Material flow analysis of an upgraded anaerobic digestion treatment plant with separated utilization of carbon and nitrogen of food waste.

Anaerobic digestion of food waste can recover carbon in the form of biogas, while the high concentration of ammonia nitrogen in the digestion effluent becomes troublesome. Therefore, some new treatment plants use three-phase centrifugation to separate homogenized food waste into nitrogen-rich fine slag for insect cultivation and carbon-rich liquid for anaerobic digestion. To analyze the effects of the carbon-nitrogen separation, an upgraded plant's material and elementary flows were investigated. The three-phase separation process redistributed carbon and nitrogen, and the biogas slurry was the primary output. The principal endpoint for C was the crude oil, capturing 57.1 ± 13.1 % of the total input; the find slag collected 48.3 ± 6.9 % of the total N input, and the biogas slag accepted 52.9 ± 4.4 % of the P input. The carbon-nitrogen separation strategy can improve digestion efficiency and increase treatment benefits significantly, marking a promising direction for future developments in food waste utilization.

Can on-site leachate treatment facilities effectively address the issue of perfluoroalkyl acids (PFAAs) in leachate?

In recent decades, the presence of perfluoroalkyl acids (PFAAs) in municipal solid waste leachate has emerged as a growing concern. Research has focused on PFAA release and occurrence characteristics in landfill and waste-to-energy leachate, highlighting their significant impact when released into wastewater treatment plants. Given the extremely high loading rate faced by current on-site leachate treatment plants (LTPs), the objective of this study is to assess whether the current "anaerobic/aerobic (A/O) + membrane bioreactor (MBR) + nanofiltration (NF) + reverse osmosis (RO)" configuration is effective in PFAAs removal. Concentrations of raw and treated leachate in 10 on-site LTPs with same treatment configuration and varying landfill ages were measured, and a comprehensive mass flow analysis of each treatment process was conducted. The results indicate that A/O treatment has limited capacity for PFAA removal, while NF and RO processes reached 77.44 % and 94.30 % removal rates of ∑PFAAs concentration, respectively. Short-chain PFAAs (> 80 % detected frequency) primarily influenced the distribution and variations of PFAAs in leachate and tend to disperse in the water phase. Correlation analysis revealed the current on-site LTPs exhibit a more efficient removal capacity for long-chain PFAAs.

Efficiency upgrading of solar PVT finned hybrid system in Bangladesh: Flow rate and temperature influences.

This research aims to determine the impact of mass flow rate and inflow temperature on the utility and effectiveness of solar thermal systems using fins with air in various applications in Bangladesh. This study examines a three-dimensional (3D) photovoltaic thermal (PVT) system where we analyze the behavior of a hybrid system with six aluminum sheets (1 mm thick fin as a heat exchange material) inside the heat exchanger where the air takes the direction to pass in waveform through the channels (made of aluminum) using fins. The top side of the fins is bent and affixed to the bottom of the floor of the PV panel to allow heat transfer utilizing the conduction-based method. This study selects inlet fluid mass flow rate and inflow temperature between (0.015-0.535 kg/s), and (10-40 °C) respectively, while comparing the result with experimental/numerical published data based on Bangladesh's weather conditions and applies the finite element method (FEM) to solve heat transfer equations. A brief analysis of the association among Reynolds number with pressure drop and fanning friction factor is included in this paper. Our model can be mounted on building rooftops or open fields where air velocity will be controlled mechanically; thus, it has many applications. This model can be implemented within an agricultural photovoltaic (APV) system, domestic functions, dry agricultural products, and provide heat for greenhouses. The result indicates that 302-514 W thermal energy has been produced for 0.015-0.535 kg/s. For growing inflow temperature, despite the reduction in electrical efficiency, the value of adding electrical and thermal efficiency (overall efficiency) comes with elevation. A 5 °C increase in inflow temperature leads to an overall efficiency increase of 0.33%. This study's findings can help researchers better comprehend air's properties as a heat exchanger in a developed design, and they can be applied to government and commercial projects.

