Technology For Removal Research Articles

Biochar in the UK Print News Media: Issue Frames and Their Implications for Opening up Debate About Land-based Greenhouse Gas Removal

ABSTRACT Biochar is a land-based greenhouse gas removal technology with potential to address the climate crisis. This article examines societal debate and discussion around biochar as represented in the UK print news media and reflects on its implications for the democratic governance of novel technologies. Using an “issue frame” analysis approach, the following frames are identified – Innovation, Economics, Security, Governance and Accountability, Risk, Justice, Substitution, Salvation and Tradition – with some more prominent than others. Economics and Innovation frames are particularly pronounced, together with the argument for market-based forms of governance, while Risk and Justice frames are weakly developed. The findings show that some frames and their associated actors dominate debate, while others are absent or side-lined. This might hinder opening up the debate to a wider group of stakeholders and publics and alternative framings, thus constraining effective governance of biochar.

Reaction mechanism investigation on Plasma-Assisted steam reforming of toluene based on emission spectrum analysis and kinetic simulation

Plasma-enhanced reforming has been widely studied as an efficient technology for online tar removal. By combining reforming experiments with kinetic modeling and in-situ optical emission spectrometry (OES) analysis, interaction mechanism and coupling rules of plasma/thermal reactions during plasma-assisted steam reforming of toluene were well explored in this study. A chemistry model was innovatively developed for plasma-assisted steam reforming of toluene, and predicted experimental results under different operations conditions with superb agreements. The rate of production and sensitivity analysis implied that OH, H and N2* mainly contributed to primary toluene conversion, while the electronic attachment dissociation of H2O, H addition onto benzene ring and benzyl oxidation by OH were the most enhancing-sensitive reactions. Resultantly, toluene conversion was greatly increased with steam addition before VfH2O = 10 %, but after which VfH2O increase deteriorated the reforming performance due to the inhibition of E-N2 collision by high VfH2O. As temperature increased, plasma and thermal synergistically promoted reforming performance before 300 °C, at which > 60 % toluene was converted into small molecules such as CO, H2 and C2H2, with yields of 23.6 %, 9.4 % and 16.3 % correspondingly at 12 kJ/L, but further temperature increase would not benefit due to the reduced discharge field strength at higher temperatures, being confirmed by the decreased relative intensity of OH, CN feature bands on OES. It was initially proposed that non-thermal plasma governed the reforming process at T < 300 °C, and thermal reactions predominated at T > 500 °C after a transition region (300 ∼ 500 °C). Increase of input energy caused higher discharge field strength, promoted the electronic collision ionization or dissociation of N2 and H2O, thus enhanced toluene conversion and gas yields. A detailed reaction pathway has also been clarified.

Simultaneous achievement of energy recovery and carbon sequestration through municipal solid waste management: A review

Effective municipal solid waste (MSW) management is a crucial component for sustainable cities, as inefficient waste disposal contributes to the release of about a billion tons of CO2-eq in greenhouse gases (GHG) annually. With escalating global waste generation, there is an untapped opportunity to integrate carbon dioxide removal (CDR) technologies into existing MSW management processes. This review explores current research on utilizing MSW for CDR, emphasizing its potential for both energy generation and carbon sequestration. The investigation covers three waste management practices: landfilling, waste-to-energy (WtE), and biochar production, revealing two paths for carbon sequestration. First, MSW serves as a feedstock in bioenergy with carbon capture and storage (BECCS), acting as a carbon-neutral resource that avoids fossil fuel and energy crop use, reducing GHG emissions and generating value through energy production. Second, direct storage of organic MSW and its derivatives, like biochar, in various carbon sinks allows for extended sequestration, offering a comprehensive approach to address the challenges of waste management and climate change mitigation. Moreover, this review advocates for an extended exploration into several subjects including in-depth analysis of waste, research on MSW-derived biochar recalcitrance across different carbon sinks, and understanding the symbiotic connections with GHG-emitting sectors like agriculture and energy. Finally, this review emphasizes the necessity of conducting life-cycle assessment studies to fully discern the benefits and assess the impacts of any future endeavors exploring the role of MSW in carbon sequestration.

