Fraction Of Municipal Solid Waste Research Articles

Organic waste and beechwood cellulose blend saccharification and validation of hydrolysates by fermentation.

This study demonstrates the sustainable advancement of fermentation media by blending the organic fraction of municipal solid waste (OFMSW) with organosolv beechwood cellulose. Investigations examined the effects of enzyme dosages and OFMSW integration into organosolv beechwood cellulose on sugar yield. The findings indicate that OFMSW inclusion and Cellic® CTec3 dosage significantly influence hydrolysis across two different batches of beechwood cellulose. Experimental data showed that OFMSW inclusion levels of 35% and 45% (w/w) produced sugar levels comparable to pure beechwood cellulose, achieving 58% to 68% (w/w) saccharification with sugar concentrations of 44 to 46g/L. This highlights OFMSW's potential as a buffer substitute during the enzymatic conversion of organosolv cellulose. The resulting sugar-rich hydrolysates, derived from OFMSW-cellulose blends and pure cellulose, were evaluated for ethanol and cell biomass production using Saccharomyces cerevisiae and Mucor indicus, yielding 30g of ethanol/L hydrolysate. Furthermore, OFMSW inclusion in beechwood cellulose proved to be an excellent alternative to synthetic nitrogen agents for S. cerevisiae cell production, reaching 12.2g of biomass/L and surpassing the biomass concentration from cultivation on cellulose hydrolysate with nitrogen supplementation by threefold. However, M. indicus did not grow in the OFMSW-cellulose blend, suggesting that the inhibitory compounds of OFMSW may be a bottleneck in the proposed process. The present study demonstrates the benefits of incorporating OFMSW into cellulose material, as it enhances both cost-effectiveness and sustainability. This is attributed to the natural buffering properties and nitrogen content of OFMSW, which reduces the need for synthetic agents in fermentation-based lignocellulose biorefineries. KEY POINTS: • OFMSW inclusion significantly influences beechwood cellulose saccharification. • OFMSW could be an excellent alternative for synthetic agents in biorefinery. • S. cerevisiae achieved higher biomass growth on OFMSW/cellulose mix compared to YPD.

Life cycle sustainability assessment of microbial oil from organic waste

Microbial oils (MOs) are lipids produced by oleaginous microorganisms, which constitute an alternative to vegetable and fossil-derived oils. They can be produced from organic waste by coupling acidogenic fermentation (AF) with oleaginous fermentation (OF). This study addresses a life cycle sustainability assessment (LCSA) of MO produced from the organic fraction of municipal solid waste. First, a system was modelled using simulation tools. This model combines AF for the production of volatile fatty acids from organic waste, OF for the production of lipid-rich yeasts, and MO extraction. LCSA results indicate the need for improvements in the disruption of yeasts and the overall efficiency of the system. Particularly, slightly acidified thermolysis turned out to involve excessively high steam requirements. An enhanced sustainability performance could be achieved by exploring alternative disruption methods or alternative sources of energy for the production of steam such as biogas from the valorisation of the sludges produced in the system.

Heat mitigation in basal compacted clay liners in municipal solid waste landfills.

In municipal solid waste (MSW) landfills, biodegradation of the organic MSW fraction results in elevated waste and basal liner temperatures which have the potential to cause the clay component of the basal liner to experience severe moisture loss over time and eventually undergo desiccation cracking. Cracking of the basal liner's clay component would result in an uncontrolled release of contaminants into the surrounding environment and ultimately give rise to a variety of major environmental concerns. Accordingly, this study examined the variation of temperature-moisture profiles along the depth of a compacted clay liner (CCL) exposed to different constant elevated waste temperatures (CETs) in the absence and presence of two heat reduction techniques, respectively. Rockwool insulation layers with varying thicknesses and galvanized steel cooling pipes with varying flowrates were introduced separately as the two heat reduction techniques. Introduction of both techniques led to a significant attenuation of the temperature rise and desiccation experienced by the CCL in the face of different CETs. An increase in rockwool thickness increments led to a progressive reduction of CCL temperature, while an increase in flow rate under turbulent condition did not have a significant influence on the temperature and desiccation reduction of the CCL. Nevertheless, the present study certainly highlights the potential of the two proposed heat reduction techniques to minimize desiccation and consequently increase the service life of CCLs exposed to different elevated temperatures in MSW landfills.