Sub-pilot scale sequential microalgal consortium-based cultivation for treatment of municipal wastewater and biomass production.

Municipal wastewater (MWW) was treated by a sequential pilot microalgal cultivation process. The cultivation was performed inside a specifically designed low-cost photobioreactor (PBR) system. A microalgal consortium 2:1 was developed using Tetraselmis indica (TS) and Picochlorum sp. (PC) in the first stage and PC:TS (2:1) in the second stage and the nutrient removal efficiency and biomass production and biomolecules production was evaluated and also compared with monoculture in a two-stage sequential cultivation system. This study also investigated the effect of seasonal variations on microalgae growth and MWW treatment. The results showed that mixed microalgal consortium (TS:PC) had higher nutrient removal efficiency, with chemical oxygen demand (COD), total phosphate (TP), and total nitrate (TN) removal efficiencies of 78.50, 84.49, and 84.20%, respectively, and produced a biomass of 2.50 g/L with lipid content of 37.36% in the first stage of cultivation under indoor conditions. In the second stage of indoor cultivation, the PC:TS consortium demonstrated maximum COD, TP, and TN removal efficiencies of 92.49, 94.24, and 94.16%, respectively. It also produced a biomass of 2.65 g/L with a lipid content of 40.67%. Among all the seasonal variations, mass flow analysis indicated that the combination of mixed consortium-based two-stage sequential process during the winter season favored maximum nutrient removal efficiency of TN i.e. 88.54% (84.12 mg/L) and TP i.e., 90.18% (43.29 mg/L), respectively. It also enhanced total biomass production of 49.10 g in 20-L medium, which includes lipid yield ∼15.68 g compared to monoculture i.e., 82.06% (78.70 mg/L) and 82.87% (40.26 mg/L) removal of TN and TP, respectively, and produced biomass 43.60 g with 11.90 g of lipids.

Compact Micro-Coriolis Mass-Flow Meter with Optical Readout.

This paper presents the first nickel-plated micro-Coriolis mass-flow sensor with integrated optical readout. The sensor consists of a freely suspended tube made of electroplated nickel with a total length of 60 mm, an inner diameter of 580 µm, and a wall thickness of approximately 8 µm. The U-shaped tube is actuated by Lorentz forces. An optical readout consisting of two LEDs and two phototransistors is used to detect the tube motion. Mass-flow measurements were performed at room temperature with water and isopropyl alcohol for flows up to 200 g/h and 100 g/h, respectively. The measured resonance frequencies were 1.67 kHz and 738 Hz for water and 1.70 kHz and 752 Hz for isopropyl alcohol for the twist and swing modes, respectively. The measured phase shift between the two readout signals shows a linear response to mass flow with very similar sensitivities for water and isopropyl alcohol of 0.41mdegg/h and 0.43 mdegg/h, respectively.

Non-Invasive Determination of the Mass Flow Rate for Particulate Solids Using Microwaves.

This paper presents a novel technique for the mass flow rate determination of particulate solids called the "Sliding Mass Technique". The mass flow rate is a measure of the mass of a substance that passes through a given cross-sectional area per unit time. Its calculation requires simultaneous detection of the concentration and velocity of the Material Under Test. A novel measurement technique is designed for determining the concentration of the mass flow without the necessity for density evaluation. The mass flow rate is determined by fusing the established concentration results with velocity results obtained from "Microwave Spatial Filtering Velocimetry". A new metamaterial-based mass flow sensor for particulate solids was designed, realized and measured in an industrial environment. A Software-Defined Radio (Ettus Research™'s USRP B210) was utilized as a sensor electronic system for DAQ purposes. A MATLAB app was developed to operate the SDR. Measurements were carried out on-site using a state-of-the-art wood pellet heating system with wood pellets with different moisture contents. The measurement results were found to be in very good agreement with the expected results, which strengthens the feasibility of this newly proposed measurement technique.

