Complete Mass Balance Research Articles

Distribution of polyelectrolytes and counterions upon polyelectrolyte complexation

HypothesisUnderstanding polyelectrolyte complexation remains limited due to the absence of a systematic methodology for analyzing the distribution of components between the polyelectrolyte complex (PEC) and the dilute phases. ExperimentsWe developed a methodology based on NMR to quantify all components of solid-like PECs and their supernatant phases formed by mixing different ratios of poly(allylamine hydrochloride) (PAH) and poly(acrylic acid)-sodium salt (PAA). This approach allowed for determining relative and absolute concentrations of polyelectrolytes in both phases by 1H NMR studies. Using 23Na and 35Cl NMR spectroscopy we measured the concentration of counterions in both phases. FindingsRegardless of the mixing ratio of the polyelectrolytes the PEC is charge-stoichiometric, and any excess polyelectrolytes to achieve charge stoichiometry remains in the supernatant phase. The majority of counterions were found in the supernatant phase, confirming counterion release being a major thermodynamic driving force for PEC formation. The counterion concentrations in the PEC phase were approximately twice as high as in the supernatant phase. The complete mass balance of PEC formation could be determined and translated into a molecular picture. It appears that PAH is fully charged, while PAA is more protonated, so less charged, and some 10% extrinsic PAH-Cl- pairs are present in the complex.

New Insights into Urea Electro-Oxidation: Complete Mass-Balances and Proof of Concept with Real-Matrix Effluent

In the present work, all the by-products formed during the urea electrooxidation (UEO) by Ni(III) in alkaline medium are identified and quantified for the first time (e.g., ). Complete mass balances are simultaneously established in both aqueous and gas phases for large urea conversion rates (>80%). The results provide clear evidence (with a maximal deviation of 2%) that, in addition to N-overoxidized by-products are produced during the UEO. Electrolyses conducted with human urine samples under identical operating conditions result in different distributions of N and C-by-products. In particular, the formation of formic and oxalic acids in these latter experiments suggests the presence of different and/or additional mechanistic pathways during the UEO process. The amount of generated at the cathode is also quantified, showing a reduction of 30% in energy consumption when compared with water electrolysis. Finally, this study assesses the energy efficiency of UEO with urea synthetic and real-matrix effluents, thereby contributing to the development of this sustainable process, which enables energy recovery from waste.

Helping WWTP managers to address the volatile methylsiloxanes issue–Behaviour and complete mass balance in a conventional plant

Volatile methylsiloxanes (VMSs) are a group of additives employed in different consumer products that can affect the quality of the biogas produced in wastewater treatment plants (WWTPs). The main objective of this study is to understand the fate of different VMSs along the treatment process of a WWTP located in Aveiro (Portugal). Thus, wastewater, sludge, biogas, and air were sampled in different units for two weeks. Subsequently, these samples were extracted and analyzed by different environment-friendly protocols to obtain their VMS (L3-L5, D3-D6) concentrations and profiles. Finally, considering the different matrix flows at every sampling moment, the mass distribution of VMSs within the plant was estimated. The levels of ∑VMSs were similar to those showed in the literature (0.1–50 μg/L in entry wastewater and 1–100 μg/g dw in primary sludge). However, the entry wastewater profile showed higher variability in D3 concentrations (from non detected to 49 μg/L) than found in previous studies (0.10–1.00 μg/L), likely caused by isolated releases of this compound that could be related to industrial sources. Outdoor air samples showed a prevalence of D5, while indoor air locations were characterized by a predominance of D3 and D4. Differences in sources and the presence of an indoor air filtration system may explain this divergence. Biogas was characterized by ∑VMSs concentrations (8.00 ± 0.22 mg/m3) above the limits recommended by some engine manufacturers and mainly composed of D5 (89%). Overall, 81% of the total incoming mass of VMSs is reduced along the WWTP, being the primary decanter and the secondary treatment responsible for the highest decrease (30.6% and 29.4% of the initial mass, respectively). This reduction, however, is congener dependant. The present study demonstrates the importance of extending sampling periods and matrices (i.e., sludge and air) to improve sample representativity, time-sensitivity, and the accuracy of mass balance exercises.

