Waste Streams Research Articles

DETERMINATION OF THE BIOMETHANE POTENTIAL OF DIFFERENT TYPES OF MANURE FROM EXTENSIVE ANIMAL FARMING

Livestock production is a potential environmental pollutan because of the high concentartions of animals on the small area. Production of biogas with anaerobic degradation from organic waste is one of the pledge alternative energetic solutions, especially from organic manure made from animal farming and other residuals of agricultural production.The aim of this paper was to determine posibillity of using manure different origin from extensive animal breeding for production of biogas in labaratory conditions. The results obtained will be based on posibillity of use waste streams from extensive animal husbandry as basic substrate for anaerobic digestion.In this regard, cosubstrates were formed as mixture 1 chicken excrement; mixture 2 sheep manure; mixture 3 cow manure; all three basic substrates were in mixture with the sludge from the wastewater treatment plant. The results showed production of 71,5 ml CH4/gVS for mixture 1, 68,65 ml CH4/gVS for mixture 2 and 48,68 ml CH4/gVS for mixture 3. KEYWORDS:extensive breeding, manure, anaerobic digestion, biogas, biomethane potentional

A four-fold interpenetrated MOF for efficient perrhenate/pertechnetate removal from alkaline nuclear effluents

The sequestration of 99Tc represents one of the most challenging tasks in nuclear waste decontamination. In the event of a radioactive waste leak, 99TcO4– (a main form of 99Tc) would spread into the groundwater, a scenario difficult to address with conventional anion exchange materials like resin and inorganic cationic sorbents. Herein, we present a nickel(II) metal-organic framework (MOF), TNU-143, featuring 3D four-fold interpenetrated networks. TNU-143 exhibits efficient ReO4– (a nonradioactive analogue of 99TcO4–) removal with fast anion exchange kinetics (<1 min), high sorption capacity (844 mg/g for ReO4–), and outstanding selectivity over common anions. More importantly, TNU-143 shows superior stability in alkaline solution and can remove 91.6% ReO4– from simulated alkaline high-level waste (HLW) streams with solid-liquid ratio of 40 g/L. The uptake mechanism is elucidated by the single-crystal structure of TNU-143(Re), showing that ReO4– anions are firmly coordinated to nickel cation to result in a 2D layered structures. Density functional theory (DFT) calculations confirm the transformation from TNU-143 to TNU-143(Re) is a thermodynamically favorable process. This work presents a new approach to the removal of ReO4–/99TcO4– from alkaline nulcear fuel using MOF sorbents.

Reverse osmosis-based water treatment for green hydrogen production

We analyze the use of excess natural gas (currently flared/vented) to instead treat oilfield-produced water via reverse osmosis (RO) to generate ultrapure electrolysis-grade water (Total Dissolved Solids (TDS): 0.028‐0.5 ppm) for green hydrogen production. We combine an analytical ε-MTU model and CPavg model to predict average permeate concentration, to obtain improved estimates of electrolysis-grade water production from RO systems. The theoretical upper limit of the recovery of a RO system (similar to Carnot efficiency of heat engines) is established. Analysis is conducted for conditions corresponding to Niobrara Shale field (TDS: 29.1 g/L), as well as for brackish water (TDS: 5-15 g/kg) and seawater (TDS: 35–45 g/kg) feeds. Results show that electrolysis-grade water production can be as high as 0.75 m3 per cubic meter of water treated, with 1.38 m3 of natural gas providing the required energy. This translates to hydrogen production of 74.6 kg per cubic meter of produced water treated. Relatively low volumes of gas can treat large water volumes (<4 % of excess gas in Niobrara Shale can treat the entire quantity of produced water). These numbers highlight the benefits of our approach of utilizing two waste streams to create a high-value commodity, critical for decarbonization.

