Additional Carbon Research Articles

The Path to Net-Zero in Dairy Production: Are Pronounced Decreases in Enteric Methane Achievable?

Achieving net-zero greenhouse gas (GHG) emissions in dairy production will require >50% reduction in enteric methane (CH4) emissions together with elimination of emissions from feed production, additional carbon sequestration, reduction in manure emissions, anaerobic digestion of manure, and decreased reliance on fossil fuel energy. Over past decades, improved production efficiency has reduced GHG intensity of milk production (i.e., emissions per unit of milk) in the United States, but this trend will continue only if cows are bred for increased efficiency. Genetic selection of low-CH4-producing animals, diet reformulation, use of feed additives, and vaccination show tremendous potential for enteric CH4 mitigation; however, few mitigation strategies are currently available, and added cost without increased revenue is a major barrier to implementation. Complete elimination of CH4 emissions from dairying is likely not possible without negatively affecting milk production; thus, offsets and removals of other GHGs will be needed to achieve net-zero milk production.

Carbon-mediated modulation pathways of phytotoxicity in chicken manure composting.

Compost phytotoxicity affects the safety of organic fertilizers returned to the field, thus hindering the breeding cycle, so it is essential to reduce the compost phytotoxicity. The phytotoxicity of compost was estimated utilizing the germination index (GI) and the aqueous substances (organics and ions) present in compost correlated closely with GI. This study assessed the effect of carbon additives from different plant sources (mushroom substrates (MS), cornstalks (CS) and garden substrates (GS)) on maturity parameters (temperature, pH, EC, C/N), content of aqueous carbon and nitrogen matters, salt ions, heavy metal ions, and microbiome of piles when composting with chicken manure and especially focused on their effect on GI. Results showed that all additives significantly improved GI (85.25%-106.28%). The primary factors influencing seed germination were Mg2+ and SO42- in CM compost, acetic acid and NH4+ in CM+MS compost, humic acid in CM+CS compost, and dissolved total nitrogen in CM+GS compost. During composting, the growth of heavy metal passivating bacteria (Bacillus) and organic matter degrading bacteria (Desemzia and Turicibacter) can be promoted by decreasing aqueous carbon and nitrogen substances (volatile fatty acids, NH4+, dissolved total nitrogen, amino acids) and increasing the content of humic acid, which improved the composting environment and provided favourable conditions for the germination of seeds, thereby increasing GI. Therefore, GS showed the best potential for accelerating degradation of organic matter and improving GI during composting with chicken manure.

Oxidative degradation of glycine in aqueous KOH/K2CO3 solutions for CO2 capture

AbstractPotassium hydroxide and potassium carbonate, being cost‐effective and environmentally friendly CO2 capture solvents, are promising candidates for carbon capture applications. Their slow absorption kinetics, however, necessitate strategies to enhance their rates, thereby reducing the capital costs of absorption equipment and saving energy for regenerating large volumes of solvent. Glycine, a potential additive, is explored for this purpose. While glycine‐based solvents are more stable than MEA, their amino functional group renders them susceptible to oxidative degradation. This study investigates the degradation of these solvents and the influence of potassium hydroxide and potassium carbonate on their stability. The experiment was performed under 100% O2 at 90 °C and 3 bar for about 3 weeks. It was observed that glycinate degraded by 53% for the glycinate‐only solution. The results also show that the addition of potassium hydroxide and potassium carbonate to a glycinate‐only solution had a mixed effect on the degradation of glycinate. Potassium hydroxide increased degradation by 5% compared to the glycinate‐only solution, while potassium carbonate decreased degradation by 4%. This order is supported by the degradation rate constants. Meanwhile, under N2, no significant change was observed in glycine concentration. Glycine's susceptibility to oxidative degradation is likely attributed to its less compact and rigid structure, resulting in weaker bonding and increased vulnerability to external factors. This instability leads to the formation of formate, carbonate, acetate, and oxalate as the primary degradation products across all studied solutions. A proposed mechanism for glycinate oxidative degradation sheds light on this process. These findings are crucial for informed decision making regarding performance trade‐offs in point source carbon capture and direct air capture, where oxygen is a prevalent gas component and potassium‐based solutions are commonly employed as absorbents. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