Impact of Integration of FO Membranes into a Granular Biomass AnMBR for Water Reuse

The granular sludge based anaerobic membrane bioreactor (G-AnMBR) has gained emphasis in the last decade by combining AnMBR advantages (high quality permeate and biogas production towards energy positive treatment) and benefits of granular biomass (boosted biological activity and reduced membrane fouling). With the aim to further reduce energy costs, produce higher quality effluent for water reuse applications and improve system efficiency, a forward osmosis (FO) system was integrated into a 17 L G-AnMBR pilot. Plate and frame microfiltration modules were step by step replaced by submerged FO ones, synthetic wastewater was used as feed (chemical oxygen demand (COD) content 500 mg/L), with hydraulic retention time of 10 h and operated at 25 °C. The system was fed with granular biomass and after the acclimation period, operated neither with gas sparging nor relaxation at around 5 L.m-2.h-1 permeation flux during at least 10 days for each tested configuration. Process stability, impact of salinity on biomass, the produced water quality and organic matter removal efficiency were assessed and compared for the system working with 100% microfiltration (MF), 70% MF/30% FO, 50% MF/50% FO and 10% MF/90% FO, respectively. Increasing the FO share in the reactor led to salinity increase and to enhanced fouling propensity probably due to salinity shock on the active biomass, releasing extracellular polymeric substances (EPS) in the mixed liquor. However, above 90% COD degradation was observed for all configurations with a remaining COD content below 50 mg/L and below the detection limit for MF and FO permeates, respectively. FO membranes also proved to be less prone to fouling in comparison with MF ones. Complete salt mass balance demonstrated that major salinity increase in the reactor was due to reverse salt passage from the draw solution but also that salts from the feed solution could migrate to the draw solution. While FO membranes allow for full rejection and very high permeate purity, operation of G-AnMBR with FO membranes only is not recommended since MF presence acts as a purge and allows for reactor salinity stabilization.

Analysis and optimisation on the energy consumption of electric arc furnace steelmaking

ABSTRACT To clarify the influence factors and optimization direction of energy consumption of EAF steelmaking, this study established a complete mass and energy balance model, comprising infiltrated air and off-gas flowrate measurement model and radiative and convective heat loss model, to forecast power and oxygen consumption. The influence of power supply, oxygen supply, carbon injection, infiltrated air, and hot metal charging on the power consumption of EAF is discussed. The results show that optimizing production parameters will effectively reduce power consumption, especially improve the infiltrated air flowrate when there are sufficient combustible gases, which is conducive to energy conservation and emission reduction. Additionally, due to the intensive energy and carbon input in the upstream process of hot metal production, the energy consumption and carbon emissions of hot metal charging EAF are much higher than those of 100% scrap charging EAF.

Biotransformation of the Novel Myeloperoxidase Inhibitor AZD4831 in Preclinical Species and Humans.

We report herein an in-depth analysis of the metabolism of the novel myeloperoxidase inhibitor AZD4831 ((R)-1-(2-(1-aminoethyl)-4-chlorobenzyl)-2-thioxo-2,3-dihydro-1H-pyrrolo[3,2-d]pyrimidin-4(5H)-one) in animals and human. Quantitative and qualitative metabolite profiling were performed on samples collected from mass balance studies in rats and humans. Exposure of circulating human metabolites with comparable levels in animal species used in safety assessment were also included. Structural characterization of 20 metabolites was performed by liquid chromatography high-resolution mass spectrometry, and quantification was performed by either 14C analysis using solid phase scintillation counting or accelerator mass spectrometry and, where available, authentication with synthesized metabolite standards. A complete mass balance study in rats is presented, while data from dogs and human are limited to metabolite profiling and characterization. The metabolism of AZD4831 is mainly comprised of reactions at the primary amine nitrogen and the thiourea sulfur, resulting in several conjugated metabolites with or without desulfurization. A carbamoyl glucuronide metabolite of AZD4831 (M7) was the most abundant plasma metabolite in both human healthy volunteers and heart failure patients after single and repeated dose administration of AZD4831, accounting for 75%-80% of the total drug-related exposure. Exposures to M7 and other human circulating metabolites were covered in rats and/or dogs, the two models most frequently used in the toxicology studies, and were also highly abundant in the mouse, the second model other than rat used in carcinogenicity studies. The carbamoyl glucuronide M7 was the main metabolite in rat bile, while a desulfurized and cyclized metabolite (M5) was abundant in rat plasma and excreta. SIGNIFICANCE STATEMENT: The biotransformation of AZD4831, a novel myeloperoxidase inhibitor inhibiting xanthine derivative bearing thiourea and primary aliphatic amine functions, is described. Twenty characterized metabolites demonstrate the involvement of carbamoylation with glucuronidation, desulfurization, and cyclization as main biotransformation reactions. The carbamoyl glucuronide was the main metabolite in human plasma, likely governed by a significant species difference in plasma protein binding for this metabolite, but this and other human plasma metabolites were covered in animals used in the toxicity studies.

