Abatement Performance Research Articles

Biodegradation of alkali lignin by Bacillus flexus RMWW II: analyzing performance for abatement of rice mill wastewater.

A potential bacterium Bacillus flexus RMWW II has been isolated from rice mill effluent, and examined for its decolorizing potential for lignin-mimicking dyes. The biodegradation of alkali lignin by the rod-shaped, Gram-positive, oxidase and catalase-positive Bacillus flexus RMWW II bacteria is due to its uptake of lignin as the sole carbon source. The lignin degradation was 100% at a lignin concentration of 50 mg L-1 but the degradation reduced to 20% at 400 mg L-1. The bacterial-mediated biodegradation of alkali lignin was suitably explained by the Edward kinetics model with a maximal specific biodegradation rate (qmax) of 0.056 h-1 and true specific biodegradation rate (q*) of 0.042 h-1. The non-toxic nature of the metabolites of alkali lignin after bacterial degradation was illustrated by phytotoxicity studies. This bacterium was utilized to treat complex rice mill wastewater, as lignin is one of the major components of the effluent. A considerable reduction of 84% of chemical oxygen demand (COD) was observed in a batch reactor in 70 h of operation. The bacterial treatment results for the actual rice mill effluent indicate that Bacillus flexus RMWW II could be a promising agent for microbial remediation of lignin-laden raw rice mill wastewater.

Barriers to low-carbon warehousing and the link to carbon abatement

Purpose Warehouses are large emitters of greenhouse gases and their impact on climate change is under increasing focus. The purpose of this paper is to investigate the barriers that inhibit the adoption of low-carbon warehousing in Asia-Pacific and their links to carbon abatement performance. Design/methodology/approach An exploratory conceptual model was first developed from a literature review of the general barriers to sustainable supply chain practices and hence potentially in low-carbon warehousing. A large contract logistics services provider in the Asia-Pacific served as the subject of a case study. The perceived barriers to low-carbon warehousing were derived from an internal survey of respondents from the case company and regressed against carbon abatement outcomes at that organization’s operations across the region. Findings Results show that the case company reduced carbon emissions by 36 percent on a revenue-normalized basis between 2008 and 2014, but with relatively lower success in emerging markets vs mature markets. An Elastic Net regression analysis confirms that technology and government-related factors are the most important barriers in the case company’s efforts to “decarbonize” its local warehousing operations. However, results suggest that the customer-related barrier, which is highly correlated with the government barrier, is in part driven by the latter. Research limitations/implications This case study is based on a single multinational company in Asia-Pacific, but nonetheless serves as an impetus for more cross-sectional studies to form an industry-wide view. Originality/value An extended stewardship framework based on the natural resource-based view has been proposed, in which logistics services providers take on a proactive boundary-spanning role to lower the external barriers to low-carbon warehousing.

The negative effect of P addition of La/HZSM-5 on the catalytic performance in methyl mercaptan abatement

The effect of P addition on the catalytic performance of La/HZSM-5 in methyl mercaptan abatement was investigated in the present work. It was shown that the addition of phosphorus could decrease the amounts of strong acid sites over the P-doped 13%La/HZSM-5 samples, but expected coke resistance ability was not obtained. To our surprise, P-doped 13%La/HZSM-5 samples exhibited decreased activity and stability for methyl mercaptan abatement. Moreover, the 13%La/HZSM-5 supported P catalysts were prepared and characterized by NH3-TPD, FT-IR, XRD and XPS, and it was found that the introduction of P species into La/HZSM-5 catalyst provokes a reaction with La2O3 and La2Ox(CO3)y species, which were reported to be active sites for methyl mercaptan conversion. As a result, P addition generated some inactive species such as AlPO4, Al(PO3)3, LaPO4 and La(PO3)3 species, causing the deactivation of the catalyst. These results conversely proved the necessary presence of active La2O3 and La2Ox(CO3)y species in the La/HZSM-5 catalyst for eliminating CH3SH.

