Simultaneous Removal Of Sulfate Research Articles

Simultaneous removal of sulfate and nitrate from real high-salt flue gas wastewater concentrate via a waste heat crystallization route

Flue gas wastewater concentrate was acidic and highly saline, and generated from the evaporator of desulfurization wastewater in power/heating plant. Its conventionally sprayed into flue gas pipeline and completely evaporated to generate hazardous halite into flue gas ash. Herein, a facile low-temperature thermal route was developed to treat the concentrate without the generation of any hazardous waste. The results showed that the concentrate was at pH 0.2 and contained 59 g/L sulfate, 13.1 g/L nitrate and 16.4 g/L chloride. When it was thermally treated at 150 °C (similar to the temperature of waste heat in power/heating plant), more than 99% sulfate and 97% nitrate were effectively removed with the addition of aluminum subacetate reagent. Without aluminum subacetate reagent, the removal of sulfate and nitrate only achieve by 2.8% and 9.1%. During the thermal treatment, the sulfate reacted with aluminum ion to form regular hexahedron natroalunite, whilst the nitrate was eliminated as nitrogen gas via the redox reaction between nitrate and organics (e.g., subacetate). The analysis of Gibbs free energy revealed that the formation of natroalunite took placed at the temperature > of 67 °C and accelerated at high temperature, but the reduction of nitrate was pH-dependent and accelerated at the initial pH < of 0.4. With the formation of natroalunite, the decrease of chloride from 16.4 g/L to 14.7 g/L were also observed, and the treated concentrate can be reused in the flue gas desulfurization triple-chambered process. In summary, this method showed merits to not only reuse the waste heat in power/heating plant for the effective removal of sulfate and nitrate from the flue gas wastewater concentrate, but also produce the recycled water and the value-added natroalunite particles.

Cost-effective desulfurization of acid mine drainage with food waste as an external carbon source: A pilot-scale and long-term study

Sulfate reduction process can be a promising method for simultaneously removing sulfate , metals and metalloids from acid mine drainage (AMD). However, organic matter in AMD is far from enough for sulfate reduction, and an additional carbon source is required, which increases operation costs for AMD treatment. In this study, a two stage AMD treatment system was established (chemical precipitation - sulfate reduction), and food waste hydrolysate was utilized as a carbon source for AMD treatment. Simultaneous removal of sulfate, organics, metals and metalloids was observed in a pilot-scale (10 m 3 ) upflow anaerobic sludge bed (UASB) for over 400 days. Introducing of food waste hydrolysate (FWHS) was not harmful for sulfate reducers in UASB. Decomposition of refractory organic matter in AMD was enhanced after FWHS addition, which led to decreasing of COD concentration (50%) in effluents of UASB. Ten out of 17 organic matter in effluents was no longer detected after FWHS addition. Metals and metalloids from both AMD and FWHS were efficiently removed during the sulfate reduction process (97.7–100%). Volatile fatty acids (acetic and valeric acids) produced during the food waste hydrolysis could be utilized as carbon source for AMD treatment. Interactions among fermentative microbes , sulfate reducers, denitrifiers and methanogens enhanced carbon, sulfur and nitrogen removal in the UASB. Therefore, a cost-effective method for AMD and food waste cotreatment (3.6 kgSO 4 2− /kgTS food waste) was established in this study by reducing carbon source addition (100%), biomass production (93%), VFA production (54.5%) and sulfide emission (50%), which might be applied for AMD recycling at mining sites. • a two-step fermentation and sulfate reduction coupling process was established. • Food waste was used as carbon and nutrients source for acid mine drainage treatment. • Sulfate, carbon, metals and metalloids were efficiently removed (87.3–100%). • The established technology might be used for acid mine drainage treatment in mines.