Progress toward a better understanding of the urea oxidation by electromediation of Ni(III)/Ni(II) system in alkaline media

Current treatments of wastewater containing urea are energy intensive and release significant quantities of gaseous nitrous oxide. The anodic oxidation of urea by electromediation of Ni(III)/Ni(II) system in alkaline media is a promising alternative: the nitrogenous pollution is decreased while producing hydrogen at the cathode. Firstly, this study aims to deeply investigate the phenomena occurring at the interface, between electrode and electrolyte, in particular by proposing an original methodology enabling to separately study both steps,i.e. the Ni(II) electro-oxidation and the subsequent indirect heterogeneous urea oxidation. Indeed, the variation the potential scan rate, enables (i) to study the effect of the operating parameters (concentration, temperature, angular velocity of a rotating disk electrode) on the rate of each mechanism step, and to (ii) determine key parameters of the overall process (activation energy, diffusion coefficient, anodic charge transfer coefficient and heterogeneous electron transfer rate constant). In a second time, results of urea electrolysis exhibiting high (∼ 80%) urea conversions, carried out at laboratory scale (1.4 g of urea) are discussed. The effect of some operating parameters (alkalinity, temperature, presence of an anionic separator or not) is examined, thanks to a set of analytical methods developed to establish complete mass balances of the products on the liquid phase. Cyanate, ammonium, carbonate and nitrite ions are identified to represent more than 80 % of the destroyed urea. Their respective quantities appear to be dependent of the operating conditions. This study constitutes an essential preliminary step before designing urea electrochemical process operating at larger scale.

Targeted PFAS analyses and extractable organofluorine – Enhancing our understanding of the presence of unknown PFAS in Norwegian wildlife

With the current possible presence of thousands of PFAS compounds in industrial emissions, there is an increasing need to assess the impacts of PFAS regulation of conventional PFAS on one hand and the exposure to emerging and yet unknown PFAS on the other. Today’s analytical methodologies using targeted approaches are not sufficient to determine the complete suite of PFAS present. To evaluate the presence of unknown PFAS, we investigated in this study the occurrence of an extended range of target PFAS in various species from the marine and terrestrial Norwegian environment, in relation to the extractable organofluorine (EOF), which yields the total amount of organofluorine. The results showed a varying presence of extractable fluorinated organics, with glaucous gull eggs, otter liver and polar bear plasma showing the highest EOF and a high abundance of PFAS as well. The targeted PFAS measurements explained 1% of the organofluorine for moose liver as the lowest and 94% for otter liver as the highest. PFCAs like trifluoroacetic acid (TFA, reported semi-quantitatively), played a major role in explaining the organic fluorine present. Emerging PFAS as the perfluoroethylcyclohexane sulfonate (PFECHS), was found in polar bear plasma in quantifiable amounts for the first time, confirming earlier detection in arctic species far removed from emission sources. To enable a complete organic fluorine mass balance in wildlife, new approaches are needed, to uncover the presence of new emerging PFAS as cyclic- or ether PFAS together with chlorinated PFAS as well as fluorinated organic pesticides and pharmaceuticals.

Valorizing the organic fraction of municipal solid waste by producing black soldier fly larvae and biomethane in a biorefinery approach

The use of organic fraction municipal solid waste (OFMSW) was evaluated by rearing black soldier fly larvae (BSFL) and by producing biomethane from the derived residual larval waste (R-OFMSW). To do so, OFMSW was sampled from two full scale plants during the year (four seasons) and OFMSW textures were also studied by considering untreated and pulped waste.Residual larval waste was then used to produce biomethane, closing the biorefinery process, and complete mass and energy balances are provided. On average, the larvae production was 155 ± 58 (n = 16) g kg− 1 OFMSWDM and biogas from R-OFMSW was 138 NL kg− 1 OFMSWDM (n = 16). No differences were observed considering seasonality, waste plants and OFMSW texture. Energy balance indicated that 37% of OFMSW energy content (ECOFMSW) was recovered as the sum of BSFL and biomethane from R-OFMSW, which was much lower than the energy recovered by producing solely biomethane directly from OFMSW, i.e. 50% of ECOFMSW, because BSFL consumed a large part of the potential of OFMSW.

