Process For Simultaneous Removal Research Articles

Highly efficient simultaneous ultrasonic-assisted adsorption of methylene blue and rhodamine B onto metal organic framework MIL-68(Al): central composite design optimization

In this work, metal organic framework (MIL-68(Al)), was synthesized by a simple, fast and low-cost process for simultaneous removal of methylene blue and Rhodamine B, regarded to be toxic and even carcinogenic, from aqueous solution.

Polishing of Chemical Oxygen Demand (COD) Using Moving Bed Bio-Reactor

The pilot-scale experiment in moving bed biofilm reactor (MBBR) with a capacity of 433 L was carried out for this study with real life situations, it was decided that the complete research work must be done under as realistic conditions as possible,i.e.with real municipal wastewater, chemical free and with local commercially available products such as carriers for biofilm reactor. The reactor was start-up in 30/9/2013 up to date, Effluent from clarifier of STP used as influence of MBBR for polishing. MBBR is using continues down flow to polish effluent municipal wastewater from a faculty of new building engineering community in UKM to get the water free from main pollutant parameters, for reuse in the irrigation or discharge to the river. Laboratory experiments will conduct with different hydraulic retention time (HRT), filling ratio of plastic (Enviro Multi Media) in the MBBR about 5%. Aerobic reactors used the majority of the decaying organic material. An average removal rate of 41.75%, 32.85%, 24.80% and 35.77% of initial chemical oxygen demand (COD) were achieved under a HRT of 24hr, 12hr, 6hr and 2hr, respectively. The model simulated results showed good agreements with experimental results. The model could be employed in the design of a full-scale MBBR process for simultaneous removal of organic carbon from effluent STP.

Advanced treatment of residual nitrogen from biologically treated coke effluent by a microalga-mediated process using volatile fatty acids (VFAs) under stepwise mixotrophic conditions

This work describes the development of a microalga-mediated process for simultaneous removal of residual ammonium nitrogen (NH4+-N) and production of lipids from biologically treated coke effluent. Four species of green algae were tested using a sequential mixotrophic process. In the first phase—CO2-supplied mixotrophic condition—all microalgae assimilated NH4+-N with no evident inhibition. In second phase—volatile fatty acids (VFAs)-supplied mixotrophic condition—removal rates of NH4+-N and biomass significantly increased. Among the microalgae used, Arctic Chlorella sp. ArM0029B had the highest rate of NH4+-N removal (0.97mg/L/h) and fatty acid production (24.9mg/L/d) which were 3.6- and 2.1-fold higher than those observed under the CO2-supplied mixotrophic condition. Redundancy analysis (RDA) indicated that acetate and butyrate were decisive factors for increasing NH4+-N removal and fatty acid production. These results demonstrate that microalgae can be used in a sequential process for treatment of residual nitrogen after initial treatment of activated sludge.

A study on removal of elemental mercury in flue gas using fenton solution

A novel technique on oxidation-separation of elemental mercury (Hg0) in flue gas using Fenton solution in a bubbling reactor was proposed. The effects of several process parameters (H2O2 concentration, Hg0 inlet concentration, Fe2+ concentration, solution temperature, solution pH, gas flow) and several flue gas components (NO, SO2, O2, CO2, inorganic ions and particulate matters on Hg0 removal were studied. The results indicate that H2O2 concentration, Fe2+ concentration, solution pH and gas flow have great effects on Hg0 removal. Solution temperature, Hg0, NO, SO2, CO32− and HCO3− concentrations also have significant effects on Hg0 removal. However, Cl−, SO42−, NO3−, O2 and CO2 concentrations only have slight effects on Hg0 removal. Furthermore, reaction mechanism of Hg0 removal and simultaneous removal process of Hg0, NO and SO2 were also studied. Hg0 is removed by oxidation of OH and oxidation of H2O2. The simultaneous removal efficiencies of 100% for SO2, 100% for Hg0 and 88.3% for NO were obtained under optimal test conditions. The results demonstrated the feasibility of Hg0 removal and simultaneous removal of Hg0, SO2 and NO using Fenton solution in a bubbling reactor.

