Biogenic Waste Research Articles

Integrated recovery of copper and gold from end-of-life LEDs using two-step leaching process with volatile fatty acids

The rising demand for precious metals in clean energy technologies, coupled with their natural scarcity, has prompted the exploration of innovative processes targeting unconventional metal sources such as end-of-life electronic devices. Hydrometallurgical techniques hold promise, but environmental concerns persist, particularly concerning environmentally friendly solvent usage. This study investigates a hydrometallurgical approach, employing a two-step leaching process with mimic organic waste-derived volatile fatty acids (VFAs) for copper (Cu) extraction following gold (Au) recovery using thiourea (TU) solution from end-of-life light-emitting diodes (LEDs). Preliminary investigations with Cu powder using various organic and inorganic ligands revealed that acetic acid (AA) with hydrogen peroxide (H2O2) as an oxidant surpassed inorganic ligands at pH 4. The subsequent application of AA for Cu recovery from end-of-life LEDs resulted in a 75.36 % Cu leaching efficiency at pH 4, emphasizing VFAs’ potential in recovering Cu elements from heterogeneous electronic waste. The solid residues from AA-treated LEDs were then dissolved in a TU solution with H2O2. yielding a substantial improvement in Au recovery efficiency—94.42 % within an hour, compared to 19.47 % via direct leaching. This study demonstrates VFAs as a sustainable alternative to traditional solvents for Cu leaching, followed by Au recovery in a two-step leaching process. This approach supports a circular economy in electronic waste management by integrating biogenic waste streams for metal recovery.

Enhancing hydrochar production and proprieties from biogenic waste: Merging response surface methodology and machine learning for organic pollutant remediation

The valorization of biogenic waste by hydrothermal carbonization is widely discussed in research. However, to our knowledge, no study has combined almond shells and olive pomace to synthesize a solid carbon material. The purpose of this study is to enhance the hydrochar process from AS and OP using RSM methodology and machine learning models: ANN, SVM and XG-Boost. Subsequently, a study was carried out on the removal of organic pollutants by the synthesized material. The optimum Co-HTC operating conditions obtained at 180 C, 90 min with acid catalyst corresponding to 71.51 % and 87.13 % for mass yield and carbon retention rate respectively according to RSM-CCD. The comparison between RSM-CCD and ML in terms of prediction concludes that RSM remains more efficient in terms of planning and optimization. However, ANN is more suitable for modeling and predicting mass yields and carbon retention rates. Hydrochar’s physicochemical properties were evaluated by the use of spectroscopic methods like FTIR, SEM, XRD, and CHNO. To conclude, we studied the performance of HCop in methylene blue adsorption, varying the following parameters: pH, contact time, initial dye concentration, adsorbent dose and temperature. In addition, kinetic and isothermal models were studied to describe the dominant mechanisms in the MB adsorption process. The MB maximal adsorption using HCop obtained at pH 9, with an initial dye concentration of 100 mg. L−1, 40-min contact time, 0.1 g/L adsorbent dose, and a temperature between 25 and 30 °C. In conclusion, these results provide important information on the use of Co-HTC to convert biogenic wastes into high-performance carbon materials for the appropriate removal of organic pollutants. More studies are needed to use the material in other fields of application.

Calcium Acetate Drug Produced from Rapana venosa Invasive Gastropod Shells: Green Process Control Assisted by Raman Technology.

The highly demanded calcium acetate (Ca(CH3COO)2) for biomedicine and various industries constantly requires green and low-cost methods of synthesis. In the present work, a sustainable approach to produce Ca(CH3COO)2 is reported as a proof of concept, processing for the first time as a starting material the worldwide highly abundant Rapana venosa shells, which is a neglected biogenic waste with high economical potential due to the rich mineral and organic pigmentary content. A green synthesis involving an eco-friendly acetic acid has been optimized at room temperature, without any additional energy consumption, and the resulting saturated Ca(CH3COO)2 solution was further slowly evaporated in three stages to obtain white Ca(CH3COO)2 crystalline powder, without impurity traces. Raman spectroscopy provided efficient structural information for every step of the process control, during demineralization as well as end product validation. Yields as high as 87.5% of highly pure Ca(CH3COO)2 mass have been achieved from raw R. venosa shells, proving the uniqueness and economic viability of the method. X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDX), and Fourier-Transform IR spectroscopy (FTIR) analyses validated the final product identity, hydration status, crystalline morphology, and composition. The purity of the resulting product suggests a high valorization potential of the abundant R. venosa shell in the context of the blue bioeconomy and offers a cleaner and efficient method of Ca(CH3COO)2 production with important applications in relevant industries.