Finding Fluorine: Photoproduct Formation during the Photolysis of Fluorinated Pesticides.

The photolysis of pesticides with different fluorine motifs was evaluated to quantify the formation of fluorinated products in buffered aqueous systems, advanced oxidation (AOP) and reduction processes (ARP), and river water. Simulated sunlight quantum yields at pH 7 were 0.0033, 0.0025, 0.0015, and 0.00012 for penoxsulam, florasulam, sulfoxaflor, and fluroxypyr, respectively. The bimolecular rate constants with hydroxyl radicals were 2 to 5.7 × 1010 M-1 s-1 and, with sulfate radicals, 1.6 to 2.6 × 108 M-1 s-1 for penoxsulam, florasulam, and fluroxypyr, respectively. The rate constants of sulfoxaflor were 100-fold lower. Using quantitative 19F-NMR, complete fluorine mass balances were obtained. The maximum fluoride formation was 53.4 and 87.4% for penoxsulam and florasulam under ARP conditions, and 6.1 and 100% for sulfoxaflor and fluroxypyr under AOP conditions. Heteroaromatic CF3 and aliphatic CF2 groups were retained in multiple fluorinated photoproducts. Aryl F and heteroaromatic F groups were readily defluorinated to fluoride. CF3 and CF2 groups formed trifluoroacetate and difluoroacetate, and yields increased under oxidizing conditions. 19F-NMR chemical shifts and coupling analysis provided information on hydrogen loss on adjacent bonds or changes in chirality. Mass spectrometry results were consistent with the observed 19F-NMR products. These results will assist in selecting treatment processes for specific fluorine motifs and in the design of agrochemicals to reduce byproduct formation.

Reduction of a Heme Cofactor Initiates N-Nitroglycine Degradation by NnlA.

Linear nitramines are potentially carcinogenic environmental contaminants. The NnlA enzyme from Variovorax sp. strain JS1663 degrades the nitramine N-nitroglycine (NNG)-a natural product produced by some bacteria-to glyoxylate and nitrite (NO2-). Ammonium (NH4+) was predicted as the third product of this reaction. A source of nonheme FeII was shown to be required for initiation of NnlA activity. However, the role of this FeII for NnlA activity was unclear. This study reveals that NnlA contains a b-type heme cofactor. Reduction of this heme-either by a nonheme iron source or dithionite-is required to initiate NnlA activity. Therefore, FeII is not an essential substrate for holoenzyme activity. Our data show that reduced NnlA (FeII-NnlA) catalyzes at least 100 turnovers and does not require O2. Finally, NH4+ was verified as the third product, accounting for the complete nitrogen mass balance. Size exclusion chromatography showed that NnlA is a dimer in solution. Additionally, FeII-NnlA is oxidized by O2 and NO2- and stably binds carbon monoxide (CO) and nitric oxide (NO). These are characteristics shared with heme-binding PAS domains. Furthermore, a structural homology model of NnlA was generated using the PAS domain from Pseudomonas aeruginosa Aer2 as a template. The structural homology model suggested His73 is the axial ligand of the NnlA heme. Site-directed mutagenesis of His73 to alanine decreased the heme occupancy of NnlA and eliminated NNG activity, validating the homology model. We conclude that NnlA forms a homodimeric heme-binding PAS domain protein that requires reduction for initiation of the activity. IMPORTANCE Linear nitramines are potential carcinogens. These compounds result from environmental degradation of high-energy cyclic nitramines and as by-products of carbon capture technologies. Mechanistic understanding of the biodegradation of these compounds is critical to inform strategies for their remediation. Biodegradation of NNG by NnlA from Variovorax sp. strain JS 1663 requires nonheme iron, but its role is unclear. This study shows that nonheme iron is unnecessary. Instead, our study reveals that NnlA contains a heme cofactor, the reduction of which is critical for activating NNG degradation activity. These studies constrain the proposals for NnlA reaction mechanisms, thereby informing mechanistic studies of degradation of anthropogenic nitramine contaminants. In addition, these results will inform future work to design biocatalysts to degrade these nitramine contaminants.