Engineering sulfur vacancies on Mo-doped FeS2 nanosheets grown on activated carbon fibers enhances peroxymonosulfate activation for efficient elimination of sulfamethazine, antibiotic resistant bacteria and antibiotic resistance genes: The dominant role of singlet oxygen

The widespread of antibiotics will induce the generation of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs), causing threats to human health. Therefore, developing a green and efficient synchronous removal technology for the removal of antibiotics, ARB and ARGs is urgent. In this study, Mo doped FeS2 nanosheet with rich sulfur vacancies (SVs) grown on activated carbon fibers was successfully synthesized and employed as a PMS activator to remove sulfamethazine (SMT), ARB and ARGs in aqueous solution. Mo-FeS2/ACFs-0.1 (MFAs-0.1, the molar ratio of Mo/Fe is 0.1) showed high performance for PMS activation, and 99.7 % SMT was removed in 60 min (250 mg/L MFAs-0.1, 0.3 g/L PMS, initial pH = 5.5). In addition, low reagent doses of MFAs-0.1 catalyst (250 mg/L) and PMS (0.5 g/L) were found to be efficient for removing 7.25-log of ARB within 30 min and restraining conjugative transfer of ARGs. Singlet oxygen (1O2) was identified as the primary reactive oxygen species for SMT degradation and ARB inactivation. Meanwhile, the integration of Mo-doping with SVs could optimize the electronic structure, generating electron-rich and highly active regions. This facilitates the adsorption of PMS onto the Fe site and boosts electrons transfer from FeS2 to PMS, as indicated by density functional theory (DFT) calculations. Overall, this study demonstrated that the MFAs-0.1 based heterogeneous system was an economically “one stop” treatment process for the removal of biological and chemical contaminants. In addition, it would provide a new insight into the fabrication of FeS2 composites-based PMS activator.

Cleansing the molten steel due to the dispersed in-situ phase induced by the composite sphere burst reaction I. Composite sphere design

In the present investigation, a novel fine inclusion removal technology due to the dispersed in-situ phase induced by composite ball burst reaction was put forward. A composite sphere with this function was designed and the composite sphere burst process at steelmaking temperature was analysed. The results indicate that the compact strength of the composite ball is so high that it will not break up as it intrudes into the molten steel. The composite sphere has a high thermal stability at steelmaking temperature. Usually, the composite sphere burst reaction takes place after it has intruded into the molten steel for a few seconds. The fine bubbles and slag droplets can be released due to the composite sphere burst reaction. Compared with the conventional technology, the bubbles and slag droplets induced by this novel technology are much finer. The size distribution of the bubble and the slag droplet is between 20 and 200 μm. The dispersion of these fine bubbles and slag droplets contributes to collision with inclusion.

Oil Removal Technology for Water Injection in Low-Permeability Reservoirs: A Micro-Vortex Flow Approach

Oil Removal Technology for Water Injection in Low-Permeability Reservoirs: A Micro-Vortex Flow Approach

A review on the synergistic efficacy of sonication-assisted water treatment process with special attention given to microplastics

The rampant spread of microplastic pollution in both natural and industrial water bodies has emerged as a paramount environmental concern. Regrettably, conventional water treatment methods (e.g., adsorption, membrane filtration, coagulation-flocculation, and electrocoagulation, processes) have been discovered to be inadequately effective in tackling this issue. However, the advent of sonication-assisted water treatment technologies has shown great promise in curbing microplastic pollution. This review article expounds on the latest trends in sonication-assisted water treatment technologies for microplastic removal. A comparison between conventional water treatment methods and sonication-assisted procedures elucidates the pros and cons of each were conducted. Additionally, an exploration of various sonication-assisted techniques and their potent efficacy in removing microplastics was undertaken. Sonochemical, Sonoelectrochemical, Sonophotocatalytic, Sonofenton, and Sonoelectrocatalytic, may be used for microplastics (MPs) removal, it has been demonstrated that ultrasonic frequencies between 100 and 1000 kHz for the sonochemical process are more useful than frequencies below 20 kHz. Generally, sonication methods have good compatibility and attachment to other biological or physical processes and increase the cavitation-induced concentration of the reactive radical in the bulk phase. Also, When Fenton processes are combined with sonication, the number of ferrous ions present in the treated water decreases due to easy handling, quick degradation, and a wide pH range that can be used. The economic aspects are the biggest challenges in synergistic efficacy of sonication-assisted water treatment for microplastics mitigation. The paramount importance of continued research and development to refine and optimize sonication-assisted water treatment technologies for practical implementation was concluded.

