 10.0 mg/L and a contact time of 15 min, by 400 and 197%, respectively. On the other hand, for surface water, it was shown that after the ozonation/UV process, the AOC and BDOC content decreased after both 10 and 30 min of radiation in comparison to the water after ozonation. The AOC content decreased by 33% and 22%, respectively, and the BDOC content by 27% and 31%, respectively. The results obtained in this study provide new information on the effect of different ozonation conditions and the combined method on the level of biodegradable organic fraction of water. It is recommended that BDOC and AOC should be monitored in Poland as routine indicators during the preparation of drinking water.

Modelling of high-rate activated sludge process: Assessment of model parameters by sensitivity and uncertainty analyses

The objective of this study is to develop a mechanistic model to predict the long-term dynamic performance of High-Rate Activated Sludge (HRAS) process, including the removal of carbon (COD), nitrogen (N), and phosphorus (P). The model was formulated with inspiration from Activated Sludge Models No. 1 and 3 (ASM1 and ASM3) to incorporate essential mechanisms, such as adsorption and storage substrate, specific to HRAS systems. A stepwise protocol was followed for calibration with dynamic data from a pilot-scale HRAS plant. Sensitivity analysis identified influential model parameters, including maximum specific growth rate (μ), growth yield (YH), storage yield (YSTO), storage rate (kSTO), decay rate (b), and half saturation of the readily biodegradable substrate for growth (KS1). The calibrated model achieved prediction efficiencies above the normalized Mean Absolute Error (MAE) of 70 % for mixed liquor suspended solids (MLSS), total chemical oxygen demand (TCOD), soluble COD (SCOD), particulate COD (XCOD), total nitrogen (TN), ammonia nitrogen (SNH), total phosphorus (TP), soluble TP (STP), and particulate TP (XTP). Uncertainty analysis revealed that SCOD was underestimated. Based on the dynamic profiles of uncertainty bands and observed data, there is potential for improving the estimation of dynamic behavior in STP. The observed discrepancies may be attributed to variations in wastewater characteristics during the monitoring period, particularly concerning the phosphorus (P) fractions of the readily biodegradable substrate (SS) and soluble inerts (SI), which were not considered as dynamically changing parameters in the model.

Exploring the potential of novel Bacillus sp. G6: Isolation, characterization, and optimization of biosurfactant production from oil-contaminated soil

Biosurfactants (BSs) are highly biodegradable, environmentally benign, and multifunctional substances having diverse industrial uses, including environment bioremediation. Because of its remarkable emulsifying properties, as well as its use in both the environment and medicine, surfactin, is considered one of the most potent BSs and belongs to the lipopeptides family. The present study was performed to isolate the potential bacteria from oil-contaminated soils. Selected bacteria were checked for biosurfactant (BS) synthesis and their characterization. Out of 32 bacteria, the most promising isolate G6 was taken for a detailed study. Based on polyphasic taxonomy it was found to belong to the novelBacillussp.Nutrient screening for higher BS synthesis usingthe Plackett-Burman design(PBD) showed thatFeSO4, NaCl andwaste engineoil have a significant influence on BS production. Further optimization utilizingBox-Behnken design(BBD) revealed that the optimized condition for higher BS synthesis wasFeSO4(2.0 %), NaCl (2.0 %), and waste engine oil (2.2 %). The highest BS yield of 3.79 ± 0.265 g/L was attained with a cell biomass of 1.51 ± 0.234 g/L with 1.92 fold increase in the yield. Based on thin-layer chromatogram (TLC),Fourier transform infrared spectroscopy(FTIR), andGas Chromatogram-Mass Spectrometry(GC–MS) studies it was observed that the probable BS was a surfactin-like molecule that is stable at a wide range of temperature (up to 100° C), pH (5–9), and salinity (3–6 %).

Spicing up membrane distillation: Enhancing PVDF membrane performance with cinnamic acid

The increasing demand for freshwater is driving the rapid development of new water treatment materials. Furthermore, there is significant pressure to replace the toxic substances often used in membrane production with environmentally friendly, biocompatible, and natural compounds. In this work, poly(vinylidene fluoride) (PVDF) membranes were modified for the first time with a naturally occurring, non-toxic, biodegradable substance – cinnamic acid. The application of its molecules for membrane modification allows for diminishing the problem of bioaccumulation and toxicity in the environment. The procedure was selected with the accordance of green chemistry principles (green modifier – cinnamic acid, and green solvent – ethanol), and employed to chemically bind the modifier to the membrane surface. The modified membranes exhibited an increase in the hydrophobicity of the surface. The water contact angle increased from 124.7° for the pristine membrane to 139.3° for the membrane modified with a 10 % concentrated solution of cinnamic acid (PVDF-Cin10). All membranes possessed an excellent salt rejection coefficient. Membrane antiwetting features have been determined under challenging conditions of salt (3 M NaCl) and low surface tension liquid (sodium dodecyl sulfate). The dynamic goniometric studies were implemented to evolve membranes' wetting stability.