Removal of Heavy Metals from Produced Water Using Activated Carbon from Coconut Husk Enhanced with Graphene Oxide

Produced water, which contains a high amount of hydrocarbons, heavy metals, and other pollutants, is one of the major waste streams in the Niger Delta's oilfields and refineries. The treatment of produced water can be done in a variety of ways, including physical (desalination, membrane separation and, adsorption), chemical (precipitation, absorption and, oxidation), and biological. The heavy metals and contaminants in the wastewater pose a threat to living creatures and the environment. This research evaluates the effectiveness of Activated carbon modified with Graphene oxide, a new thriving material for researchers derived from graphite, to improve the adsorption capacity of coconut husk using the “wet impregnation technique” for the removal of heavy metals from produced water. Batch adsorption of the pollutant was studied for the Activated Carbon, and the modified activated carbon (AC-GO) at a time intervals, for each of the adsorbents. The removal efficiency of the adsorbent was found to increase proportionately from 6.71% to 92.96%, 3.01% to 52.23% and 51.28% to 67.77% for Cd, Ni and Pb respectively with increasing contact time. Atomic absorption spectroscopy (AAS) analysed the treated produced water samples. The adsorption isotherms and kinetics studies of the adsorbed metals were evaluated and correlated with empirical models.

Olive leaves upgrading applying a novel two-stage organosolv pretreatment: Techno-economic and environmental assessment

This research study evaluates the techno-economic and environmental performance of an olive leaves based biorefinery to produce antioxidants, bioethanol, and organosolv lignin. The biorefinery comprises processes such as organosolv extraction, organosolv pretreatment and simultaneous saccharification and fermentation, which were simulated in Aspen Plus v9.0. Experimental data were used to simulate the process, assuming a linear up-scaling. The techno-economic evaluation was carried out considering financial indicators such as net present value (NPV) and internal rate of return (IRR). The environmental assessment was done applying the life cycle assessment methodology. The results shows that 100 g olive leaves can produce 16.58 g antioxidant extract, 11.12 g organosolv lignin, and 2.85 g bioethanol. The proposed biorefinery was feasible at a processing scale of 30,000 t/y with a NPV of 47.9 million USD and an internal rate of return of 27.8%. The proposed biorefinery can be implemented in Jaén (Andalusia-Spain) based on the high amount of olive leaves produced in this region. Stillages are the most polluting waste stream of the process. The carbon footprint of the biorefinery was 1.13 kgCO2-eq/kg olive leaves. The application of the biorefinery concept revealed that olive leaves could be transformed into value-added products from a techno-economic and environmental perspective.

Co-digestion of filter cake, biogas effluent, and anaerobic sludge for hydrogen and methane production: Optimizing energy recovery through two-stage anaerobic digestion

This study assesses a two-stage anaerobic digestion process designed to efficiently recover energy through hydrogen and methane production by co-digesting filter cake (FC), biogas effluent (BE), and anaerobic sludge (AS) from the sugar and ethanol industry. The optimal proportions of FC, BE, and AS were determined in batch fermentation experiments using Design Expert software, which identified a suitable ratio of 31.05:28.95:0.00 (g VS/L), respectively. The results indicated that hydrogen production in the first stage could occur solely through the hydrogenic bacteria present in the BE and FC mixture, without the need for AS as an inoculum. This optimized FC:BE ratio was then applied in a semi-continuous fermentation system, achieving a hydrogen production rate of 193.6 mL H2/L.d and a hydrogen yield of 9.8 mL H2/g VS at an optimal hydraulic retention time (HRT) of 3 d. In the subsequent second stage, the effluent from the hydrogen reactor was used for methane production. This stage achieved a methane production rate of 422.0 mL CH4/L·d and a methane yield of 140.2 mL CH4/g VS, with an HRT of 20 d. Overall, the two-stage process exhibited an impressive energy output, peaking at 5.17 kJ/g VS. This suggests the potential for an annual electricity generation of 194,655 MWh and an estimated reduction of 85,668 tCO2eq/year in greenhouse gas emissions. This study highlights the efficiency of the two-stage anaerobic digestion process for harnessing energy through the co-digestion of FC and BE, without the need for additional AS inoculum. The findings demonstrate the potential for sustainable energy recovery from industrial waste streams while mitigating environmental impacts.

Exploring the substrate spectrum of phylogenetically distinct bacterial polyesterases.