Effects of sulfamethoxazole/trimethoprim on corncob-supported solid-phase denitrification and removal performance: Microbial community, biotransformation pathways, and antibiotic resistance genes

The widespread use of antibiotics inevitably results in their discharge into the water environment from the wastewater treatment plant (WWTP) effluents. Corncob-supported solid-phase denitrification (CC-SPD) has been identified as a promising technology for nitrogen removal of WWTP effluents. The effects of sulfamethoxazole (SMX)/trimethoprim (TMP) on nitrogen removal in up-flow CC-SPD reactors and the influencing mechanisms are studied at microbial and genetic levels, and the antibiotic removal performance, degradation pathways, and antibiotic resistant genes (ARGs) are also extensively investigated. Long-term experimental results indicated that 0.05 and 2 mg/L SMX/TMP, either individually or in combination, had no inhibition on nitrogen removal performance in CC-SPD reactors. The NO3–-N removal capacity was approximately 125.60–142.91 mg NO3–-N/g CC. Although the microbial community structure evolved to adapt to the 0.05 mg/L SMX/TMP, the relative abundances (RAs) of denitrification genes and genes related to electron donor behaviours did not significantly alter. Furthermore, SMX, with a higher removal efficiency of 42.17%, was more easily degradable compared to TMP, and the degradation products of SMX were more readily mineralized. Additionally, microorganisms degrade antibiotics through processes such as ring opening, hydrogenation, and bond cleavage, with the toxicity of intermediates often being lower than that of parent compounds. Moreover, 0.05 mg/L SMX/TMP did not significantly change the RAs of ARGs and movable genetic elements (MGEs). This study provides important basis for the antibiotic risk prevention in WWTP effluents and the practical application of SPD technology.

Formation keeping control for deorbiting an uncooperative satellite by laser ablation

This paper proposes the formation keeping control law for deorbiting debris by a laser ablation. Laser ablation is vital technology for contactless active debris removal, where a chaser satellite with a laser system irradiates laser pulses to a target object to generate the ablation force for deorbiting. The deorbiting force decelerates the target, and the chaser must maintain its relative position and continue irradiating. In other words, both the chaser and the target are supposed to be deorbited simultaneously, where both have accelerations. Although conventional formation flying missions assume that only a chaser maneuvers, the formation flying in this paper considers that both a chaser and a target have accelerations. Thus, this paper derives the relative equations of motion between the chaser and the target in powered flight and their analytical solution using relative orbital elements. A control law based on the analytical solution is proposed, which determines the timings and directions of the laser ablation and the electrical thrust so that the formation periodically returns to a desired formation. Numerical simulations first examine the control law in two cases with different maneuver timings. Then, a Monte Carlo simulation is performed to verify the effectiveness of the control law for a variety of desired formations.

Anthropogenic gadolinium in the Tone River (Japan): an update showing a 7.7-fold increase from 1996 to 2020

BackgroundAnthropogenic gadolinium (Gd), originating from Gd-based contrast agents (GBCAs) used in magnetic resonance imaging (MRI), is widely identified in the aquatic environment with concerns about toxicity and accumulation. We aimed to present new data on anthropogenic Gd in the Tone River, which has the largest drainage area in Japan, and then to compare the current data with those obtained in 1996.MethodsThe water samples were collected on August 9−10, 2020, at 15 different locations of the Tone River in Japan. The concentrations of the rare earth elements (REEs) were measured by inductively coupled plasma-mass spectrometry and normalized to Post-Archean Australian Shale to construct shale-normalized REE patterns. The degree of Gd-anomaly was defined as the percentage of anthropogenic Gd to the geogenic background and used to compare the water samples from different locations. Pearson’s correlation coefficients were calculated.ResultsAll the samples displayed positive Gd anomalies. The Gd-anomaly ranged from 121 to 6,545% and displayed a repeating decrease-and-increase trend. The Gd-anomaly showed strong positive correlations to the number of hospitals (r = 0.88; p < 0.001) and their MRI units (r = 0.89; p < 0.001).ConclusionsOur study revealed notable anomalies of Gd concentrations in river water in Japan, with strong positive correlations to the number of major hospitals and their MRI units. Compared with the previous report in 2000, the Gd-anomaly in Tone River increased from 851% (sampled in 1996) to 6,545%, i.e., 7.7 times, reflecting the increased use of GBCAs in hospitals.Relevance statementNotable Gd concentration anomalies in river water in Japan were observed. This result underlines the importance of more extensive research on anthropogenic gadolinium, and investigations of risks to human health as well as the development of effective removal technologies may be necessary.Key points• All water samples from Tone River displayed positive Gd anomalies.• The Gd anomalies increased to 7.7 times higher over the past 24 years.• Correlations between Gd values and the number of hospitals and MRI units were observed.Graphical

