Non-thermal Plasma Technology Research Articles

Eco-Conscious Approach to Synthesizing Aluminum Oxides Using Nonthermal Plasma Technology

AlO is a prevalent oxide compound composed of aluminum and oxygen, with the chemical formula Al2O3. This study aims to prepare aluminum oxide nanoparticles using aluminum nitrate nonahydrate Al(NO[Formula: see text] 9H2O through direct exposure to a plasma jet system using argon gas, as plasma is the fourth state of matter and a common effective method. The major study in the preparation of Al2O3 nanoparticles, which is a physical method, examines the effect of aluminum oxide nanoparticles against bacteria and fungi. Different methods were used for diagnosis. The X-ray diffraction examination showed an average particle size of 37.8 nm. It was also found through the UV-Vis examination that a surface plasmon resonance was formed at 300 nm with an energy gap value of 4.21 eV. The electron microscope field emission scanning (FE-SEM) was used to study the surface morphology. The results of biological testing showed that aluminum oxide nanoparticles have high antibacterial and antifungal activity.

Comparative life cycle assessment of non-thermal plasma for the removal of pharmaceuticals from wastewater

Wastewater effluents are a continuous source of pharmaceuticals in water bodies, which pose a serious environmental threat to aquatic ecosystems. This work provides a comprehensive technical, environmental and cost assessments of different advanced quaternary treatments for wastewater effluents, with special focus on novel Non-Thermal Plasma technology. For this porpouse Non-Thermal Plasma, Sand Filtration + Ozonation, Ultrafiltration, Ultrafiltration + Nanofiltration and Ultrafiltration + Reverse Osmosis technologies were compared with UV disinfection-based technology. This work applies the Life Cycle Analysis tool for the impact environmental assessment using both ReciPE 2016(H) method and, for a more detailed analysis of the contribution of pharmaceuticals to freshwater ecotoxicity category of impact, the USETOX method, which was integrated with 7 new characterisation factors. The results obtained showed overall removal efficiency of pharmaceuticals always higher than 80%, with performances in descending order of Ultrafiltration + Reverse Osmosis > Sand Filtration + Ozonation > Ultrafiltration + Nanofiltration > Non-Thermal Plasma, being Sand Filtration + Ultraviolet disinfection and standalone Ultrafiltration comparatively not suitable for pharmaceuticals removal. Regarding the target pharmaceuticals proposed on the EU Directive 271/91 revision, the Non-Thermal Plasma perform better towards venlafaxine than Sand Filtration + Ozonation, and towards diclofenac and carbamazepine than Ultrafiltration + Nanofiltration. Ultrafiltration + Nanofiltration and Non-Thermal Plasma showed better environmental performance than Sand Filtration + Ozonation and Ultrafiltration + Reverse Osmosis in 7 out of 18 categories of impact (ReciPe method), with Ultrafiltration + Nanofiltration being more advantageous than Non-Thermal Plasma in human and ecotoxicity-related categories of impact, and Non-Thermal Plasma more advantageous in Global Warming, Fossil Resource Scarcity, and Fine Particulate Matter Formation. Regrading Freshwater Ecotoxicity (USEtox method), the quaternary treatment configuration and its energy demand affect the Freshwater final value of impact more than the presence of pharmaceuticals. Under the conditions tested, the Non-Thermal Plasma provided the lower OPEX (0.24 € m−3) than other tested technologies, showing an interesting compromise between pharmaceuticals removal efficiency, environmental impacts, and economic operational cost.

High-Speed Removal Process for Organic Polymers by Non-Thermal Atmospheric-Pressure Spark Discharge at Room Temperature and Its Mechanism

Heel marks (HMs) are a type of dirt stain consisting of polyester-based urethane rubber on polyvinyl chloride (PVC) floor surfaces. The rapid removal of HMs was achieved by using non-thermal atmospheric-pressure plasma technology. Mimetic HMs were prepared by coating PVC floor samples with HMs to a thickness of 13.9 μm. The removal area, thickness, and volume were measured after applying spark discharges at high voltage and a repetition rate of 50 kHz. The treated surfaces were analyzed by using X-ray photoelectron spectroscopy (XPS) and pyrolysis–gas chromatography with time-of-flight mass spectrometry (Py-GC/TOFMS). Removal rates of 20 mm2/min in area, 52 mm3/min in volume, and 7 μm/min in depth were achieved with an inter-electrode distance of 10.0 mm and an air flow rate of 20 standard liters per minute. A removal depth of 10 μm/min was achieved without air supply. The mechanism of stain removal by spark discharge was modeled by decomposing the original high-molecular-weight molecules in polyester-based urethane rubber into low-molecular-weight molecules, such as methylene diisocyanate (MDI) components. The results of this study may facilitate the development of a novel electric vacuum cleaner capable of removing floor stains.

