Influence of balance gas mixture on decomposition of dimethyl sulfide in a wire-cylinder pulse corona reactor

Mitigation Strategies of Air Pollutants for Mechanical Ventilated Livestock and Poultry Housing—A Review

The fast development of large-scale intensive animal husbandry has led to an increased proportion of atmospheric pollution arising from livestock and poultry housing. Atmospheric pollutants, including particulate matter (PM), ammonia (NH3), hydrogen sulfide (H2S), and greenhouse gases (GHG), as well as other hazardous materials (e.g., gases, bacteria, fungi and viruses), have significant influences upon the local atmospheric environment and the health of animals and nearby residents. Therefore, it is imperative to develop livestock and poultry housing mitigation strategies targeting atmospheric pollution, to reduce its negative effects on the ambient atmosphere and to promote sustainable agricultural production. In this paper, we summarize the various strategies applied for reducing outlet air pollutants and purifying inlet air from mechanical ventilated livestock and poultry housing. This review highlights the current state of knowledge on the removal of various atmospheric pollutants and their relative performance. The potential optimization of processes and operational design, material selection, and other technologies, such as electrostatic spinning, are discussed in detail. The study provides a timely critical analysis to fill the main research gaps or needs in this domain by using practical and stakeholder-oriented evaluation criteria.

Emissions, measurement, and control of odor in livestock farms: A review

Odor emissions from intensive livestock farms have attracted increased attention due to their adverse impacts on the environment and human health. Nevertheless, a systematic summary regarding the characteristics, sampling detection, and control technology for odor emissions from livestock farms is currently lacking. This paper compares the development of odor standards in different countries and summarizes the odor emission characteristics of livestock farms. Ammonia, the most common odor substance, can reach as high as 4100 ppm in the compost area. Sampling methods for point and area source odor emissions are introduced in this paper, and odor analysis methods are compared. Olfactometers, odorometers, and the triangle odor bag method are usually used to measure odor concentration. Odor control technologies are divided into three categories: physical (activated carbon adsorption, masking, and dilution diffusion), chemical (plant extract spraying, wet scrubbing, combustion, non-thermal plasma, and photocatalytic oxidation), and biological (biofiltration, biotrickling, and bioscrubbing). Each technology is elucidated, and the performance in the removal of different pollutants is summarized. The application scopes, costs, operational stability, and secondary pollution of the technologies are compared. The generation of secondary pollution and long-term operation stability are issues that should be considered in future technological development. Lastly, a case analysis for engineering application is conducted.

Effects of electrode geometry on the performance of dielectric barrier/packed-bed discharge plasmas in benzene degradation

In this study, the effects of electrode geometry on benzene degradation in a dielectric barrier/packed-bed discharge plasma reactor with different electrodes were systematically investigated. Three electrodes were employed in the experiments, these were coil, bolt, and rod geometries. The reactor using the coil electrode showed better performance in reducing the dielectric loss in the barrier compared to that using the bolt or rod electrodes. In the case of the coil electrode, both the benzene degradation efficiency and energy yield were higher than those for the other electrodes, which can be attributed to the increased role of surface mediated reactions. Irrespective of the electrode geometry, the packed-bed discharge plasma was superior to the dielectric barrier discharge plasma in benzene degradation at any specific applied voltage. The main gaseous products of benzene degradation were CO, CO2, H2O, and formic acid. Discharge products such as O3, N2O, N2O5, and HNO3 were also detected in the outlet gas. Moreover, the presence of benzene inhibited the formation of ozone because of the competing reaction of oxygen atoms with benzene. This study is expected to offer an optimized approach combining dielectric barrier discharge and packed-bed discharge to improve the degradation of gaseous pollutants.

Removal of H₂S in a novel dielectric barrier discharge reactor with photocatalytic electrode and activated carbon fiber

A novel dielectric barrier discharge (DBD) reactor was applied for removal of H2S. Activated carbon fiber (ACF) and a photocatalytic electrode prepared from sintered metal fibers (SMF) were introduced into the novel reactor. H2S removal rate was enhanced dramatically due to the synergism between DBD and ACF. Peak voltage, initial concentration, resident time and humidity were important factors that influenced the H2S removal rate. 75 mg/m(3) H2S removal rate reached 99.9% at a peak voltage of 25 kV and with a resident time of 2s in the novel reactor. Humidity had an inhibition to H2S decomposition at low peak voltages. And the inhibition became slight at high peak voltages (>20 kV). The novel reactor exhibited better by-products (SO2 and O3) control than other reactors did. And it also had excellent performance stabilization in a long-term operation (30 d).

