Multi-pollutants simultaneous removal from flue gas

The multi-stages humidifier semi-dry flue gas cleaning technology, the CRS plasma flue gas cleaning technology and oxidative additive flue gas cleaning technology were investigated for multi-pollutants removal. The semi-dry flue gas cleaning technology using multi-stages humidifier and additive can improve oxidation and absorption, and it can achieve high multi-pollutants removal efficiency. The CRS discharge can produce many OH radicals that promote NO oxidation. Combining NaOH absorption can achieve high deSO2 and deNO, efficiencies. It is fit for the reconstruction of primary wet flue gas desulfurization （WFGD）. In addition, using NaClO2 as additive in the absorbent of WFGD can obtain very high removal efficiency of SO2 and NOx.

Simultaneous nitrification and denitrification in step feeding biological nitrogen removal process

The simultaneous nitrification and denitrification in step-feeding biological nitrogen removal process were investigated under different influent substrate concentrations and aeration flow rates. Biological occurrence of simultaneous nitrification and denitrification was verified in the aspect of nitrogen mass balance and alkalinity. The experimental results also showed that there was a distinct linear relationship between simultaneous nitrification and denitrification and DO concentration under the conditions of low and high aeration flow rate. In each experimental run the floc sizes of activated sludge were also measured and the results showed that simultaneous nitrification and denitrification could occur with very small size of floc.

Nitrogen Removal by Simultaneous Nitrification and Denitrification via Nitrite in a Sequence Hybrid Biological Reactor

Sequence hybrid biological reactor （SHBR） was proposed, and some key control parameters were investigated for nitrogen removal from wastewater by simultaneous nitrification and denitrification （SND） via nitrite. SND via nitrite was achieved in SHBR by controlling demand oxygen （DO） concentration. There was a programmed decrease of the DO from 2.50 mg·L^-1 to 0.30 mg·L^-1, and the average nitrite accumulation rate （NAR） was increased from 16.5% to 95.5% in 3 weeks. Subsequently, further increase in DO concentration to 1.50 mg·L^-1 did not destroy the partial nitrification to nitrite. The results showed that limited air flow rate to cause oxygen deficiency in the reactor would eventually induce only nitrification to nitrite and not further to nitrate. Nitrogen removal efficiency was increased with the increase in NAR, that is, NAR was increased from 60% to 90%, and total nitrogen removal efficiency was increased from 68% to 85%. The SHBR could tolerate high organic loading rate （OLR）, COD and ammonia-nitrogen removal efficiency were greater than 92% and 93.5%, respectively,, and it even operated under low DO concentration （0.5 mg·L^-1） and maintained high OLR （4.0 kg COD·m^-3·d^-1）. The presence of biofilm positively affected the activated sludge settling capability, and sludge volume index （SVI） of activated sludge in SHBR never hit more than 90 ml·L^-1 throughout the experiments.

A study on simultaneous removal of NO and SO2 by using sodium persulfate aqueous scrubbing

Nitric oxide （NO） removal and sulfur dioxide （SO2） removal by sodium persulfate （Na2S2O8） were studied in a Bubble Column Reactor. The proposed reaction pathways of NO and SO2 removal are discussed. The effects of temperatures （35-90℃）, Na25208 （0.05-0.5 mol·L-1）, FeSO4 （0.5-5.0 m mol·L-1） and H2O2 （0.25 mol·L-1） on NO and SO2 removal were investigated. The results indicated that increased persulfate concentration led to increase in NO removal at various temperatures. SO2 was almost completely removed in the temperature range of 55-85 ℃. Fe2 ＋ accelerated persulfate activation and enhanced NO removal efficiency. At 0.2 mol· L- 1 Na2S2O8 and 0.5-1.0 mmol· L-1Fe2 ＋, NO removal of 93.5%-99% was obtained at 75-90 ℃, SO2 removal was higher than 99% at all temperatures. The addition of 0.25 mol. L i H202 into 0.2 mol·L-1· Na2S2O8 solution promoted NO removal efficiency apparently until utterly decomposition of H2O2, the SO2 removal was as high as 98.4% separately at 35 ℃ and 80 ℃.