The rapid escalation of plastic waste accumulation presents a significant threat of the modern world, demanding an immediate solution. Over the last years, utilization of the enzymatic machinery of various microorganisms has emerged as an environmentally friendly asset in tackling this pressing global challenge. Thus, various hydrolases have been demonstrated to effectively degrade polyesters. Plastic waste streams often consist of a variety of different polyesters, as impurities, mainly due to wrong disposal practices, rendering recycling process challenging. The elucidation of the selective degradation of polyesters by hydrolases could offer a proper solution to this problem, enhancing the recyclability performance. Towards this, our study focused on the investigation of four bacterial polyesterases, including DaPUase, IsPETase, PfPHOase, and Se1JFR, a novel PETase-like lipase. The enzymes, which were biochemically characterized and structurally analyzed, demonstrated degradation ability of synthetic plastics. While a consistent pattern of polyesters' degradation was observed across all enzymes, Se1JFR stood out in the degradation of PBS, PLA, and polyether PU. Additionally, it exhibited comparable results to IsPETase, a benchmark mesophilic PETase, in the degradation of PCL and semi-crystalline PET. Our results point out the wide substrate spectrum of bacterial hydrolases and underscore the significant potential of PETase-like enzymes in polyesters degradation.

Volumetric lattice Boltzmann method for pore-scale mass diffusion-advection process in geopolymer porous structures

Porous materials present significant advantages for absorbing radioactive isotopes in nuclear waste streams. To improve absorption efficiency in nuclear waste treatment, a thorough understanding of the diffusion-advection process within porous structures is essential for material design. In this study, we present advancements in the volumetric lattice Boltzmann method (VLBM) for modeling and simulating pore-scale diffusion-advection of radioactive isotopes within geopolymer porous structures. These structures are created using the phase field method (PFM) to precisely control pore architectures. In our VLBM approach, we introduce a concentration field of an isotope seamlessly coupled with the velocity field and solve it by the time evolution of its particle population function. To address the computational intensity inherent in the coupled lattice Boltzmann equations for velocity and concentration fields, we implement graphics processing unit (GPU) parallelization. Validation of the developed model involves examining the flow and diffusion fields in porous structures. Remarkably, good agreement is observed for both the velocity field from VLBM and multiphysics object-oriented simulation environment (MOOSE), and the concentration field from VLBM and the finite difference method (FDM). Furthermore, we investigate the effects of background flow, species diffusivity, and porosity on the diffusion-advection behavior by varying the background flow velocity, diffusion coefficient, and pore volume fraction, respectively. Notably, all three parameters exert an influence on the diffusion-advection process. Increased background flow and diffusivity markedly accelerate the process due to increased advection intensity and enhanced diffusion capability, respectively. Conversely, increasing the porosity has a less significant effect, causing a slight slowdown of the diffusion-advection process due to the expanded pore volume. This comprehensive parametric study provides valuable insights into the kinetics of isotope uptake in porous structures, facilitating the development of porous materials for nuclear waste treatment applications.

Evaluation of recycled galvanised steel as a resource for Zn production

The high reduction potential of zinc has enabled its extensive use in the steel industry as a protective galvanising coating. Galvanising, which consumes approximately 50-60% of the global production of zinc, significantly increases the life span of steel products and contributes towards addressing the costly global problem of corrosion. While there does not appear to be a readily available and agreed-upon annual quantity of galvanised steel produced, it has been estimated by the authors to be 320-390 Mt/a (equating to 15-20% of the annual steel production). Due to the various methods employed to galvanise steel and different steel shapes which are coated, there is no clarity on the average percentage of zinc which galvanised steel is comprised of. However, a zinc content of between 1.5-2.5% appears to correlate with the estimated annual galvanised steel production.The reprocessing of secondary zinc streams is becoming increasingly important due to legislation changes and increased consumer demand for recycled and low carbon metals. Within the steel industry this will include the recycling of galvanised scrap steel, using primary process routes, as well as the re-processing of waste streams, such as steel dusts, using additional technologies such as the Waelz kiln. Zinc associated with galvanised scrap steel would exclusively report to these dusts, and thus represents a key resource for recycled zinc.Although there are two main steel process routes preceding the galvanising process, the focus here is on the Electric Arc Furnace (EAF) process route due to its ability to incorporate high levels of secondary (zinc containing) steel feeds, and the dust produced typically contains economically recoverable levels of zinc. EAF dust production is estimated between 5-10 Mt/a at a zinc content of 10-36%. Failure to recover this zinc would represent a loss of 0.5-3.6 Mt Zn/a to waste. The Waelz kiln is the most prominent technology utilised to recover Zn from EAF dust. However, this process requires additional energy, and thus the associated carbon footprint needs to be included in the evaluation of the potential of Waelz oxide as a secondary Zn resource. To this end, model analysis of a simplified Waelz kiln using the HSC simulation software shows that the carbon footprint associated with the processing of EAF dust ranges from 4-12 kg CO2/kg Zn dust at 10 wt.% Zn in the dust to 1-4 kg CO2/kg Zn at 35 wt.% Zn in the dust.