Occurrence, behavior and fate of liquid crystal monomers in municipal wastewater.

Liquid crystal monomers (LCMs), the essential substances used in the display screen of electronic devices, have been proposed as a class of emerging chemicals of concern. Despite their detection in various environmental matrices, little is known about the presence of LCMs in municipal sewage systems. This study aimed to investigate the occurrence, distribution, and fate of 64 LCMs released into the aqueous environment from a municipal wastewater treatment plant (WWTP) in Hong Kong, China. In total 14 LCMs were detected in WWTP samples. Specifically, the Σ14LCMs concentrations in crude influent, final effluent, and final sludge were found to be 16.8 ± 0.3 ng/L, 2.71 ± 0.05 ng/L, and 19.2 ± 1.0 ng/g dry weight, respectively. Among them, 10 fluorinated LCMs (F-LCMs) were determined to be present at concentrations of 8.90 ± 0.10 ng/L, 1.69 ± 0.05 ng/L, and 9.94 ± 1.00 ng/g dry weight, respectively. The predominant non-fluorinated LCMs (NF-LCMs) detected in all samples were 3OCB and EPhEMOB, while 2OdF3B was the dominant F-LCM. The overall removal rate of total LCMs was 83.8 ± 0.3 %, with 25.4 ± 4.8 % being removed by biodegradation and UV treatment. Compared to NF-LCMs, F-LCMs were more resistant to biodegradation. Despite the significant removal of LCMs through WWTP, the remaining LCMs in final effluent could result in an annual emission of 3.04 kg of total LCMs from the population of Hong Kong. This study provides the first evidence of LCMs contamination in municipal wastewater, possibly arising from routine electronic devices usage. Further investigation is needed to elucidate the potential impact of LCMs emission via WWTP effluent on the aquatic receiving ecosystem.

Material and Carbon Footprints of Machinery Capital.

Machinery and equipment, integral as technology-specific capital goods, play a dual role in climate change: it acts as both a mitigator and an exacerbator due to its carbon-intensive life cycle. Despite their importance, current climate mitigation analyses often overlook these items, leaving a gap in comprehensive analyses of their material stock and environmental impacts. To address this, our research integrates input-output analysis (IOA) with dynamic material flow analysis (d-MFA) to assess the carbon and material footprints of machinery. It finds that in 2019, machinery production required 30% of global metal production and 8% of global carbon emissions. Between 2000 and 2019, the metal footprint of the stock of machinery grew twice as fast as the economy. To illustrate the global implications and scale, we spotlight key countries. China's rise in machinery material stock is noteworthy, surpassing the United States in 2008 in total amount and achieving half of the US per capita level by 2019. Our study also contrasts economic depreciation─a value-centric metric─with the tangible lifespan of machinery, revealing how much the physical size of the capital stock exceeds its book values. As physical machinery stocks saturate, new machinery can increasingly be built from metals recycled from retired machinery.

CFD-Assisted Process Optimization of an Integrated Photocatalytic Membrane System for Water Treatment.

An integrated photocatalytic membrane system (IPMS) was developed for potential use in the remediation of naproxen using real water samples from a drinking water treatment plant. Key parameters such as time, pH, water matrix, mixing speeds, flow rate, and light intensity undeniably affected photocatalytic and membrane separation processes. The system optimization was based on improving irradiation to generate a more reactive species and mass transfer to increase the reaction rate. Upon optimization, IPMS achieved 99% naproxen removal efficiency. Computational fluid dynamics (CFD) simulated the flow patterns and radiation distribution inside the photocatalytic membrane reactor to improve irradiation and mass transfer during operation. The simulated flow field revealed the presence of dead zones with different velocities in the photocatalytic membrane reactor; this limited the mass transfer of reactive species in the reactor, resulting in uneven distribution of reactive radicals. The dead zones were mitigated by increasing the mixing speed, and as a result, convective mass flow improved process performance. The governing parameters (flow patterns and radiation distribution) of the simulated and experimental data were in agreement. The absorption of irradiation by the active site of the membranes improved with light intensity; at higher light intensities, the light irradiated deeper into the membrane. As such, the CoFe2O4 nanoparticles incorporated inside the membrane pores became highly activated, thus enhancing degradation. The obtained space-time yield (STY) (1.23 × 1011 mol/cm2.s) and photocatalytic space-time yield (PSTY) (4.39 × 1011 mol/W.s) showed that the developed IPMS was efficient regarding energy intensiveness and throughput for treatment of pollutants in water.