NO Removal by Plasma-Enhanced NH3-SCR Using Methane as an Assistant Reduction Agent at Low Temperature

The effects of using CH4 as an assistant reduction agent in plasma-assisted NH3–SCR were investigated. The new hybrid reaction system performed better than DBD–NH3–SCR when the O2 concentration varied from 2% to 12%. Compared with DBD–NH3–SCR, DBD–NH3–CH4–SCR (NH3:CH4 = 1:1) showed a more significant promotion effect on the performance and N2 selectivity for NOX abatement. When the O2 concentration was 6% and the SIE was 512 J/L, the NO removal efficiency of the new hybrid system reached 84.5%. The outlet gas components were observed via FTIR to reveal the decomposition process and its mechanism. This work indicated that CH4, as an assistant agent, enhances DBD–NH3–SCR in excess oxygen to achieve a new process with significantly higher activity at a low temperature (≤348 K) for NOX removal.

Enhanced anaerobic performance and SMD process in treatment of sulfate and organic S-rich TMBA manufacturing wastewater by micro-electric field-zero valent iron-UASB.

This study focused on investigating reactor performance, simultaneous methanogeneis and denitrifiction (SMD) process for treatment of a sulfate plus organic sulfur - rich 3,4,5-Triethoxybenzaldehyde (TMBA) manufacturing wastewater with variable COD/TSO42- (total sulfate) ratio by micro-electric field- zero-valent-iron (ZVI) UASB for 390 days. The initial COD/TSO42- was set as 1.42, 0.9 and 0.5, respectively by manually introducing sulfate. The experimental results indicated that micro-electric field- zero-valent-iron UASB was an attractive integrated option for satisfactory COD removal, nitrate reduction and a reasonable methane yield rate even at COD/TSO42- as low as 0.9. Further declining the COD/TSO42- to 0.5 can result in a moderate inhibition of SMD process. The behavior of organic S release was not inhibited over the entire experimental period. Thus, surprisingly, sulfate concentration in the effluent was always higher than that in the influent. In comparison with sludge sample at Day-1, sludge at Day-390 was characterized with high abundant Tissierella Soehngenia, Anaerolinaceae and Brevundimonas diminuta, which played critical role in promising performance in COD abatement. The relatively low abundance of sulfate reducing bacteria (SRB) such as Desulfobulbus and Desulfomicrobium can explain the lower sulfate reduction efficiency in term of high concentration of sulfate plus released from organic S-rich compounds.

THIRD‐PARTY CERTIFICATION AND THE EFFECTIVENESS OF VOLUNTARY POLLUTION ABATEMENT PROGRAMS: EVIDENCE FROM RESPONSIBLE CARE

We analyze whether third‐party certification has been successful in improving the performance of voluntary pollution abatement in the Responsible Care (RC) program which made certification mandatory from 2005 onward. We use facility‐level panel data from 821 plants between 1996 and 2010, and exploit the change in the program requirements to estimate the causal impact of third‐party certification on participating facility emissions compared to non‐RC plants in the U.S. chemical industry. We address endogenous selection into RC via instrumental variables, and explore heterogeneity in the treatment effect. We find that, on average, there is no statistically discernible effect of third‐party certification on facility emissions, and that this result is robust to a variety of models that correspond to different assumptions related to identification. (JEL Q53, Q58, L60)

Enhanced photocatalytic NOx oxidation and storage under visible-light irradiation by anchoring Fe3O4 nanoparticles on mesoporous graphitic carbon nitride (mpg-C3N4)