Effects of Biochar on Arsenic-Contaminated Soil: Chemical Fractionation, Vegetation Growth, and Oral Bioaccessibility.

Contamination by arsenic (As) is a pressing environmental and public health issue requiring urgent remediation strategies. One cost-effective and eco-friendly method involves adding stabilizing agents to soils to reduce As mobility. However, remediation projects must also address potential ecotoxicological effects. These effects may include harmful impacts on both aquatic and terrestrial organisms, including plants, disruption of ecosystem balance, and the potential bioaccumulation of toxic substances in the food chain. Biochar from organic fraction of municipal solid waste (OFMSW) shows promise for As-contaminated soil remediation. Pot experiments were conducted with soil contaminated with As (100 mg kg-1) and amended with biochar produced at three different temperatures (300, 500, and 700 °C) and addition rates (1 and 5%, w/w). Chemical fractionation showed higher As concentration in a less accessible fraction (F4). Biochar amendments did not significantly differ from the control in As immobilization, but enhanced maize (Zea mays) growth and reduced As uptake, with the most promising results seen with 1% of biochar produced at 700 °C. The bioaccumulation factor (BCF) and translocation factor (TF) were both lower than 1, indicating a low absorption of As and minimal translocation from the root to the shoot. The bioaccessible percentage was higher in the samples treated with biochar compared to the control. According to the results, biochar showed no satisfactory potential for As immobilization and its approach of pretreatment/modification should be tested regarding possible improvements in the immobilization performance of As. Since most contaminations involve multiple contaminants simultaneously, it is essential to test the interactions between arsenic and other pollutants to understand the effects of biochar in such complex scenarios, which will be explored in future studies. Graphical abstract.

Experimental and performance analysis of organic fraction of municipal solid waste in downdraft gasifier

It is anticipated that the production of municipal solid waste will increase from 2.10 billion tonnes in 2023 to 3.80 billion tonnes by 2050. About 170 billion metric tonnes of biomass is produced worldwide each year. On a wet basis, the composition of municipal solid waste (MSW) includes approximately 20% of wood, 70% of food waste, 60% of yard trimmings, and 50% of other organic materials. Gasification of waste biomass is one of the most efficient processes for creating gaseous fuel and subsequently power with reduced environmental impact. The current work presents a novel strategy to reduce MSW by converting waste into briquettes and feeding it in gasifiers to produce syngas. The downdraft gasifier is employed in the syngas generation process. With a calorific value of 22.6 MJ/kg and a higher lignin concentration of approximately 31%, MSW proves to be suitable for thermochemical conversion processes. This article presents the results during gasification of briquette made from organic fraction of municipal solid waste (OFMSW) with significant heating value of 22.6 MJ/kg. The fuel produced by the gasifier has a heating value ranging from 920 to 1150 kcal/m3, making it clean-burning. Its primary components consist of 19% to 23% carbon monoxide and 17% to 21% hydrogen. This study offers a unique investigation into the gasification behavior of the organic fraction of OFMSW in a downdraft gasifier, with an emphasis on optimizing operational parameters and evaluating the yield and quality of syngas. Although gasification has been widely studied as a thermochemical conversion method for biomass, the specific performance of OFMSW in this process has received limited attention. By focusing on this underexplored area, the study enhances the understanding of OFMSW's potential in gasification and its contribution to sustainable energy production, thereby addressing key issues in both waste management and renewable energy generation.