Biopolymer-based composite adsorbent beads for the removal of methylene blue dyes

Dyes containing waste streams are the most common pollutants found in wastewater, posing a severe threat to both the ecosystem and the environment. Adsorption emerges as one of the most effective and widely applied treatments for removing dyes due to its simple operation, high efficiency, and low cost. Sodium alginate, as a biopolymer, is one of the alternative adsorbents used in the adsorption process. However, the lack of active sites and low rigidity limits the adsorption capacity performance of this biopolymer. This study aims to introduce biopolymer-based composite adsorbent beads for removing methylene blue (MB) dye from an aqueous solution. Herein, TA/PANI/SA composite adsorbent beads consisting of tannic acid (TA) and polyaniline (PANI) were prepared by the cross-linking method of sodium alginate (SA) with the presence of divalent cations in calcium chloride. Characterization was performed using FTIR analysis to determine the changes in surface-modified composite beads. The results indicated that the removal efficiency of MB dye exhibited a significant enhancement of up to 72% when compared to untreated alginate beads, which only achieved approximately 30% removal. It was also found that the interactions occurred during the cross-linking process as well as during the adsorption process of MB dye onto the composite adsorbent beads. The adsorption mechanisms of MB dye by composite adsorbent beads include electrostatic interaction, π-π interactions, and hydrogen bonding. The improvement in the removal efficiency and the possibility of interactions during the cross-linking process suggested that the biopolymer-based composite beads have great potential to be used as adsorbents for removing dye in an aqueous solution.

Improvements in Hydrolytic Stability of Alkali-Activated Mine Tailings via Addition of Sodium Silicate Activator.

Over 14 billion tons of mine tailings are produced throughout the world each year, and this type of waste is generally stored onsite indefinitely. Alkali activation is a promising strategy for the reuse of mine tailings to produce construction materials, converting this waste stream into a value-added product. One major problem with alkali-activated mine tailings is their low durability in water (i.e., low hydrolytic stability). In this article, the influence of a mixed sodium hydroxide/sodium silicate alkali activator on the compressive strength, hydrolytic stability, and microstructure of alkali-activated materials (AAMs) were systematically investigated. XRD, FTIR, NMR, and NAD were used to investigate microstructural changes, and a water immersion test was used to show improvements in hydrolytic stability. For gold mine tailings activated with pure sodium hydroxide, the compressive strength was 15 MPa and a seven-day water immersion test caused a strength loss of 70%. With an addition of 1 M sodium silicate in the activator, the AAMs achieved a compressive strength of over 30 MPa and strength loss of only 45%. This paper proposes a mechanism explaining why the strength and hydrolytic stability of AAMs are dependent on the dosage of soluble silicate. A high dosage of sodium silicate inhibits the depolymerization of the source material, which results in a sample with less amorphous aluminosilicate gel and, therefore, lower hydrolytic stability.

STUDIES TO ESTABLISH THE SCALING FACTOR METHODOLOGY FOR LIQUID RADIOACTIVE WASTE GENERATED BY TRIGA REACTOR

During TRIGA reactor operation significant amounts of liquid radioactive waste are generated requiring appropriate management to ensure their safe disposal. Radiological characterization is an important activity needed to accomplish the waste acceptance criteria for different management steps including disposal. The purpose of this paper is to assess the activity concentrations of the (_1^3)H , (_38^90)Sr, (_28^63)Ni (difficult-to-measure), and gamma emitters (easy-to-measure) radionuclides in liquid radioactive waste generated by the TRIGA reactor operation and to establish a correlation among them to determine the scaling factors for this waste category. The radiological protocols applied for (_28^63)Ni and (_38^90)Sr, separation and purification involve extraction chromatography using selective resins, while for (_1^3)H separation the distillation technique was applied. The assessment of gamma emitters was carried out using gamma-ray spectrometry and the detection of (_1^3)H , (_38^90)Sr, and (_28^63)Ni was performed by liquid scintillation counting. The chemical yield of each experiment was determined by measuring the carrier added in each test by inductively coupled plasma optical emission spectrometry. The activity concentrations of (_38^90)Sr, and (_28^63)Ni obtained were correlated with the activity concentration of (_27^60)Co for establishing the scaling factor for the liquid radioactive waste stream. There were obtained good correlations but more experimental data are needed to determine the relevant scaling factors for these difficult-to-measure radionuclides. The scaling factors, once established, will improve and optimize the radiological characterization methodology applied for liquid radioactive waste as an easy and rapid method for assessment of concentration activities of difficult-to-measure radionuclides. Until now, no scaling factors data were reported for this liquid radioactive waste generated by TRIGA reactor operated by Institute for Nuclear Research Pitesti. The results obtained in this work represent preliminary data for establishing correlations between difficult-to-measure and easy-to-measure radionuclides and will be used for developing a scaling factor methodology. This will further be used to determine the inventory of difficult-to-measure radionuclides in different waste streams generated by TRIGA operation and decommissioning (foreseen after 2035).