Biogas potential of organosolv pretreated wheat straw as mono and co-substrate: substrate synergy and microbial dynamics

Anaerobic digestion (AD) technology can potentially address the gap between energy demand and supply playing a crucial role in the production of sustainable energy from utilization of biogenic waste materials as feedstock. The biogas production from anaerobic digestion is primarily influenced by the chemical compositions and biodegradability of the feedstock. Organosolv-steam explosion offers a constructive approach as a promising pretreatment method for the fractionation of lignocellulosic biomasses delivering high cellulose content.This study showed how synergetic co-digestion serves to overcome the challenges of mono-digestion's low efficiency. Particularly, the study evaluated the digestibility of organosolv-steam pretreated wheat straw (WSOSOL) in mono as well as co-digesting substrate with cheese whey (CW) and brewery spent grains (BSG). The highest methane yield was attained with co-digestion of WSOSOL + CW (338 mL/gVS) representing an enhanced biogas output of 1–1.15 times greater than its mono digestion. An ammonium production was favored under co-digestion strategy accounting for 921 mg/L from WSOSOL + BSG. Metagenomic study was conducted to determine the predominant bacteria and archaea, as well as its variations in their populations and their functional contributions during the AD process. The Firmicutes have been identified as playing a significant role in the hydrolysis process and the initial stages of AD. An enrichment of the most prevalent archaea genera enriched were Methanobacterium, Methanothrix, and Methanosarsina. Reactors digesting simpler substrate CW followed the acetoclastic, while digesting more complex substrates like BSG and WSOSOL followed the hydrogenotrophic pathway for biomethane production. To regulate the process for an enhanced AD process to maximize CH4, a comprehensive understanding of microbial communities is beneficial.

Optimisation of the Production of Bio-Based Basic Chemicals from Biogenic Secondary Waste Through Dispersion

Biogenic waste from waste treatment plants, also known as secondary waste, can be used to produce bio-based carboxylic acids. Conventionally, these are produced by chemically synthesis of petroleum-based raw materials or synthesis of natural oils (e.g. coconut or palm kernel oil). Using organic residues and waste materials in a cascade to produce bio-based products can contribute to the circular bioeconomy. In the biological treatment process for production of bio-based carboxylic acids, microorganisms that are already present in the secondary waste use ethanol to convert short-chain carboxylic acids (with one to three carbon atoms) into medium-chain carboxylic acids (with four to ten carbon atoms). During the treatment process, medium-chain carboxylic acids are separated from the secondary waste by using in-situ extraction (liquid-liquid extraction). In previous studies, bioreactors without a dispersing function were used on a laboratory scale. In order to optimise the production and extraction of the formed medium-chain carboxylic acids, the bioreactors should be upgraded with a device for dispersing the extraction solvent in the secondary waste. Dispersing can increase the surface area between the extraction solvent and the secondary waste and therefore also the ability to extract the medium-chain carboxylic acids. To evaluate the effects of dispersing on the production of bio-based carboxylic acids, the production and extraction rates of static bioreactors without dispersing are compared with those of dynamic bioreactors with dispersing on a laboratory scale. Leachate from a composting plant was used as secondary waste. According to the results of the current study, it can be confirmed that dispersion has a positive effect on the biological treatment process. In addition to the increased degradation of the nutrient ethanol, the production of medium-chain carboxylic acids in the secondary waste as well as the extracted medium-chain carboxylic acids could be increased by dispersing.