Innovative Circular Biowaste Valorisation—State of the Art and Guidance for Cities and Regions

The management of the organic fraction of municipal solid waste (OFMSW), also called urban biowaste, and urban wastewater sludge (UWWS) represents a challenge for cities and regions, which want to adopt innovative urban bioeconomy approaches for their treatment and production of high-added-value products beyond the traditional anaerobic digestion (AD) and compost. This adoption is often restricted by the availability and maturity of technologies. The research object of this manuscript, based on the findings of EU Horizon 2020 project HOOP, is the identification of state-of-the-art circular technologies for material valorisation of OFMSW and UWWS, following a novel screening methodology based on the scale of implementation (tested at least at pilot scale). The screening resulted in 25 technologies, which have been compared and discussed under a multidisciplinary assessment approach, showing their enabling factors and challenges, their current or potential commercial status and their compatibility with the traditional technologies for urban biowaste treatment (composting and AD). The bioproducts cover market sectors such as agriculture, chemistry, nutrition, bioplastics, materials or cosmetics. Therefore, the results of this review help project promoters at city/region level to select innovative technologies for the conversion of OFMWS and UWWS into high value products.

Machine learning based prediction of biogas generation from municipal solid waste: A data-driven approach

This study aims to imply different machine learning (ML) (artificial neural network (ANN), linear regression, XGBoost, random forest (RF), support vector machine (SVM)) models to predict and optimize biogas production yield from organic fractions of municipal solid waste (MSW). The data set for six key input variables, including moisture content, C/N ratio, lignocellulose content and MSW age was analyzed and processed using ML models. Further, data exploratory analysis (EDA) analysis was performed using various steps such as data preprocessing, feature selection, train-test-validation splitting, model testing and evaluation. The results revealed that XGBoost and RF regression model exhibited superior performance efficacy. Both the models achieved a higher R2 values of 0.88 and 0.68, and low root mean square error (RMSE) values of 305 and 496, respectively. Furthermore, feature importance analysis was performed to identify the relative significance of input variables in biogas prediction. SVM model revealed significant contributions of moisture content (20.86 %), cellulose (60.21 %), hemicellulose (34.91 %), lignin content (62.84 %), and MSW age (17.23 %) in predicting biogas production. The findings of the study can be a resource for techno-crates/researchers to develop an efficient ML based decision-making tools for accurate predictions and process optimization.

Characterization of municipal solid waste with the perspective of biofuels and bioproducts recovery in Northeast Mexico

This work focuses on analyzing the physical composition of municipal solid waste (MSW) and the physicochemical characterization of the organic fraction of municipal solid waste (OFMSW) in a city in Northeast Mexico to propose an adequate treatment and valorization system. Diverse samples were analyzed over 5 months at the city of Saltillo landfill, where the daily discarded MSW was classified into household (HW), central market waste (CMW), and public areas and parks waste (PPW). For the HW and CMW, the fraction with the highest proportion was the organic residues from food products, with 22.15 and 25.78%, followed by other organic wastes (manure, yard waste, leaves, etc.) at 12.58 and 10.24%, respectively. Furthermore, the organic fraction was segregated from the rest of the MSW and classified into four subtypes, and their physical composition and physicochemical characteristics were determined. The results contribute to laying the foundations for the proper treatment of the OFMSW not just in the studied region but also in cities with similar conditions. Moreover, the OFMSW’s feasibility in treating via bioenergy technologies is revealed, and this research proposes a biorefinery treatment pathway through dark fermentation followed by high solids anaerobic digestion generating bioenergy and diverse bioproducts.

