Advanced Materials Research Vols. 955-959

Abstract: Experimental study the degradation efficiency of toluene by bipolar corona discharge coupled with TiO₂ photocatalysis. Bipolar corona discharge can degrade the toluene efficiently and rapidly, the final products are mainly carbon dioxide and water. Toluene removal efficiency reduces when the initial concentration of toluene increasing, while toluene removal quantity is increased. Removal of toluene decreases with the gas flow rate increasing, the removal quantity first increases and then decreases. Bipolar corona discharge and a photocatalytic coupling can inprove the degradation efficiency further. Increase of the applied voltage help to improve the removal of toluene, and also to improve the coupling effect of the photocatalyst. In optimized conditions, the removal efficiency of toluene can be more than 90%. The chemical reaction process of the toluene oxidation and the TiO₂ catalysis mechanism are discussed. It is pointed out that the OH* produced by corona discharge has important significance for rapid oxidation of toluene.

Abstract: The problem of atmospheric pollution has become the primary issue all over the world. The atmospheric pollution of the subtle particles PM2.5 has already cause a serious threat to people’s health. This passage is on the side of the causes and the characteristics of this problem. Structuring multivariate grey to prove that the model is accurately through the experiment with great applied on the part of atmospheric pollution.

Abstract: The mainly pollutant from coal-fired power plants are SO₂ and NO_X. Equipments of desulphurization and denitrification step by step are expensive and have a lower efficiency. Comparing with them, Combined Removal of SO₂ and NO_X technology have great advantages, such as, the simplified complication, better operation property, lower cost and less using area. So Combined Removal of SO₂ and NO_X in one system become the keystone in the research of cleaning technology .On the base of looking up a lot of references, this paper makes a detailed introduction about Combined Removal of SO₂ and NO_X technology lately in China and other countries, including the removal principle, the mainly advantages and defects, the present situation and the application of technology. The contrast of economic and technical standard is given .Through analysis, synthesis and comparison of two kinds of technology-Combined Removal of SO₂/NO_X in boiler and in flue gas, the key of research in future is found out. These contents can reference in improvement and exploiture of technology later.

Abstract: To investigate the removal of thiocyanate () in the actual coking wastewater through granular bio-film reactor, two lab-scale granular bio-film reactors (EGSB reactor) (RA and RB) were continuously operated at three stages for about 16 months: anaerobic vs. micro-aerobic for EGSB reactor, varied influent concentrations and varied shock-loading (abrupt and gradual shock-loading) for micro-aerobic EGSB reactor. Compared with anaerobic operation condition, micro-aerobic operation conditions could distinctly strengthen average removal in the EGSB reactor treating actual coking wastewater (47.8% vs.5.3%). At micro-aerobic operation conditions (only with 2000-5000ml·min^-1 air flow rate in the external aeration column), with 12h HRT and varied influent concentrations of 200-540mg·L^-1, the EGSB reactor could always keep very high removal of 87.6%-94.1%. Microaerobic EGSB reactor had very strong ability of supporting load shock. During the whole operation stage of continuous loads shock (for about 60 days)(from 0.32kgSCN·m^-3·d^-1 to 1.08 kgSCN·m^-3·d^-1), removal ability showed a constantly increasing tendency. Micro-aerobic EGSB reactor was a simple and high effectively treatment strategy for the in the actual coking wastewater, and meanwhile high COD, ammonia, phenol and cyanide removal was also kept in the micro-aerobic EGSB reactor.

Abstract: To investigate the possibility of simultaneous high efficient removal of COD and NH₃-N in the actual coking wastewater through micro-aerobic granular bio-film reactor, two-stage granular bio-film reactor system (EGSBI+ EGSBII) were continuously operated through two effluent recirculation ways for about 5 months: ERW1(24L.h^-1 self-recirculation) and ERW2(15 L.h^-1 self-recirculation +15 L.h^-1 crossed recirculation). Compared with ERW1, through using ERW2, the two-stage EGSB reactor system could attain high COD and NH₃-N removal efficiencies (86.7%-96.9% and 48.6%-80.4%) and low effluent NO₂^- and NO₃^- concentrations (0-25mg.L^-1 and 7-71mg.L^-1). Using ERW1, the two-stage EGSB reactor system melt with difficult of NO₂^- accumulation in the EGSBII (accompanied with low NH₃-N removal of only 41.4%). Using ERW2, the difficult of accumulation in the EGSBII was solved and simultaneously high efficient removal of NH₃-N and NO₂^- in the EGSBI was achieved.