Experimental Investigation on Compact Current Non Thermal Plasma Assisted Hydrocarbon Reforming Hydrogen Rich Gas

On-board vehicle hydrogen-rich gas extraction of gasoline reforming utilizing for fuel cells and GDI-engine lean burn combustion enhancement NOx trap applications. A non-thermal plasma discharge electrode that produces a reduce current, increased voltage 15kV source arc plasma fuel reformer is designed to operate at an arc frequency of 50 Hz. The operating factors gasoline equivalence ratio between 4 and 6.and electronically control by the fuel injector and eliminating ground spark plug plasma arc generation. The plasma arc non-thermal reformer gasoline converted into gas that contains partial oxidation contains combustible gases like hydrogen (H2), CO, non-combustible gases like CO2, N2, and a small quantity of H2O. The nonthermal plasma technology alternative for on-board hydrogen vehicle applications.

Exploring non-thermal plasma technology for microalgae removal

The global population and economic development surge has substantially increased water demand, resulting in heightened sewage and pollutant generation, posing environmental hazards. Addressing this challenge necessitates the implementation of efficient and cost-effective water reclamation methods. Non-thermal plasma technology (NTP) has emerged as a promising solution, garnering attention for its superior efficiency compared to alternatives. While existing studies have predominantly focused on energy efficiency and pollutant removal, limited research has delved into the biological removal aspect, particularly concerning algae. This study utilized a dielectric barrier plasma diffuser to eliminate Spirulina microalgae (Spirulina platensis) from wastewater solutions, demonstrating higher algae removal and superior mass transfer compared to alternative plasma methods. The effect of sample volume, input voltage and power, flow rate, and initial solution concentration on the algae removal was investigated. Investigation of operational parameters revealed the best condition resulting in a 98 % removal rate and 20 g/kWh energy efficiency. The best conditions for the removal of Spirulina microalgae were considered in a sample volume of 50 mL, a voltage of 7.6 kV, a flow rate of 700 mL/min, and an initial solution concentration of 1280 mg/liter. Scanning Electron Microscope (SEM) images illustrated the impact of active species on cell structure, leading to the destruction of spiral form and loss of reproductive ability. The study underscores the potential of NTP for efficient algae removal and identifies key active species involved in the process. The removal of Spirulina microalgae was attributed to a combination of singlet oxygen (1O2), hydroxyl radicals, and ozone.

Experimental investigation and Monte Carlo simulation of landfill leachate treatment using physicochemical method and a non-thermal plasma reactor

ABSTRACT Leachate treatment is one of the challenging subjects in the field of waste management. Leachate as a dumpling sites hazardous byproduct due to the high concentration of chemical oxygen demand (COD) and toxic compounds with dark colour is a potential pollutant of the environment, causing a lot of problems in the absence of treatment and direct discharge to the environment. In this study, the combinatory performance of sequential chemical flocculation and coagulation process and non-thermal plasma (NTP) technology on leachate from the Sarāvān city former controlled landfill, Iran, was investigated. The outcomes of Jar test illustrated that hydrated aluminium sulphate (PAC) was selected the best coagulant compared with hydrated aluminium sulphate (HAS) and ferric chloride (FC) to remove suspended solids and colour. The optimised parameters for 10% PAC pre-treatment were obtained 3 g lime and cationic 0.1 g polyelectrolyte per 1 litre of leachate. After pre-treatment by using jar test, NTP was used to remove turbidity, colour, COD and so forth. The sequential system-based all stages of pretreatment and NTP diminished the turbidity and colour removal to 98.6% and 99.2%, respectively. Furthermore, COD, BOD5, TSS, and TDS were also reduced. As a result, combination of pre-treatment and NTP technology are able to remove the landfill leachate effectively. Monte Carlo calculations exhibited that Al3+ and H2O2 had the most effects to decompose HA (Humic acid) compound in physicochemical pre-treatment and treatment stages.

The Application Progress of Nonthermal Plasma Technology in the Modification of Bone Implant Materials.