Bioremediation of Kraft Lignin in Wastewater: Optimization of Temperature and Isolation of Valuable Compounds

Conventional methods for the treatment of complex lignin found in the pulp and paper mill effluent is a strenuous and expensive process. Microbial degradation is a promising technique to degrade lignin efficiently due to its adaptability and rapid growth of microbes in diverse environments. This study is focused on the isolation of potential ligninolytic bacterial strains from agricultural soil and decomposed wood sources for successful degradation of lignin present in the wastewater. Initially, 15 ligninolytic strains were identified and three dominant species, Staphylococcus lentus (SB5), Bacillus megaterium (RWB15) and Pseudomonas geniculata (RWP9) were isolated as per their growth tolerance pattern with different lignin concentrations. The lignin degradation study was carried out at different temperatures (25-45℃) with 1000 mg/l of feed lignin concentrations. The optimum degradation temperature of all the strains fell within the range 30-35℃. The maximum lignin degradation of SB5, RWB15 and RWP9 was identified as 89, 77 and 90% at the end of the 6th, 3rd and 7th day of biodegradation, respectively. There was a steep reduction of COD by all three microbes before attaining the stationary phase and thereafter COD reduction was sluggish due to the death phase. Besides, the microbes used in this study showed the transformation of lignin into valuable low-molecular by-products, vanillin, vanillic acid and adipic acid with their concentration being quantified as 28, 101 and 130 mg/l, respectively. This study shows the successful degradation of waste lignin and the recovery of valuable byproducts from waste streams.

Phytin recovered from grain distillation can serve as a phosphorus fertilizer for maize and soybean

AbstractPhosphorus (P) recovery from waste streams can increase food system P use efficiency while simultaneousl mitigating point source P losses. Phytin is a P‐rich waste product generated from maize grain biorefineries, largely located in the US Midwest. However, since the majority of P in phytin is organic, phytin‐P is likely to have limited crop availability in soil following application, as it must first be mineralized to orthophosphate‐P by soil phosphatases. To evaluate the fertilizer potential of phytin recovered from a maize wet milling plant and test hypothesized mechanisms of P mineralization, a five‐step gradient of phytin substitution for monoammonium phosphate (MAP) (0%, 25%, 50%, 75%, and 100% substitution) was evaluated for maize (Zea mays L.) and soybean (Glycine max L.) growth in a P‐deficient Aquic Argiudoll. Irrespective of crop species, aboveground biomass at end of vegetative growth (VT stage) was similar for up to 75% phytin substitution as MAP, but was 21% lower for maize and 49% for soybean when phytin was fully substituted for MAP. Soil microbial biomass carbon (C), nitrogen (N), and P, as well as activities of phosphomonoesterase and phosphodiesterase were invariant across the phytin substitution gradient, suggesting negligible mineralization of phytin P. Full substitution of MAP with phytin lowered soil microbial biomass C:N by 121% for maize and by 153% for soybean, and soil phosphatase activities per unit microbial biomass C were 24% higher under soybean. Our results indicate that phytin can be partially substituted for highly water‐soluble P fertilizers for the two major crop species of the US Midwest in which phytin waste generation is co‐located.