Estimating countries’ additional carbon accountability for closing the mitigation gap based on past and future emissions

Quantifying fair national shares of the remaining global carbon budget has proven challenging. Here, we propose an indicator—additional carbon accountability—that quantifies countries’ responsibility for mitigation and CO2 removal in addition to achieving their own targets. Considering carbon debts since 1990 and future claims based on countries’ emission pathways, the indicator uses an equal cumulative per capita emissions approach to allocate accountability for closing the mitigation gap among countries with a positive total excessive carbon claim. The carbon budget is exceeded by 576 Gigatonnes of fossil CO2 when limiting warming below 1.5 °C (50% probability). Additional carbon accountability is highest for the United States and China, and highest per capita for the United Arab Emirates and Russia. Assumptions on carbon debts strongly impact the results for most countries. The ability to pay for this accountability is challenging for Iran, Kazakhstan and several BRICS+ members, in contrast to the G7 members.

Enhancing Li+ Transportation at Graphite‐Low Concentration Electrolyte Interface Via Interphase Modulation of LiNO3 and Vinylene Carbonate

ABSTRACTThe solvent‐rich solvent sheath in low‐concentration electrolytes (LCEs) not only results in high desolvation energy of Li+, but also forms organic‐rich solid electrolyte interface film (SEI) with poor Li+ conductivity, which hinders Li+ transport at the electrode‐electrolyte interface and greatly limits the application of LCEs. Here, the electrochemical performance of the LCEs is enhanced by dual interfacial modification with LiNO3 and vinylene carbonate (VC) additives. Results show that LiNO3 is preferentially reduced at about 1.65 V to form an inorganic‐rich but incomplete SEI inner layer. The formation of Li3N and LiNxOy inorganic components helps to achieve rapid Li+ transport in the SEI film, and the bare electrode surface caused by the incomplete SEI inner layer provides a place for the subsequent decomposition of VC. Then, at a lower potential of about 0.73 V, VC is reduced to generate the poly(VC)‐rich SEI outer layer, which provides lithium‐philic sites and greatly weakens the interaction between Li+ and ethylene carbonate (EC). The interaction modulates the Li+ solvation structure at the interface and reduces the desolvation energy of Li+. This ingenious design of the bilayer SEI film greatly enhances Li+ transport and inhibits the decomposition of traditional carbonate solvents and the swelling of graphite. As a result, the electrochemical performance of the battery using 0.5 M LiPF6 EC/diethyl carbonate (DEC) + 0.012 M LiNO3 + 0.5 vt% VC is improved to a higher level than the one using 1.0 M LiPF6 EC/DEC electrolyte. This research expands the design strategy and promising applications of LCEs by constructing a favorable SEI to enhance Li+ transport at the electrode‐electrolyte interface.

Promoting the grinding of wheat bran through treatment by sodium carbonate and its mechanism

This work investigated the effect of treatment by sodium carbonate on grinding of wheat bran and the related mechanism. Specifically, wheat bran was treated by sodium carbonate solutions at the ratio of 1:2 to make addition of sodium carbonate at 0.0%, 4.0%, 8.0%, 12.0%, 15.0%, and 30.0% based on the mass of bran, dried, and ground using the universal high-speed grinder. It was found that treatment by sodium carbonate significantly reduced the particle size of ground bran and this effect was positively correlated with the sodium carbonate content, which suggested that treatment by sodium carbonate promoted the grinding of wheat bran. Besides, treatment by sodium carbonate improved the hardness of bran. On the other hand, treatment by sodium carbonate damaged the crystal structure, the cell wall and lignin of bran. Moreover, treatment by sodium carbonate converted bound phenolics, including ferulic acid, into free phenolics and insoluble dietary fiber, including unextractable arabinoxylan, into soluble dietary fiber. These results suggested that treatment by sodium carbonate had already damaged the structure of bran and altered the texture of bran before the mechanical stress during grinding was applied. As a result, treatment by sodium carbonate promoted the grinding of wheat bran.