With the accelerating trend of global aging, bone damage caused by orthopedic diseases, such as osteoporosis and fractures, has become a shared international event. Traffic accidents, high-altitude falls, and other incidents are increasing daily, and the demand for bone implant treatment is also growing. Although extensive research has been conducted in the past decade to develop medical implants for bone regeneration and healing of body tissues, due to their low biocompatibility, weak bone integration ability, and high postoperative infection rates, pure titanium alloys, such as Ti-6A1-4V and Ti-6A1-7Nb, although widely used in clinical practice, have poor induction of phosphate deposition and wear resistance, and Ti-Zr alloy exhibits a lack of mechanical stability and processing complexity. In contrast, the Ti-Ni alloy exhibits toxicity and low thermal conductivity. Nonthermal plasma (NTP) has aroused widespread interest in synthesizing and modifying implanted materials. More and more researchers are using plasma to modify target catalysts such as changing the dispersion of active sites, adjusting electronic properties, enhancing metal carrier interactions, and changing their morphology. NTP provides an alternative option for catalysts in the modification processes of oxidation, reduction, etching, coating, and doping, especially for materials that cannot tolerate thermodynamic or thermosensitive reactions. This review will focus on applying NTP technology in bone implant material modification and analyze the overall performance of three common types of bone implant materials, including metals, ceramics, and polymers. The challenges faced by NTP material modification are also discussed.

A general strategy for synthesizing bimetallic Pt-based nanoclusters supported on carbon black via non-thermal plasma

Downsizing Pt-based catalysts to generate a higher surface-to-volume ratio and maximize atom utilization efficiency has been recognized as an effective strategy to achieve high mass activity. However, the synthesis of homogeneous, ultra-small bimetallic nanoclusters remains a significant challenge due to the difficulties in controlling stoichiometry and surface state control, large miscible gaps between different metals and surface state changes induced by the reaction gas environment. In this paper, bimetallic Pt-based nanoclusters such as PtPd, PtRu, PtCu deposited on carbon black (Vulcan XC72R) were fabricated by the reduction of H2 plasma.The structure and morphology of those prepared catalysts were revealed by HAADF-STEM, HR-TEM, EDS and XPS. The results indicated the prepared Pt-based nanoclusters displayed high dispersibility and small size owning to the non-equilibrium characteristics of non-thermal plasma (NTPs). The average sizes of PtPd, PtRu and PtCu were 2.06 ± 0.68 nm, 3.66 ± 1.34 nm and 1.98 ± 0.7 nm, respectively. Meanwhile, the synthesized PtPd nanoclusters with the ratio of 3:4 exhibited high catalytic activity in the hydrogen evolution reaction (HER). The Pt3Pd4/VR-P displayed a low overpotential (19 mV) at 10 mA/cm2 and achieved a high mass activity of 5.4 A/mg for HER in 0.5 M H2SO4 solution, which was 13.8 times higher than those of the commercial Pt/C catalysts. Moreover, the Pt3Pd4/VR-P demonstrated excellent stability with a negatively shifting about 40 mV after 10,000 cycles at a current density of 10 mA/cm2, which was close to that of JM-Pt/C (32 mV). The results prove NTPs technology is effective for the preparation of bimetallic Pt-based nanoclusters.

Mechanical and statistical pathway for the experimental investigation of the dairy industry effluent using non-thermal plasma

Globally, there is still a demand for effective removal of industrial pollutants using modern treatment technologies. Therefore, to achieve industrial implementation, treatment efficiency and energy demand, at present the new Non-Thermal Plasma (NTP) technology is adopted to treat the dairy industry pollutants. Falling Film Dielectric Barrier Discharge reactor (FF-DBD) is developed whereas the reactor is further characterized by the various operating parameters including electric field, gas source, flow rate and pH for the removal of COD and lactose content for different experimental conditions. In this present study, experimental works are carried out in ‘lab-scale experimental hardware to analyze the degradation efficiency of dairy effluent based on COD and lactose. For the maximum of 68 % and 75.56 % of COD and lactose removal is achieved at the maximum voltage of 30 k,Vp-p. Moreover, the interaction between COD and lactose is analyzed by using ANOVA and the p-value is < 0.001. Comparing to the air, oxygen as a discharge gas in a DBD reactor gives more treatment efficiency because it produces more oxygen-based oxidative species. Further the 2D - simulation model is employed to find the velocity profile of effluent inside the FF-DBD reactor.