Metabolic route and bacterial community changes induced by inactivation of indigenous bacteria in dark fermentation

Biohydrogen production by dark fermentation (DF) can be achieved using only indigenous bacteria from substrates or by adding an external inoculum. This study aims to provide new insights on the role of indigenous bacteria in DF process operation by investigating DF performances and microbiological aspects. DF tests are performed with only indigenous bacteria, with indigenous and exogenous bacteria and with only exogenous bacteria by inactivating indigenous bacteria by gamma irradiation. Sorghum irradiation reduces DF performances for both hydrogen (17.8 ± 12.8 versus 45.2 ± 1.7 mLH2/gVSadded) and total metabolite (0.22 ± 0.01 versus 0.30 ± 0.01 gCOD/gVSadded) yields. In contrast, no difference is observed with the organic fraction of municipal solid waste, suggesting a distinct role of indigenous bacteria for both substrates. Indigenous bacteria inactivation strongly modifies the metabolic routes and final bacterial community composition. This study proves the key role of indigenous bacteria in influencing metabolite production and bacterial composition.

Single- vs. two-stage fermentation of an organic fraction of municipal solid waste for an enhanced medium chain carboxylic acids production − The impact of different pH and temperature

Single-stage fermentation was characterized by low medium chain carboxylic acids concentrations and different mesophilic temperatures had little effect on the process performance, whereas thermophilic conditions and pH 5.5 led to lactate and ethanol accumulation. Two-stage fermentation enabled almost twofold increase in the caproate productivity, that reached 0.8 g/L-d (1.7 ± 0.1 gCOD/L-d) with a caproate concentration of 4.0 g/L (8.4 gCOD/L) at specificity of 37 % and led to a reduced release of carbon dioxide. Under pH 6.5 and temperature of 37°C the production of medium chain carboxylic acids required higher concentrations of ethanol. Number of reads annotated to fatty acid biosynthesis pathway exceeded the number of sequences assigned to the reverse β-oxidation pathway. Core microorganisms encoding these pathways belonged to Caproiciproducens, Caproicibacterium and Clostridium. This study provides a valuable insight for valorisation of organic fraction of municipal solid waste into carboxylates in a single- and two-stage systems.

Efficient production of hydrogen through bioaugmentation of the organic fraction of municipal solid waste by the newly isolated Clostridium sartagoforme SA1

Bio-hydrogen from organic waste holds promise as renewable energy. However, its large-scale production is limited by technical challenges, with low H2 yields and the absence of robust microbial strains being the major ones.To address these limitations, H2-producing microbes have been isolated from a full-scale anaerobic digestor treating complex organic waste. Clostridium sartagoforme SA1 was selected because of high H2 yields from glucose, soluble starch, and carboxymethylcellulose. The strain was then tested for H2 production from the Organic Fraction of Municipal Solid Waste (OFMSW), rich in starch and cellulose, with productions up to 55 mLH2 g/VS. Additionally, C. sartagoforme SA1 confirmed high H2 performances even in the presence of OFMSW’s indigenous microflora, increasing the H2 yield by 38 % and highlighting its robustness in a highly competitive environment. This is the first report describing the efficient adoption of a C. sartagoforme strain for bioaugmentation of non-sterile OFMSW towards high H2 yields.

Different aspects of biochar addition on semi-dry anaerobic digestion of organic fraction of municipal solid waste in continuous mode

This study investigated the use of biochar, derived from a wood gasifier, in semi-dry anaerobic digestion of organic fraction of municipal solid waste (OFMSW). The experiment was conducted in three phases, without biochar and changing the hydraulic retention time (HRT) from 50 to 15 days until first acidification condition (on pH = 6.5), with biochar at an optimal concentration of 30 g/L in HRT= 20–10 day. Also, countermeasures for the acidified reactor with biochar during the dormancy period were investigated. The results demonstrated that adding biochar led to a rapid recovery of the acidified reactor, improved stability parameters, and removed foaming as a disturbance. Biochar addition (30 g/L) enhanced the organic loading rate (OLR) up to 11 kgVS/m3.day with an HRT of 20 days leading to specific methane production of 383 L/kgVS and a volumetric production increase of biomethane by 85 %. However, at higher OLRs with HRT of 10 days, acidification condition resurfaced leading to homogeneous foaming. Excess adding of biochar did not have significant treatment effects but necessitated a no-feeding period (about 45 days) and gentle stirring with long intervals for stable conditions. Overall, the use of biochar along with the OFMSW biogas plant was demonstrated to enhance production efficiency.