Simultaneous catalytic removal of NOx and diesel PM over La_(0.9) K_(0.1) CoO_3 catalyst assisted by plasma

The simultaneous removal of NOx and particulate matter(PM) from diesel exhaust is investigated over a mixed metal oxide catalyst of La 0.9 K 0.1 CoO 3 loaded on γ-Al 2O 3 spherules with the assistant of plasma. It was found that NOx was reduced by PM in oxygen rich atmosphere, the CO 2 and N 2 were produced in the same temperature window without considering the N 2 formed by plasma decomposition. As a result, the temperature for the PM combustion decreases and the reduction efficiency of NOx to N 2 increases during the plasma process, which indicated that the activity of the catalyst can be improved by plasma. The NOx is decomposed by plasma at both low temperature and high temperature. Therefore, the whole efficiency of NOx conversion is enhanced.

Simultaneous removal of nitrogen and phosphorus from swine wastewater in a sequencing batch biofilm reactor

In this study, the performance of a sequencing batch biofilm reactor(SBBR) for removal of nitrogen and phosphorus from swine wastewater was evaluated. The replacement rate of wastewater was set at 12.5% throughout the experiment. The anaerobic and aerobic times were 3 h and 7 h, respectively, and the dissolved oxygen concentration of the aerobic phase was about 3.95 mg·L-1. The SBBR process demonstrated good performance in treating swine wastewater. The percentage removal of total chemical oxygen demand(COD), ammonia nitrogen(NH4+-N), total nitrogen(TN), and total phosphorus(TP) was 98.2%, 95.7%, 95.6%, and 96.2% at effluent concentrations of COD85.6 mg·L-1, NH4+-N 35.22 mg·L-1, TN 44.64 mg·L-1, and TP 1.13 mg·L-1, respectively. Simultaneous nitrification and denitrification phenomenon was observed. Further improvement in removal efficiency of NH4+-N and TN occurred at COD/TN ratio of 11:1, with effluent concentrations at NH4+-N 18.5 mg·L-1and TN 34 mg·L-1, while no such improvement in COD and TP removal was found. Microbial electron microscopy analysis showed that the filler surface was covered with a thick biofilm, forming an anaerobic–aerobic microenvironment and facilitating the removal of nitrogen, phosphorus and organic matters. A long-term experiment(15 weeks) showed that stable removal efficiency for N and P could be achieved in the SBBR system.

Simultaneous removal of Cr(Ⅵ), Cd, and Pb from aqueous solution by iron sulfide nanoparticles: Influencing factors and interactions of metals

Cadmium(Cd),lead(Pb),and hexavalent chromium(Cr(Ⅵ)) are often found in soils and water affected by metal smelting,chemical manufacturing,and electroplating.In this study,synthetic iron sulfide nanoparticles(FeS NPs) were stabilized with carboxymethyl cellulose(CMC) and utilized to remove Cr(Ⅵ),Cd,and Pb from an aqueous solution.Batch experiments,a Visual MINTEQ model,scanning electron microscopy(SEM),X-ray diffraction(XRD),and X-ray photoelectron spectrometer(XPS) analysis were used to determine the removal efficiencies,influencing factors,and mechanisms.The FeS NP suspension simultaneously removed Cr(Ⅵ),Cd,and Pb from an aqueous solution.The concentrations of Cr(Ⅵ),Cd,and Pb decreased from 50,10,and 50 mg·L^(-1) to 2.5,0.1,and 0.1 mg·L^(-1),respectively.The removal capacities were up to 418,96,and 585 mg per gram of stabilized FeS NPs,respectively.The acidic conditions significantly favored the removal of aqueous Cr(Ⅵ) while the alkaline conditions favored the removal of Cd and Pb.Oxygen slightly inhibited the removal of Cr(Ⅵ),but it had no significant influence on the removal of Cd and Pb.A potential mechanism was proposed for the simultaneous removal of Cr(Ⅵ),Cd,and Pb using FeS NPs.The interactions of the three heavy metals involved a cationic bridging effect on Cr(Ⅵ) by Cd,an enhanced adsorption effect on Cd by [Cr,Fe](OH)_3,precipitation of PbCrO_4,and transformation of PbCrO_4 to PbS.Therefore,FeS NPs have a high potential for use in the simultaneous removal of Cr(Ⅵ),Cd,and Pb from contaminated aqueous solutions.