Several mesoporous graphitic carbon nitride (mpg-C3N4) photocatalysts were synthesized by using a hard-templating method comprising thermal polycondensation of guanidine hydrochloride over silica spheres at three different temperatures (450, 500 and 550 ℃). After structural characterization of these mpg-C3N4 photocatalysts, they were tested in NO(g) photo-oxidation under visible (VIS) light. The effects of polycondensation temperature on the structure and photocatalytic performance of mpg-C3N4 in NO photo-oxidation were studied. The results revealed that polycondensation temperature has a dramatic effect on the photocatalytic activity of mpg-C3N4 in NO photo-oxidation, where mpg-C3N4 synthesized at 500 ℃ (mpg-CN500) showed the best performance in NOx abatement as well as a high selectivity towards solid state NOx storage under VIS light illumination. Photocatalytic performance of the mpg-CN500 was further enhanced by the anchoring of 8.0 ± 0.5 wt.% Fe3O4 nanoparticles (NPs) on it. Fe3O4/mpg-CN500 photocatalyst showed both high activity and high selectivity along with extended reusability without a need for a regeneration step. Enhanced photocatalytic NOx oxidation and storage efficiency of Fe3O4/mpg-CN500 photocatalyst was attributed to their mesoporous structure, high surface area and slow electron-hole recombination kinetics, efficient electron-hole separation and facile electron transfer from mpg-CN500 to Fe3O4 domains enhancing photocatalytic O2 reduction, while simultaneously suppressing nitrate photo-reduction and decomposition to NO2(g).

Coral-like CoMnOx as a Highly Active Catalyst for Benzene Catalytic Oxidation

The search for efficient and durable catalysts for volatile organic compounds oxidation is essential for environmental remediation. Herein, porous coral-like cobalt–manganese oxide (CoMnOx) catalyst was synthesized through annealing Co–Mn–1,3-propanediol precursors at 300 °C in air and applied for the catalytic oxidation of benzene. The as-prepared CoMnOx exhibited uniform porous coral-like structure, with an improved benzene catalytic abatement performance as compared to those of Mn3O4 and Co3O4 samples prepared by the same method, respectively. According to BET, H2-TPR, O2-TPD, and XPS analysis, the as-obtained CoMnOx catalyst showed the highest BET surface area, better low-reducibility temperature, and high content of absorbed oxygen groups when compared to Mn3O4 and Co3O4, which makes significant contribution to its catalytic benzene oxidation activity. Moreover, a plausible surface reaction mechanism for benzene oxidation over CoMnOx catalyst was also proposed through the in situ DRIFTS study.

Modeling of the Competitive Storage of NOx and Sulfur in Automotive Exhaust Catalysts

Automotive exhaust catalysts with NOx and/or oxygen storage functionalities remain one of the key contributors to the high environmental performance of internal combustion engines. However, the exposure of catalysts to sulfur during real-world operation reduces progressively their NOx abatement performance. The aim of this paper is to demonstrate the capability of advanced physico-chemical models to simulate the competitive storage of sulfur and NOx on the catalyst surface and predict the various interactions, in particular the negative effect of sulfur on NOx storage and reduction efficiency. It is clarified that predicting the sulfur storage on sites where NOx can be adsorbed and on sites which are not related to NOx storage allows the accurate simulation of the NOx storage efficiency over sulfur loading. Moreover, the spatial interplay of the formed nitrites, nitrates and sulfates during the sulfation of the catalyst is highlighted. The model is validated in steady state conditions using synthetic gas bench tests and ultimately in transient conditions using actual driving cycles data derived from engine test bench measurements.

Unique mesoporous amorphous manganese iron oxide with excellent catalytic performance for benzene abatement under UV-vis-IR and IR irradiation

Mesoporous amorphous manganese iron oxide exhibits excellent catalytic activity with UV-vis-IR and IR irradiation due to light-driven thermocatalysis and novel photoactivation.

Preparation and reactivation of magnetic biochar by molten salt method: Relevant performance for chlorine-containing pesticides abatement