Simultaneous removal of sulfur and nitrogen compounds with methane production from concentrated latex wastewater in two bioreactor zones of micro‐oxygen hybrid reactor

AbstractBACKGROUNDA micro‐oxygen hybrid reactor (MOHR), a two‐zone reactor with suspended sludge zone (SZ) and attached biofilm zone (AZ) at its lower and upper parts respectively, was applied to simultaneously remove sulfur and nitrogen compounds with methane production from concentrated latex wastewater with high concentrations of sulfate (1200 mg L−1) and ammonium (235 mg L−1). Microbial community structures coupled with microbial activities were analyzed and discussed for clarifying relationships of microorganisms in both zones of the MOHR.RESULTSThe operating dissolved oxygen in the MOHR was controlled at 0.10–0.15 and 0.05 mg L−1 in the SZ and AZ respectively at various loading rates (LRs) and hydraulic retention times (HRTs). The average optimal overall performances of the MOHR for sulfate (SO42−), total Kjeldahl nitrogen (TKN) and chemical oxygen demand (COD) removal efficiencies were 90.3, 67.8 and 93.0% respectively at HRT 10 days. Elemental sulfur and nitrogen gas were evaluated as major end‐products at 90.2 and 67.9% respectively, with 0.27 L CH4 g−1 CODremoved of methane selectivity. The genera Desulfobulbus and Dongia as well as Thiobacillus denitrificans served as dominant microorganisms in biological sulfate removal. The largest abundance belonged to denitrifying microorganisms with nitrous oxide reductase (nosZ) as target gene.CONCLUSIONThe MOHR achieved high performance in simultaneous removal of sulfur and nitrogen compounds along with methane production at HRT 10 days. Microorganisms involved in sulfur and nitrogen compound removal processes were more prevalent in the SZ than in the AZ, whereas methanogenic activity was higher in the AZ than in the SZ. © 2019 Society of Chemical Industry

Performance and microbial consortium structure in simultaneous removal of sulfur and nitrogen compounds under micro-oxygenated condition

Effects of COD/SO42− and SO42−/NH4+ ratios on simultaneous removal of sulfate- and ammonium-rich synthetic wastewaters were investigated under micro-oxygenated condition (dissolved oxygen concentration at 0.10–0.15 mg/L). Lactate was served as carbon source to generate COD/SO42− ratios of 2.0, 2.5, 3.0 3.5 and 4.0. The batch experimental results indicated that the highest sulfate (72.1%) and ammonium (62.8%) removal efficiencies could be reached at COD/SO42− ratio of 4.0. The main metabolic products were elemental sulfur (0.63 g S0/g SO42−–Sadded) and nitrogen gas (0.57 g N2/g NH4+–Nadded). Subsequently, various SO42−/NH4+ ratios (0.5, 1.0, 1.5, 2.0 and 2.5) were performed at controlled COD/SO42− ratio of 4.0. The highest SO42−/NH4+ ratio of 2.5 provided 76.6 and 72.8% sulfate and ammonium removal efficiencies, respectively, and also reached the highest yield of elemental sulfur and nitrogen gas of 0.68 g S0/g SO42−–Sadded and 0.66 g N2/g NH4+–Nadded, respectively. Microbial consortium structure providing the highest removal efficiencies was consequently analyzed using Illumina sequencing and polymerase chain reaction-denaturing gradient gel electrophoresis approaches. Taxonomic assignments demonstrated that Proteobacteria (46%), Firmicutes (15%), and Bacteroidetes (14%) were the most abundant phyla. Almost core genera analysis with two distinguished approaches demonstrated similar results. Aside from microbial community analysis, quantitative real-time polymerase chain reaction was used to validate existing abundance of aforementioned seven dominant microorganisms. The nitrous oxide reductase gene was shown the most abundance (~ 108 copies/µL) which plays a crucial role for simultaneous removal of sulfur and nitrogen compounds.

Simultaneous removal of sulfate and selenate from wastewater by process integration of an ion exchange column and upflow anaerobic sludge blanket bioreactor

ABSTRACTThe application of an integrated process configuration comprising of an ion exchange (IX) column and an upflow anaerobic sludge blanket (UASB) bioreactor for the simultaneous removal of SO42- and total Se from synthetic mine wastewater was evaluated. Use of an IX column as a pre-treatment (not as post-treatment) to the UASB bioreactor gave the best overall removal performance. The combined treatment reduced the total Se and SO42- concentration from 8.0 and 1441 mg/L to 0.2 and 28.0 mg/L, respectively. This study demonstrated for the first time that an IX process as a pre-treatment to a biological process can significantly improve the oxyanion removal efficiency and the overall treatment of Se-laden wastewaters.

