Residential Solid Waste Research Articles

Axial compressive properties of round bamboo-fiber reinforced phosphogypsum composite short columns

Bamboo is an ideal green building material with excellent mechanical properties. Phosphogypsum (PG) is a kind of solid waste residue which is in urgent need of resource utilization and has been used as construction material. In this paper, a kind of round bamboo-fiber reinforced phosphogypsum composite short column was proposed. Axial compression tests of pure bamboo columns, bamboo columns filled with phosphogypsum inside, bamboo columns with phosphogypsum outside and bamboo columns with phosphogypsum inside and outside were carried out to explore the failure mode and mechanical properties of the short columns. The effects of the parameters include bamboo node, hose hoops, size of the bamboo tube and the strength of phosphogypsum on the mechanical properties of the short columns were analyzed, and the theoretical calculation method of the bearing capacity of the short columns was put forward. The results show that the bamboo nodes and hose hoops can improve the bearing capacity, initial stiffness and ductility of the column. The larger the size of the bamboo tube, the better the mechanical properties of the short column. The bearing capacity of round bamboo—phosphogypsum composite short column is higher than that of pure bamboo column. The ductility of bamboo columns with phosphogypsum outside is obviously higher than that of pure bamboo columns. The finite element analysis results are in good agreement with the test results. The theoretical calculation method of the bearing capacity of columns considering the strength reduction coefficient, the bamboo node effect coefficient and the constraint effect in this paper has high accuracy.

Exploring Nigeria’s waste-to-energy potential: a sustainable solution for electricity generation

Abstract This research explored the potential of waste-to-energy (WtE) technology as a sustainable solution to Nigeria’s energy deficit and waste management challenges. Various WtE technologies were reviewed, including incineration, anaerobic digestion, gasification, and pyrolysis, highlighting their applicability and benefits for Nigeria. The potential energy yield from different waste streams, combined with economic viability, environmental benefits, and social impacts, demonstrates the importance of WtE technology for the country. The lower heating value of municipal solid waste and agricultural residue significantly affects energy yield. The incineration of 27.36 million tons of organic waste annually while using relevant technology with energy recovery could generate between 14.52 and 23.08 TWh of electricity per annum. The inclusion of paper and textiles increases the potential yield to 18.69 and 29.71 TWh per year. The potential power generation from agricultural residues is estimated at 80.3 GW. However, Nigeria must address technical, economic, and policy challenges to realize this potential. This can be achieved by developing a robust regulatory framework, fostering public–private partnerships, enhancing local capacity, engaging communities, and investing in research and development. The implementation of WtE projects will facilitate sustainable waste management, improve energy security, create jobs, and promote environmental stewardship.

Insight into efficient photocatalytic degradation of norfloxacin over a simple, economical biochar-based magnetic photocatalyst under solar illumination: a statistical and experimental approach.

The transformation of residual agricultural solid waste into an efficient value-added carbon product has been an ongoing strategy for solid waste management and a sustainable economy. Meanwhile, the upsurgence of antibiotic contamination in water bodies due to their inadvertent use poses a serious threat to human health and leads to antimicrobial resistance. Hence, to neutralize two evils in one stroke simultaneously, a simple, easy, and cost-effective pea shell-based magnetic photocatalyst (PSMC) has been synthesized and characterized by XRD (X-ray diffraction), VSM (vibrating sample magnetometer), XPS (X-ray photoelectron spectroscopy), TGA (thermogravimetric analysis), and FTIR (Fourier-transform infrared) spectroscopy techniques. Batch experimental studies revealed that PSMC efficiently eliminates norfloxacin (91.3%) within 180min from wastewater and mineralizes it into innocuous products at optimum parameters of norfloxacin concentration of 20mg/L, catalyst dosage of 15mg, and pH 3.5. Additionally, statistical parameters for the photodegradation of NX obtained from ANOVA by applying the Box-Behnken design are in close agreement with batch experiment parameters. PSMC has surplus advantages of facile recovery for recycling up to seven consecutive cycles by an external magnet and efficacy in natural solar light, making it cost-effective and economical. Radical scavenging studies revealed that O2•- and OH• were the potent reactive species in the photocatalytic degradation process.