Rapid susceptibility of Carbapenem resistant Pseudomonas aeruginosa and its resistance gene to non-thermal plasma treatment in a batch reactor

The critically ranked carbapenem-resistant Pseudomonas aeruginosa has been observed to infect immunocompromised patients that consume polluted waters, leading to critical infections and more hospital costs. To save lives and unburden the public health sectors of preventable costs, non-thermal plasma (NTP) technology was investigated as an alternative disinfection step that could be applied in wastewater treatment plants (WWTPs) to inactivate this bacterium and its prominent carbapenem resistance gene (blaNDM-1). Culture and molecular-based techniques were employed to confirm carbapenem resistance in P. aeruginosa (27853). Culture suspensions of carbapenem-resistant ATCC P. aeruginosa (16 h culture) were prepared from confirmed isolates and subjected to plasma treatment at varying time intervals (3 min, 6 min, 9 min, 12 min and 15 min) in triplicates. The plasma treated samples were evaluated for re-growth and the presence of blaNDM-1. The treatment resulted in a 0.68 log reduction after 3 min and the highest log reduction of ≥8 after 12 min, suggesting that plasma disinfection has a great potential to be an efficient tertiary treatment step for WWTPs. Moreover, the gel image showed that band intensity of blaNDM-1 reduced with treatment time, thereby suggesting a probable reduction of amplified genes. Notwithstanding, longer treatment time, a grounded electrode with a larger surface (≥ 40 mm diameter) and/or oxygen-containing feeding gas is warranted to completely inactivate its antibiotic resistance gene (ARG), which might be bound by biofilms as they seem to protect P. aeruginosa from the action of non-thermal plasma (NTP) disinfection.

Non-thermal obliteration of critically ranked carbapenem-resistant Acinetobacter baumannii and its resistance gene in a batch atmospheric plasma reactor

Wastewater treatment plants (WWTPs) have been implicated as direct key reservoir of both antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs) associated with human infection, as high concentrations of ARBs and ARGs have been detected in recycled hospital wastewater. Among the ARBs, the carbapenem-resistant Acinetobacter baumannii has been ranked as priority 1 (critical) pathogen by the World Health Organization (WHO), due to its overwhelming burden on public health. Therefore, this study is aimed at investigating non-thermal plasma (NTP) technology as an alternative disinfection step to inactivate this bacterium and its ARGs. Culture-based method and PCR were employed in confirming the carbapenem resistance gene blaNDM-1 in A. baumannii (BAA 1605). Suspension of carbapenem-resistant A. baumannii (24 h culture) was prepared from the confirmed isolate and subjected to plasma treatment at varying time intervals (3 min, 6 min, 9 min, 12 min, and 15 min) in triplicates. The plasma-treated samples were evaluated for re-growth and the presence of the resistance gene. The treatment resulted in a 1.13 log reduction after 3 min and the highest log reduction of ≥ 8 after 15 min, and the results also showed that NTP was able to inactivate the blaNDM-1 gene. The log reduction and gel image results suggest that plasma disinfection has a great potential to be an efficient tertiary treatment step for WWTPs.

Biphasic gas–liquid millifluidic system for carbon dioxide plasma chemistry: Application to controlled selective epoxidation

The integration of nonthermal CO2 plasma for olefin epoxidation within a biphasic gas–liquid millifluidic system is presented. In this innovative approach, CO2 is efficiently reduced to CO and O atoms, facilitating the epoxidation of olefins. Analysis of the system’s effluent shows that epoxide production efficiency and yields, optimized to 90 %, significantly surpass those of traditional plasma methods, attributed to the enhanced gas–liquid mass transfer within the millifluidic environment. Moreover, O atoms generated from CO2 decomposition was observed to travel up to 30 mm in the post-plasma discharge area, enhancing the gas–liquid flow system’s efficiency. By capturing O atoms in the epoxidation reaction with olefins, the reverse reaction with CO is minimized, which in turn, markedly increases CO yield under the same conditions without olefins. These findings demonstrate that olefin epoxidation can be activated through CO2 plasma discharge in a controlled, selective, and catalyst-free manner under gentle conditions. This synergy between nonthermal plasma and millifluidic technologies paves the way for overcoming current limitations in plasma chemistry with industrial relevance.