Integrative process of preoxidation and absorption for simultaneous removal of SO2, NO and Hg0

This paper proposes a novel semidry integrative process for simultaneous removal of SO2, NO and Hg0, in which, the insoluble NO and Hg0 are first pre-oxidized by a vaporized aqueous complex oxidant (ACO) composed of NaClO2 and NaBr, then NO2 and Hg2+ are absorbed by Ca(OH)2. The effects of various influencing factors such as the molar ratio of NaClO2 to NaBr in ACO, the injection rate of ACO, the ACO pH, the reaction temperature and the concentrations of O2, CO2, NO and SO2 on the simultaneous removal were systematically investigated, and the average simultaneous removal efficiencies were 100%, 91% and 93% for SO2, NO and Hg0, respectively under the optimal reaction conditions. The reaction mechanism was proposed based the characterizations of removal products by UV–Vis, SEM, XRD, EDS, XPS and AFS, and the literature references.

Effective start-up biofiltration method for Fe, Mn, and ammonia removal and bacterial community analysis

Three identical lab-scale biofilters were employed to optimize the start-up process for simultaneous removal of iron (Fe), manganese (Mn), and ammonia from potable water supplies. Nitrifying sludge and backwashing sludge containing Mn-oxidizing bacteria (MnOB) were used as the inocula. The start-up strategies consisted of simultaneous and separate inoculation of the two kinds of sludge. The influent Fe was removed immediately when the biofilters began to operate. The effects of nitrification for ammonia removal showed no significant difference between these biofilters. However, the beginning of Mn removal with separate inoculation was faster than that of simultaneous inoculation. The Mn removal can be described by using first order reaction; and the k (rate constant, min−1) values were 0.147±0.007 (mean±standard deviation) and 0.153±0.006. Besides the commonly reported MnOB genus Crenothrix, MnOB genera were also found to be related to the genera rarely reported in the potable water treatment systems.

Integrative Process for Simultaneous Removal of SO2 and NO Utilizing a Vaporized H2O2/Na2S2O8

A novel integrative process for simultaneous removal of SO2 and NO from coal-fired flue gas was designed, in which, SO2 and NO were initially oxidized by a vaporized complex oxidant composed of hydrogen peroxide (H2O2) and sodium persulfate (Na2S2O8) (HN solution) and then absorbed by the Ca(OH)2 that followed. The effects of various reaction factors on the simultaneous removal were investigated, such as the concentration of Na2S2O8, the transition metal additives, the HN pH, the adding rate of HN, the residence time of flue gas, the reaction temperature, and the concentrations of coexistence gases O2, SO2, NO, and CO2. Under the optimal conditions, the simultaneous removal efficiencies of 98.9% for SO2 and 79.6% for NO were obtained. The reaction mechanism was speculated based on the characterization of removal products by scanning electron microscopy and X-ray diffraction and related literature references. Meanwhile, the macrokinetics of desulfurization and denitrification were also calculated.

Simultaneous desulfurization and denitrification of flue gas by catalytic ozonation over Ce–Ti catalyst

A novel oxidation-removal process for simultaneous removal of NOX and SO2 was developed, which utilized the catalytic ozonation over Ce–Ti catalyst and assisted with a glass made ammonia-based washing tower. Compared with conventional flue gas treatment, the present method acquires non-secondary pollution, minimal waste production and low operating costs. The main byproducts, ammonia sulfate and nitrate, are important fertilizers and industrially raw materials. A maximum removal of 95% for NOX and nearly complete SO2 removal were obtained with the assistance of washing tower under the following experimental conditions: O3 concentration, 8.5mg·L−1; flow of oxidant mixtures, 100mL·min−1; simulated flue gas temperature, 120°C; H2O flow, 2.4mL·min−1; and total gas flow, 400mL·min−1. The reaction mechanisms are discussed, and the final oxidation products are characterized. The experimental results show that the OH radicals from catalytic ozonation have an oxidation-removal effect of NOX and SO2. The multipollutant capacity of the washing tower is largely enhanced with the Ce–Ti catalyst. And the present method performs better stability with the assistance of the washing tower.