Continuous biological sulfate reduction from phosphogypsum waste leachate

This work explores the possibility to utilize biological sulfate reduction in the treatment of phosphogypsum leachate, with a simultaneous removal of sulfate and phosphorus in continuous flow bioreactors. An efficient sulfate reduction was achieved and proof of elemental removal was acquired. The method described in this work is suggested to be applied as a passive type of installment with environmental pollution control as the primary target. In addition to sulfate reduction, rare earth elements (REE) were monitored during the process, as these valuable elements are commonly found in phosphogypsum waste.

Simultaneous removal of sulfate and arsenic using immobilized non-traditional SRB mixed culture and alternative low-cost carbon sources

This study was designed to obtain simultaneous sulfate (SO42−) and As(III) ions removal by non-traditional sulfate-reducing bacteria (SRB) growing in the presence of a protein biomass (PCF), a solid residual material produced by the poultry industry. Microbial cells and PCF were immobilized into calcium alginate beads to reduce mass losses. Microbial consortium efficiency was tested under different operational conditions: sodium lactate, glycerol and PCF as carbon sources; increasing As(III) content; acidic pH (5.0). Microbial diversity was evaluated by PCR-DGGE. Pantoea agglomerans, Enterobacter sp., Citrobacter sp., Cupriavidus metallidurans, Ralstonia sp. and Burkholderia cepacia were found. With the aim to obtain SO42− and As(III) simultaneous removal, three semi-continuous up-flow reactors were constructed and operated for more than 100 days to prove their feasibility and reliability. Both SO42− and As(III) ions were removed with 74.8% and 80% efficiency, respectively. Solid products were characterized by SEM-EDX, confirming PCF and non-traditional SRB roles during arsenic immobilization. Arsenic/sulfur compounds (possibly As/sulfides) were produced by reaction between As(III) and biogenic sulfide. Microbial consortium proved its ability of growing in an acidic environment without losing its sulfate reductive capacity by using glycerol and PCF as alternative carbon sources and tap water as micronutrients source. The non-traditional SRB culture removed both SO42− and As(III) ions simultaneously, with no prior step needed to guarantee As(III) oxidation to As(V). Two different mechanisms could be involved: (i) precipitation as arsenic sulfide or, (ii) adsorption onto PCF/cells calcium alginate beads.

Characteristics of O3 Oxidation for Simultaneous Desulfurization and Denitration with Limestone–Gypsum Wet Scrubbing: Application in a Carbon Black Drying Kiln Furnace

The special process for producing carbon black precludes the application of traditional, mature flue-gas treatments (e.g., SNCR and SCR) to reduce NOx emissions. However, simultaneous removal of sulfur and nitrogen by the combination of ozone oxidation with limestone–gypsum wet scrubbing is suitable for the conditions found in carbon black flue gas. This article presents the first industrial-scale deployment of this technology in a 100000 t/year carbon black production line (flue-gas volume of 60000 Nm3/h). Optimizations were performed by studying the effectiveness of desulfurization and denitration for various operating parameters such as O3/NOx molar ratio, spray-tower liquid/gas ratio, initial NOx concentration, and forced oxidation. The results showed that (1) the O3/NOx molar ratio is the determining factor in denitration efficiency, (2) both forced oxidation and increasing initial NOx concentration improve the denitration efficiency but reduce the desulfurization efficiency, and (3) increasing the l...

Sulfate reduction and denitrifying sulfide removal as a natural remediation process in an inland river

The simultaneous removal of sulfate, nitrate and organic carbon by biological processes in engineered systems is a relatively new area of research. This study is the first to demonstrate that these biological processes occur in natural systems resulting in the remediation of polluted river water. Samples of water and sediment were collected from a 5km-long section of Liming River, Daqing, China, in August and September, 2012. Sections with reduced sulfate concentration, autotrophic denitrification and heterotrophy, together with their dominant strains, were identified. Over a river section that was 3km long, sulfate reduction (SR) and denitrifying sulfide removal (DSR) processes together removed approximately 2100 tons of sulfate, 2300 tons of nitrate, and 3200 tons of chemical oxygen demand (COD) from the river water annually. Microbial community was shifted to adapt to transformation of pollutants and point-source pollution in the studied river.