Enhanced boron removal without pre-pH adjustment via redox-mediated electrodialysis assisted by ion-exchange resins

Boron presents challenges in desalination owing to its small size and lack of charge. While various methods, such as reverse osmosis, capacitive deionization, and electrodeionization, have been utilized to control boron, they often suffer from high levels of energy consumption and complex processes requiring pH adjustment to generate the charged form of boron. Herein, we introduce a novel approach, i.e., redox-mediated electrodialysis (redox-ED) assisted by ion-exchange resins, aimed at energy-efficient boron control without requiring pH adjustment. Our system displays a remarkable boron removal efficiency of 99% with a low energy consumption of 0.009 kWh/g (0.09 kWh/m3). These results are likely due to the dissociation of water on the surface of the ion-exchange resins, which led to a local pH gradient and reduced systemic resistance through additional ion flux. Furthermore, via techno-economic analysis, the total cost of the redox-ED for boron removal revealed a 50% reduction with the scale-up strategy of electrode stacking, compared to those of traditional EDI systems. Overall, this study demonstrates the new potential of a sustainable boron removal technology without pH adjustment through the redox-ED system assisted by ion-exchange resins, providing an attractive option applicable to the boron removal industry.

Law of respirable dust pollution induced by cutting-advancing support in a fully mechanized mining face and spatial stereoscopic dust control and removal technology

Law of respirable dust pollution induced by cutting-advancing support in a fully mechanized mining face and spatial stereoscopic dust control and removal technology

Expert insights into future trajectories: assessing cost reductions and scalability of carbon dioxide removal technologies

IntroductionTo achieve net-zero targets, it is essential to evaluate and model the costs and scalability of emerging carbon dioxide removal technologies like direct air capture with CO2 storage (DACCS) and bioenergy with carbon capture and storage (BECCS). Yet such efforts are often impeded by varying assessments of the climate impact and potential contributions of these technologies. This study explores the future costs and scalability of DACCS and BECCS to advance net-zero goals.MethodsWe analyze expert opinions on these technologies’ potential costs and deployment scales for 2030, 2040, and 2050. Data was collected from 34 experts, comprising 21 DACCS and 13 BECCS specialists. They provided 90% confidence interval estimates and ‘best estimates’ for future costs and deployment under two International Energy Agency (IEA) policy scenarios—Stated Policies (STEPS) and Net Zero Emissions by 2050 (NZE).ResultsWe find that BECCS costs start at a lower level but decrease more slowly, whereas DACCS costs decline more steeply from a higher initial cost. However, DACCS estimates varied significantly among experts, showing no convergence over time. Regarding potential scalability, both technologies are associated with substantially higher deployment under the NZE scenario. Yet the combined estimated capacity of DACCS and BECCS by 2050 is only about a quarter of the CO2 removals projected by the IEA for its NZE scenario (1.9 GtCO2).DiscussionThis study provides valuable insights into the future of DACCS and BECCS technologies in Europe, especially since our experts expect that DACCS and BECCS costs will be even higher (and deployment scales lower) than those predicted by recent IEA tracking, opening future research directions.

Scaling carbon removal systems: deploying direct air capture amidst Canada’s low-carbon transition

Carbon dioxide removal (CDR) technologies, such as direct air carbon capture and storage (DACCS), will be critical in limiting the rise of the average global temperature over the next century. Scaling up DACCS technologies requires the support of a complex array of policies and infrastructure across multiple overlapping policy areas, such as climate, energy, technology innovation and resource management. While the literature on DACCS and other CDR technologies acknowledges the path-dependent nature of policy development, it has tended to focus on abstract policy prescriptions that are not rooted in the specific political, social and physical (infrastructural) context of the implementing state. To address this gap, this paper provides a country-level study of the emerging DACCS policy regime in Canada. Drawing on the existing literature that identifies idealized (acontextual) policy objectives that support DACCS development and effective regulation, we identify the actionable policy objectives across six issue domains: general climate mitigation strategies; energy and resource constraints; carbon storage and transport regulation and infrastructure; financing scale-up and supporting innovation; removal and capture technology availability and regulation; and addressing social acceptability and public interest. Using a database of Canadian climate policies (n = 457), we identify policies within the Canadian (federal and provincial) policy environment that map to the idealized policy objectives within each of these domains. This exercise allows us to analyze how key policy objectives for DACCS development are represented within the Canadian system, and enables us to identify potential niches, and landscape influences within the system, as well as gaps and potential barriers to the system transition process. This paper contributes to our understanding of national DACCS policy development by providing a framework for identifying components of the DAC system and linking those components to desired policy outcomes and may provide a basis for future cross-country comparisons of national-level DACCS policy.