Non-thermal plasma technology for air pollution control and bacterial deactivation

Non-thermal plasma technology for air pollution control and bacterial deactivation

Oxidative Desulfurization of Model Fuel by Non-Thermal Plasma Technology

Oxidative Desulfurization of Model Fuel by Non-Thermal Plasma Technology

Mechanistic study of cefixime degradation with an atmospheric air dielectric barrier discharge – Influence of radical scavengers and metal ion catalyst

The ineffective removal of antibiotic residues and their metabolites by conventional wastewater treatment setups lead to their continuous discharge into the environment, causing risks to both aquatic life and human health. This study explored the use of a non-thermal plasma (NTP) generated by atmospheric air for the degradation of cefixime (CFX), a widely consumed and recalcitrant antibiotic. This study achieved a complete degradation of CFX using an NTP technology in 8 min treatment time at 6 kV and 20 kHz applied AC voltage and frequency, respectively using a high voltage alternating current power supply unit. An energy yield of 0.42 g/kWh was estimated. The degradation of the pollutant was influenced by solution flow rate, applied voltage and the solution characteristics. Five degradation by-products were identified based on quadrupole time-of-flight (Q-TOF) mass spectrum (MS) analysis and a possible degradation pathway for the pollutant was proposed. Also, radical scavenger experiments were set up to understand the specific chemical species facilitating CFX degradation. The effect of Fe2+ catalyst on the degradation of CFX was investigated in the aqueous solution. This low-cost metal ion catalyst has been known to improve the degradation of organic compounds by facilitating the oxidizing power of H2O2. Considering this, a new idea was examined in this study which was the degradation of the antibiotic in the presence of both Fe2+ catalyst and some radical scavengers (iso-propyl alcohol – IPA, tert-butyl alcohol – TBA, and sodium hydrogen carbonate – NaHCO3). When Fe2+ was introduced into CFX solutions containing TBA, IPA and NaHCO3, respectively, the degradation and kinetics increased by at least 33 %. In these mixed additives, the degradation of the pollutant was enhanced by the consumption of H2O2.

Analyzing atmospheric plasma's potential for diesel soil remediation: Insightful mechanisms

The remediation of diesel-contaminated soil is a critical environmental concern, driving the need for effective solutions. Recently, the methodology of Non-thermal Atmospheric Plasma (NTAP) technology, which is equipped with a Dielectric Barrier Discharge (DBD) electrode and has become a feasible approach, was proven to be viable. The reactive species from the plasma were exposed to the contaminated soil in this investigation using the NTAP technique. The reacted soil was then extracted using dichloromethane, and the amount of Total Petroleum Hydrocarbon (TPH) removed was assessed. Investigation into varying power levels, treatment durations, and hydrogen peroxide integration revealed significant findings. With an initial concentration of 3086 mg of diesel/kg of soil and a pH of 5.0, 83% of the diesel was removed from the soil at 150 W in under 20 min. Extended exposure to NTAP further improved removal rates, highlighting the importance of treatment duration optimization. Additionally, combining hydrogen peroxide (H2O2) with NTAP enhanced removal efficiency by facilitating diesel breakdown. This synergy offers a promising avenue for comprehensive soil decontamination. Further analysis considered the impact of soil characteristics on removal efficacy. Mechanistically, NTAP generates reactive species that degrade diesel into less harmful compounds, aiding subsequent removal. Overall, NTAP advances environmental restoration efforts by offering a quick, economical, and environmentally benign method of remediating diesel-contaminated soil especially when used in tandem with hydrogen peroxide.

Adjusting Ag0 on oxygen-deficient Ag/MnO2 through electronic metal-support interaction to enhance mineralization of toluene in post-plasma catalytic system

While nonthermal plasma (NTP) technology exhibits notable efficacy in removing volatile organic compounds (VOCs), its practical application is impeded by a restricted carbon dioxide (CO2) selectivity. In this work, Ag-loaded α-MnO2 nanorods with strong electronic metal-support interaction (EMSI) were synthesized to enhance the mineralization of toluene in post-plasma system (PPC). EMSI was constructed between Ag species and MnO2 by anchoring Ag on hydroxyl groups. Increasing Ag loading facilitated the generation of oxygen vacancies, which promoted electron transfer from MnO2 to Ag sites, reinforcing EMSI and favoring the formation of Ag0. The results showed that the 3% Ag-loaded α-MnO2 nanorods exhibited better activity than bare MnO2, with a remarkable boost in CO2 selectivity to 77.5%, far exceeding the 33% CO2 selectivity of MnO2. It was concluded that both oxygen vacancies and Ag0 affected the toluene conversion by enhancing the conversion of ozone (O3) to reactive oxygen species (ROS). Through in-situ DRIFTS, it was found that Ag0 transformed O3 to a higher concentration of atomic oxygen (O*), capable of degrading organic intermediates to CO2. Additionally, Ag0 facilitated the direct ring-opening of adsorbed toluene. This research introduces a novel method for designing catalysts with EMSI to improve the mineralization of VOCs.