Turning Waste into Treasure: Utilizing Environment-Pollutant Graphite Tailings as Photocatalyst for Photocatalytic Building Materials

Graphite tailings, as solid waste residuals from graphite extraction and refinement, pose serious risks to the surrounding ecological environment and the safety of residents’ lives. However, it is desirable but challenging how to rationalize the utilization of graphite tailings and further to develop their functionality. Herein, we demonstrate a "turning waste into treasure" strategy: capitalizing on the characteristics of graphite tailings in visible light absorption and rich metal catalytic sites, graphite tailings are employed as photocatalysts and fine aggregates to manufacture photocatalytic building materials, achieving sustainable use. Tailings powder from Luobei, Heilongjiang Province is selected as the photocatalyst, we discover that it exhibits photocatalytic degradation capability for methylene blue (MB) in water under visible-light irradiation: the degradation rates reach 70% within one hour and near-complete degradation within two hours, accompanying good recyclability. Structural analysis reveals that the graphite tailings are enriched with Fe2O3 and TiO2. They are capable of forming type-II heterojunction that enable efficient charge separation and transfer processes, transmitting photogenerated electrons to the active catalytic site to accomplish the photocatalytic degradation of MB. Moreover, other tailings, such as those from Jixi, also achieve photocatalytic degradation of MB, and cement specimens made with graphite tailings also bespoke photocatalytic degradation performance. This work is to provide solutions for the reuse of graphite tailings in the field of functional building materials, and to explore the feasibility of transforming graphite tailings from industrial solid waste to photocatalytic building materials.

Magnetic porous functional material from coal mine waste for simultaneous removal of cadmium and arsenic in water and soil: Synergistic effect of iron-containing minerals and porous structure

Heavy metals such as cadmium and arsenic (Cd/As) can cause harmful effects on human health. Coal mine waste (coal gangue) is a solid waste residue without commercial values produced abundantly in the coalfield. Hence, treating Cd and As concurrently with reutilizing coal gangue (CG) is critical to ecologically sustainable growth. This work successfully synthesized the magnetic porous functional materials (MPCG) based on CG using a two-step method for the simultaneous removal of Cd and As in water and soil. First, MPCG exhibited an irregular network porous structure. Then, it consisted of iron (Fe), mainly in magnetite, hematite, and pyrite forms. Such properties also exhibited excellent pH adaptability and coadsorption capacity by removing up to 103.79 mg g−1 and 579.43 mg g−1 for Cd(II) and As(V), respectively. There is a synergistic effect between the iron-containing minerals and porous structure to enhance the adsorption capacity of MPCG for Cd(Ⅱ) and As(Ⅴ). Several primary potential adsorption mechanisms by MPCG for Cd(Ⅱ) and As(Ⅴ) were identified. The potential mechanisms of Cd(II) adsorption mainly include ion exchange, electrostatic attraction, surface complexation and precipitation/co-precipitation, and the potential mechanisms of As(V) adsorption mainly include electrostatic attraction, surface complexation and precipitation. In addition, the removal rates of MPCG for Cd and As in soil were as high as 44.78 and 38.44 %, respectively. In conclusion, MPCG has excellent potential as an efficient and environmentally compatible functional material, which provides a potential way to realize efficient heavy metal removal from our ecosystems.

Strength test and reinforcement mechanism of gangue-building solid waste-based cement filling material improved by soda residue

To utilize solid soda residue (SR) and building solid waste (BSW), this study proposes to use SR for modification and preparation of mining-used soda residue-gangue-building solid waste-based cement filling material (SGBCFM). In this study, we studied the influence of fly ash (FA) content, SR content, BSW content, and mass concentration (MC) on the early strength and later strength of SGBCFM. Through XRD and SEM tests, we analyzed the hydration products and microstructure of SGBCFM and investigated the mechanism of SR enhancing the later strength of SGBCFM. The results show that these influencing factors have a weaker impact on the early strength of SGBCFM, but a significant impact on later strength. These influencing factors can be ranked from the most significant impact to the least impact as follows: MC, SR content, FA content, and BSW content. A proper amount of SR can effectively improve the later strength of the material, but an excessive amount of SR leads to a decrease in strength; SR has combined effects such as micro-aggregate filling, alkali activation, and promoting cementation reactions. These effects can increase the original cementitious substances and generate new compounds, effectively enhancing the later strength of SGBCFM.