Microstructure, adsorption site energetics, and formation enthalpy control for FAU-Zeolite Cs+ exchange

Cs-137 is a radionuclide fission product that poses a significant risk to life, making it crucial to develop effective methods for its separation and sequestration from nuclear waste streams. Zeolitic structures have emerged as promising materials. This work examines the influence of structure, exchange site energetics, and formation enthalpies of nascent and cation-exchanged Faujasite-X, -Y, and -HY zeolites in terms of their Cs-exchange selectivity. Their interplay was quantified with the application of high-temperature calorimetry, adsorption isotherms, X-ray diffraction and density functional theory (DFT) calculations. Greater efficacy of Cs+ exchange was demonstrated for the Na+-substituted Fau-Y (NaY) zeolite than that of the Fau-X (NaX) and Fau-HY (Na-HY) zeolites. This is explained by a higher amount of Na+ in un-exchangeable sites in the case of NaX and a lower stability in NaY that favors the ionic exchange with Cs+. Moreover, Cs+ incorporation in the structure increases the stability of each kind of zeolite. Correspondingly, structure and DFT analyses demonstrated site-exchange thermodynamic favorability as well as the contribution from cage cell, which resulted in an energy landscape far more conducive to Cs+ incorporation for NaY than either NaX or Na-HY.

Immobilization of radioactive sulphate waste simulate in polymer–cement composite based on recycled expanded polystyrene foam: evaluation of the final waste form resistance for Cs-134 and Co-60 leachability

The present study investigates to incorporate spiked sulfate solution simulate into polymer–cement composite (PCC) based on recycled expanded polystyrene foam. The main aim is to convert the waste stream into leach resistance solid forms able to slow down or even to retard the back release of hazardous radionuclides to the surrounding. Effective parameters e.g. leachant medium, temperature, radioactivity contents, leachant volumes and radionuclides speciation versus the leaching time were studied. The incremental leach rate (Rn, cm/day) and the leach index (Lx) were evaluated for the final waste form after 145 days. The experimental results revealed that the Lx for the all variances can fulfil the waste acceptance criteria for the disposal facility and are above the threshold value of 6. Moreover, leach rate percentages for Cs-134 and Co-60 were not exceeding 2%. The acquired data, based on lab leaching experiments, can recommend the developed PCC under consideration for solidification of radioactive sulphate waste stream safely.

Preparation and Characterization of Periwinkle Shell Based Chitosan-Kenaf fibre Copolymer and its Derivatives for Selective Binding of Cu (II) and Zn (II) ions from Electroplating Effluent

The levels of heavy metal in industrial waste streams, if not remediated before discharge to eco-system, could pose a threat to flora and fauna. The objective of this study was to evaluate the suitability of a novel adsorbent materials from periwinkle shell-based chitosan-kenaf fibre copolymer and its ethylene glycol diglycidyl ether crosslinked derivatives for the selective removal of Cu2+and Zn2+ from electroplating effluent using batch experimental protocol. Results showed that the crosslinked copolymers were more effective for the sorption of these metal ions from effluent solution with percentage sorption range of 76-87% and 84-93% for Cu2+ and Zn2+ respectively. Kinetic data depicts pseudo-second-order model fits for the adsorbent materials and confirm chemosorption as the mechanism for metal ion complexation with adsorbent surfaces. Based on R2 correlation values, sorption of the metal ions by the pristine adsorbent materials fit well with Langmuir isotherm model, in contrast, those for crosslinked adsorbent materials were best described by Freundlich isotherm model. The results present the adsorbent materials with auspicious potentials, especially the crosslinked derivatives, and stand them in exceptional good stead as suitable bioresource materials for column packing in waste abatement equipment for remediation of these metal ions from electroplating effluent solution.

Mechanical Properties of Virgin and Recycled Polymer for Construction Pile Application

Annual polymer waste generated in Malaysia has increased significantly to more than 1 million tonnes. The prolonged degradation periods required by diverse industrial polymer waste streams are a matter of significant concern, with some taking up to 1000 years to fully degrade. Pursuing a similar environmental concern, the use of bakau piles as supports for lightweight structures in Sarawak, including drainage systems, roads, sewerage, and other water-related structures, has become a matter of concern due to the deforestation of mangrove forests. Both bakau deforestation and polymer waste issues are significant environmental and global concerns. The idea of mitigating mangrove degradation and the non-biodegradable nature of polymer waste has led to the conceptualization of an alternative solution whereby recyclable thermoplastic polymer piles are utilized to supplant bakau piles in providing support for lightweight structures during civil engineering construction projects. Therefore, the study of polymer piles is conducted to examine their mechanical properties in the form of virgin (V) and recycled (R) thermoplastic polymers. In this study, high-density polyethylene (HDPE), polypropylene (PP), and polyvinyl chloride (PVC) are considered, and the possibility of being utilized in pile application has been discussed. Based on the results, all virgin types of thermoplastic polymers (HDPE, PP, and PVC), 50%V:50%R for PP, PP(R), and PVC(R), respectively, exceed the bakau ultimate tensile strength. Thermoplastic polymer piles showed great potential to be the substitution for bakau piles to serve in the construction industry, with the recorded experimental tensile and compressive strength tests.