Abstract: Aiming to the problem that the removal rates of COD, BOD₅, SS is low, economic benefits and efficiency are poor on traditional treatment of cassava starch wastewater, a new treatment which combines UASB,CASS with coagulation was presented. The UASB anaerobic reactor is used to remove most of the wastewater containing organic carbon as a pretreatment. Then, CASS aerobic treatment equipment is presented to dislodge organic carbon left and materials such as nitrogen and phosphorus as a secondary process. The coagulation process combined with UASB and CASS was applied to eliminate the residual organic matter in waste water and make the emission up to the standard finally. The UASB-CASS-Coagulation treatment was applying in a certain starch factory and the results show that the proposed method has higher efficiency compared to traditional treatment of cassava starch wastewater. It can directly bring environmental benefits by reducing emissions and economic benefits by recycling methane and yellow pulp. So it has a wider application prospects, and can be popularized easily.

Abstract: A simple process was developed for preparation of highly photoactive V and F codoped TiO₂-SiO₂ composite film. The as-prepared specimens were characterized using Brunauer–Emmett–Teller (BET) surface area, photoluminescence (PL) spectra, and UV–Vis spectroscopy. The BET results revealed that the surface area of the modified TiO₂ sample was 413 m² g^-1, while pure TiO₂ 103 m² g^-1. The PL results showed that the recombination rate of the photo-generated electrons and holes was effectively prohibited via the multi-modification. The photocatalytic activities of the films were evaluated by degradation of methyl green (MG) dye. Compared with pure TiO₂ film, the multi-modified TiO₂ film exhibited excellent photocatalytic activity and clearly responsive to the visible light. Keywords: V and F codoping; TiO₂-SiO₂ composite film; Photocatalytic activity

Abstract: Peroxymonosulfate (PMS) was used in wet scrubbing removal of odorous gas methyl mercaptan (CH₃SH) under acidic condition (pH = 2) for the first time. Even though CH₃SH can hardly dissociate as CH₃S⁻ under acidic solution (pK_a = 10.3), quick oxidizing reaction may occur at the gas-liquid interface by PMS alone or Co²⁺ activated PMS oxidation. When the gas flow is 0.5 L min^-1, PMS alone can remove 94% of 60 ppm/v CH₃SH. The absorption of CH₃SH is the rate controlling step of the removal process, however, quick oxidizing reaction with the dissolved CH₃SH_(aq) molecule could improve the mass transfer of CH₃SH from the gas phase into the liquid phase.

Abstract: NO reduction by iron was conducted in a one-dimensional ceramic tubular reactor at 300 - 1100 °C in N₂ and simulated flue gas atmosphere with 0.4% methane and 0.01%~0.04% SO₂. The evolution of metallic iron was investigated by X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and energy dispersive spectrum (EDS) methods. The results showed that SO₂ did not place negative effect on NO reduction by iron. XRD patterns showed that FeS was formed when there was SO₂ in the flue gas. The iron oxides were FeO and Fe₃O₄ when methane was not and was used as reducing agent respectively. Rough and raised surface making up of a series of round smooth juts was formed over the iron surface after reaction with NO in N₂ atmosphere when there was 0.04% SO₂. Porous surface consisting serried particles was formed when methane was used as reductant. White attachments were found locally on the iron surface when SO₂ existed in the flue gas, which was proved by EDS analysis to be FeS.

Abstract: The structure and the techniques of carrousel oxidation ditch process on nitrogen and phosphor removal are introduced in this paper. The problems in running and their corresponding resolve are also pointed. At last, the author showed the up to date research improvement and the mainly future research direction.