Rescue and homogenization of 140 years of glacier mass balance data in Switzerland

Abstract. Glacier monitoring in Switzerland has resulted in some of the longest and most complete data series globally. Mass balance observations at individual locations, starting in the 19th century, are the backbone of the monitoring as they represent the raw and original glaciological data demonstrating the response of snow accumulation and snow/ice melt to changes in climate forcing. So far, however, the variety of sources of historic measurements has not been systematically processed and documented. Here, we present a new complete and extensive point glacier mass balance dataset for the Swiss Alps that provides attributes for data quality and corresponding uncertainties. Original sources were digitized or re-assessed to validate or to correct existing entries and to identify metadata. The sources of data are highly diverse and stem from almost 140 years of records, originating from handwritten field notes, unpublished project documents, various digital sources, published reports, and meta-knowledge of the observers. The project resulted in data series with metadata for 63 individual Swiss glaciers, including more than 60 000 point observations of mass balance. Data were systematically analysed and homogenized, e.g. by supplementing partly missing information based on correlations inferred from direct measurements. A system to estimate uncertainty in all individual observations was developed indicating that annual point balance is measured with a typical error of 0.07 m water equivalent (w.e.), while the average error in winter snow measurements is 0.20 m w.e. Our dataset permits further investigating the climate change impacts on Swiss glaciers. Results show an absence of long-term trends in snow accumulation over glaciers while melt rates have substantially increased over the last 3 decades. The complete dataset is available at DOI https://doi.org/10.18750/massbalance.point.2021.r2021 (GLAMOS, 2021).

Design of the installation of a small wastewater treatment plant using a Tubular Biological Reactor in the Xochimilco canals

This work proposes the generation of a preliminary project based on the biological treatment process called the Tubular Biological Reactor (RBT), to treat the wastewater discharges that contaminate the Xochimilco canals. The main focus of the work is: through the use of the FEL methodology to generate a design for the installation of a small wastewater treatment plant and thus be able to establish a treatment train based on RBT technology and thus translate it into a diagram of process blocks, subsequently constructing the Process Flow Diagram (DFP) which includes the pre-treatment equipment and main treatments that make up the treatment train, a material balance was prepared that considers urban wastewater as effluent in the tributary of the plant, the systems analyzed in the mass balance are; pretreatment, the sludge produced by the biological reactor as well as its treatment, the aeration systems and the disinfection of the effluent. To comply with NOM- 003- SEMARNAT-1997. With the complete mass balance, the pipeline and instrumentation diagram (DTI) was built and a Layout diagram was made to locate the equipment, this methodology allowed to generate a design that can be applied at various points of the Xochimilco channels, mainly where sewage discharges occur. wastewater treatment; tubular biological reactor.

Circular economy and life cycle assessment of alumina production: Simulation-based comparison of Pedersen and Bayer processes

The excessive production of bauxite residue (red mud) in the Bayer process is one of the major challenges amongst alumina producers. The Pedersen process is known as a combination of smelting reduction of bauxite and leaching treatment of the produced slag for alumina production, and the process also produces an inert bauxite residue (grey mud), which is more suitable for further processing compared to the red mud. This paper describes the life cycle assessment for two alumina production processes, the current commercialized Bayer process and the alternative Pedersen process, based on the complete mass and energy balance simulation. Process simulation and environmental software are applied to quantify the metallurgical processes and their related environmental effects. By assuming the same treatments for the bauxite residues, it is found that, with the production of pig iron, the Pedersen process shows the best performance in mineral resource scarcity but requires a higher energy demand and generates twice the amount of bauxite residue compared to the Bayer process. The final, relative performance in climate change impact depends on the carbon intensity of energy and the bauxite ore composition.

Electric fuel conversion with hydrogen production by multiphase plasma at ambient pressure