Hydrogen transfer in transformations of olefin and thiophene compounds for the refining of gasoline fractions

Hydrogen transfer reactions in the transformations of mixtures of model hydrocarbons (hydrogen donors and acceptors) on zeolite catalysts were studied. Hydrogen donors were represented by various classes of hydrocarbons, and acceptors—by unsaturated (olefin) and thiophene compounds. The [H]-donor activity series of hydrocarbons was revealed. Strong differences in the transformation pathways of 1-hexene and 1-octene under the conditions of catalytic refining were demonstrated. A new method for the refining of low-rank gasoline fractions was proposed. The method is based on the hydrogen transfer reactions between hydrogen donor hydrocarbons and hydrogen acceptor hydrocarbons, which proceed without molecular hydrogen. The proposed method allows the simultaneous removal of sulfur (more than 95%) and unsaturated (more than 90%) compounds.

Simultaneous Removal of Sulfur and Nitrogen Compounds in the C4 Gas from Fluidized Catalytic Cracking Using Modified Activated Carbons

Simultaneous Removal of Sulfur and Nitrogen Compounds in the C4 Gas from Fluidized Catalytic Cracking Using Modified Activated Carbons

Removal of sulfur from commercial kerosene using nanocrystalline NiFe2O4 based sorbents

This paper deals with the simultaneous removal of sulfur from commercial kerosene at room temperature using sorbents containing NiFe2O4 nanoparticles. The nanocrystalline NiFe2O4 based sorbents were prepared using the combustion route. The effect of fuel content on the surface properties and desulferization activity of Ni/Fe mixed oxide sorbents has been studied.It was observed that incorporation of metal cations (Ni2+) into the hematite (α-Fe2O3) crystal structure alters the surface properties and desulferization activity of the investigated oxides, which in turn depends on the nature and concentration of the incorporated metal cation and the released heat during the combustion process. The effect of fuel content in modifying the resultant surface area could be directly related to the variations in the rate of crystal growth of the solids studied depending upon preparation temperature. Interestingly, all the prepared ferrites exhibit a narrow pore size distribution in the range of 0.9–2nm. The capacity of NiFe2O4 to adsorb sulfur from commercial kerosene was evaluated in terms of their textural and chemical characteristics.

Simultaneous sulfide and acetate oxidation under denitrifying conditions using an inverse fluidized bed reactor

AbstractBACKGROUND: Simultaneous removal of sulfur, nitrogen and carbon compounds from wastewaters is a commercially important biological process. The objective was to evaluate the influence of the CH3COO−/NO3− molar ratio on the sulfide oxidation process using an inverse fluidized bed reactor (IFBR).RESULTS: Three molar ratios of CH3COO−/NO3− (0.85, 0.72 and 0.62) with a constant S2−/NO3− molar ratio of 0.13 were evaluated. At a CH3COO−/NO3− molar ratio of 0.85, the nitrate, acetate and sulfide removal efficiencies were approximately 100%. The N2 yield (g N2 g−1 NO3−‐N consumed) was 0.81. Acetate was mineralized, resulting in a yield of 0.65 g inorganic‐C g−1 CH3COO−‐C consumed. Sulfide was partially oxidized to S0, and 71% of the S2− consumed was recovered as elemental sulfur by a settler installed in the IFBR. At a CH3COO−/NO3− molar ratio of 0.72, the efficiencies of nitrate, acetate and sulfide consumption were of 100%, with N2 and inorganic‐C yields of 0.84 and 0.69, respectively. The sulfide was recovered as sulfate instead of S0, with a yield of 0.92 g SO42−‐S g−1 S2− consumed.CONCLUSIONS: The CH3COO−/NO3− molar ratio was shown to be an important parameter that can be used to control the fate of sulfide oxidation to either S0 or sulfate. In this study, the potential of denitrification for the simultaneous removal of organic matter, sulfide and nitrate from wastewaters was demonstrated, obtaining CO2, S0 and N2 as the major end products. Copyright © 2008 Society of Chemical Industry