Effect of the component and the concentration ratio on the removal of volatile organic compound mixtures by non-thermal plasma

The feasibility and efficiency of the degradation of volatile organic compounds (VOCs) by non-thermal plasma (NTP) has been extensive investigated and proved in laboratory experiments with single target component. In practical, multicomponent VOCs are emitted during industrial production. It is urgent need to study the abatement of multicomponent VOCs to evaluate the effectiveness of NTP technology in application, and explore the impact of interactions between VOCs components on degradation efficiency. This study focused on the degradation of VOCs mixtures composed of toluene (TOL), acetone (AC), and ethyl acetate (EA) by dielectric barrier discharge (DBD) plasma in room temperature. Through changing the target gas in turn and the concentration ratio of additive gas in binary mixture, the influence of the composition and the concentration ratio of the additive gases on the target gas degradation have been investigated by comparing the decomposition of the single compound. The results showed that AC and EA had little or no inhibitory effect on degradation of TOL. When AC was added and degraded together with TOL, the degradation rate of TOL remained almost unchanged with slight fluctuations in the range of 75.3 ± 1.0% as the ratio of added AC increased. However, TOL significantly inhibited the degradation of EA and AC, and more seriously on AC. When the ratio of added TOL increased, the degradation rates of EA or AC changed from 41.1% or 34.5% to 29.8% or 12.2%, which were 11.3% or 22.3% reduced respectively. It is indicated that there was a mutual inhibitory effect between the AC and EA when they were degraded together, and a stronger inhibitory effect of EA on AC was observed. When the ratio of added AC to EA changed from 0:1 to 3:1, the degradation rate of EA decreased by 9.5%, from 49.8% to 40.3%. When the ratio of added EA to AC changed from 0:1 to 3:1, the degradation rate of AC decreased by 16.0%, from 37.9% to 21.9%.

Synergistic effect on simultaneous treatment of Cr(VI) and chloramphenicol using a non-thermal plasma technology

Toxic organic and heavy metal contaminants commonly exist in industrial waste stream(s) and treatment is of great challenge. In this study, a dielectric barrier discharge (DBD) non-thermal plasma technology was employed for the simultaneous treatment of two important contaminants, chloramphenicol (CAP) and Cr(VI) in an aqueous solution through redox transformations. More than 70% of CAP and 20% of TOC were degraded in 60 min, while Cr(VI) was completely removed in 10 min. The hydroxyl radicals were the main active species for the degradation. Meanwhile, the consumption of hydroxyl radicals was beneficial to the reduction of Cr(VI). The synergistic effect was investigated between CAP degradation and Cr(VI) reduction. The reduction of Cr(VI) would be enhanced in the presence of CAP with a low concentration and could be inhibited under a high concentration, because part of hydroxyl radicals could be consumed by the low-concentration CAP and the obtained intermediates with a higher kinetic rate. However, CAP with a high concentration could react with such reductive species as eaq− and •H, which could compete with Cr(VI) and inhibit the reduction. In addition, the presence of Cr(VI) enhanced the degradation and mineralization of CAP; the study of obtained intermediates indicated that the presence of Cr(VI) changed the degradation path of CAP as Cr(VI) would react with reductive species, enhance the generation of hydroxyl radicals, and cause more hydroxylation reactions. Moreover, the mechanism for the simultaneous redox transformations of CAP and Cr(VI) was illustrated. This study indicates that the DBD non-thermal plasma technology can be one of better solutions for simultaneous elimination of heavy metal and organic contaminants in aquatic environments.

Improved hydrolysis of sewage sludge by air-assisted non-thermal plasma for enhanced biomethane recovery.

Conventional pretreatment technologies have been assessed to resolve the slow hydrolysis of sewage sludge, but high operating costs have prevented their wide use. This study investigated non-thermal plasma (NTP) technologies as an alternative to promote anaerobic digestion (AD). Various contact time (CT) and temperature (T) conditions were used to assess how NTP pretreatment improves the methane conversion of organics in sewage sludge. A multi-response surface model (RSM) using a central composite design (CCD) identified the optimal CT (4.6h) and T (45°C). This statistical optimization of NTP pretreatment led to an enhanced biochemical methane potential of 297 ± 46mL CH4 g-1 COD by reducing operating cost as power consumption as low as 0.08 USD L-1. The result was comparable to those of other advanced oxidation processes (0.14 - 0.60 USD L-1) demonstrating that accelerated hydrolysis of sewage sludge using NTP pretreatment show potential for improving renewable energy recovery from sewage sludge.