Removal of dimethyl sulfide by the combination of non-thermal plasma and biological process

A bench scale system integrated with a non-thermal plasma (NTP) and a biotricking filtration (BTF) unit for the treatment of gases containing dimethyl sulfide (DMS) was investigated. DMS removal efficiency in the integrated system was up to 96%. Bacterial communities in the BTF were assessed by PCR-DGGE, which play the dominant role in the biological processes of metabolism, sulfur oxidation, sulfate-reducing and carbon oxidation. The addition of ozone from NTP made microbial community in BTF more complicated and active for DMS removal. The NTP oxidize DMS to simple compounds such as methanol and carbonyl sulfide; the intermediate organic products and DMS are further oxidized to sulfate, carbon dioxide, water vapors by biological degradation. These results show that NTP-BTF is achievable and open new possibilities for applying the integrated with NTP and BTF to odour gas treatment.

Innovative approach for benzene degradation using hybrid surface/packed-bed discharge plasmas

An innovative plasma reactor, which generates hybrid surface/packed-bed discharge (HSPBD) plasmas, was employed for the degradation of benzene. The HSPBD reactor was found to display remarkably better benzene degradation, mineralization, and energy performance than surface or packed-bed discharge reactors alone. The degradation efficiency, CO2 selectivity, and energy yield in the HSPBD reactor were 21%, 11%, and 3.9 g kWh-1 higher, respectively, than in a surface discharge reactor and 30%, 21%, and 5.5 g kWh-1 higher, respectively, than in a packed-bed discharge reactor operated at 280 J L-1. Particularly, the benzene degradation in the HSPBD reactor exhibited an unambiguous synergistic enhancement rather than a simple additive effect using the surface discharge and packed-bed discharge reactors. Moreover, in the HSPBD reactor, the formation of byproducts, such as NO2, was suppressed, while O3 was promoted. The use of N2 as the carrier gas was found to be effective for benzene degradation because of the fast reaction rate of N2(A3∑u+) with benzene, and oxygen species derived from the dissociation of O2 were found to be significant in the mineralization process. Thus, the addition of O2 to N2 allows for efficient degradation of benzene, and the optimized amount of O2 was determined to be 3%.

Regeneration of activated carbon saturated with odors by non-thermal plasma

The dielectric barrier discharge (DBD) regeneration process of an activated carbon (AC) saturated with dimethyl sulfide was studied on a laboratory scale. The results showed sustainable high regeneration efficiency (RE) (>90%) in successive regeneration cycles (10 cycles). Energy density, humidity and oxygen content were key factors for DBD system, with optimum conditions of 761JL(-1), 0-1vol% and 5%, respectively. The high efficiency was likely attributed to the improvement of structure and surface properties of AC by DBD. After the first regeneration, surface area, micropore volume and total pore volume of AC increased by 8%, 23% and 15% respectively, while average pore size decreased by 9.5%. The number of carboxylic groups doubled (from 0.22 to 0.48mmolg(-1)) while that of phenolic groups remarkably decreased (from 0.48 to 0.26mmolg(-1)) after successive regeneration cycles, which helped to maintain high RE. The results suggested DBD as a novel, efficient alternative process for odor-saturated AC regeneration.

Potential of electric discharge plasma methods in abatement of volatile organic compounds originating from the food industry

Increased volatile organic compounds emissions and commensurate tightening of applicable legislation mean that the development and application of effective, cost-efficient abatement methods are areas of growing concern. This paper reviews the last two decades' publications on organic vapour emissions from food processing, their sources, impacts and treatment methods. An overview of the latest developments in conventional air treatment methods is presented, followed by the main focus of the paper, non-thermal plasma technology. The results of the review suggest that non-thermal plasma technology, in its pulsed corona discharge configuration, is an emerging treatment method with potential for low-cost, effective abatement of a wide spectrum of organic air pollutants. It is found that the combination of plasma treatment with catalysis is a development trend that demonstrates considerable potential. The as yet relatively small number of plasma treatment applications is considered to be due to the novelty of pulsed electric discharge techniques and a lack of reliable pulse generators and reactors. Other issues acting as barriers to widespread adoption of the technique include the possible formation of stable oxidation by-products, residual ozone and nitrogen oxides, and sensitivity towards air humidity.