Cement paste column for simultaneous removal of fluoride, phosphate, and nitrate in acidic wastewater

Cement paste, a cured mixture of cement and water, was reported to have considerable capacity for fluoride removal. In this study, heavily mixed fluoric acid wastewater from a semiconductor fabrication plant was applied to a column packed with cement paste granules to evaluate its capacity for the removal of fluoride and three other contaminants, phosphate, nitrate, and sulfate, as well as to investigate the interactions between these contaminants and cement components. The column reduced fluoride to remarkably low levels since fluorite was formed at highly elevated concentrations of calcium and the residual fluoride was further sorbed into the amorphous calcium phosphate that precipitated the entire amount of phosphate until breakthrough. The simultaneous removal of sulfate in the earlier stage was followed by significant removal of nitrate in exchange with the gradual release of sulfate. This behavior was explained by the co-precipitation of sulfate with calcium phosphate or calcium aluminate solids and the subsequent substitution of nitrate for the interlayer sulfate of monosulfate. However, the overall removal capacity of cement paste was reduced due to the high effluent loss of calcium and competition for calcium between fluoride and phosphate.

Interactions Between Chloride and Sulfate or Silica Removals from Wastewater Using an Advanced Lime‐Aluminum Softening Process: Equilibrium Modeling

Interactions among chloride, sulfate, and silica removals from recycled industrial wastewater using an ultra-high lime with aluminum process (UHLA) were studied. An equilibrium model that is able to accurately predict the chemical behavior and interactions between chloride and sulfate or silica with UHLA at various initial conditions and chemical reagents was developed. X-ray diffraction (XRD) analysis was conducted to identify the precipitated solids formed in the UHLA process. Model predictions indicated that simultaneous removal of sulfate and chloride can be best described by the formation of a solid solution containing calcium chloroaluminate, calcium sulfoaluminate (ettringite), calcium monosulfate, tricalcium hydroxyaluminate, and tetracalcium hydroxyaluminate. However, simultaneous removal of silica and chloride can be best described by precipitation of calcium silicate and calcium aluminosilicate in addition to a solid solution containing calcium chloroaluminate, tricalcium hydroxyaluminate, and tetracalcium hydroxyaluminate. The XRD results indicated the presence of the same solids assumed by the equilibrium model.

HYDROPROCESSING OF A NORTH GUJARAT CRUDE OIL BLEND

Hydroprocessing of a North Gujarat Crude oil (of Indian Origin) in a light gas oil solution was carried out over a commercial hydrotreating catalyst at a temperature between 300 to 450°C and a pressure of 6.8 to 20 Mpa in a laboratory reactor. About 30 to 60% of the long residue (365° C + cut) in the solution is converted to light distillates. Simultaneous removal of sulfur, nitrogen, oxygen and metals took place in substantial quantities.

A Novel Desulfurization Process for Fuel Oils Based on the Formation and Subsequent Precipitation of S-Alkylsulfonium Salts. 4. Desulfurization and Simultaneous Denitrogenation of Vacuum Gas Oil

The simultaneous removal of sulfur- and nitrogen-containing compounds from vacuum gas oil (VGO), based on alkylation and a subsequent precipitation method using alkylating agents (CH3I and AgBF4), has been investigated. Desulfurization and denitrogenation reactivities for various compounds in VGO have been studied by means of field ionization−mass spectrometry (FI−MS) and gas chromatography−atomic emission detection (GC−AED), respectively. The sulfur and nitrogen compounds in the VGO were found to be methylated by the addition of the alkylating agents under moderate conditions and were removed successfully as the precipitates of the corresponding S-methylsulfonium and N,N-dimethylcarbazolium tetrafluoroborates. By this means, the sulfur and nitrogen concentrations of the VGO were reduced simultaneously to less than 0.1% and 7.0% of the corresponding feed values, in the presence of a 20-fold molar excess of CH3I and a 10-fold molar excess of AgBF4, respectively, based on the initial sulfur concentration of...