Partial upgrading of heavy oils by catalytic aquathermal visbreaking with dispersed iron oxide catalysts

The impact of water and red mud-like Fe oxide catalysts on aquavisbreaking (AVB) of heavy-oils was studied under various circumstances. Vacuum residue (VR) was employed as a good substitute for low-viscous bitumen grades. The reaction products were separated into SARA fractions using open-column liquid chromatography (OCLC), and boiling point groups were classified using thermogravimetric analysis (TGA). In addition, Fourier-transform infrared (FTIR) spectroscopy was used to study the structural features of VR and its derivatives. It was observed that the thermal visbreaking of VR led to a severe coke formation with asphaltene (ASP) to coke selectivity over 130 %, while the addition of water and Fe catalyst could increase the conversion of ASP to liquid oil products while inhibiting coke formation, resulting in improved conversion of ASP. Furthermore, the structural properties of spent catalysts recovered after reactions were analyzed using X-ray absorption near edge structure (XANES) and X-ray diffraction (XRD) to identify the active phase, confirming that the Fe precursor is converted to a 20–30 nm Fe2O3 and Fe3O4 during VR AVB. Moreover, the addition of carbon additives to AVB further improved the dispersion of ASP and catalyst particles, contributing to the decrease of the selectivity for ASP conversion to coke by 50 %.

The Influence of Carbon Fiber on Crystallization and Morphology of Poly(Ether Ketone Ketone) Composites Towards High Rate Thermoplastic Manufacturing Processes

Recent interest in thermoplastic composites for aerospace applications is driven by the need for high-volume manufacturing of materials that display excellent mechanical, thermal, and solvent resistive properties. Specifically, a large component of the composite properties of thermoplastic composites are highly dependent on the crystalline fraction of the semi-crystalline polymer matrix of the reinforced system. This work investigates the melting behavior of poly (ether ketone ketone) (PEKK) and the influence of temperature and fiber on crystallization kinetics and morphology of (PEKK) composites utilizing, differential scanning calorimetry, Velaris-Sefaris modelling, and polarized optical microscopy (POM). Annealing temperatures of 380°C and above were required to fully erase crystalline ordering in the PEKK matrix. Furthermore, carbon fibers accelerated crystallization kinetics in PEKK at a range of temperatures observed via DSC, and Velaris-Sefaris modelling implied a shift from bulk to surface induced nucleation by the addition carbon fiber to the PEKK matrix, reducing activation energy of crystallization events. This nucleation behavior was visually confirmed through POM with observation of transcrystalline domains nucleated from the surface of a single carbon fiber.

The Influence of Carbon Fiber on Crystallization and Morphology of Poly(Ether Ketone Ketone) Composites Towards High Rate Thermoplastic Manufacturing Processes

Recent interest in thermoplastic composites for aerospace applications is driven by the need for high-volume manufacturing of materials that display excellent mechanical, thermal, and solvent resistive properties. Specifically, a large component of the composite properties of thermoplastic composites are highly dependent on the crystalline fraction of the semi-crystalline polymer matrix of the reinforced system. This work investigates the melting behavior of poly (ether ketone ketone) (PEKK) and the influence of temperature and fiber on crystallization kinetics and morphology of (PEKK) composites utilizing, differential scanning calorimetry, Velaris-Sefaris modelling, and polarized optical microscopy (POM). Annealing temperatures of 380°C and above were required to fully erase crystalline ordering in the PEKK matrix. Furthermore, carbon fibers accelerated crystallization kinetics in PEKK at a range of temperatures observed via DSC, and Velaris-Sefaris modelling implied a shift from bulk to surface induced nucleation by the addition carbon fiber to the PEKK matrix, reducing activation energy of crystallization events. This nucleation behavior was visually confirmed through POM with observation of transcrystalline domains nucleated from the surface of a single carbon fiber.