Science Letters:Simultaneous removal of nitrate and heavy metals by iron metal

Great attention should be paid now to simultaneously removing common pollutants, especially inorganic pollutants such as nitrate and heavy metals, as individual removal has been investigated extensively. Removing common pollutants simul- taneously by iron metal is a very effective alternative method. Near neutral pH, heavy metals, such as copper and nickel, can be removed rapidly by iron metal, while nitrate removal very much slower than that of copper and nickel, and copper can accelerate nitrate removal when both are removed simultaneously. Even a little amount of copper can enhance nitrate removal efficiently. Different mechanisms of these contaminants removal by iron metal were also discussed.

Simultaneous removal of ethyl acetate, benzene and toluene with gliding arc gas discharge

The simultaneous removal of ethyl acetate, benzene and toluene with relatively low or high initial concentration is studied using a laboratory scale gliding arc gas discharge (GA) reactor. Good decomposition efficiencies are obtained which proves that the GA is effective for the treatment of volatile organic compounds (VOCs) with either low or high concentration. A theoretical decomposition mechanism is proposed based on detection of the species in the plasma region and analysis of the decomposition by-products. This preliminary investigation reveals that the GA has potential to be applied to the treatment of exhaust air during color printing and coating works, by either direct removal or combination with activated carbon adsorption/desorption process.

Simultaneous removal of ethanol, acetaldehyde and nitrogen oxides over V-Pd/γ-Al_2O_3-TiO_2 catalyst

V-Pd/γ-Al2O3-TiO2 catalysts with different vanadium contents were prepared by a combined sol-gel and impregnation method. X-ray diffraction （XRD）, N2 adsorption-desorption （BET）, X-ray photoelectron spectroscopy （XPS） and catalytic removal of ethanol, acetaldehyde and nitrogen oxides at low temperature （〈300 ？C） were used to assess the properties of the catalysts. The results showed that the sample with 1wt% vanadium exhibited an excellent catalytic performance for simultaneous removal of ethanol, acetaldehyde and nitrogen oxides. The conversions of ethanol, acetaldehyde and nitrogen oxides at 250 ？C were 100%, 74.4% and 98.7%, respectively. V-Pd/γ-Al2O3-TiO2 catalyst with 1 wt% vanadium showed the largest surface area and higher dispersion of vanadium oxide on the catalyst surface, and possessed a larger mole fraction of V4＋ species and unique PdO species on the surface, which can be attributed to the strong synergistic effect among palladium, vanadium and the carriers. The higher activity of V-Pd/γ-Al2O3-TiO2 catalyst is related to the V4＋ and Pd2＋ species on the surface, which might be favorable for the formation of active sites.

Simultaneous Removal of Soot and NO_x over Precious Metal Catalysts O_2-Rich Atmospheres and in the Presence of H_2O and SO_2

The activities of ZrO_2-supported precious metal catalysts for simultaneous removal of soot and NO_x in the presence of rich O_2and H_2O as well as SO_2 have been studied by keeping loose contact between catalyst and soot.The results show that only Ru,Ir and Rh have catalytic activity for simultaneous removal of soot and NO_x and the order of catalytic activity is Ru > Ir > Rh.Pt has the catalytic activity only for the removal of soot,and Ag,Pd,and Au have hardly any catalytic activities for the removal of soot and NO_x.The relationships between catalytic activity of precious metal catalysts and various reaction conditions were discussed.

Mechanism of Simultaneous Nitrogen Removal and Electricity Generation by Microbial Fuel Cell

The working mechanism of MFC used for simultaneous nitrogen removal and electricity generation was studied.The results show that the electrode biofilms and suspension had different modes of electron transfer.The microorganisms growing on the electrodes and bioflocs could transfer electrons by direct contact and intermediaries respectively.The electrode biofilms and bioflocs were dominant in different functional spaces,and played a synergistic role in the process of contaminant removal,but showed a certain competitive relationship in the process of electricity generation.This study can provide a theoretical basis for the development of a new low-consumption wastewater treatment technology and promote technological innovation in wastewater treatment.