The Costs of Straw in Germany: Development of Regional Straw Supply Costs between 2010 and 2020

BackgroundThe bioeconomy relies strongly on the availability of biomass, including biogenic waste, residues and by-products. The cost of supply often represents a significant proportion of the total value of the resource. However, there is limited insight into the current supply costs of wastes, residues and by-products. This includes straw, which is the most important agricultural by-product in Germany. Despite its importance, standardised information on supply costs or market prices, as well as their temporal and spatial variation, is missing.AimTherefore, there is an urgent need for the temporal and spatial monitoring of individual cost components within total supply costs. This is essential to identify the most cost-effective options for the utilisation of agricultural by-products. Therefore, this study focuses on the case of straw to develop a model capable of visualising and mapping regional supply costs over time.MethodWe use an activity-based costing approach to calculate and monitor regional supply costs, defined as the monetary expenditure required to make straw available at the farm level. Our methodology combines typical technical and operational aspects of straw collection and transport with regional wage statistics, yield data, farm sizes, fuel prices and labour costs. We also consider storage costs and opportunity costs associated with nutrient replacement and conduct sensitivity analyses to measure their impact. To validate our calculations, we compare them with actual straw prices. To establish a reliable cost monitoring system, we propose an approach to assess the quality of input data.ResultIn 2011, the regional supply costs for straw varied from 45.72 EUR/Mg[FM] to 92.92 EUR/Mg[FM], showing a wide range. Over the years, the German average supply cost for straw increased from 56.78 EUR/Mg[FM] in 2010 to 58.79 EUR/Mg[FM] in 2020, with a peak of 61.24 EUR/Mg[FM] in 2018. This suggests that the temporal impact on mass-specific costs is relatively moderate compared to the spatial distribution of supply costs. The sensitivity analysis highlights storage time and costs, straw yield and wage levels as the main drivers of supply costs. Doubling the storage period from 3 to 6 months increases total costs by 20%. On average, the costs explain 75% of the straw price across all federal states, depending on annual price and cost levels. The quality assessment of input data shows that currently 68% of the data cannot be automatically extracted for continuous monitoring. Detailed results are available in a corresponding data publication: https://doi.org/10.5281/zenodo.8145082.ConclusionIn the absence of standardised market prices, the model presented provides an approach to estimating the supply costs of straw, expressed in terms of the monetary cost to farmers of mobilising straw. This cost information could be a valid database for further techno-economic assessments or models to evaluate the economic feasibility of straw valorisation. Due to the modular structure of the model, the future development of supply costs can be considered if the input data are adapted to future scenarios.Graphical

Synthesis of Novel Nanocomposite CaO/AC/ZnO from Biogenic Wastes of Date Palm Seeds from The Najran Region (Saudi Arabia) and Eggshells for Degradation of Methylene Blue

Metal nanoparticles and activated carbon-based nanocomposite materials are gaining popularity due to their numerous potential applications in a wide range of materials science areas. The current study aims to create novel photocatalyst frameworks for nanocomposites that were synthesized from biogenic waste and used to photodegrade methylene blue (MB) in wastewater under visible light. The activated carbon from date seeds was calcinated at a temperature of 700°C for two hours, and its surface was improved using zinc oxide nanoparticles and calcium oxide nanoparticles manufactured from eggshells at 900oC. XRD, FT-IR, SEM, BET, and TEM analyses were used to characterize the produced nanocomposites. The synthesized nanocomposite photocatalytic activity was evaluated by degrading MB dyes, its model of water pollution. The results showed that the nanocomposite CaO/AC/ZnO has a mesoporous structure with great sorption capability. Also, the photodegradation efficiency of MB using AC, CaO, AC/ZnO, and CaO/AC/ZnO nanocomposite was 33.23, 37.58, 54.61, and 88.92%, respectively, after100 min of sunlight irradiation indicating that photodegradation efficiency increases by improving the surface properties of AC. The CaO/AC/ZnO nanocomposite exhibited a 96.7% removal efficiency of MB following 120 min of visible light radiation exposure. Therefore, the CaO/AC/ZnO nanocomposite has a promising opportunity to function as a versatile and effective photocatalyst for photodegradation of organic dyes in wastewater.