Facile constructing ZrO2 nanoparticles equipped with high conductivity carbon networks as pseudocapacitive anodes for removing phosphorus

Phosphorus pollution can seriously disrupt water quality and endanger ecosystem sustainability. Nonetheless, a few typical methods have been employed to remove phosphorus, but there are still challenges in controlling phosphorus from sewage. Capacitive deionization (CDI) displays the merits of having eco-friendliness and low energy consumption when capturing phosphorus. However, traditional carbon electrodes often suffer from the limitation that phosphorus uptake sites are insufficient. Herein, a novel ZrO2 nanoparticle equipped with a highly conductive carbon network (NZrC) was fabricated by a facile co-pyrolysis process. Na2EDTA can provide additional carbon backbones, N species, and metal chelation sites. Zr-MOF was applied as the ZrO2 precursor with abundant phosphorus trapping sites. The results suggested that Na2EDTA favors improving the ZrO2 dispersion, mesoporous channel formation, and pseudocapacitive behavior. NZrC-21 at 1.2 V displays low energy consumption and the optimal phosphorus uptake capacity of 10.99 mg P/g because of its rich mesoporous structure, abundant pyrrolic-N, graphitic-N, and ZrO2 active sites, and outstanding electrochemical properties. Furthermore, several key parameters were investigated for their effect on phosphorus removal performance. The mechanism revealed that hydrogen bonds, ligand exchange, and electrostatic attraction are the main uptake processes. This work presents a novel perspective for the facile construction and utilization of metal oxide nanoparticles equipped with a highly conductive carbon network for removing phosphorus.

Contrasting Future Growth of Norway Spruce and Scots Pine Forests Under Warming Climate.

Forests are essential to climate change mitigation through carbon sequestration, transpiration, and turnover. However, the quantification of climate change impacts on forest growth is uncertain and even contradictory in some regions, which is the result of spatially constrained studies. Here, we use an unprecedented network of 1.5 million tree growth records from 493 Picea abies and Pinus sylvestris stands across Europe to predict species-specific tree growth variability from 1950 to 2016 (R2 > 0.82) and develop 21st-century gridded projections considering different climate change scenarios. The approach demonstrates overall positive effects of warming temperatures leading to 25% projected conifer growth increases under the SPP370 scenario, but these additional carbon gains are spatially inhomogeneous and associated with geographic climate gradients. Maximum gains are projected for pines in Scandinavia, where growth trajectories indicate 50% increases by 2071-2100. Smaller but significant growth reductions are projected in Mediterranean Europe, where conifer growth shrinks by 25% in response to warmer temperatures. Our results reveal potential mitigating effects via forest carbon sequestration increases in response to global warming and stress the importance of effective forest management.

Carbon emission reduction associated with dapagliflozin compared to standard of care in the UK: translating the DAPA-HF and DELIVER trial findings to an environmental context