A novel dielectric barrier discharge reactor with photocatalytic electrode based on sintered metal fibers for abatement of xylene

A novel dielectric barrier discharge (DBD) reactor was made for the abatement of xylene. This reactor has a photocatalytic electrode prepared by a modified anodic oxidation method which was proposed in this work. The photocatalytic electrode has nano-TiO(2) deposited on sintered metal fiber (SMF). The reactor using the nano-TiO(2)/SMF electrode shows much better performance in abating xylene compared with reactors using other electrodes such as resistance wire or SMF. The conversion ratio of xylene reaches 92.7% in the novel reactor at a relatively voltage (23.6 kV). This ratio is much higher than the conversion ratios of xylene in the traditional reactors with resistance wire or SMF electrodes, which are ~64.7%. The selectivity of CO(2) of the reactor using the nano-TiO(2)/SMF electrode (300 pps, 23.6 kV) was observed to be 86.6%, which is about twice as large as that of a traditional reactor using a resistance wire electrode. If a traditional DBD reactor is replaced by the novel reactor, at the same specific input energy, the energy yield can increase from 0.391 to 0.556 mg/kJ. Finally, the xylene decomposition mechanism with the nano-TiO(2)/SMF electrode was also briefly discussed.

Potential particulate pollution derived from UV-induced degradation of odorous dimethyl sulfide

UV-induced degradation of odorous dimethyl sulfide (DMS) was carried out in a static White cell chamber with UV irradiation. The combination of in situ Fourier transform infrared (FT-IR) spectrometer, gas chromatograph-mass spectrometer (GC-MS), wide-range particle spectrometer (WPS) technique, filter sampling and ion chromatographic (IC) analysis was used to monitor the gaseous and potential particulate products. During 240 min of UV irradiation, the degradation efficiency of DMS attained 20.9%, and partially oxidized sulfur-containing gaseous products, such as sulfur dioxide (SO2), carbonyl sulfide (OCS), dimethyl sulfoxide (DMSO), dimethyl sulfone (DMSO2) and dimethyl disulfide (DMDS) were identified by in situ FT-IR and GC-MS analysis, respectively. Accompanying with the oxidation of DMS, suspended particles were directly detected to be formed by WPS techniques. These particles were measured mainly in the size range of accumulation mode, and increased their count median diameter throughout the whole removal process. IC analysis of the filter samples revealed that methanesulfonic acid (MSA), sulfuric acid (H2SO4) and other unidentified chemicals accounted for the major non-refractory compositions of these particles. Based on products analysis and possible intermediates formed, the degradation pathways of DMS were proposed as the combination of the O(1D)- and the OH- initiated oxidation mechanisms. A plausible formation mechanism of the suspended particles was also analyzed. It is concluded that UV-induced degradation of odorous DMS is potentially a source of particulate pollutants in the atmosphere.

Abatement of malodorants from pesticide factory in dielectric barrier discharges

Traditional odor control methods are limitative technically and economically for the abatement of odor from pesticide factory due to its toxicity and complicated composition. Non-thermal plasma (NTP) methods, typically characterized by high removal efficiency, energy yields and good economy, offer possible alternative solutions. This paper provides laboratory scale experimental data on the removal of simulated odors from pesticide factory with various humidity (0-0.8 vol%) and oxygen contents (0-21%) by a dielectric barrier discharge (DBD) reactor. Peak voltage and initial dimethylamine (DML) concentration are important factors that influence the DML removal efficiency and energy yield. The conversion of DML of 761 mg/m(3) reaches 100% at a peak voltage of 41.25 kV. Under the experiment conditions, the conversion of DML increases with an increase of oxygen contents. And the highest DML conversion was achieved with the gas stream containing 0.3% water. Simultaneously, the concentration of O(3) and OH radical in reactor was measured. Higher conversion, higher energy yield and fewer byproducts were found in mixed odor (DML+dimethyl sulfide (DMS)) treatment than that in single odor treatment. The energy yield is promoted from 2.13 to 5.20mg/kJ.