Quantitative calculation of gases generation during low-temperature oxidation of coal.

The gases evolution during the low-temperature oxidation of coal is an essential parameter used to assess the state of coal oxidation and to estimate the gaseous pollutants. However, the current semi-quantitative method, which employs gas concentration as the measurement standard, is flawed. This paper presents a quantitative calculation method for gas products during coal oxidation. N2 is used as the tracer gas in the experiment, because nitrogen is an inert gas that will not participate in the reaction, and the amount of matter will not change in the reaction. According to the formula [Formula: see text], the corresponding mass flow rates of each gases component were calculated, and the gas yields during the reaction period were determined by comprehensive calculation. To this end, experiments were conducted on the low-temperature oxidation of coal using a flow reactor. After undergoing quantitative calculations, the main gas products' mass flow rates, yields, and energies, including CO, CO2, CH4, C2H4, C2H6, C2H2, and C3H8 between 30 and 180 °C were obtained. The findings showed that CO2 > CO > CH was generated in all the coal samples. The amount of gases produced in the low-temperature oxidation of coal is proportional to the level of oxygen concentration. When the oxygen concentration ranges from 0 to 21%, the gaseous production of MTH coal ranges from 381.44 g/ton to 8562.80 g/ton. The results of gaseous energy calculations showed that the energy loss for low temperature oxidation of the four coal samples ranged from 4334.14~26,772.73 kJ/ton under air atmosphere. Energy loss is also significantly affected by the oxygen concentration, and the energy loss of MTH coal increases significantly from 520.52 kJ/ton at 0% oxygen concentration to 26,772.73 kJ/ton at 21% oxygen concentration, an increase of about 50 times. Significantly, this method not only reflects the real gas evolution during low-temperature oxidation of coal but also computes the gas emission and energy loss, which is crucial for studying the mechanism of coal spontaneous combustion and assessing gases pollutants.

Investigating the influence of temperature-dependent rheological properties on nanofluid behavior in heat transfer.

Nanofluids are advanced heat transfer fluids whose performance is influenced by various thermo-physical properties, including nanoparticle volume fraction, base fluid, and temperature. Rheological mathematical models have been established by using empirical data in order to characterize these features as dependent on parameters such as volume fraction, base fluid composition, and temperature. These models have been integrated into transport equations. Nanofluids composed of metallic oxides (Al2O3, SiO2) and carbon nanostructures (PEG-GnP, PEG-TGr) dispersed in deionized H2O, with nanoparticle concentrations ranging from 0.025% to 0.1%, and temperatures between 30 °C and 50 °C, were utilized to investigate flow over thin needle. The rheological models contained transport equations include the partial differential equations. The transport equations were simplified through various transformations and then solved numerically. The results in form of velocity and temperature distributions were obtained, along with boundary layer parameters, Nusselt number and coefficient of skin friction. The present study contributes to the existing knowledge by elucidating the intricate relationship between nanoparticle volume fraction, base fluid properties, and temperature in nanofluid behavior.

Mass flow of per- and polyfluoroalkyl substances (PFAS) in a Swedish municipal wastewater network and wastewater treatment plant.