Simultaneous removal of nitrate, hydrogen peroxide and phosphate in semiconductor acidic wastewater by zero-valent iron

The zero-valent iron (ZVI) wastewater treatment has been applied to simultaneous removal of nitrate, hydrogen peroxide and phosphate in semiconductor acidic wastewaters. The simultaneous removal occurs by the reactions performed due to the sequential transformation of ZVI under the acidic condition. Fortunately the solution pH of semiconductor acidic wastewaters is low which is effective for the sequential transformation of ZVI. Firstly the reduction of nitrate is taken place by electrons generated by the corrosion of ZVI under acidic conditions. Secondly the ferrous ion generated by the corrosion of ZVI reacts with hydrogen peroxide and generates ·OH radical (Fenton reaction). The Fenton reaction consists of the degradation of hydrogen peroxide and the generation of ferric ion. Finally phosphate precipitates out with iron ions. In the simultaneous removal process, 1.6 mM nitrate, 9.0 mM hydrogen peroxide and 1.0 mM phosphate were completely removed by ZVI within 100, 15 and 15 min, respectively. The synergy among the reactions for the removal of nitrate, hydrogen peroxide and phosphate was found. In the individual pollutant removal experiment, the removal of phosphate by ZVI was limited to 80% after 300 min. Its removal rate was considerably improved in the presence of hydrogen peroxide and the complete removal of phosphate was achieved after 15 min.

Simultaneous Removal of NO and SO2 from Flue Gas by Ozone Oxidation and NaOH Absorption

Exhaust flue gas from fossil fuel combustion usually contains a large quantity of SO2 and NO. In this paper, a process of simultaneous removal of NO and SO2 by ozone oxidation combined with NaOH absorption was chosen. The main investigations involved O3 decomposition, factors affecting NO oxidation (O3 dosage, reaction temperature, NO initial concentration, and presence of SO2), and NaOH absorption. The results indicated O3 decomposition rate increased as temperature rose and was less affected by initial concentration of O3. The optimal temperature for NO oxidation was 150 °C. NO oxidation efficiency increased with the increase of O3 dosage at a fixed temperature. NO initial concentration and the presence of SO2 had a slight effect on NO oxidation. The NO oxidation efficiency remained above 90% when nO3/nNO was 1. Absorption by NaOH solution resulted in the final removal of above 99% NO, 90% NO2, and nearly 100% SO2 at pH above 11.

Kinetic Modeling and Simulation of Zero-Valent Iron Wastewater Treatment Process: Simultaneous Reduction of Nitrate, Hydrogen Peroxide, and Phosphate in Semiconductor Acidic Wastewater

A kinetic model for the simultaneous removal of nitrate, hydrogen peroxide, and phosphate in semiconductor acidic wastewater by zero-valent iron (ZVI) has been developed on the basis of the Eley–Rideal mechanism. The simultaneous removal process consists of the reactions linked up with the transformation of ZVI from Fe0 to Fe2+ and then to Fe3+ under the acidic condition. The reduction of nitrate, degradation of hydrogen peroxide, and precipitation of ferric or ferrous phosphate took place as consequence of ZVI transformation. In modeling, nitrate reduction to ammonium and nitrogen gas, hydrogen peroxide degradation by Fenton reaction, phosphate removal by the complexation with ferric and ferrous ions, and reduction of adsorbed proton were considered as well as ZVI corrosion and adsorption of proton, nitrate, phosphate and ferric ion at the active site on the iron surface. The rate equations for iron ions and OH radical, which are key species in the transformation of ZVI, were also taken into account. The simulation results by the proposed kinetic model could satisfactorily describe the experimental results for the simultaneous removal of nitrate, hydrogen peroxide, and phosphate driven by the transformation of ZVI. The complicated dynamic behaviors of iron ions playing an important role in the synergy among the reactions could be simulated reasonably well. The kinetic model based on the Eley–Rideal mechanism may be useful to predict dynamic behaviors of ZVI wastewater treatment processes.