Abstract Background Healthcare systems account for 4–5% of UK national greenhouse gas emissions with delivery of care a major component.1 Preventing events that use healthcare resources should contribute to a reduction in emissions, in addition to the primary humanitarian aim of improving patient outcomes. The Dapagliflozin And Prevention of Adverse-outcomes in Heart Failure (DAPA-HF) and the Dapagliflozin Evaluation to Improve the Lives of Patient with Preserved Ejection Fraction Heart Failure (DELIVER) trials demonstrated that dapagliflozin reduced the frequency of hospitalizations for heart failure (hHF), urgent heart failure visits (UHFV) and cardiovascular (CV) death for patients with heart failure (HF).2,3 Purpose The study objective was to translate predicted differences in clinical events associated with dapagliflozin use in HF to a predicted carbon emission reduction from a UK perspective. Methods A previously published model4 based on pooled DAPA-HF and DELIVER event rates was used to predict hHF, UHFV and CV deaths in a cohort of 1,000 HF patients over a 3-year time horizon. Composite greenhouse gas (GHG) emissions (as kg CO2 equivalent) were calculated from components sourced from the Sustainable Healthcare Coalition’s Care Pathway Calculator according to assumed clinical pathways and were applied to predicted incidence of hHF, UHFV and CV death events. Average length of stay was sourced from the National Heart Failure Audit.5 CV deaths occurring outside hospital were assumed to incur no additional carbon emission except that associated with cremation. Proportion of funerals by cremation and associated GHG emissions were sourced from literature.6,7 Future emissions were not discounted, representing the NHS’s aim to approach ‘net zero’. Results Over a 3-year time horizon, treatment with dapagliflozin was projected to prevent 74 hHF events, 9 UHFV events and 20 CV deaths per 1,000 patients treated versus placebo. Total estimated GHG emissions associated with hHF (233.2 kg CO2e), UHFV (177.4 kg CO2e), and CV death (251.4 kg CO2e) were 85,660 kg CO2e per 1,000 patients treated with dapagliflozin versus 109,618 kg CO2e per 1,000 patients treated with placebo. The projected total reduction associated with dapagliflozin treatment was 23,958 kg CO2e over 3 years, a 22% reduction versus placebo. Per population (~690,000 HF patients), total emissions prevented by dapagliflozin over 3 years were projected to be equivalent to driving 42 million miles in an average gasoline-powered passenger vehicle. Conclusion While the main aim of any therapeutic intervention is to save lives and improve patient outcomes, to capture the full spectrum of benefit to stakeholders the environmental consequences of new therapies should be considered in addition to their clinical and economic effects. Our analysis suggests treating patients with dapagliflozin may contribute to reducing the environmental burden of HF in addition to improving patient outcomes.

Synthesis, characterization, and antioxidant activity of novel diorganotin(IV) complexes derived from Ibuprofen-5-aminosalicylic acid ligand

This study focuses on the preparations of a new ligand prepared by the condensation reaction between two substances ibuprofen and 5-aminosalicylic acid, and complexes of di organotin(IV) salts were prepared using this produced ligand to yield the appropriate complexes. The generated compounds were identified using FTIR and elemental analysis, in addition (tin, proton and carbon) magnetic resonance (119Sn, 1H, and 13C, NMR). Octahedral geometry was suggested for the synthesized complexes based on the observations of the spectra. Two techniques were used to examine the antioxidant activity of the compounds: DPPH and CUPRAC. Because the tin element was present, the resultant complexes exhibited a higher rate of inhibition than the ligand. Di-methyltin-di-IAS also showed a greater effect as antioxidants than the other compounds. KEY WORDS: Diorganotin(IV), Antioxidant activity, Ligand (IAS), DPPH method, CUPRAC method Bull. Chem. Soc. Ethiop. 2025, 39(1), 101-110. DOI: https://dx.doi.org/10.4314/bcse.v39i1.8

On the legality of national carbon pricing instruments alongside the new EU ETS 2

With the EU ETS 2 a new EU-wide emissions trading system is introduced that covers the greenhouse gas emission of the buildings and road transport sectors, i.e. sectors the decarbonization of which has so far been the responsibility of the Member States under the Effort Sharing Regulation. Since they will remain responsible for the achievement of their national greenhouse gas emission reduction targets under that regime, the question arises whether the Member States can maintain or introduce additional carbon pricing instruments alongside the new EU ETS 2. Hence, this paper examines the legality of such an approach, by assessing relevant provisions of EU secondary and primary law. Without going deep into the economic and political considerations, it concludes that from a legal perspective, the coexistence of national carbon pricing instruments and the EU ETS 2 is not prohibited.With the latest reform of the EU Emissions Trading System Directive (ETS Directive), the European Union (EU) has introduced a new EU emissions trading system for buildings and road transport (EU ETS 2)1. The decarbonization of those sectors traditionally falls within the responsibility of the EU Member States under the regime of the Effort Sharing Regulation (ESR). The ESR introduces legally binding national greenhouse gas (GHG) emission reduction targets. Hence, over the last few years, the Member States have introduced different measures in order to reach their targets. Those include carbon pricing instruments, understood as measures that put a price on the emission of GHG and thus create an incentive to reduce those emissions. Carbon pricing instruments include carbon taxes, as well as emissions trading systems2. With the introduction of the new ETS 2, the question arises whether the Member States can maintain (or introduce) such national carbon pricing instruments in parallel to the new EU ETS 2.