Industrial optical sorting for marine plastic litter management

The aim of this study is to evaluate the possibility of incorporating marine litter from the coast into the management system of the non-selectively collected fraction of Municipal Solid Waste (MSW). With this purpose, the technical feasibility of automatic separation of marine plastic litter is evaluated, which would allow for subsequent recycling. This solution requires mechanical–biological-treatment plants (MBT) to be able to sort marine plastic litter. Poly (ethylene terephthalate) (PET) bottles constitute one of the most commonly reported types of marine plastics. Considering the sorting methods employed in MBT plants, optical sorting tests were performed with marine PET litter and compared with those for post-consumer municipal PET waste, in order to assess whether the current technology implemented in these plants would allow their automatic sorting. Results show that the separation efficiency of PET degraded under marine conditions and outdoors is very high, and close to that of post-consumer municipal PET waste. The separation efficiency by transparent colour for different types of PET materials evaluated is also very effective and similar to that obtained for separation by chemical composition. Therefore, the chemical differences observed would not affect the efficiency of automatic sorting of marine origin PET in a waste treatment plant.

Technical feasibility and modeling of enzymatic pre-treatments of organic fraction of municipal solid waste to improve anaerobic digestion

The study explored the combined effects of enzymatic pre-treatment and anaerobic digestion (AD) on the organic fraction of municipal solid wastes (OFMSW) through experimental and multicriteria decision-making approaches. Five enzymes (UPP2, MPCS, USC4, USE2, and A. niger) and their dosages were studied. AD parameters included two inoculum origins (waste active sludge - WAS - and cow-agricultural sludge - CAS), the substrate: inoculum (SI) ratio, and inoculum incubation time (INOC). Desirability functions were used to optimize the multiple experimental responses simultaneously by converting each of them into values from 0 (unacceptable) to 1 (completely acceptable) and then combining these into a global desirability (D). D highlighted that higher enzyme dosages, INOC, and SI, improved AD performances, with optimal DOSE (at the highest level adopted for each enzyme) and INOC (5–10 d). AD tests with the five enzymes increased CH4 production by 10–13%v/v compared to untreated OFMSW. For UPP2 and MPCS, increasing DOSE boosted the biogas production, while increasing INOC enhanced the CH4 content. MPCS reached the highest efficiency (478. 43 NL CH4/kg VS with CAS, SI = 2:1, INOC = 10 d), followed by UPP2. Furthermore, higher INOC reduced A. niger doses, increasing CH4 production by 9%v/v compared to literature, with 5–10 d INOC (452.86 NL s/kg VS with WAS, SI = 2:1).

Exploring resource recovery from diverted organics: Life cycle assessment comparison of options for managing the organic fraction of municipal solid waste

Diversion of the organic fraction of municipal solid waste (OFMSW) from landfills is increasing. Previous life cycle assessment studies have evaluated subsets of OFMSW management options, but conclusions are inconsistent, and none have evaluated diverse applications of material by-products. The primary objective of this work was to identify sustainability-based improvements to the selection, design, implementation, and operation of organics waste diversion management technologies. Process modeling and life cycle assessment were used to compare OFMSW composting, anaerobic digestion, and pyrolysis, with biochar used as a landfill cover, leachate treatment sorbent, and land applicant. Material and energy flows, calculated by newly developed models for the defined functional unit (1 kg MSW over a 20-year timeframe), were translated to environmental performance using ecoinvent and USLCI databases and TRACI method. Additionally, uncertainty, sensitivity, and scenario analyses were conducted to evaluate the implications of model uncertainties, design decisions, and resource recovery tradeoffs. OFMSW pyrolysis usually (65 % of uncertainty assessment simulations) had the best global warming performance mostly due to energy recovery and biochar's carbon sequestration benefit, which was independent of fate. Pyrolyzing the biosolids from OFMSW anaerobic digestion recovered the most energy and had the best performance in 34 % of uncertainty simulations. Material recovery amounts were large (e.g., more biochar was produced than required for novel uses) and warrant feasibility considerations. Global warming performance was more sensitive to uncertainty in carbon sequestration and primary energy production than in fertilizer offset, energy conversion, or heat offset approach. Practical implications include the potential for biochar supply to outweigh demand, and inconsistent revenue from the sale of recovered energy and carbon credits; future research could focus on evaluating the relative social and economic sustainability of the OFMSW management technologies.