Porous-structured FeS2@C nanoparticles prepared from spent LiFePO4 cathodes with excellent rate performance for potassium-ion batteries

Recycling spent cathode materials is crucial for sustainably developing lithium-ion battery technology. To achieve the high-value utilization of spent LiFePO4 (LFP) cathodes, this paper proposes a method for preparing MIL-100(Fe) based on solid waste residues from spent LFP cathodes. R-FeS2@C derived from MIL-100(Fe) can serve as an anode material for potassium-ion batteries featuring a porous structure. Electrochemical tests demonstrate that the R-FeS2@C exhibits more stable cycling performance compared with the FeS2@C derived from the traditional MIL-100(Fe), reaching 525 mAh g−1 after 100 cycles at a current density of 100 mA g−1. Impressively, R-FeS2@C also showcases excellent rate performance (343 mAh g−1 specific capacity at 5 A g−1). Furthermore, full cells assembled with PI@rGO cathodes also exhibit excellent rate performance and stable cycling performance. The porous structure of R-FeS2@C provides numerous voids to accommodate volume changes and introduces sufficient channels for electrolyte penetration. The higher carbon content enhances the electrical conductivity improving the kinetics of the K+ migration reaction. These researches can provide guidance for the recycling of spent lithium-ion batteries and the design of sulfide electrodes for PIBs.

Preparation of calcium aluminate and spinel by hydrolysis and calcination from secondary aluminum dross

AbstractThe direct extraction of alumina from secondary aluminum dross (SAD), which is a dangerous solid waste, is difficult. Moreover, this process easily produces a large amount of solid waste residue, which is not easily utilized. In this paper, a new green process was developed to prepare calcium aluminate and Mg‐Al spinel from SAD by hydrolysis–calcification roasting. The effects of calcium oxide (CaO) content, sintering temperature, and holding time on the properties of calcium aluminate were investigated by single‐factor experiments. The phase transformation mechanism of calcium aluminate was studied by thermodynamic analysis, X‐ray diffraction analysis, X‐ray fluorescence spectroscopy, and scanning electron microscopy. Under the optimal conditions (Ca/Al molar ratio of 0.8, sintering temperature of 1300°C, and holding time of 2 h), the main calcium aluminate phases are CaAl2O4 and Ca2Al2SiO7, the soluble alumina content of the calcium aluminate sample is 49.71 wt.%, and the main phases of the acid‐insoluble residue are Mg‐Al spinel and a very small amount of CaTiO3. The Ca/Al ratio is the key factor affecting the calcium aluminate phase—with increasing Ca/Al ratio, the calcium aluminate phase is transformed from CaAl4O7 to CaAl2O4 and eventually to Ca12Al14O33, and the Si‐containing phase changes from Ca2Al2SiO7 to CaSiO4.

Co-pyrolysis behavior of municipal solid waste and food waste residue: A thermogravimetric study to discern synergistic effect

Effective solid waste disposal necessitates suitable combination and clean conversion technologies to maximize resource utilization. Thus, this study investigates the behavior of co-pyrolysis in municipal solid waste (MSW) and food waste (FW) via thermogravimetric analysis, aiming to discern synergistic effects and optimize waste to energy conversion. The impacts of heating rate and blending ratios were evaluated under an inert N2 atmosphere, within a temperature range of 30–900℃, during single and combined pyrolysis processes respectively. Results revealed slight variations in weight loss patterns and thermal decomposition behavior. When heating rate increased from 10 to 30℃.min−1, decomposition process delayed, resulting in higher initial (Ti), peak (TP), and final (Tf) temperatures due to inadequate heat transfer. As food waste increased, mass loss rose and favorable synergistic effect was observed at 20 % FW during medium temperatures, while other blends showed inhibitory effects. The pyrolytic index (D) rose nonlinearly from 6.29 × 10−7 to 7.72 × 10−7 with a higher FW proportion, peaking at 20 % FW, suggesting an optimal MSW and FW mixing ratio. This blend also exhibited the lowest activation energy, indicating a more efficient thermal decomposition process. Those outcomes offer crucial insights for optimizing co-pyrolysis systems and provide essential information for co-disposal of MSW and FW, potentially reducing pollutant emissions and enhancing waste to energy conversion.