The treatment of animal manure wastewater by coupled simultaneous methanogenesis and denitrification (SMD) and shortcut nitrification–denitrification (SND)

AbstractBACKGROUNDThe anaerobic–aerobic system is considered an efficient process for simultaneous removal of organic matter and nitrogen from animal manure wastewater. In this work, coupled simultaneous methanogenesis and denitrification (SMD) and shortcut nitrification–denitrification (SND) was investigated to treat animal manure wastewater having high concentrations of nitrogen and organic matter.RESULTSThe best COD and NO2−‐N removal efficiency was achieved when the influent COD loading rate in the anaerobic reactor was 3 kg m‐3 d−1 and the COD/NO2−‐N ratio was above 30. It was advantageous to the treatment of high‐strength ammonia animal manure wastewater to adopt SND when the pH and free ammonia were about 8.0 and 18 mg L−1, respectively. The average efficiency of of removal COD, NH4+‐N, and total nitrogen when adopting the coupling technology was 96.7%, 94.9% and 86.5%, respectively, and the nitrite accumulation rate reached 94.55%.CONCLUSIONThis study suggested that it was technically feasible to adopt SMD–SND coupling technology of to treat animal manure wastewater with high concentrations of nitrogen and organic matter. © 2013 Society of Chemical Industry © 2013 Society of Chemical Industry

The study of Fenton oxidation process efficiency in the simultaneous removal of phenol, cyanide, and chromium (VI) from synthetic wastewater

Background and objectives: phenol, cyanide, and chromium (VI) are toxic pollutants. They can be discharged from different industries simultaneously such as iron and steel industry, coal mining, automobile manufacturing of parts. Presence of these pollutants in water and wastewater is a serious hazard and these substances lead to undesirable effects on both the environment and human. Thus, control of these contaminants is essential for human health and environment. The main objective of this study was to assess the efficiency of Fenton process for simultaneous removal of phenol, cyanide, and chromium (VI) from synthetic wastewater. Materials and methods: This study is an experimental study in lab scale that was carried out in a batch system. Variations of this study including pH, chemicals concentration (Fe2+ and H2O2 and molar ratio Fe2+/H2O2), and reaction time were investigated. Cyanide, phenol, and total chromium were determined respectively by colorimetric method (spectrophotometer), high-performance liquid chromatography, and atomic absorption spectrophotometer. Results: The results of this research showed that simultaneous removal efficiency of phenol, cyanide, and chromium (VI) from synthetic wastewater by Fenton process were 88, 86 and 92%, respectively (conditions: pH = 4, Cr6+ and CN- = 10 mg l-1, Phenol = 150 mg l-1, H2O2 = 150 mg l-1, Fe2+ = 140 mg l-1 (Fe2+/H2O2 = 0.58) after 30 min reaction time). Conclusion: According to the results, it can be concluded that Fenton process can be considered as a suitable process for cyanide, phenol, and chromium (VI) removal to achieve environmental standards.

Insights into environmental remediation of heavy metal and organic pollutants: Simultaneous removal of hexavalent chromium and dye from wastewater by zero-valent iron with ligand-enhanced reactivity

The pollution of heavy metal and organic pollutants is a global environmental issue. Up to now, the simultaneous removal of heavy metal and organic pollutants is still a great challenge. The removal of heavy metal and organic pollutants by zero-valent iron (ZVI) has been extensively studied, but the removal efficiency of pollutants is low using single ZVI for remediation application. In this paper, a low-cost method by ZVI in presence of ethylenediaminetetraacetic acid (EDTA) and oxalate ligands has been developed to simultaneously remove Cr(VI) and dye from wastewater. This innovative process combines the reduction of Cr(VI) to Cr(III) with the reduction/oxidation of the dye by ZVI with the aid of ligand. EDTA and oxalate ligands can significantly increase the removal efficiency of Cr(VI) and dye since the ligands can accelerate ferrous iron oxidation and increase the generation of hydroxyl radical. In contrast, oxalate ligand possessed better removal efficiency in simultaneous removal process than EDTA, and oxalate generated lower TOC than EDTA. At the optimal conditions, the removal efficiency higher than 98% for Cr(VI) and higher than 81% for dye was observed in presence of 3.0mM oxalate. X-ray Photoelectron Spectroscopy, Fourier Transform Infrared Spectroscopy and UV–visible spectrometer were used to study the reaction mechanism among Cr(VI), ZVI and dye in presence of ligand.