Effect of HTC and Water-Leaching of Low-Grade Biomasses on the Release Behavior of Inorganic Constituents in a Calcium Looping Gasification Process at 650 °C.

The release of alkali metals (K, Na) and nonmetals (S, Cl) during a calcium looping (CaL) gasification process of waste derived-hydrochars, water-leached samples, and CaO-biomass blends was investigated. Special attention was paid to biomasses that are not particularly promising for gasification requirements but have a large occurrence in Europe, including Grape Bagasse, Organic Fraction of Municipal Solid Waste (OFMSW), Green Waste, and Out-of-use woods from construction debris and discarded furniture. The release experiments were performed at 650 °C in a flow channel reactor to investigate the behavior of inorganic trace substances. Hot-gas analysis was performed by Molecular Beam Mass Spectrometry (MBMS). Thermodynamic equilibrium calculations via FactSage indicate H2S, carbonyl sulfide (COS), KCl, NaCl, and HCl as the main inorganic impurities. Thus, the focus of the experiments was placed on these species. It was found that the concentrations of trace elements released during gasification at 650 °C, such as H2S, SO2, KCl, and NaCl, are hardly affected by intense water-leaching. In contrast, carbonaceous materials from hydrothermal carbonization exhibit a higher concentration of trace potassium substances (K, KCl, and K2Cl+). When biomass samples are combined with CaO, the total amount of inorganic trace compounds (K, Na, and S compounds) in the resulting syngas could be decreased.

Synergetic association of hydroxyapatite-mediated biofilm and suspended sludge enhances resilience of partial nitrification/anammox (PN/A) system treating high-strength anaerobic membrane bioreactor (AnMBR) permeate

A single-stage partial nitrification/anammox (PN/A) system with biocarriers was used to treat the permeate from an anaerobic membrane reactor (AnMBR) processing organic fraction of municipal solid wastes. The suitable Ca/P ratio and high pH in the AnMBR permeate facilitated hydroxyapatite (HAP) formation, enhancing the biofilm attachment and the settleability of suspended sludge. This maintained sufficient biomass and a stable microbial structure after flushing to mitigate the free nitrous acid inhibition. Robust anammox bacteria in the biofilm and ammonia-oxidizing bacteria in the suspended sludge ensured that the PN/A system achieved an 87.3 % nitrogen removal efficiency at an influent NH4+-N concentration of 1802 mg/L. This study demonstrates that AnMBR permeate with high Ca, P and NH4+-N content is suitable for single-stage PN/A system with biocarriers due to the high resilience enhanced by HAP, offering a reference for the treatment of high-strength AnMBR permeate.