PER: and polyfluoroalkyl substances (PFAS) are ubiquitously distributed in wastewater, due to their numerous uses in industry and consumer products, but little is known of PFAS mass flows in municipal wastewater network systems and within wastewater treatment plants (WWTPs). This study assessed mass flows of 26 PFAS in a wastewater network and WWTP, to provide new insights into their sources, transport, and fate in different treatment steps. Wastewater and sludge samples were collected from pumping stations and the main WWTP in Uppsala, Sweden. PFAS composition profiles and mass flows were used to identify sources within the sewage network. Wastewater from one pumping station showed elevated concentrations of C3-C8 PFCA, likely caused by an industrial source, and two stations had elevated concentrations of 6:2 FTSA, probably originating from a nearby firefighter training facility. Within the WWTP, short-chain PFAS dominated in wastewater, whereas long-chain PFAS dominated in sludge. The ratio of perfluoroalkyl sulfonates (PFSA) and ethylperfluorooctanesulfonamidoacetic acid (EtFOSAA) to ∑26PFAS decreased during the WWTP process, likely due to sorption to sludge, but also transformation (EtFOSAA). Overall, PFAS were not efficiently removed in the WWTP, with mean removal efficiency of 10 ± 68% for individual PFAS, resulting in discharge of 7000 mg d-1 ∑26PFAS into the recipient. This shows that conventional WWTPs are inefficient in removing PFAS from wastewater and sludge, so advanced treatment techniques are needed.

Modeling, Fabrication, and Testing of a 3D-Printed Coriolis Mass Flow Sensor.

This paper presents the modeling, fabrication, and testing of a 3D-printed Coriolis mass flow sensor. The sensor contains a free-standing tube with a circular cross-section printed using the LCD 3D-printing technique. The tube has a total length of 42 mm, an inner diameter of about 900 µm, and a wall thickness of approximately 230 µm. The outer surface of the tube is metalized using a Cu plating process, resulting in a low electrical resistance of 0.5 Ω. The tube is brought into vibration using an AC current in combination with a magnetic field from a permanent magnet. The displacement of the tube is detected using a laser Doppler vibrometer (LDV) that is part of a Polytec MSA-600 microsystem analyzer. The Coriolis mass flow sensor has been tested over a flow range of 0-150 g/h for water, 0-38 g/h for isopropyl alcohol (IPA), and 0-50 g/h for nitrogen. The maximum flow rates of water and IPA resulted in less than a 30 mbar pressure drop. The pressure drop at the maximum flow rate of nitrogen is 250 mbar.

Combining geophysics, remote sensing and numerical simulation to assess GLOFs: Case study of the Namulacuo Lake in the Southeastern Tibetan Plateau.

The current highest glacial lake outburst floods (GLOFs) risk level is centered in the eastern Himalaya. GLOFs represent a serious threat to downstream inhabitants and ecological environment. In the context of climate warming on the Tibetan Plateau, such GLOFs will continue or even intensify in the future. Remote sensing and statistical methods are often used to diagnose glacial lakes with the highest outburst probability. These methods are efficient in large-scale glacial lake risk assessment but do not take into consideration the complexity of specific glacial lake dynamics and triggering factor uncertainty. Therefore, we explored a novel approach to integrate geophysics, remote sensing, and numerical simulation in glacial lake and GLOF disaster chain assessments. In particular, geophysical techniques are rarely applied to the exploration of glacial lakes. The Namulacuo Lake located in the southeastern Tibetan Plateau is considered as the experimental site. The current status of the lake, including landform construction and identifying potential triggering factors, was first investigated. Secondly, the outburst process and disaster chain effect were evaluated by numerical simulation based on the multi-phase modeling frame proposed by Pudasaini and Mergili (2019) implemented in the open source computational tool r.avaflow. The results allowed verifying that the Namulacuo Lake dam was a landslide dam with an obvious layered structure. Also, the piping-induced flood might have more severe consequences than the short-term ultra-high discharge flood caused by surge. The blocking event caused by a surge disappeared faster than that caused by piping. Therefore, this comprehensive diagnostic approach can assist GLOF researchers to increase their understanding of key challenges they are facing regarding GLOF mechanisms.