Boboiboy Animation Episode, Care of the Earth: Managing Solid Waste with the 3R Method

The increasing volume of domestic solid waste needs a sustainable solution to avoid complex environmental issues. The 3R practice of reuse, reduce, and recycle is said to be one of the efforts taken to educate the community on how to manage residential solid waste. A practice that wants to be cultured in the community must begin as early as childhood. As the saying goes, strike while the iron is hot. The application of environmental care practices to the younger generation can be implemented in the form of entertainment by inserting animation which attracts children’s attention. This study analyses solid waste management with the 3R method featured in Boboiboy animation. There are three episodes of Boboiboy’s animation of “Jagalah Bumi” used as the main study text (episodes 21, 22, and 23). Based on this analysis, it was found that this animation have successfully highlighted the 3R concept in three episodes of "Jagalah Bumi" including showing how the does solid waste management process is carried out at the landfill. The explanation of this method was successfully presented clearly and easily understood by the audience. This is able to influence and leave an impression on the audience indirectly.

Study on the Synthesis of LTA-Type Molecular Sieves from Coal Gangue and Aluminum Ash and Its Adsorption Properties towards Cu2+

Coal gangue and aluminum ash emerge as quintessential constituents within the ambit of coal-derived solid waste and industrial residue, respectively. Leveraging coal gangue as a primary substrate and aluminum ash as an adjunct aluminum source, molecular sieves can be synthesized through hydrothermal means. By modulating the dosage of aluminum ash, molecular sieves with varying crystalline structures can be obtained. The synthesized LTA-type molecular sieves manifest in two distinct morphologies: regular tetrahedral and stratified spherical stacking, evincing commendable Cu2+ adsorption efficacy. The Cu2+ adsorption phenomenon predominantly transpires via chemisorption, albeit with ancillary manifestations of physical adsorption. The valorization of coal gangue and aluminum ash towards the synthesis of molecular sieves not only underscores the elevation of industrial solid waste towards high-value utility, but also underscores the praxis of waste remediation through upcycling.

Biosolid Mixtures Applied in Tropical Soils and Their Effect on Coriandrum sativum and Ocimum basilicum Nutritional Uptake

Agricultural soils are degraded worldwide as result of anthropogenic activities; environmental contamination; and excessive use of chemicals, fertilizers, and pesticides. Scientists are concerned about this problem; during the past few years sewage compost and sludge have been used as alternatives to improve the soil’s physical and chemical characteristics. Recycling solid waste residues can be a cost-effective way to reduce landfill material disposal and improve macro and micronutrients’ availability in agricultural soils. In this study, two types of biosolids (compost and sludge) were added to tropical soils (coloso and voladora series) to improve the nutritional content in two edible herbs (basil and coriander). Soil mixtures were made by volume percentage; compost was constant, at 25%, and soil and sludge were incorporated in different proportions to complete the 100% (25 comp/75 soil, 25 comp/62.5 soil/12.5 sludge, 25 comp/50 soil/25 sludge and 25 comp/37.5 soil/37.5 sludge). pH and electrical conductivity were measured in soil mixtures. Basil and coriander were cultivated in pots for 30 days at an open greenhouse (5 replicates per soil mixtures). Germination percentage, stems’ length, total chlorophyll (SPAD 502), acid digestions of plant tissues and an ICP-OES analysis were performed for both plants cultivated in all the soil mixtures. In voladora soil, the pH increased from 4.55 ± 0.10 to 5.64 ± 0.22 and EC from 0.0563 ± 0.0003 dS/m to 1.39 ± 0.01 dS/m in a 25% comp/37.5% soil/37.5% sludge mixture. In the coloso soil, the pH increased from 6.38 ± 0.13 to 6.82 ± 0.07 and electrical conductivity from 0.117 ± 0.001 to 1.310 ± 0.009 dS/m in 25% compost/37.5% soil/37.5% sludge mixture. Significant differences (p < 0.05) were found in the chlorophyll content and stem length for both plants. The highest chlorophyll value was in basil leaves from a 25% compost/50% soil/25% sludge mixture (43.20 ± 074) compared to the coloso soil (26.99 ± 0.43). In the voladora soil, the highest chlorophyll content was in a 25% compost/37.5% soil/37.5% sludge mixture (39.97 ± 0.83). In coriander leaves, the highest chlorophyll content was 33.01 ± 0.84 in the 25% compost/62.5% coloso/12.5% sludge mixture. In the voladora soil, chlorophyll content in leaves did not show a significant difference between treatments. Larger basil stems were found at 25% compost/75% voladora mixture (17.50 ± 2.39 cm) and in a 25% compost/62.5% coloso/12.5% sludge mixture (9.95 ± 0.71 cm) compared to control plants (3.45 ± 0.18 cm). Greater coriander stems were observed in a 25% compost/50% voladora/25% sludge mixture (2.43 ± 0.11 cm) and in a 25% compost/50% coloso/25% sludge mixture (2.17 ± 0.10 cm) compared to control plants (2.05 ± 0.07 cm). Macro and micronutrient content in plants increased with biosolids’ incorporation to soils. Mg content in basil leaves increased from 8.61 ± 0.70 mg/g in the voladora soil to 10.31 ± 0.60 mg/g in a 25% compost/37.5% soil/37.5% sludge mixture. In coriander leaves, Mg increased from 6.91 ± 0.06 mg/g in a 25% compost/75% soil mixture to 9.63 ± 0.02 mg/g in a 25% compost/50% soil/25% sludge mixture. The Mn uptake by basil leaves increased from 0.076 ± 0.005 mg/g in the coloso soil to 0.152 ± 0.019 mg/g in a 25% compost/75% soil mixture. In coriander leaves, Mn increased from 0.357 ± 0.002 mg/g in a 25% compost/75% soil mixture to 0.651 ± 0.006 mg/g in a 25% compost/37.5% soil/37.5% sludge mixture.