Catalytic pyrolysis of FeAlOx and medical plastic waste: Kinetic, slag conversion, and gas emission patterns

The globally substantial increase in medical waste stream and types renders efficient disposal and circularity strategies imperative. Currently, most medical waste disposed of is predominantly plastic materials. A promising approach for its recycling efficiency involves using catalytic pyrolysis to transform plastic waste into reusable pyrolysis oil. This study aimed to characterize gas products and bottom slag of the catalytic pyrolysis of medical waste infusion tubes (PVC) via thermogravimetric (TG) and pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) analyses. As s bimetallic catalyst known for its exceptional ability as a carbon carrier that can turn carbon into CO at high pyrolysis temperatures, FeAlOx was synthesized and characterized. The addition of 50% (wt) FeAlOx yielded the lowest activation energy (Eα = 108.11 kJ/mol). The catalyst facilitated the breaking of the C-Cl bond in PVC, increasing HCl and light hydrocarbon gases, such as CH4. Prolonged pyrolysis residence times reduced chlorine remnants in the bottom slag, increased its alumina content, and achieved a stable slag composition. The reaction model with varying catalyst additions was dynamically evolved as follows: F1.6→F2→F2.2→F1.5 in the first stage and F2.3→F2.8→F4.8→F2 in the second stage, thus achieving an optimal kinetic and thermodynamic ratio of 5:5. The addition of the catalyst reduced not only the energy consumption and complexity of the two pyrolysis stages of PVC but also the production of pollutants, thus improving the circularity. This study provides actionable insights into the potential of the catalyst-assisted pyrolysis as an effective method for the circular management of medical waste.

Investigation of Rare Earth Element Binding to a Surface-Bound Affinity Peptide Derived from EF-Hand Loop I of Lanmodulin.

Bioinspired strategies have been given extensive attention for the recovery of rare earth elements (REEs) from waste streams because of their high selectivity, regeneration potential, and sustainability as well as low cost. Lanmodulin protein is an emerging biotechnology that is highly selective for REE binding. Mimicking lanmodulin with shorter peptides is advantageous because they are simpler and potentially easier to manipulate and optimize. Lanmodulin-derived peptides have been found to bind REEs, but their properties have not been explored when immobilized on solid substrates, which is required for many advanced separation technologies. Here, two peptides, LanM1 and scrambled LanM1, are designed from the EF-hand loop 1 of lanmodulin and investigated for their binding affinity toward different REEs when surface-bound. First, the ability of LanM1 to bind REEs was confirmed and characterized in solution using circular dichroism (CD), nuclear magnetic resonance (NMR), and molecular dynamics (MD) simulations for Ce(III) ions. Isothermal titration calorimetry (ITC) was used to further analyze the binding of the LanM1 to Ce(III), Nd(III), Eu(III), and Y(III) ions and in low-pH conditions. The performance of the immobilized peptides on a model gold surface was examined using a quartz crystal microbalance with dissipation (QCM-D). The studies show that the LanM1 peptide has a stronger REE binding affinity than that of scrambled LanM1 when in solution and when immobilized on a gold surface. QCM-D data were fit to the Langmuir adsorption model to estimate the surface-bound dissociation constant (Kd) of LanM1 with Ce(III) and Nd(III). The results indicate that LanM1 peptides maintain a high affinity for REEs when immobilized, and surface-bound LanM1 has no affinity for potential competitor calcium and copper ions. The utility of surface-bound LanM1 peptides was further demonstrated by immobilizing them to gold nanoparticles (GNPs) and capturing REEs from solution in experiments utilizing an Arsenazo III-based colorimetric dye displacement assay and ultraviolet-visible (UV-vis) spectrophotometry. The saturated adsorption capacity of GNPs was estimated to be around 3.5 μmol REE/g for Ce(III), Nd(III), Eu(III), and Y(III) ions, with no binding of non-REE Ca(II) ions observed.