Simultaneous Removal of Thiophene and Dibenzothiophene by Immobilized Pseudomonas delafieldii R-8 cells

Biodesulfurization （BDS） is a promising technology for deep desulfurization. In this work, Pseudomonas delafieldii R-8 cells are immobilized in calcium alginate beads and used for BDS of transportation fuels. It is found that thiophene and dibenzothiophene （DBT） can be simultaneously metabolized by immobilized R-8 cells. The initial sulfur content in the model oil is 300 mg·kg-1 （thiophene ＂ DI3T= 1 ＂ 1）. After 10 h of treatment, the thiophene concentration is reduced by 40%, while DBT is reduced by 25%. The utilization rate of thiophene is faster than that of DBT. Moreover, the oil/water ratio of alginate immobilized cells is studied to reduce the water volume in desulfurization systems. Long-term recycling of BDS by alginate immobilized cells is carried out with oil/water ratio at 5 ： 1. The immobilized cells are successfully reused over 15 batch cycles. In the last batch, the desulfurization activity remains at least 75% of the first batch.

Simultaneous Removal of SO2 and NOx From Flue Gas

In this paper,the recent progress of simultaneous removal of SO_2 and NO_x process at home and abroad is reviewed.We mainly introduced calcium based absorbent catalytic oxidation method,complexation absorption process,Electron beam method et al,principle of each technology are described,and the development direction was put forward in the future.

Simultaneous nitrification and autotrophic denitrification in fluidized bed reactors using pyrite and elemental sulfur as electron donors

In this study, simultaneous nitrification and autotrophic denitrification (SNAD) with either elemental sulfur or pyrite were investigated in fluidized bed reactors in mesophilic conditions. The reactor performance was evaluated at different ammonium (12-40 mg/L of NH4+-N), nitrate (35-45 mg/L of NO3--N), and dissolved oxygen (DO) (0.1-1.5 mg/L) concentrations, with a hydraulic retention time of 12 h. The pyrite reactor supported the SNAD process with a maximum nitrogen removal efficiency of 139.5 mg/(L·d) when the DO concentration was in the range of 0.8-1.5 mg/L. This range, however, limited the denitrification efficiency of the reactor, which decreased from 90.0% ± 5.3% in phases II-V to 67.9% ± 7.2% in phases VI and VII. Sulfate precipitated as iron sulfate (FeSO4/Fe2(SO4)3) and sodium sulfate (Na2SO4) minerals during the experiment. The sulfur reactor did not respond well to nitrification with a low and unstable ammonium removal efficiency, while denitrification occurred with a nitrate removal efficiency of 97.8%. In the pyrite system, the nitrifying bacterium Nitrosomonas sp. was present, and its relative abundance increased from 0.1% to 1.1%, while the autotrophic denitrifying genera Terrimonas, Ferruginibacter, and Denitratimonas dominated the community. Thiobacillus, Sulfurovum, and Trichlorobacter were the most abundant genera in the sulfur reactor during the entire experiment.

Simultaneous removing SO_2 and NO by a new system containing cobalt complex

Absorption and catalytic oxidation of nitric oxide can be achieved by using cobalt（Ⅲ） ethylenediamine （Co（en）3^3＋. When simultaneous absorbing SO2 and NO, the precipitation of Co2（SO3）3 will be yielded and the NO removal will be decreased. A new catalyst system using Co（en）3^3＋ coupled with urea has been developed to simultaneous remove NO and SO2 in the flue gas. NO is absorbed and catalytically oxidized to nitrite and nitrate by Co（en）3^3＋. The dissolved oxygen in scrubbing solution from the feed stream acts as oxidant. Urea restrains the precipitation of Co2（SO3）3 by oxidizing SO3^2-to SO4^2- as COSO4 is more soluble in water. The experimental results proved that nearly all SO3^2- can be oxidized to SO4^2- and the high NO and SO2 removal could be obtained with the new system. The NO removal is influenced by gas flow rate, the concentration of Co（en）3^3＋ and urea in the absorption solution, the temperature of the scrubbing solution and the content of oxygen in the flue gas. The low gas flow rate is favorable to increase the NO removal. The experiments proved that the NO removal could be maintained at more than 95% by the system of 0.02 mol/L Co（en）3^3＋ and 1% urea at 50℃ with 10% O2 in the flue gas.