A Study of the Zn-based Desulfurization Sorbents for H2S Removal in the IGCC

The various Zn-based sorbents were prepared by physical mixing method and co-precipitation method. The sulfur removing capacity and regeneration properties of the various sorbents were measured in fixed bed reactor at middle temperature condition (sulfidation process 480 °C, regeneration process 580 °C). The sulfur removing capacities of the sorbents were depended on the physical properties such as pore volume, surface area and particle size. The Zn-based sorbents prepared by co-precipitation method were higher pore volume, surface area and smaller particle size resulting in the higher capacities than those prepared by the physical mixing method. To improve the regeneration properties of the sorbents, the various promoters such as cobalt, iron, nickel and cerium were added to the sorbents. The promoters have various roles with the kind of promoter. The roles of promoters could be explained by heat effect and catalytic effect of the promoters. Also, the alloyed structure like spinel structure (ZnTi2O4) has been proposed to explain the superior regeneration properties compared to the single ZnO structure. In addition, the simultaneous removals of the H2S and NH3 over the Zn–Al-based sorbents were tested at 650 °C. So, the new process for simultaneous removal using the developed Zn-based sorbents could be proposed. The role of promoters, effect of hydrogen potential pressure and the deactivation mechanism including the sulfidation of metal oxide to metal sulfide were also discussed.

Next Generation Post- combustion Capture: Combined CO2 and SO2 Removal

A major consideration for post-combustion CO2 capture is the adverse effect of the presence of SO2 on the absorption desorption process. The most common approach is to remove the SO2 from the flue gases in a flue gas desulfurization (FGD) unit prior the CO2 recovery process. This paper reports the experimental and modeling results of a new process for simultaneous removal of CO2 and SO2 for post-combustion applications. This process is named CASPER (CO2-capture And Sulphur Precipitation for Enhanced Removal), and is based on the precipitation of K2SO4 for sulphur removal. The selected CO2 absorbing solvent is an amino-acid, preferably a potassium amino-acid salt solution. The presence of potassium leads to the subsequent formation of K2SO4, which solubility in the CO2 loaded aqueous solvent solution changes depending on the applied conditions. The optimal crystallization conditions were first determined by characterization of K2SO4 solubility window and then evaluated in the lab-scale crystallization unit. In the next step the model system based on potassium beta-alanate solutions, also with addition of sulphate, were tested for CO2 absorption and desorption pressures by performing VLE (Vapor Liquid Equilibrium) measurements at 40°C and 120°C, respectively. Obtained values were included in preliminary technical assessment, which showed an energetic improvement of 0.7%-points for the CASPER model solvent system in comparison to the baseline 30wt% MEA case.

Spectroscopic studies of dye-surfactant interactions with the co-existence of heavy metal ions for foam fractionation

The interaction between a cationic dye Methylene Blue (MB) and an anionic surfactant sodium dodecyl sulfate (SDS) with the presence of Cd2+ was investigated spectrophotometrically in a certain concentration range. The spectrophotometric measurements of dye-metal ion-surfactant system were carried out. The results indicated that the SDS concentration had a significant influence on the dye spectrum, while the addition of Cd2+ hardly caused change of the maximum value of absorbance. According to this observation, we concluded that electrostatic and hydrophobic interaction between dye and surfactant occurred up to a certain level, and the homo-ions Cd2+ almost exerted no effect on the dye-surfactant complexation, establishing a theoretical foundation for simultaneous removal of organic dye and heavy metal using foam fractionation. Meanwhile, the effects of their interaction on foam performance were investigated. The results showed that the addition of Cd2+ favored the tendency to ameliorate foam properties just contrary to MB. The feasibility of foam separation for dye and heavy metal removal from simulated wastewater was also confirmed using a continuous foam fractionator. In the simultaneous removal process, with the initial SDS concentration ranging from 0.5 to 5.0 mmol/L, the maximum removal efficiencies of MB and Cd2+ were obtained as 99.69% and 99.61%, respectively. The enrichment ratios were reduced from 24.34 to 7.65 for MB and from 22.01 to 3.35 for Cd2+.