ABSTRACTMolten salt has been regarded as a versatile and environmental-friendly method for the material preparation and waste destruction. In this work, molten FeCl3 was utilized for the generation of magnetic biochar (MBC) derived from simultaneous activation and magnetization of biomass. The sample characterization indicated that MBC had a rough surface with BET surface area of 404 m2/g and total pore volume of 0.35cm3/g. Highly dispersed Fe3O4 and nitrogen could be deposited on the surface, leading to an excellent magnetization property. The MBC exhibited a great 2,4-Dichlorophenol (2.4-DCP) and atrazine removal performance in solution with the maximum adsorption capacity achieved 298.12 mg/g and 102.17 mg/g. Kinetics results demonstrated that MBC adsorption met the Pseudo-first-order model better. Molten NaOH-Na2CO3 was provided for the re-activation of exhausted MBC. 2,4-DCP was firstly desorbed from the MBC and subsequently destructed by the active species in the melt medium. Chlorine can be captured in the molten alkaline medium from the XRD pattern of residues.The MBC could be easily recovered with a yield of 98.2% and fixed carbon content of 61.0% after the molten salt regeneration process. With no 2,4-DCP detected, 65.5% and 31.69% of initial Cl was found in washing water and residues with the molten NaOH-Na2CO3, respectively. After 4 cycles of regeneration and adsorption, 60.55%-72.22% of initial adsorption capacity can be kept. This preparation and regeneration method can be an effective way to reduce the risk of secondary pollution of chlorinated organic compounds during adsorbent regeneration.Implications: Molten salt (MS) is a salt or multiple salts with a low melting point, and has been applied in many sectors and is regarded as a crucial role in terms of energy, environmental, and resource sustainability. In our paper, magnetic biochar was prepared by one-step activation and magnetization of fir dust using molten FeCl3∙6H2O. Meanwhile, a regeneration method using molten alkaline salt was provided. Magnetic biochar generated in our study performed well in the 2,4-dichlorophenol and atrazine adsorption. After four cycles of regeneration and adsorption, 72.2% of initial 2,4-DCP adsorption capacity can be kept.

Interaction between NO and SO2 removal processes in a pulsed corona discharge plasma (PCDP) reactor and the mechanism

The interaction between De-NO and De-SO2 from flue gas in a pulsed corona discharge plasma (PCDP) reactor was studied experimentally. A mechanism and kinetic scheme of De-NO and De-SO2 inside the PCDP reactor has been proposed and verified by comparison of the simulated and experimental results. The dominant radicals and elementary reactions are confirmed through sensitivity analysis. It has been found that there is significant interaction between the De-NO and De-SO2 processes in a PCDP reactor, and that the De-NO reactions prevail over the De-SO2 ones. The interaction consists of competitive reactions between NO and SO2 involving oxidative radicals, as well as interaction reactions between NO, SO2 and their derivatives. Through sensitivity analysis it has been found that the most effective elemental reaction to De-NO is NO + HO2 <=> OH + NO2 and that the most helpful radical is HO2. The most effective reaction for De-SO2 is SO2 + O <=> SO3 and the most helpful radical is atomic O. The study reveals the interaction mechanism between De-NO and De-SO2 in PCDP and provides a theoretical basis to improve the performance of simultaneous NO and SO2 abatement in a PCDP reactor.

Improved Performance for Toluene Abatement in a Continuous-Flow Pulsed Sliding Discharge Reactor Based on Three-Electrode Configuration

The degradation of toluene by non-thermal plasma has been evaluated in a continuous-flow sliding dielectric barrier discharge (SLDBD) reactor based on three-electrode configuration and compared with a traditional surface dielectric barrier discharge reactor. In order to optimize the electrical and geometry parameters of the SLDBD reactor, the effects of positive pulsed high-voltage (U+pulse), negative DC voltage (U−DC), pulse-forming capacitance (Cp)), inter-electrode gap, discharge length, and dielectric material have been systematically investigated. Morphological characterizations demonstrate that the steamer channels can propagate more homogeneously along the dielectric surface when a sufficient U−DC is applied under the condition of slight increase in energy. The average discharge power of the SLDBD reactor mainly depends on U+pulse, while which is less affected by U−DC. Unexpectedly, both toluene degradation efficiency and energy yield using the SLDBD increase significantly as U−DC, indicating that VOC degradation is not only determined by the energy primarily provided by U+pulse, but also depends on the drift of the ionized species induced by U−DC. Increasing Cp enhances the energy injected into the SLDBD reactor and leads to a higher toluene degradation efficiency, but lowers the energy yield when the other parameters remains unchanged. The optimal Cp is 0.67 nF. Shorter inter-electrode gap and longer discharge length appear to be more advantageous in terms of toluene degradation and energy yield. Quartz plate exhibits remarkably better degradation and energy performance than ceramic and polytef ones, leading to the maximum toluene degradation efficiency of 58% and energy yield of 0.85 g/kWh in this work.