Microwave Irradiation Melt-Quenching Preparation of 45S5 Bioglass Using Biogenic Wastes as Alternative Materials

Microwave Irradiation Melt-Quenching Preparation of 45S5 Bioglass Using Biogenic Wastes as Alternative Materials

Composition of public waste - a case study from Austria

Waste from public places like parks, pedestrian zones or sidewalks is a visible yet unexploited waste stream. Publications and information on the amounts and makeup of this waste flow are very scarce. To evaluate the resource potential and enable waste management planning, this study aims to assess the quality and quantity of public waste in a detailed waste characterisation campaign. For the first time, an analysis at this level of detail was conducted in a medium-sized town (25,000 inhabitants) in Austria. The sampling campaign included the whole town area. In total, almost 1000 kg of waste was sorted in up to 88 different fractions, which allows the detailed composition of, for example, packaging waste and single-use plastics to be delineated. We found that the amount of waste collected in public street bins is approximately 2.6 % of the total mixed municipal solid waste, resulting in 4.1 kg of public waste per inhabitant annually. The vast majority of this waste is currently collected as mixed waste. The results indicate a high share (52 %) of recyclable materials (glass, metal, paper and lightweight packaging) in mixed public waste, most of which is packaging (44 % of total waste). Other large shares include dog feces (18 % of total waste) and biogenic waste (17 % of total waste). The results lay the foundation for further investigations into, for example, exploiting recycling potential or evaluating possible improvements in separate waste collection in public spaces. Further, the collected data serve as an essential knowledge basis for policymakers and local authorities.

To spread or not to spread? Assessing the suitability of sewage sludge and other biogenic wastes for agriculture reuse

Sewage sludge (biosolids) management represents a worldwide issue. Due to its valuable properties, approximately one half of the EU production is recovered in agriculture. Nevertheless, growing attention is given to potential negative effects deriving from the presence of harmful pollutants. It is recognized that a (even very detailed) chemical characterization is not able to predict ecotoxicity of a mixture. However, this can be directly measured by bioassays. Actually, the choice of the most suitable tests is still under debate. This paper presents a multilevel characterization protocol of sewage sludge and other organic residues, based on bioassays and chemical-physical-microbiological analyses. The detailed description of the experimental procedure includes all the involved steps: the criteria for selecting the organic matrices to be tested and compared; the sample pre-treatment required before the analyses execution; the chemical, physical and microbiological characterisation; the bioassays, grouped in three classes (baseline toxicity; specific mode of action; reactive mode of action); data processing. The novelty of this paper lies in the integrated use of advanced tools, and is based on three pillars:•the direct ecosafety assessment of the matrices to be reused.•the adoption of innovative bioassays and analytical procedures.•the original criteria for data normalization and processing.

Waste ashes from burned sunflower hulls as new fertilising materials

Closing the loop – An EU action plan for the circular economy identified the Fertilisers Regulation revision as a key legislative proposal to boost the market for secondary raw materials. The European Commission has adopted recently EU Fertilising Products Regulation EU 2019/1009 expanding its scope to secondary-raw-material-based products (from biogenic wastes and other secondary raw materials). During the industrial processing of sunflowers, sunflower husks used as alternative fuels resulting in the generation of waste ash. Sunflower ash is a known material as a good and cheap source of potassium. In present study the tested samples of ashes is characterized as a starting raw material for the producing fertilizers in an accredited and authorized Laboratory for fertilisers quality. The tested samples is not loaded with heavy metals and the risk of recycling contaminants has not been assessed. According to the content of available (water-soluble) elements, the content of soluble phosphorus and micronutrients is very low, while potassium is completely water-soluble (40 to 50% K2O m/m), therefore, the tested ashes can be regarded as a good raw material as a source of potassium component in the final product. The pH reaction of the samples is extremely alkaline, therefore it is necessary to neutralize pH reaction in the industrial processing of this raw material, or to restrict the final product for use on acid reaction soils.