A feasible process for simultaneous removal of CO2, SO2 and NOx in the cement industry by NH3 scrubbing

With the rapid economic and industrial development, the concentration of carbon dioxide in the atmosphere is increasing enormously, which has greatly affected the global climate and human living environment. At present, a lot of technologies have been applied to CO2 removal in fossil fuel-fired power plants, which are one of the main CO2 emission sources. But few researches have been done in the cement industry, which is the third largest CO2 emission source. There is no mature technology of CO2 removal in cement industry mentioned before. This paper proposes a feasible process for simultaneous removal of CO2, SO2 and NOx in the cement industry by NH3 scrubbing. As there is no ready steam source for the regeneration of CO2-rich loading solvent after absorption, a process with the final product of ammonium bicarbonate is developed. With the oxidative additive of NaClO2 added in the aqueous ammonium absorbent, the simultaneous removal of CO2, SO2 and NOx is feasible by NH3 scrubbing. The products of the process are mainly ammonium bicarbonate, ammonium sulfate and ammonium nitrate, which are all good fertilizers for crops and plants. The crystallization of NH4HCO3 is easier for storage and transportation than that for liquid carbon dioxide, which becomes more stable when dicyandiamide (DCD) is added. The thermodynamic analysis proves that the proposed process has the advantages of energy conservation and high thermodynamic perfection degree compared with the traditional ones.

Simulation of Simultaneous Removal of SO2 and NO Using Pulsed Discharge

AbstractIn order to provide the basis to efficiently reduce the energy consumption and improve the removal rate, the simultaneous removal processes of SO

Synergistic effect of nickel ions on the coupled dechlorination of trichloroethylene and 2,4-dichlorophenol by Fe/TiO 2 nanocomposites in the presence of UV light under anoxic conditions

The coupled removal of priority pollutants by nanocomposite materials has recently been receiving much attention. In this study, trichloroethylene (TCE) and 2,4-dichlorophenol (DCP) in aqueous solutions were simultaneously removed by Fe/TiO 2 nanocomposites under anoxic conditions in the presence of nickel ions and UV light at 365 nm. Both TCE and DCP were effectively dechlorinated by Fe/TiO 2 nanocomposites, and the pseudo-first-order rate constants ( k obs) for TCE and DCP dechlorination were (1.39 ± 0.05)×10 −2 and (1.08 ± 0.05)×10 −2 h −1, respectively, which were higher than that by nanoscale zerovalent iron alone. In addition, the k obs for DCP dechlorination was enhanced by a factor of 77 when Fe/TiO 2 was illuminated with UV light for 2 h. Hydrodechlorination was found to be the major reaction pathway for TCE dechlorination, while DCP could undergo reductive dechlorination or react with hydroxyl radicals to produce 1,4-benzoquinone and phenol. TCE was a stronger electron acceptor than DCP, which could inhibit the dechlorination efficiency and rate of DCP during simultaneous removal processes. The addition of nickel ions significantly enhanced the simultaneous photodechlorination efficiency of TCE and DCP under the illumination of UV light. The k obs values for DCP and TCE photodechlorination by Fe/TiO 2 in the presence of 20–100 μM Ni(II) were 30.4–136 and 13.2–192 times greater, respectively, when compared with those in the dark. Electron spin resonance analysis showed that the photo-generated electron-hole pairs could be effectively separated through Ni ions cycling, leading to the improvement of electron transfer efficiency of TCE and DCP by Fe/TiO 2.