Reactive species in the plasma interact with both liquid hydrocarbons and natural gas at the gas–liquid interface producing desired intermediate molecules and hydrogen. Electric (plasma) conversion of fuels. Traditional fuel processing uses combustion and heat for conversion. Through plasma processing we show electricity can be used to convert fuels more efficiently and as economically as traditional processing. A fossil fuel processing industry based on electricity is more flexible, cleaner, greener, and can transition to a future based on renewable energy and liquid fuels. • Transient multiphase non-thermal plasma efficiently integrates renewable energy into chemical change. • High conversion (50%) to high quality products and low energy cost (<$4/barrel). • Operating at near ambient conditions, robust and easy to manufacture and maintain. • Adaptable to renewable energy sources minimizing GHG emissions. Electrifying refinery for unconventional/heavy oils, significant emission reductions, and alternative/bio fuels, faces major technological challenges: conversion, energy efficiency, modularity and integration with renewable electricity. Here, we introduce a multi-phase non-thermal plasma reactor that uses electrical discharges to co-convert liquid fuel and natural gas. Normal hexadecane was treated with methane plasma to validate conversion chemistry, and quantify the pathways of vapor, condensate, liquid and residue mass conversion. A complete mass balance and characterization of all products were determined. Using 500 kJ/kg-hexadecane energy input (∼1% of hexadecane’s energy content) this plasma process co-converts 9.36% of the hexadecane and 20% of the methane by mass. Distribution of products are: 2.18% hydrogen, 45.9% C 2 -C 4 , 28.9% high octane gasoline (C 5 -C 11 ), 16.4% diesel (C 12 -C 18 ), 2.78% heavier hydrocarbons, and 1.7% coke. Lighter product yields (C 5 -C 15 ) were ∼ 9 molecules/100 eV, and modeled by a molecule dissociation mechanism. Hydrogen yield was 34.8 kWh/kg-H 2 with minimal GHG emissions. Plasma-chemical conversion efficiency was ∼ 30%. This conversion process has higher efficiency, and reduces GHG emission compared to traditional technologies.

Tracking Fluorine during Aqueous Photolysis and Advanced UV Treatment of Fluorinated Phenols and Pharmaceuticals Using a Combined 19F-NMR, Chromatography, and Mass Spectrometry Approach.

Fluorine incorporation into organic molecules has increased due to desirable changes in the molecular physiochemical properties. Common fluorine motifs include: aliphatic fluorines and -CF3, or -F containing groups bonded directly onto an aromatic (Ar-CF3 and Ar-F) or heteroaromatic ring. Photolysis of these compounds, either in natural or engineered systems, is a potential source of new fluorinated byproducts. Given the potential persistence and toxicity of fluorinated byproducts, monitoring of product formation during photolysis of various fluorinated motifs is needed. 19F-NMR is a means to detect and quantify these species. Ar-CF3 and Ar-F model compounds (2-, 3-, and 4-(trifluoromethyl)phenol, 2-, 3-, 4-fluorophenol, and 2,6-, 3,5-difluorophenol) were photolyzed under a variety of aqueous conditions: pH 5, pH 7, pH 10, 1 mM H2O2 at pH 7 to form •OH, and 0.5 mM SO3 2- at pH 10 to form eaq -. Pharmaceuticals with the Ar-CF3 (fluoxetine) and Ar-F plus pyrazole-CF3 (sitagliptin) motifs were treated similarly. Parent molecule concentrations were monitored with high pressure liquid chromatography with a UV detector. Fluorine in the parent and product molecules was quantified with 19F-NMR and complete fluorine mass balances were obtained. High resolution mass spectrometry was used to further explore product identities. The major product for Ar-F compounds was fluoride. The Ar-CF3 model compounds led to fluoride and organofluorine products dependent on motif placement and reaction conditions. Trifluoroacetic acid was a product of 4-(trifluoromethyl)phenol and fluoxetine. Additional detected fluoxetine products identified using mass spectrometry resulted from addition of -OH to the aromatic ring, but a dealkylation product could not be distinguished from fluoxetine by 19F-NMR. Sitagliptin formed multiple products that all retained the pyrazole-CF3 motif while the Ar-F motif produced fluoride. 19F-NMR, mass spectrometry, and chromatography methods provide complementary information on the formation of fluorinated molecules by modification or fragmentation of the parent structure during photolysis, allowing screening for fluorinated photoproducts and development of fluorine mass balances.

Analysis of the Long-Term Mass Balance and Efficiency of Waste Recovery in a Municipal Waste Biodrying Plant

The aim of this study was to determine the role of an installation based on biodrying of municipal waste in a Circular Economy by taking into account the quantitative and qualitative changes in its selectively collected waste stream. As a case study, the Mechanical-Biological municipal waste treatment installation in Olsztyn, Poland, was selected, which is equipped with a separate section for valorizing the selectively collected waste stream. The scope of the work included a complete mass balance of the waste treatment plant, an assessment of the technological efficiency of the municipal waste biodrying installation, and determination of the changes in the main waste from 2016 to 2020. This paper proposes an empirical method for estimating process loss during biodrying and provides many technological results. The average process loss was 23.47%, and on average, 88.9% of the waste produced by biodrying consisted of the Refuse-Derived Fuel fraction. The recovery of commercial assortments from selectively collected waste increased from 84.82% in 2016 to 89.26% in 2020. Considering the current morphology of municipal waste in this region, the maximum share of waste subjected to material and organic recycling processes in the analyzed region could be increased to around 60%, which indicates that Circular Economy targets can be achieved. This work should provide a compendium of information for countries implementing a Circular Economy.