Plastics in the global environment assessed through material flow analysis, degradation and environmental transportation.

Knowledge on environmental plastic emission and spatial and temporal accumulation is vital for the development of successful mitigation strategies and risk assessments of plastics. In this study, emissions of both micro and macro plastic from the plastic value chain to the environment were assessed on a global level through a mass flow analysis (MFA). All countries, 10 sectors, 8 polymers and 7 environmental compartments (terrestrial, freshwater or oceanic) are distinguished in the model. The results assess a loss of 0.8 million tonnes (mt) of microplastics and 8.7 mt of macroplastics to the global environment in 2017. This is respectively 0.2 % and 2.1 % of plastics produced in the same year. The packaging sector contributed most for macroplastic emissions, and tyre wear for microplastic emissions. With the MFA results, accumulation, degradation and environmental transportation are considered in the Accumulation and dispersion model (ADM) until 2050. This model predicts macro- and microplastic accumulation in the environment to 2.2 gigatonnes (Gt) and 3.1 Gt in 2050 respectively (scenario: yearly consumption increase of 4 %). This will be 30 % less when a yearly production reduction of 1 % until 2050 is modeled to 1.5 and 2.3 Gt macro and microplastics respectively. Almost 2.15 Gt of micro and macroplastics accumulate in the environment until 2050 with zero plastic production after 2022 due to leakage from landfills and degradation processes. Results are compared to other modeling studies quantifying plastic emissions to the environment. The current study predicts lower emissions to ocean and higher emissions to surface waters like lakes and rivers. Non aquatic, terrestrial compartments are observed to accumulate most plastics emitted to the environment. The approach used results in a flexible and adaptable model that addresses plastic emissions to the environment over time and space, with detail on country level and environmental compartments.

Quantifying environmental emissions of microplastics from urban rivers in Melbourne, Australia.

This study aims to understand the amount and type of microplastics flowing into Port Phillip Bay from urban rivers around Melbourne. Water samples were collected from the Patterson, Werribee, Maribyrnong, and Yarra Rivers, which contribute 97 % to the total flow into Port Phillip Bay. On average, the rivers contained a mean of 9 ± 15 microplastics/L and ranged from 4 ± 3 microplastics/L (Patterson) to 22 ± 11 microplastics/L (Werribee). Of the eight polymers investigated, polyamide and polypropylene were the most frequently detected polymers. Using the mean concentration of each river, the flow of microplastics into Port Philip Bay was estimated to be 7.5 × 106 microplastics per day and 3.7 × 1010 microplastics per year. To fully understand the fate and transport of microplastics into Port Phillip Bay, this study would be the foundation for a more in-depth investigation. Here, further samples will be collected at more points along the river and at the midpoint of each season.

Design configuration and operational parameters of bi-fluid PVT collectors: an updated review.

The bi-fluid photovoltaic thermal (PVT) collector was introduced to provide more heating options along with improved cooling capabilities for the PV module. Since its introduction, this type of PVT system has been investigated thoroughly in various original works. In this review paper, we intend to put the concept and applications of this technology into question and revise the main achievements and discoveries through research and development with a focus on climatic and operational parameters. The paper encompasses a critical review of the discussed research and future directions for PVT collectors. The main utilized operational modes are discussed in detail, which are (i) water used in both channels, (ii) water in one channel and air in the other, and (iii) air in both channels. The modes were found to lead to different enhancement and performance effects for the utilized photovoltaic modules. The impact of mass flow rate was also taken by keeping one working fluid constant while varying the other to obtain its impact on the energy and exergy efficiency of the collector. In some cases, the fluids were run simultaneously and, in other cases, independently.