Optimization of the intermediate chamber improves desalination performance in flow electrode capacitive deionization (FCDI): A comparative study

Flow electrode capacitive deionization (FCDI), a novel ion removal technology, is influenced by various factors such as electrode material properties, fluid flow rate, and device structure. In the FCDI system, the intermediate chamber is the core element where ions migrate towards the cathode and anode to complete the adsorption process. In this study, we designed a hollow plastic plate with channels (PP) and a hollow graphite plate with channels (GP) as the intermediate chamber, compare and study with conventional plastic mesh (PM) chambers. CFD simulations revealed that the newly designed PP and GP chambers significantly reduced the hydraulic stagnation zone. The results of the desalination experiments revealed that the desalination efficiency of the GP-FCDI was 1.5 and 1.9 times higher than that of the PP-FCDI and PM-FCDI, respectively. At the same time, in situ potential measurement (ISPM) was used to monitor the voltage drop of each component in FCDI, thereby accurately calculated the proportion of energy consumption in the intermediate chamber. The results indicate that the energy consumption of the intermediate chamber of GP-FCDI was 54 % less than that of PM-FCDI. The current work will help us provide new insights for the design and optimization of FCDI systems.

Coupling physiochemical adsorption with biodegradation for enhanced removal of microcystin-LR in water

To innovate the design of water treatment technology for algal toxin removal, this research investigated the mechanisms of cyanotoxin microcystin-LR (MC-LR) removal by a coupled adsorption-biodegradation. Eight types of woody carbonaceous adsorbents with and without Sphingopyxis sp. m6, a MC-LR degrading bacterium, were tested for MC-LR removal in water. All adsorbents showed good adsorption capability, removing 40 % to almost 100 % of the MC-LR (4.5 mg/L) within 48 h in batch experiments. Adding Sphingopyxis sp. m6 continuously promoted MC-LR biological removal, and successfully broke the barrier of adsorption capacity of tested adsorbents, removing >90 % of the MC-LR in most of the coupled adsorption-biodegradation tests, especially for those adsorbents had low physiochemical adsorption capacity. Variance partitioning analysis indicated that mesopore was the dominant contributor to adsorption capacity of MC-LR in pure adsorption treatments, which acted synergistically with electrical conductivity, polarity and total functional groups on the absorbent. Pore structure was the key factor beneficial for the growth of Sphingopyxis sp. m6 (51% contribution) and subsequent MC-LR biological removal rate (80 % contribution). Overall, pinewood-based carbonaceous adsorbents (especially pinewood activated carbon) exhibited the highest adsorption capacity towards MC-LR and provided the most favorable conditions for biological removal of MC-LR, largely because of their high mesopore volume, total functional groups and electric conductivity. The research outcomes not only deepened the quantitative understanding of mechanisms for MC-LR removal by the coupled process, but also provided theoretical basis for future materials' selection and modification during the practical application of coupled process.

Rapid reactivation of long-term frozen preservation anammox granular sludge by biochar: Performance, mechanism and artificial neural network optimization

Anaerobic ammonia oxidation (Anammox) is an efficient nitrogen removal technology for wastewater, and has been successfully applied in practical wastewater treatment. The preservation and rapid reactivation of anammox bacteria (AnAOB) play an important role in the anammox application. Biochar has been widely used in the water treatment industry due to its stable structure, economic and environmental protection characteristics. Hence, this study used biochar to accelerate anammox granular sludge (AnGS) performance recovery after 60 d preservation under low-temperature frozen (−20 °C). The time of AnGS recovery in the group with biochar addition was shortened by 15 d than the natural recovery group. Meanwhile, biochar addition improved the shock loading resistance of the anammox system. EPS secretion, and the types and quantities of functional groups in EPS increased under biochar stimulation, especially tighter PN. The functional groups in biochar can act as electron shuttles during anammox process, accelerating the electron transfer rate. Biochar addition enhanced the relative abundance of AnAOB, especially Candidatus Brocadia. PICRUSt analysis indicated that biochar promoted key gene related to anammox process and accelerated the recovery of frozen sludge. In addition, the changes in effluent nitrogen removal efficiency were successfully predicted by artificial neural network modeling with R = 0.9895 and MSE = 0.0048. This result may provide a new technological idea for the rapid recovery of AnGS under long time frozen conditions.