Nitrogen and phosphorus removal in pilot-scale anaerobic-anoxic oxidation ditch system

To achieve high efficiency of nitrogen and phosphorus removal and to investigate the rule of simultaneous nitrification and denitrification phosphorus removal （SNDPR）, a whole course of SNDPR damage and recovery was studied in a pilot-scale, anaerobicanoxic oxidation ditch （OD）, where the volumes of anaerobic zone, anoxic zone, and ditches zone of the OD system were 7, 21, and 280 L, respectively. The reactor was fed with municipal wastewater with a flow rate of 336 L/d. The concept of simultaneous nitrification and denitrification （SND） rate （rSND） was put forward to quantify SND. The results indicate that： （1） high nitrogen and phosphorus removal efficiencies were achieved during the stable SND phase, total nitrogen （TN） and total phosphate （TP） removal rates were 80% and 85%, respectively; （2） when the system was aerated excessively, the stability of SND was damaged, and rSND dropped from 80% to 20% or less; （3） the natural logarithm of the ratio of NOx to NH4^＋ in the effluent had a linear correlation to oxidation-reduction potential （ORP）; （4） when NO3^- was less than 6 mg/L, high phosphorus removal efficiency could be achieved; （5） denitrifying phosphorus removal （DNPR） could take place in the anaerobic-anoxic OD system. The major innovation was that the SND rate was devised and quantified.

Simultaneous adsorption of lead and cadmium on MnO_2-loaded resin

MnO2-10aded D301 weak basic anion exchange resin has been used as adsorbent to simultaneously remove lead and cadmium ions from aqueous solution. The effects of adsorbent dosage, solution pH and the coexistent ions on the adsorption were investigated. Experimental results showed that with the adsorbent dosage more than 0.6 g/L, both Pb^2＋ and Cd^2＋ were simultaneously removed at pH range 5-6. Except for HPO4^2-, the high concentration coexistent ions such as Na^＋, K^＋, Cl^-, NO3^-, SO4^2- and HCO3^-, showed no significant effect on the removal efficiency of both Pb^2＋ and Cd^2＋ under the experimental conditions. The coexistence of Mg^2＋, Ca^2＋ caused the reduction of Cd^2＋ removal, but not for Pb^2＋. The adsorption equilibrium for Pb^2＋ and Cd^2＋ could be excellently described by the Langmuir isotherm model with R^2 〉 0.99. The maximum adsorption capacity was calculated as 80.64 mg/g for Pb^2＋ and 21.45 mg/g for Cd^2＋. The adsorption processes followed the pseudo first-order kinetics model. MnO2-loaded D301 resin has been shown to have a potential to be used as an effective adsorbent for simultaneous removal of lead and cadmium ions from aqueous solution.

Novel strategy of nitrogen removal from domestic wastewater using pilot Orbal oxidation ditch

A pilot-scale Orbed oxidation ditch was operated for 17 months to optimize nitrogen removal from domestic wastewater of average COD to total nitrogen ratio of 2.7, with particular concern about the roles of dissolved oxygen （DO）, mixed liquor suspended solids （MLSS） and return activated sludge （RAS） recycle ratio. Remarkable simultaneous nitrification and denitrification （SND） was observed and mean total nitrogen （TN） removal efficiency up to 72.1% was steadily achieved, at DO concentration in the out, middle and inner channel of 0.1, 0.4 and 0.7 mg/L, respectively, with an average M LSS of 5.5 g/L and RAS recycle ratio of 150%. Although the out channel took the major role in TN removal, the role of middle channel should never be ignored. The denitrification potential could be fully developed under low DO, high MLSS with adequate RAS ratio. The sludge settleability was amazingly improved under low DO operation mode, and some explanations were tried. In addition, a scries of simplified batch tests were done to determine whether novel microorganisms could make substantial contribution to the performance of nitrogen removal. The results indicated that the SND observed in this Orbal oxidation ditch was more likely a physical phenomenon.

Experimental study on simultaneous desulfurization and denitrifi- cation based on highly active absorbent

Simultaneous removal of SO2 and NO from flue gas by the highly active absorbent prepared from fly ash, lime and a few oxidizing manganese compound additive was studied using a flue gas circulating fluidized bed （CFB） under different experimental conditions. The effects influencing the removal effiencies were discussed. The optimal flue gas temperature, flue gas humidity, gas velocity of CFB and Ca/（S＋N） molar ratio with this process were approximately 110℃, 6%, 1.8 m/s and 1.05, respectively. Removal efficiencies of 92.3% for SO2 and 60.88% for NO were obtained under the optimal experimental conditions. While the spent absorbent appeared in the form of dry powder, the mechanism of removal for SO2 and NO based on the highly active absorbent was investigated by a scanning electron microscope （SEM）, a X-ray energy spectrometer and the chemical analysis methods. The valuable references can be provided for industrial application by the process. The foreground of application will be vast in China and in the world.