Fundamental drying and agglomeration experiments with bio-fraction and refuse derived fuel for the development of pyrolysis reactor feed.

The EU's circular economy concept necessitates increasing the recycling ratio of municipal solid wastes. There are many existing mechanical-biological processing plants in Hungary for the preparation of residual municipal solid wastes (RMSWs). The two most important products of these plants are the bio-fraction and the refuse derived fuel (RDF). Currently, there are problems with both of these material streams in Hungary, since most of the bio-fraction is still landfilled, and the local thermal utilisation of the RDF has not been implemented yet. The high moisture content of the produced bio-fraction and RDF causes difficulties for the downstream operations; therefore, there is recent engineering interest in drying and agglomeration of these materials. The authors have carried out systematic and parallel drying and briquetting experimental series to study the effect of the material, material composition, mass (volume or surface) of the material, particle size distribution and pre-treatment with a cutting mill on drying intensity in a 1 m3 oven and their effect on briquettability by a laboratory briquette press. The initial slope of the relative moisture loss as function of time was determined. Process engineering design methods of convective hot air-drying can be further developed taking into account the research results. Results can be used for the design of the feed of a pyrolysis reactor once reactor experiments have provided the optimal feed requirements.

Modest governance as a condition for separating benevolent from malevolent recycling practices in the Netherlands

The municipal government of Hengelo (Netherlands) has introduced reversed collection and differentiated tariffs for waste collection as two policies to stimulate the separation of household waste at source and reduce residual waste. It has also launched other innovative ways of reducing residual solid waste. While most people comply with the new policies, the citizenry has also reacted with fierce protests and in an astounding diversity of ways to the disposal of their waste, unforeseen by the municipality. Two negative effects of the citizens’ creative reactions have been haphazard separation and the littering of the street. The municipality has reacted with condescension by imposing a mixture of control and pedagogic strategies. The aim of this article is first to demonstrate the amazing width of municipal policies, second, to understand the negative reactions of citizens, and, third, the reasons why municipal responses to these reactions have partly remained without success. We argue that ‘modest governance’, which is more sensitive to the citizens’ life worlds, is necessary if the service co-production of waste management is to be a success.