Density Functional Theory Study on Mechanism of Mercury Removal by CeO2 Modified Activated Carbon

Doping of CeO2 on activated carbon (AC) can promote its performance for mercury abatement in flue gas, while the Hg0 removal mechanism on the AC surface has been rarely reported. In this research, density functional theory (DFT) calculations were implemented to unveil the mechanism of mercury removal on plain AC and CeO2 modified AC (CeO2-AC) sorbents. Calculation results indicate that Hg0, HCl, HgCl and HgCl2 are all chemisorbed on the adsorbent. Strong interaction and charge transfer are shown by partial density of states (PDOS) analysis of the Hg0 adsorption configuration. HCl, HgCl and HgCl2 can be dissociatively adsorbed on the AC model and subsequently generate HgCl or HgCl2 released to the gas phase. The adsorption energies of HgCl and HgCl2 on the CeO2-AC model are relatively high, indicating a great capacity for removing HgCl and HgCl2 in flue gas. DFT calculations suggest that AC sorbents exhibit a certain catalytic effect on mercury oxidation, the doping of CeO2 enhances the catalytic ability of Hg0 oxidation on the AC surface and the reactions follow the Langmuir–Hinshelwood mechanism.

Treatment of Dairy Effluents in Biological Fluidized-Bed Reactors using Oyster Shells as Ecological Garnishing

We investigated the effectiveness of a new ecological garnishing of natural origins in MBBR reactors: The shells of oysters, used for the biological treatment of dairy effluents, in the presence of fungi <em>Aspergillus niger</em> and <em>Penicillium chrysogenum</em>. The abatement performance of organic matter was compared with the same bioreactor design in the presence of a common reference support (Kaldnes K3), conventionally used on an industrial scale. Pollution parameter monitoring results (Chemical Oxygen Demand COD, total nitrogen soluble NKT, phosphorus P, suspended matter SM and biochemical oxygen demand BOD5) obtained using oyster shells as garnishing media, are favorable after only 24 h of biological treatment. Organic matter removal efficiencies are comparable sometimes even better than K3 media. All the results show that oyster shells can provide an ecological support for biofilm colonization in MBBR reactors and allow for a satisfactory pollution abatement rate.

Quantitative analysis of methane monooxygenase (MMO) explains process robustness in continuous and feast-famine bioreactors treating methane

The ability of methanotrophs to rapidly respond to intentional or accidental stress conditions caused by operational failures or process fluctuations is of utmost importance to guarantee the robustness of CH4 abatement biotechnologies. In this study, the performance of a continuous and two feast-famine (5:5 days feast-famine cycles) stirred tank reactors treating diluted CH4 emissions (4–5% v/v) was comparatively assessed for 149 days. The robustness of the three bioreactors towards a 5 days CH4 deprivation episode was thoroughly evaluated at a molecular level (pmoA gene expression level) and correlated to macroscopic process performance. The bioreactors recovered their steady-state abatement performance (in terms of CH4 elimination capacity and CO2 production rate) within 1.5–2 h following CH4 supply resumption concomitantly with a maximum in pmoA gene expression, regardless of the previous operational mode. However, while methanotrophs from the continuous unit maintained higher basal levels of pmoA expression as a strategy for a rapid CH4 metabolism initiation, the strategy of the feast-famine adapted-methanotrophs consisted on a more accurate regulation of their pmoA transcripts levels along with a higher and/or more rapid induction of the pmoA gene by CH4 availability.

Synthesis of SrFexTi1-xO3-δ nanocubes with tunable oxygen vacancies for selective and efficient photocatalytic NO oxidation