High-temperature gasification of woody biomass in a drop tube reactor: A special focus on the particle size and axial temperature gradient

Pine sawdust (PS) was gasified in a drop-tube reactor (DTR) using air as a gasifying agent. An almost complete mass balance was achieved by establishing a burning operation after gasification to determine the carbon deposits (CD) inside the reactor tube, providing an authentic depiction of the feedstock conversion. The results indicated that particle size reduction led to a significant improvement in the gasification performance. When the particle size of PS was below 0.25 mm, almost complete char gasification was achieved at 1300 °C, while soot remained a major particulate in the syngas. An experimental approach is proposed to simulate the axial temperature gradient (ATG) inside an auto-thermal entrained-flow gasifier by setting two different temperature zones in the DTR. The results revealed that char was rapidly and almost completely exhausted in the high-temperature zone (1300 °C). When the ATG between the upper and lower heater zones was above 300 °C, both homogeneous reforming and heterogeneous gasification proceeded slowly or almost stagnated in the lower temperature zone. An evident enhancement of soot formation was observed at ATG = 200 °C. After that, the soot yield monotonously decreased with decreasing ATG due to the substantial enhancement of the heterogeneous gasification kinetics, contributing more to carbon conversion and CGE than char gasification.

Viral lysis modifies seasonal phytoplankton dynamics and carbon flow in the Southern Ocean

Phytoplankton form the base of marine food webs and are a primary means for carbon export in the Southern Ocean, a key area for global pCO2 drawdown. Viral lysis and grazing have very different effects on microbial community dynamics and carbon export, yet, very little is known about the relative magnitude and ecological impact of viral lysis on natural phytoplankton communities, especially in Antarctic waters. Here, we report on the temporal dynamics and relative importance of viral lysis rates, in comparison to grazing, for Antarctic nano- and pico-sized phytoplankton of varied taxonomy and size over a full productive season. Our results show that viral lysis was a major loss factor throughout the season, responsible for roughly half (58%) of seasonal phytoplankton carbon losses. Viral lysis appeared critically important for explaining temporal dynamics and for obtaining a complete seasonal mass balance of Antarctic phytoplankton. Group-specific responses indicated a negative correlation between grazing and viral losses in Phaeocystis and picoeukaryotes, while for other phytoplankton groups losses were more evenly spread throughout the season. Cryptophyte mortality was dominated by viral lysis, whereas small diatoms were mostly grazed. Larger diatoms dominated algal carbon flow and a single ‘lysis event’ directed >100% of daily carbon production away from higher trophic levels. This study highlights the need to consider viral lysis of key Antarctic phytoplankton for a better understanding of microbial community interactions and more accurate predictions of organic matter flux in this climate-sensitive region.

A complete mass balance for plastics in a wastewater treatment plant - Macroplastics contributes more than microplastics

A complete plastic particle mass balance was established at Sweden's second-largest wastewater treatment plant. It comprised material collected at its two bar screens, a 20 mm and a 2 mm one, in the influent water after the 20 mm screen, the effluent water, and the digested sludge. Macro- and microplastics above 500 µm were analysed individually applying ATR-FTIR, while microplastics of 10–500 µm were analysed by µFTIR imaging with automated particle recognition. Masses of plastics >500 µm were determined by weighting, while the mass of the smaller microplastics was estimated from the imaging. The total plastic load on the plant was 202.2 kg d−1, of which the two screens retained 73%. The remaining plastic mass was found in the sludge (13.6%) and the effluent (0.4%). The missing 12.7% could be caused by sampling and measuring uncertainties and potentially also fragmentation below the size detection limit of the analytical approach, or by degradation. The bar screens furthermore retained plastics smaller than the screen size, indicating that this material should be taken into account also when solely looking at smaller particles. The overall treatment efficiency of the plant was high: 99.6% considering both macro- and microplastics, and 98.8% considering only microplastics <500 µm.