Soluble carbon source recovery using preconditioning coagulants for applicable short-term fermentation of waste activated sludge in WWTPs

A huge production of waste activated sludge (WAS) has been a burden for wastewater treatment plants (WWTPs) with high disposal cost and little benefit back to wastewater purification. The short-chain fatty acids (SCFAs) produced by a short-term acidogenic fermentation of WAS before methane production have been proven to be a high-quality carbon source available for microbial denitrification process. The dual purpose of full recovery of fermentation liquid products and facilitating disposal of residual solid waste necessitate an efficient solid-liquid separation process of short-term fermentation liquid. The transformation and loss of various soluble carbon sources between solid and liquid are very important issues for carbon recovery efficiency when combining short-term fermentation and sludge dewatering in WWTPs. Here we testified the three conventional preconditioning coagulants, Polyferric Sulfate (PFS), Poly Aluminum Chloride (PAC) and Polyacrylamide (PAM), to improve the efficiency of subsequent solid-liquid separation. The results show that conversion yield of SCFAs in the liquid phase of sludge after short-term fermentation was 195 mg COD/g VSS, when using the coagulants PFS, PAC, and PAM for recovery, the recovery ratio was 79.5%, 82.0%, and 85.9%, respectively, while the dewaterability could be improved after preconditioning short-term fermentation sludge. The complexation of Al3+/Fe3+ in metal coagulants with carboxyl groups of SCFA demonstrated by Density Functional Theory calculation led to small part of soluble carbons co-migration to the solid phase, mainly a loss of high molecular weight organic compounds (carbohydrate, proteins, humic acids), while the application of PAM had little impact on carbon recovery. Economic calculations further showed PAM preconditioning short-term fermentation liquid of WAS could achieve higher recovery benefits.

GREEN TECHNOLOGY FOR SUSTAINABLE AGRICULTURE: BIO-FERTILIZER PRODUCTION FROM MUNICIPAL WASTE TO PRESERVE THE ENVIRONMENT

This study addresses the pressing issue of municipal waste (MW) management by proposing an innovative approach to transform residential solid waste into a valuable resource using green technology. MW, sourced from diverse sectors, undergoes various disposal methods, including incineration, recycling, and landfilling. In Malaysia, the composition of MW aligns with global trends, with food waste and plastic being the predominant categories. This research focuses on producing fertilizer from residential solid waste through a green technology process, utilizing a sequential procedure involving high pressure, high temperature, and energized water to de-polymerize hemicellulose and lignin, followed by microbial enzymatic fermentation. The developed green technology introduces a novel apparatus designed for treating MW in a high-temperature, low-pressure rotating vessel using indirect heating with thermal fluid. The experimental protocol involves four batches of MW samples, evaluating the mass differential before and after the treatment process. Furthermore, a 7-week observation period assesses chili plant growth as an indicator of fertilizer effectiveness. Results indicate a significant 71% mass reduction of MW, amounting to 201.26 kg, emphasizing the efficacy of the developed process. The investigation extends to plant height, comparing MW-derived fertilizer with commercial fertilizer over a 5-week period. Remarkably, chili plants fertilized with MW-derived fertilizer exhibit a greater height of 8.6 cm, surpassing the 7.3 cm observed with commercial fertilizer. This study concludes that MW-derived fertilizer is highly recommended for enhancing plant growth and health in Malaysia, suggesting a sustainable production system. The research not only contributes to waste management but also aligns with broader goals of promoting environmentally conscious and sustainable agricultural practices, emphasizing the potential of green technology in addressing the challenges of municipal waste.

Liquid membrane coupled electrodialysis system for highly-efficient lithium recovery from fly ash acid leaching solution

Recovering lithium (Li) from high Li-bearing coal fly ash (CFA) is a challenging task due to CFA's complexity and minor content of Li. Acid leaching is a common treatment, but it faces the difficulties of complex leaching solution and selective separation of Li+. This work evaluated a liquid membrane coupled with the electrodialysis (LME) system to separate Li+ from the CFA leach liquor. The liquid membrane (LM) performs as an ion carrier to selectively transport Li+, while the electric field can drive the ion migration. The results show that the LM TBP+[HOEmim][NTf2] (v/v, 5:5) exhibits the best recognition and releasing ability toward Li+. The selective migration of Li+ can be achieved in acidic environment in the presence of concentrated Al3+. The Al/Li ratio decreases from 30 of the feed to 0.55 in the receiving solution after 12 h at 3 V. The practical application in the CFA leach liquor indicates that the system has preferential selectivity for transmembrane transport of Li+, while other multivalent ions were mostly hindered. This work presents a new idea for Li recovery from the solid waste residues, and offers a deep insight into the separation of valuable metal ions from complex solutions.