Comparative Hydrogen Production Routes via Steam Methane Reforming and Chemical Looping Reforming of Natural Gas as Feedstock

Hydrogen production is essential in the transition to sustainable energy. This study examines two hydrogen production routes, steam methane reforming (SMR) and chemical looping reforming (CLR), both using raw natural gas as feedstock. SMR, the most commonly used industrial process, involves reacting methane with steam to produce hydrogen, carbon monoxide, and carbon dioxide. In contrast, CLR uses a metal oxide as an oxygen carrier to facilitate hydrogen production without generating additional carbon dioxide. Simulations conducted using Aspen HYSYS analyzed each method’s performance and energy consumption. The results show that SMR achieved 99.98% hydrogen purity, whereas CLR produced 99.97% purity. An energy analysis revealed that CLR requires 31% less energy than SMR, likely due to the absence of low- and high-temperature water–gas shift units. Overall, the findings suggest that CLR offers substantial advantages over SMR, including lower energy consumption and the production of cleaner hydrogen, free from carbon dioxide generated during the water–gas shift process.

The Impact of the EU Carbon Border Adjustment Mechanism on Chinas Exports and Suggestions on Countermeasures

The European Parliament plans to gradually introduce the Carbon Border Adjustment Mechanism in 2023, with a complete implementation set for 2026. As an essential trading partner of the EU, China will shoulder an additional carbon border tariff due to the lack of low-carbon technology and the dependence on extensive development patterns. These extra costs will undermine the profit margins of Chinas carbon-intensive industry sectors, possibly resulting in decreased exports and a restructuring of production. The latest estimate of the exact costs of Chinas embedded carbon exports to the EU is a problem that has received limited academic attention. Using the IPCC carbon emission accounting methodology and non-competitive single-region input-output analysis, this research precisely measures the embedded carbon in Chinas exports to the EU for the nine most affected industries. Furthermore, this study quantifies the impact of the CBAM on Chinas exports of these nine industry sectors. The findings suggest that China should improve the domestic carbon emission trading system and take the initiative to participate in formulating a carbon pricing consultation and dialogue mechanism, mitigating the negative impact of the EU CBAM on exports.

Synthesis of Rod‐Like Sb2Se3@MWCNT as Conductive‐Additive Free Anode for Sodium‐Ion Batteries

AbstractAntimony selenide (Sb2Se3) is a promising electrode material for sodium‐ion batteries (SIBs) due to its high theoretical capacity. However, volume expansion during sodiation/desodiation and the low conductivity of Sb2Se3 reduce the electrochemical performance. Herein, we synthesized Sb2Se3 nanorods (NRs) and combined them with multi‐walled carbon nanotubes (MWCNTs) using one‐step composite process to address these issues. MWCNTs can accommodate volume expansion and provide high conductivity. The fabricated Sb2Se3 NRs@MWCNT electrode exhibits improved cycle performance and cyclic stability without additional conductive carbons. The Sb2Se3 NRs@MWCNT electrode showed an enhanced specific capacity of 440 mAhg−1 at a current density of 0.1 Ag−1, compared to 220 mAhg−1 for the Sb2Se3 NRs electrode. Additionally, it exhibited good stability at high current density. The in‐situ electrochemical impedance spectroscopy (EIS) and Galvanostatic intermittent titration technique (GITT) were used to estimate the electrochemical properties and kinetics of Sb2Se3 NRs@MWCNT. These results showed that Sb2Se3 NRs@MWCNT have the potential as a conductive‐free anode material in SIBs.