Carbon reduction trade-off between pretreatment and anaerobic digestion: A field study of an industrial-scale biogas plant

With the implementation of municipal solid waste source segregation, the enormous sorted biogenic waste has become an issue that needs to be seriously considered. Anaerobic digestion, which can produce biogas and extract floating oil for biodiesel production, is the most prevalent treatment in China for waste management and greenhouse gas (GHG) emissions reduction, in accordance with Sustainable Development Goal 13 of the United Nations. Herein, a large-scale biogas plant with a capacity of 1000 tonnes of biogenic waste (400 tonnes of restaurant biogenic waste and 600 tonnes of kitchen biogenic waste) per day was investigated onsite using material flow analysis, and the parts of the biogas plant were thoroughly analyzed, especially the pretreatment system for biogenic waste impurity removal and homogenization. The results indicated that the loss of the total biodegradable organic matter was 41.8% (w/w) of daily feedstock and the loss of biogas potential was 18.8% (v/v) of daily feedstock. Life cycle assessment revealed that the 100-year GHG emissions were −61.2 kgCO2-eq per tonne biogenic waste. According to the sensitivity analysis, pretreatment efficiency, including biodegradable organic matter recovery and floating oil extraction, considerably affected carbon reduction potential. However, when the pretreatment efficiency deteriorated, GHG benefits of waste source segregation and the subsequent biogenic waste anaerobic digestion would be reduced.

Impact of Dispersing on the Production and Extraction of Bio-Based Basic Chemicals from Biogenic Secondary Waste

Abstract Biogenic waste from waste treatment plants, secondary waste, can be used to produce bio-based carboxylic acids, conventionally produced by chemical synthesis from petroleum-based feedstocks or by synthesis from natural oils. The cascading use of organic residues and wastes to produce bio-based products can contribute to the circular bioeconomy. In the process of biologically treating waste to produce bio-based carboxylic acids, microorganisms already present in the secondary waste use ethanol to convert short-chain into medium-chain carboxylic acids. The medium-chain carboxylic acids were separated from the secondary waste using in-situ extraction (liquid-liquid extraction). In previous studies, laboratory-scale bioreactors without a dispersing function were used. To optimise production and extraction of medium-chain carboxylic acids, the bioreactors were equipped with a device to disperse the extraction solvent in the secondary waste. By increasing the surface area between the phases, the ability to extract the medium-chain carboxylic acids was improved. The study aimed to evaluate the impact of this dispersing process. Production and extraction rates of static bioreactors without dispersing were compared to those of dynamic bioreactors with dispersing on a laboratory scale, using leachate from a composting plant as secondary waste. The results confirmed that dispersion has a positive effect on the process. Dispersing increased the reduction of the nutrient ethanol, the production of medium-chain carboxylic acids in the secondary waste and the extracted medium-chain carboxylic acids.

Biogenic Waste from Two Varieties of Plantain in Ghana Contain Pectin with Potential Binding Properties in Conventional Tablets.

Pharmaceutical formulations have traditionally relied on plants and their derivatives for various APIs and excipients. In Ghana, the widespread utilization of plantains, irrespective of their ripeness, generates significant waste at every stage of processing, posing disposal issues. Fascinatingly, these wastes, often discarded, possess significant economic potential and can be recycled into valuable raw materials or products. Pectin, a polysaccharide that occurs naturally, has seen a surge in interest in recent times. It has found widespread use in the pharmaceutical sector, particularly as a binding agent in tablet formulations. This study aimed to evaluate pectin from two popular plantain varieties, Apem (M) and Apantu (T) at different ripening stages, for pharmaceutical use as a binding agent in immediate-release tablets. The ripening stages selected were the matured-green (G), half-ripe (H), and full-ripe (R). Acid (D) and alkaline (L) mediums of extraction were employed for each ripening stage for both varieties. Wet granulation method was used to prepare the granules using paracetamol as a model drug, and their flow properties were subsequently assessed. Postcompression tests including, hardness, friability, weight uniformity, disintegration, assay, and in vitro dissolution were also assessed. Granules from all formulation batches had good flow properties indicated by their angle of repose (14.93 ± 1.41-21.80 ± 1.41), Hausner ratio (0.96 ± 0.27-1.22 ± 0.02), and compressibility (%) (7.69 ± 0.002-20.51 ± 0.002). All the tablets passed the uniformity of weight with none deviating by ±5%. The hardness of all the formulated tablets ranged between 3.96 ± 0.32 and 13.21 ± 0.36, while the friability for all tablets was below 1%. The drug content was between 100.1 ± 0.23% and 103.4 ± 0.01%. Tablets formulated with pectin as a binding agent at concentrations of 10% w/v and 15% w/v successfully met the disintegration test criteria for immediate release tablets. However, those prepared with a concentration of 20% w/v (MGL, MHD, MHL, MRD, MRL, TGL, THD, THL, and TRL) did not pass the disintegration test. Consequently, all batches of tablets successfully met the dissolution test requirement (Diss, Q > 75%), except for the batches that did not pass the disintegration test (Diss, Q < 75%). Ultimately, pectins extracted from the peels of Apem and Apantu at different ripening stages using acid and alkaline extraction can be commercially exploited as pharmaceutical binders at varying concentrations in immediate-release tablets.