The effect of carbon dioxide absorption using buton asphalt residue through carbonation on calcium carbonate precipitated efficiency

The study investigated the efficiency of generating precipitated calcium carbonate (PCC) by chemical dissolution and carbonation from extracted natural asphalt solid waste residue. This residue was then further transformed into calcium carbonate through a series of steps involving calcination at a temperature of 900 °C for 5 hours and ammonium salt dissolution. Subsequently, the calcined residue is dissolved in ammonium salt solutions (2M - NH4Cl, and NH4NO3) under a temperature condition of 60°C. Next, CO2 was injected into the solution contained a high concentration of calcium sources under a predetermined pressure. Additionally, the solution’s initial pH changed to 12 to be the ideal degree of alkalinity. A flow rate of 1 L/min of acetic acid as the extracting agent would result in the highest level of carbonation efficiency. This process yielded vaterite calcium carbonate with a purity of 99.4%, as verified through X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) tests. The vaterite of polymorphic calcium carbonate has a spherical morphology, according to studies utilizing scanning electron microscopy (SEM), confirming the morphological structure of calcium carbonate. The study could add knowledge on preparing the wastes into the high value of vaterite with low processing procedures.

Pyrolysis of municipal solid waste: A kinetic study through multi-step reaction models

The present study endeavors to establish a comprehensive kinetic analysis of Municipal Solid Waste residue pyrolysis. As the sample exhibits four distinct degradation stages, it has been carried out by adopting a multi-step process behavior. Different approaches have been compared, including five isoconversional methods (Kissinger-Akahira-Sunose, Ozawa-Flynn-Wall, Starink, Friedman and Advanced integral Vyazovkin), Mathematical Deconvolution Analysis, and Independent Parallel Reaction Model. The study focuses on the two active pyrolysis steps, the first one corresponds to the biomass components between 150 and 400 °C, with the decomposition peak between 300 and 350 °C, whereas the second corresponds to the plastic fraction with temperature ranging between 400 and 520 °C. The activation energy values obtained from the different kinetic methods for both steps are estimated at 240 and 250 kJ/mol, respectively. It was observed that the biomass components degradation obeys a third-order kinetic model, while the plastic fraction follows a first-order kinetic model. The analytical pyrolysis of the two main stages allows for the identification and semi-quantification of the compounds produced during municipal solid waste pyrolysis. Through analytical pyrolysis, it has been determined that up to 64 % of hydrocarbons are produced, of which 24 % correspond to aromatic compounds. Meanwhile, 20 % of oxygenated compounds were obtained, with ketones, furans, and acids being the most predominant families.

Waste-to-Energy Pipeline through Consolidated Fermentation–Microbial Fuel Cell (MFC) System

The rise in population, urbanization, and industrial developments have led to a substantial increase in waste generation and energy demand, posing significant challenges for waste management as well as energy conservation and production. Bioenergy conversions have been merged as advanced, sustainable, and integrated solutions for these issues, encompassing energy generation and waste upcycling of different types of organic waste. Municipal solid waste (MSW) and agricultural residues (AR) are two main resources for bioenergy conversions. Bioenergy production involves feedstock deconstruction and the conversion of platform chemicals to energy products. This review provides a detailed overview of waste sources, biofuel, and bioelectricity production from fermentation and microbial fuel cell (MFC) technology, and their economic and environmental perspectives. Fermentation plays a critical role in liquid biofuel production, while MFCs demonstrate promising potential for simultaneous production of electricity and hydrogen. Fermentation and MFCs hold a significant potential to be integrated into a single pipeline, enabling the conversion of organic matter, including a variety of waste material and effluent, into diverse forms of bioenergy via microbial cultures under mild conditions. Furthermore, MFCs are deemed a promising technology for pollutant remediation, reducing COD levels while producing bioenergy. Importantly, the consolidated fermentation–MFC system is projected to produce approximately 7.17 trillion L of bioethanol and 6.12 × 104 MW/m2 of bioelectricity from MSW and AR annually, contributing over USD 465 billion to the global energy market. Such an integrated system has the potential to initiate a circular economy, foster waste reduction, and improve waste management practices. This advancement could play a crucial role in promoting sustainability across the environmental and energy sectors.