Effect of carbon content on the microstructure and stress rupture properties of a 4th-generation nickel-based single crystal superalloy

The balance between the stress rupture properties and castability of a 4th-generation Ni-based single crystal superalloy can be achieved by addition of appropriate carbon content. In this work, the effects of carbon content on the microstructure and stress rupture properties of a 4th-generation Ni-based single crystal superalloy were investigated in detail. The results showed that minor carbon addition could aggravate the dendrite segregation, while the addition of carbon had no obvious effect on the rafting and distortion of γ′ phase during stress rupture deformation. At 760 °C/810 MPa and 1100 °C/210 MPa, the stress rupture lives of the three experimental alloys initially increased and subsequently decreased with the increasing carbon content. However, under condition of 1140 °C/137 MPa, the increased carbon content resulted in the reduction of the stress rupture lives of alloy. It was discovered that minor carbon elements addition (0.045 wt%) can promote formation of interfacial dislocation networks and improve creep resistance at high temperatures. At intermediate temperature, the introduction of carbon could reduce the stacking fault (SF) energy of γ matrix, thus facilitating the formation of SFs in γ matrix. The M6Cgranular carbides precipitated at high temperature, which was considered to be beneficial to stress rupture properties.

Calcium Carbonate as Dephosphorization Agent in Direct Reduction Roasting of High-Phosphorus Oolitic Iron Ore: Reaction Behavior, Iron Recovery, and Dephosphorization Mechanism

Calcium carbonate, renowned for its affordability and potent dephosphorization capabilities, finds widespread use as a dephosphorization agent in the direct reduction roasting of high-phosphorus oolitic hematite (HPOIO). However, its precise impact on iron recovery and the dephosphorization of iron minerals with phosphorus within HPOIO, particularly the mineral transformation rule and dephosphorization mechanism, remains inadequately understood. This study delves into the nuanced effects of calcium carbonate on iron recovery and dephosphorization through direct reduction roasting and magnetic separation. A direct reduction iron (DRI) boasting 95.57% iron content, 93.94% iron recovery, 0.08% phosphorus content, and an impressive 92.08% dephosphorization is achieved. This study underscores how the addition of calcium carbonate facilitates the generation of apatite from phosphorus in iron minerals and catalyzes the formation of gehlenite by reacting with silicon dioxide and alumina, inhibiting apatite reduction. Furthermore, it increases the liquid phase, enhancing the dissociation of metallic iron monomers during the grinding procedure, thus facilitating efficient dephosphorization.

Fixing collapsed dry anaerobic digestion system of kitchen waste caused by severe VFAs accumulation

Severe inhibition by volatile fatty acids (VFAs) frequently occurs during the dry anaerobic digestion of kitchen waste at high organic load rate (OLR), leading to decreased biogas production and even the collapse of the anaerobic digestion system. In this study, VFAs accumulation was significantly reduced by adding powder-activated carbon (PAC) or alkaline additives (AA), thus restoring the collapsed system to a stable operating state. With the addition of PAC or AA, the maximal OLR reached 11.14 g VS/(L·d), which was 30 % higher than observed without any additives (control group), while the VFAs concentration was maintained below 3000 mg/L. At this OLR, the volumetric biogas production rate stabilized at 5.1 L/(L·d) in the presence of PAC and AA, while that of the control group gradually decreased to zero. The VFAs concentration with PAC addition was 86 % lower than that of the control group, possibly because PAC might stimulate the formation of direct interspecies electron transfer between syntrophic bacteria and methanogens (Methanosarcina), thereby promoting VFAs degradation. The addition of AA, which resulted in a 95 % decrease in ammonia-nitrogen concentration, can provide a good growth environment for the microorganisms involved in acidogenesis and hydrogenotrophic methanogenesis.