Mitigating the exchange flux of sedimented phosphorus in invasive water Hyacinth (Pontederia crassipes) bloom system using a biogenic waste material

Calcium rich materials have been studied as sediment capping agents, but the high cost and the potential toxicity of extraneous metal ion constituents have been identified as impediments to field-scale applications. Therefore, Gastropod shell (GS), a biogenic waste material predominated with calcium mineral phase is assessed as a sediment capping agent in P. crassipes bloom system. Using the overlying water and sediment samples collected from a P. crassipes bloom system, the P-binding capacity of thermally treated GS was evaluated. Two microcosm aquatic systems (i.e., oxic and anoxic systems), with GS amended and unamended sediment, were created. The systems were incubated for fifty (50) days and the temporal trend in the physicochemical characteristics, and nutrient exchange flux across the sediment-water interface were monitored. The proof-of-concept was tested using pot experiment in a screenhouse. The two reactive materials showed significant capacity to sequestrate both the aqueous and sediment phase P, but the GS1000 showed better performance. The GS amended sediment trapped the sedimented P, and precluded the release into the overlying water phase, but a significant increase in the pH value of the overlying water was noted. In the field trial, the GS1000 amended sediment mitigated the exchange flux of sedimented P, which led to the death of the P. crassipes within twenty-four (24) days. Further studies are recommended to ascertain the role of extreme pH value created by the sediment amendment on the growth profile of P. crassipes.

A Location Model for the Agro-Biomethane Plants in Supporting the REPowerEU Energy Policy Program

Biomethane represents one of the solutions towards the European Union (EU) energy transition, being capable to decarbonize the EU’s energy system and to reduce the dependence on imported natural gas, as underlined by the “REPowerEU” energy policy program. As its production is expected to expand primarily from biogenic wastes and residues, such as agricultural residues and animal effluents, it is necessary to make its deployment cost-efficient, taking into account factors such as local resources, existing infrastructure, and raw material and investment costs. From this perspective, this paper proposes a replicable predictive model for locating agro-biomethane plants according to raw material potential, relative economic factors, and territorial characteristics. To this end, an analysis was conducted in the Geographic Information System environment, based on location theory. The analysis included testing the minimum transport cost of feedstock in a case study of a rural area in Southern Italy. Three optimal locations for 2 MW size plants were selected where some key element conditions had been identified. The research findings may provide useful information for the EU policymakers in defining more specific energy planning strategies, in accordance with the REPowerEU objectives, addressing the increase in biomethane production by 2030.

Densification of Calcium Phosphate from Biogenic Waste for Biomedical Application

Introduction: Calcium phosphate-based biomaterial is commonly employed in biomedical applications such as dental applications, bone substitution and filler tissue engineering. Its excellent biocompatibility and potential bio-implant material have attracted many researchers to broaden their hydroxyapatite (HA) studies. Methods: The present work used waste eggshells as the source of calcium precursor to synthesize HA via a solid-state reaction. The eggshells were calcined at 700°C and mixed with the phosphate precursor, dicalcium phosphate dihydrate (DCPD). Following this, the mixture was ball-milled at 400 rpm for 2h and then heat treated at 800°C to produce pure eggshell-derived HA powder. The synthesized HA powder was then consolidated by uniaxial pressing (~6.5 – 7.1 tons) and sintered at 4 different temperatures of 1100°C, 1150°C, 1200°C and 1250°C. Results: From the XRD analysis of the sintered HA samples, it was found that an increase in sintering temperature up to 1250°C did not affect the phase stability of the HA phase. Besides that, grain size, relative density and hardness of the sintered HA samples were also increased with sintering temperature. It was observed that HA dense sample prepared by compacting at 7.1 tons followed by sintering at 1250°C showed the best combination of mechanical properties among all samples with a relative density of 94.6% and a hardness of 3.7 GPa. Conclusion: The current result is significant in supporting the potential of the synthesized eggshell-derived calcium phosphate powder as an ideal alternative for the creation of cost-effective, biocompatible biomaterials for biomedical applications.