Polypropylene Post-Consumer Recyclate Compounds for Thermoforming Packaging Applications.

Polypropylene (PP) plastic packaging waste consists of a variety of different plastic packaging products with a great span in rheological and mechanical behavior. Therefore, the resulting post-consumer recyclates usually show melt mass-flow rates (MFR) in the region of injection molding grades and intermediate mechanical properties. High-quality packaging applications demand a distinct property profile that is met by tailor-made PP grades and cannot be met by recyclates with intermediate performance. One such application with high market volume is high-stiffness thermoforming trays. The aim of this research was to blend intermediate-performance recyclates with a virgin PP grade to obtain compounds that fulfill the rheological and mechanical demands of this application. Three commercially available PP post-consumer recyclates were acquired and compounded with different blending ratios with a high stiffness, low MFR virgin PP grade. As the pure recyclates show different rheological properties, the blending ratios had to be adapted for each of them to fit into the MFR range of 2-4 g/10 min which is desirable for thermoforming applications. The resulting PP recyclate compounds show a distinct correlation of recyclate content with rheological and mechanical performance. However, the resulting property profile was directly dependent on the performance of the originally used recyclate. The best-performing recyclate could be used in a blending ratio of 65 m% recyclate content while adhering to both property limits, the MFR of 2-4 g/10 min and the lower bound tensile stiffness of 1500 MPa.

Balance of total mass and nitrogen fluxes through consecutive digestate processing steps: Two application cases.

The high water content and low nutrient concentration of digestate complicate its storage, transportation, and utilization. Subsequent digestate processing can effectively remove water and influence nutrient partitioning among digestate fractions and final products. The current study was carried out to evaluate the performance of two typical digestate processing chains, solid and liquid ones, respectively, and to give practical recommendations for optimization. Two fully operating biogas plants with advanced heat utilization were considered as data sources. The digestate mass flow balance of dry matter (DM), water, total N (TN), and ammonium-N mass flows was performed and the efficiency of the examined processing units was calculated. It was found that solid-liquid separation of raw digestate shifted 73-87% of TN and 60-93% of NH4-N to the liquid phase. Subsequent drying of separated solid fraction removed about 6% of the initial water and required 84% less thermal energy per kg N recovered than the processing of separated liquid. The final product, pellets, contained 14% of initial TN, but only 2% of initial NH4-N as a result of microbial conversion of inorganic N during drying. Vacuum evaporation of separated liquid fraction removed 34% of the initial water and left a DM-rich concentrate. At the same time, an ammonium sulfate solution (ASS) containing 21% of initial TN and 34% of initial NH4-N was produced. Both evaluated processing chains showed specific advantages and challenges. Solid products were characterized by a high share of recalcitrant organic compounds and could serve as a soil improver. Liquid processing concentrated plant-available N in ASS, which could be used as valuable inorganic fertilizer.

Hydrogen-rich gas production from disposable COVID-19 mask by steam gasification.

Globally, the demand for masks has increased due to the COVID-19 pandemic, resulting in 490,201 tons of waste masks disposed of per month. Since masks are used in places with a high risk of virus infection, waste masks retain the risk of virus contamination. In this study, a 1 kg/h lab-scale (diameter: 0.114 m, height: 1 m) bubbling fluidized bed gasifier was used for steam gasification (temperature: 800 °C, steam/carbon (S/C) ratio: 1.5) of waste masks. The use of a downstream reactor with activated carbon (AC) for tar cracking and the enhancement of hydrogen production was examined. Steam gasification with AC produces syngas with H2, CO, CH4, and CO2 content of 38.89, 6.40, 21.69, and 7.34 vol%, respectively. The lower heating value of the product gas was 29.66 MJ/Nm3 and the cold gas efficiency was 74.55 %. This study showed that steam gasification can be used for the utilization of waste masks and the production of hydrogen-rich gas for further applications.