Oxygen vacancies of metal oxides play critical roles in tunning activity and selectivity for many photocatalysis mediated reactions, yet the mechanism of NO oxidation on defect enriched photocatalyst surface is seldomly discussed. Herein, we provide detailed insight into the relationship between oxygen vacancy manipulation by extrinsic Fe3+ substitution in SrTiO3 host lattice and the photocatalytic performance of NO abatement. In particular, the hydrothermal synthesized SrFexTi1-xO3-δ nanocubes (denoted as SFTO-hyd sample) rather than the impregnated-post annealing sample, enabled oxygen vacancy formation, and promoted O2 adsorption and superoxide anion radicals (O2−) formation. The SFTO-hyd (x = 5%) sample showed remarkably higher NO removal activity and selectivity under Xe lamp (λ > 420 nm), in comparison with the pristine SrTiO3, P25 and impregnation-doped SFTO sample, underlining the important roles played by coexisted Fe3+ sites and oxygen vacancies. The in situ diffuse reflectance IR spectroscopy (DRIFTS) mechanically revealed that SrTiO3 provided Lewis acidic sites for NO dark adsorption and photoreaction with nitrates as final products; the substitutional Fe3+ sites provided more active sites for NO adsorption and photoreaction with enhanced number of radicals. This study deepens the understanding of photocatalytic NO abatement on defective surface, and may also provide a simple and cost effective strategy for synthesizing efficient and selective photocatalysts for environmental remediation.

Incentive policy for reduction of emission from ships: A case study of China

Particulate matter (PM) emissions from ships in ports are a major contributor to air pollution and smog in port cities. The issue of how to reduce PM emissions has become a critical concern for port city residents and governments. This paper establishes an incentive policy to reduce PM emissions from ships in ports. Using a Panamax bulk carrier as a case study, eight alternative approaches that could be adopted by shipping companies are compared and their operational benefits are estimated. By restricting the analysis to emission control areas (ECAs), the net present value (NPV) model shows that the diesel particulate filter (DPF) is the most advantageous approach with the highest NPV, while the exhaust gas scrubber (EGS) approach is the most economically inefficient. Meanwhile, due to DPF's excellent performance in PM abatement, it is suggested that governments should prioritize the DPF approach when promoting the application of emission reduction technologies. From the perspective of social welfare, a positive social benefit of about US $20,000 will be generated over the life cycle of a ship. However, a low government pricing in China will reduce shipping companies’ operational performance as the emission control zone (ECZ) gradually expands. As a result, an appropriate subsidy scheme is necessary to encourage shipping companies to apply emission reduction technologies.

Catalytic performance for toluene abatement over Al-rich Beta zeolite supported manganese oxides

Catalytic combustion of toluene has been widely investigated due to importance of abatement of volatile organic compounds (VOCs), and in this work we have successfully prepared highly efficient heterogeneous catalysts for toluene combustion by impregnation of manganese oxides with Al-rich Beta zeolites (Beta-SDS) with H-form (MnOx/H-Beta-SDS) and K-form (MnOx/K-Beta-SDS) as well as pure siliceous Beta zeolite (MnOx/Si-Beta). Catalytic tests show that these zeolite-supported catalysts have higher activities than alumina-supported manganese oxides (MnOx/Al2O3). By comprehensive consideration of reducibility, adsorbed oxygen species, and lattice oxygen species in the catalysts, it is shown that the adsorbed oxygen species play more important roles than others for the catalytic activity. The good catalytic performance and understanding of active sites over the MnOx/H-Beta-SDS might be helpful for preparation of catalysts in VOCs abatement.

Advances regarding a new method for measuring the in situ noise abatement performance of urban noise reducing devices

Recent works regarding urban noise reducing devices have clearly shown the interest of such solutions in order to improve the sound quality in urban areas. To accompany the development of new products, it now becomes necessary to provide a technical regulatory framework for all stakeholders (manufacturers, city planners, consulting acoustical engineers, etc.) in order to guarantee quality, efficiency, and compliance with urban implementation requirements. This is the main purpose of the technical group CNEA-U, affiliated to the French commission for standardization of road traffic noise reducing devices. As part the technical group activities, a new method for measuring the in situ noise abatement performance of urban devices adapted to the urban context has been developed. The purpose of the method is to provide an indicator of the noise reduction effect of a particular product, measurable in situ but depending as little as possible on environmental effects. To reach this purpose, the parameters of the method have first been studied numerically and optimized. Then the method has been tested experimentally with several industrial prototypes in a controlled environment. In this paper, the framework of the method as well as results of preliminary analyses are presented and discussed.