MSW-TO-RDF CONVERSION FOR CEMENT PLANT IN INDONESIA THROUGH PILOT PROJECT AND MODELING

Aiming for sustainable MSW and cement industry practices, this study assessed the conversion of municipal solid waste (MSW) to refuse-derived fuel (RDF) in four major Indonesian areas. Physical and chemical properties, particle size distribution, and MSW fraction analysis were performed to characterize the MSW before utilizing the MSW for the pilot project. In the pilot project, MSW was shredded and separated to produce RDF and low-grade RDF. RDF produced was quantified, and the output was analyzed to determine the RDF quality. RDF modeling was set based on the pilot project outcome, where the potential quantity, analysis, and feasibility were evaluated. The analysis revealed a need for better MSW processing due to a low heating value (LHV) of 5.4 MJ/kg and high moisture content (MC) of 52-57%. Combustible materials were found to be crucial for RDF quality. A pilot processing 1,000 Mg of MSW resulted in RDF with an LHV of 8.7 MJ/kg and MC of 47% and low-grade RDF with an LHV of 3.0 MJ/kg and MC of 61%, highlighting the importance of drying phase to meet quality standards. The modeling incorporated a two-step drying process, including hot gas utilization at the cement plant. 13 RDF units processing 6,500 MSW Mg/day were needed to produce 3100 Mg/day of RDF (equal to 50% fuel substitution), which could significantly reduce CO2 emissions and MSW by 45% in Jakarta and its neighboring cities, marking an effort for eco-friendlier cement manufacturing.

Bio-physical pre-treatments in anaerobic digestion of organic fraction of municipal solid waste to optimize biogas production and digestate quality for agricultural use

This study optimized the anaerobic digestion (AD) of separated collected organic fractions of municipal solid waste (OFMSW) to produce energy and digestate as biofertilizer. Due to OFMSW’s partial recalcitrance to degradation, enzymatic (UPP2, MCPS, USC4, USE2, A. niger) and physical (mechanical blending, heating, hydrodynamic cavitation) pre-treatments were tested. Experimental and modeling approaches were used to compare AD performance regarding energy sustainability and digestate quality. Digestate was separated into solid and liquid fractions, and then chemically and physically characterized by investigating the nutrient release mechanisms. Principal Component Analysis was applied, equally weighing energy and digestate productions. Unlike previous studies focusing only on biogas, this study evaluated the effects of pre-treatments on both biogas and digestate production, viewing AD as a biorefinery process for urban waste valorization. Results showed that all pre-treatments were energetically sustainable, but enzymatic pre-treatments yielded digestates richer in nutrients (increase of 80% N, 200% P and 150% K as compared to OFMSW) and with greater organic matter degradation compared to physical pre-treatments. The liquid fraction of digestate from enzymatic pre-treatments had higher nutrient concentrations, while those from physical pre-treatments had more balanced nutrient content, making them more suitable for fertigation.

RETRACTED: Life cycle analysis of biowaste-to- biogas/biomethane processes: Cost and environmental assessment of four different biowaste scenarios organic fraction of municipal solid waste and secondary sewage sludge

Biowaste-to-biogas processes have been introduced to design a valuable and green renewable plant to achieve a sustainable society and environment. The biomethane production process through biogas upgrading instead of designing a combined heat and power (CHP) system can be more attractive. This study presents a life cycle analysis (LCA) from both cost and environmental standpoints for four biowaste-to-biogas/biomethane process scenarios. Biogas production is achieved through anaerobic co-digestion of the organic fraction of municipal solid waste (OF-MSW) and secondary sewage sludge (S-SS), incorporating a pre-treatment process based on the dark co-fermentation process (DCFP). Each scenario offers distinct methods for utilizing the hydrogen-rich gas and biogas, with varying degrees of energy recovery and efficiency. Two sensitivity studies were conducted under various utilizations of the recovered biomethane and the anticipated electricity mix. Scenario SC-1 (CHP-from-biogas) was found to be the most co-friendly favorable in eight out of eleven impact categories (under the CML/IA technique). Further, biogas upgrading-integrated options exhibited lower impacts. Replacing biomethane instead of petrol in scenarios with upgraded biogas was identified as the most effective approach against climate change. Financial analysis indicated that all layouts are economically viable, each demonstrating a positive NPV over a 20-year period (up to $11.57 million).