Photochemical Desulfurization and Denitrogenation Process for Vacuum Gas Oil Using an Organic Two-Phase Extraction System

The simultaneous removal of sulfur- and nitrogen-containing compounds from vacuum gas oil (VGO), based on the combination of UV irradiation and liquid−liquid extraction using an oil/acetonitrile two-phase system, has been investigated. Detailed desulfurization and denitrogenation reactivities for the various compounds in VGO have also been studied by means of field ionization mass spectrometry (FI-MS) and gas chromatography with atomic emission detection (GC-AED), respectively. When VGO and acetonitrile are mixed and photoirradiated, the sulfur and nitrogen compounds in the VGO are distributed into the acetonitrile phase and photodecomposed there to form highly polarized compounds, which do not distribute into the lower-polarity VGO. The successive removal of these compounds from VGO to acetonitrile can therefore be carried out under moderate conditions, such that the sulfur and nitrogen contents for the VGO are decreased simultaneously to less than 1% of the feed values. FI-MS and GC-AED analyses reveal that dinaphthothiophenes, tetrahydrodinaphthothiophenes, tetrahydrodibenzothiophenes, and carbazoles, having large carbon numbers of the alkyl substituents, are the most difficult compounds to remove by the present photochemical organic two-phase extraction process. The removal efficiencies for sulfur and nitrogen compounds obtained from VGO were compared with the results obtained for light oil feedstocks, and the applicability of the present process to the refining of VGO was examined. From a consideration of the above results, a fully organized overall refining process for petroleum-derived middle and heavy feedstocks has been developed.

Characterization and alkaline decomposition/cyanidation of beudantite–jarosite materials from Rio Tinto gossan ores

Jarosite-type minerals are the major silver carriers in the gossan ores from Rio Tinto (Spain). Two types of minerals were found: one corresponding to beudantite variable enriched in sulfate; the other is potassium jarosite containing various amounts of arsenate and lead. They are isostructural with cell parameters intermediate between those reported for end members. Silver is present in both jarosites as dilute solid solution (230 ppm Ag in average). The cyanidation of potassium jarosite in saturated Ca(OH) 2 at 70–100°C consists of two step in series: a slow step of alkaline decomposition followed by a fast step of Ag complexation from the decomposition solids. The alkaline decomposition is characterized by the simultaneous removal of sulfate and K ions and the formation of an amorphous hydroxy-arsenate of Fe, Pb and Ca. The kinetics are chemically controlled, with an activation energy of 86.5 kJ mol −1. The nature of the alkaline decomposition of beudantite was similar but extremely slow at ≤100°C.

Second row transition metal sulfides for the hydrotreatment of coal-derived naphtha II. Removal of individual sulfur compounds

The disappearance of individual sulfur compounds has been investigated during the hydrotreatment (simultaneous removal of sulfur, nitrogen and oxygen) of coal-derived naphtha over each of the bulk second row transition metal sulfides. The sulfur compounds in the naphtha mainly consist of thiols/sulfides, thiophene and substituted thiophenes. Thiols/sulfides are, in general, more easily converted than thiophenic compounds are. Lighter thiols/sulfides are intermediates in the conversion of higher boiling thiols/sulfides or thiophenes. Side chain alkyl CC bond breaking is predominant during the disappearance of thiophenes over the Zr and Nb catalysts while CS bond breaking is predominant over the other catalysts. Thiophenic compounds are hydrogenated prior to desulfurization over the Mo, Ru, Rh and Pd sulfides. Highly substituted thiophenes are the compounds most difficult to convert over the Mo, Ru, Rh and Pd sulfides. The substituted thiophenes exhibit different reactivity trends over molybdenum sulfide, on one hand, and the Group VIII sulfides, on the other, indicating different adsorption modes and surface mechanisms for their conversion over these catalysts. Individual sulfur compounds do not follow first order kinetics and the disappearance rate is limited by product inhibition. The overall removal of sulfur does not follow simple first or second order kinetics since the individual compounds do not react in parallel, independent or first order reactions.