Pretreatment as a Microplastics Generator during Household Biogenic Waste Treatment

Mechanical pretreatment is an indispensable process in biological treatment plants that remove plastics and other impurities from household biogenic waste (HBW). However, the imperfect separation of plastics in these pretreatment methods has raised concerns that they pose a secondary formation risk for microplastics (MPs). To validate this presumption, herein, quantities and properties of plastic debris and MPs larger than 50 μm were examined in the full chain of three different pretreatment methods in six plants. These facilities received HBW with or without prior depackaging at the source. The key points in the secondary formation of MPs were identified. Moreover, flux estimates of MPs were released, and an analysis of MPs sources was provided to develop an overview of their fate in HBW pretreatment. Pretreated output can contain a maximum of (1673 ± 279) to (3198 ± 263) MP particles per kilogram of wet weight (particles·kg−1 ww) for those undepackaged at source, and secondary MPs formation is primarily attributed to biomass crushers, biohydrolysis reactors, and rough shredders. Comparatively, HBW depackaged at the source can greatly reduce MPs by 8%–72%, regardless of pretreatment processes. Before pretreatment, 4.6–205.6 million MP particles were present in 100 tonnes of HBW. MPs are produced at a rate of 741.11–33 124.22 billion MP particles annually in anaerobic digester feedstock (ADF). This study demonstrated that HBW pretreatment is a competitive source of MPs and emphasized the importance of implementing municipal solid waste segregation at the source. Furthermore, depackaging biogenic waste at the source is recommended to substantially alleviate the negative effect of pretreatment on MPs formation.

Effect of withdrawal speed variations on coating quality of electrophoretically deposited biogenic hydroxyapatite on AISI 316L

The use of biogenic waste for multipurpose materials has started to be encouraged in the current decade to support the world’s environmental sustainability campaign. Biogenic calcium phosphate-derived materials are potential biomaterials because of their similar properties to human bone. This paper used hydroxyapatite (HAp) powder derived from green mussel shells (Perna viridis) to coat the AISI 316L metallic implant material using the electrophoretic deposition coating method. In this study, the post-deposition withdrawal speeds of 5mm/s, 3mm/s, and 1mm/s were varied to find their effect on the quality of the HAp coating layer. Crystallography, micrography, and image processing were used to characterize the coating and calculate the percentage of HAp layer and cracks. The crystallographic data shows the HAp peaks, which conclude that the green mussel shells HAp successfully coat the substrate and can be used to coat the AISI 316L implant material. However, the appearance of the substrate crystal peaks and color difference on high withdrawal speed specimens conclude that the coating layer has cracks. In conclusion, the emergence of cracks can be minimized using 1mm/s post-deposition withdrawal speed and eventually produce high-quality HAp coating.

Gasification kinetics of chars from diverse residues under suitable conditions for the Sorption Enhanced Gasification process

Gasification kinetics for six chars from residual origin have been determined in a relatively low temperature range, low CO2 and high H2O partial pressures, typical from Sorption Enhanced Gasification (SEG) processes. In general, models based on the Random Pore Model (RPM) are the best fitting experimental results, but ash composition (in terms of alkali and alkaline earth metals) was crucial for the selection of the reaction model to be applied. Char conversion from biogenic waste with ash content higher than 30 % wt. was modelled with RPM model, but reaction rate for chars with the highest K/Si ratio was better described with modified versions of the RPM capable of predicting maximum reaction rates at high char conversion. For chars with similar ash content and composition, textural properties determined the pre-exponential factor and the activation energy for the gasification reaction (with both CO2 and H2O), while identical fitting parameters for the semi-empirical model were capable of predicting char conversion with time.