Theoretical and experimental studies of NO removal in alkaline H2O2 system

NO in flue gas is one of the atmospheric pollutants, and it is necessary to study effective NO removal technology. It was identified that the alkaline H2O2 system achieved over 98 % NO removal efficiency with a gas–liquid contact time of 3 s in this paper. This paper investigates the mechanism of NO removal in alkaline H2O2 solution through both experimental and theoretical calculations. The results reveal the NO removal process can be divided into three phases by the NaOH/H2O2 molar ratio. (1) The ∙O2– dominated phase, where trace metal Fe catalyzes ∙O2– radical generation from H2O2 as Fe (OH)2+, reacting primarily with NO to form ONOO–. The energy barrier for this process is1.299 kcal/mol, with a reaction rate constant of 9.12 E + 11 s-1M−1. (2) The HO2– dominated phase, HO2– was generated through OH– and H2O2 neutralization, which converts NO to NO2 and regenerating OH–. The energy barrier for HO2– reacting with NO is 3.833 kcal/mol, and the reaction rate constant is 2.07E + 10 s-1M−1. (3) The O22– dominated phase, O22– was a further ionization of HO2– and converting NO to NO2– directly. The energy barrier for this process is 7.079 kcal/mol, and the reaction rate constant is 1.49 E + 08 s-1M−1.

Fabrication of Activated Carbon Derived from Glycerin Pitch for Desulfurization of Model Fuel Oil and Electrode Application.

One of the world's challenging energy issues is introducing practical and affordable technology for organosulfur removal in fuel. Adsorptive desulfurization (ADS) can address this issue if highly effective activated carbon (AC) derived from industrial waste with excellent textural properties is used. In this study, the derived ACs from glycerin pitch loaded with P and Fe (AC/P and AC/Fe) were used as adsorbents for the ADS of model fuel oils, such as dibenzothiophene (DBT) at mild operating conditions. Under the optimized experimental conditions, 0.3 g of adsorbent dosage, 60 min reaction time, 30 °C temperature, and pH 4, the maximal DBT removal of 96.28 and 43.64%, respectively, for AC/P and AC/Fe was realized. The results indicated that the phosphorus-doped AC/P increases the selectivity of the ADS mechanism for DBT removal. Kinetic investigations disclosed that the adsorption process follows second-pseudo-order kinetics and the Langmuir adsorption isotherm model. The adsorbents remained active for five successive reuses, indicating their robust real-world applications. The electrochemical properties of the fabricated carbon electrodes were analyzed via cyclic voltammetry by coating the ACs with polytetrafluoroethylene (PTFE) as a binder. The transition-metal-doped AC/Fe, though exhibiting 5 times lower surface area, showed the highest specific capacitance at a scan rate of 5 mVs-1 (0.65 μF cm-2). Similarly, the extended AC:PTFE capacitor at a 10% binder ratio offered the maximum capacitance value (1.13 μF cm-2). The synthesized ACs demonstrated potential application as an electrode material, and hence glycerin pitch could be a low-cost precursor to improve the feasibility of commercial production of AC.

Cleansing the molten steel due to the dispersed in situ phase induced by the composite sphere explosion reaction II. Inclusion removal

Industrial trials have been carried out on the base of the former experimental research and the CaCO3 proportion in composite sphere, feeding amount, and composite sphere feeding mode have been investigated. The fine inclusion removal mechanism has been analyzed. The results indicate that feeding composite sphere in RH degasser is a novel process and small inclusion in the molten steel can be removed effectively. CaCO3/CaO ratio in composite sphere has a great effect on the inclusion removal efficiency. More feeding times and a little feeding amount can increase the composite sphere utilization efficiency. Compared with the conventional inclusion removal technology, the number density of the oxide inclusion can be decreased to a lower level and the inclusion size becomes much finer. Using this novel process, T.O. in the as-cast slab can approach to 6 ppm.