Query: hydrogen sulfide removal by using ferric sulfate

title: Removal of Hydrogen Sulfide from Gaseous Streams by a Chemical Method using Ferric Sulfate Solution
abstract: Hydrogen sulfide is a toxic and odorous compound present in biogas produced by the anaerobic digestion of biosolids and other organic materials. Reactive absorption of hydrogen sulfide into aqueous ferric sulfate solution is a direct process for HS removal and Sulfur recovery. Apart from sulfur, only HO i s 2 2 generated in the process and consequently, no waste treatment facilities are required. A distinct advantage of the process is that the reaction of H S with is so rapid and complete that there remains no danger of discharging 2 toxic waste gas. Effective operation parameters on this process considered. Results show that high temperature and low pressure are suitable for absorption reaction. Variation of hydrogen sulfide concentration and Fe 3+ concentration with time in absorption reaction shown that the reaction of ferric sulfate and hydrogen sulfide is first order with respect to the both reactant. At low concentration of Fe (SO the absorption rate of H S 2 4 2 increase with increasing the Fe (SO concentration. At higher concentration, a decrease in the absorption rate 2 4 3 was found. At higher concentration of Fe (SO the ionic strength and viscosity of solution increase 2 4 3

title: Oxidation of iron sulfide and surface bound iron to regenerate granular ferric hydroxide for in situ hydrogen sulfide control by persulfate, chlorine and peroxide
abstract: Hydrogen sulfide emission from sediments in storm drainage networks, estuaries and marine seafloor is a nuisance. The regeneration of the GFH for reuse is crucial to make dosing granular ferric hydroxide (GFH) an effective, long lasting solution than doing liquid oxidants to the control of sedimentary hydrogen sulfide. This paper investigated the oxidation of iron sulfide and surface bound iron compounds to regenerate GHF using persulfate, chlorine and peroxide for the in situ control of hydrogen sulfide. The hydrogen sulfide removal capacities of virgin, persulfate chlorine and peroxide regenerated GFH were 68.34, 77.49, 67.87 and 57.59 mg S/g, respectively. The recovery of the capacities was mainly attributed to the oxidation of iron sulfide, surface bound Fe(II) and released Fe2+ to amorphous ferric hydroxides. Iron sulfide was mainly oxidized to sulfate (SO42 (97.8% by persulfate, and to elemental sulfur (S(0) (5.8 and 25% thiosulfate (S2O32 (27.7 and 11.3% and SO42 (66.5 and 63.7% by chlorine and peroxide, respectively. In addition to the oxidation by persulfate, the reaction between persulfate and the surface Fe(II) compounds also generated sulfate radicals and hydroxyl radicals, which enhanced the oxidation of the iron sulfide and surface bound iron compounds on the GFH surface and regenerated GFH more completely.

title: Reactive Absorption of Hydrogen Sulfide in Aqueous Ferric Sulfate Solution
abstract: Many commercial processes are available for the removal of H2S from gaseous streams. The desulfurization of gas streams using aqueous ferric sulfate solution as washing liquor is studied. Apart from sulfur, only H2O is generated in the process, and consequently, no waste treatment facilities are required. A distinct advantage of the process is that the reaction of H2S with is so rapid and complete that there remains no danger of discharging toxic waste gas. In this study, the reactive absorption of hydrogen sulfide into aqueous ferric sulfate solution has been studied and design calculations for equipments have been done and effective operation parameters on this process considered. Results show that high temperature and low pressure are suitable for absorption reaction. Variation of hydrogen sulfide concentration and Fe concentration with time in absorption reaction shown that the reaction of ferric sulfate and hydrogen sulfide is first order with respect to the both reactant. At low Fe2(SO4)3 concentration the absorption rate of H2S increase with increasing the Fe2(SO4)3 concentration. At higher concentration a decrease in the absorption rate was found. At higher concentration of Fe2(SO4)3, the ionic strength and viscosity of solution increase remarkably resulting in a decrease of solubility, diffusivity and hence absorption rate.  Absorption, Fe2(SO4)3, H2S, Reactive Absorption.

title: Trichloroethylene Removal Using Sulfate Reducing Bacteria and Ferric Iron
abstract: Sulfate reducing bacteria (SRB) is universally distributed in the sediment, especially in marine environment. SRB reduce sulfate as electron acceptor to hydrogen sulfide in anaerobic condition. Hydrogen sulfide is reducing agent enhancing the reduction of the organic and inorganic compounds. With SRB, therefore, the degradability of organic contaminants is expected to be enhanced. Ferrous iron reduced from the ferric iron which is mainly present in sediment also renders chlorinated organic compounds to be reduced state. The objectives of this study are: 1) to investigate the reduction of TCE by hydrogen sulfide generated by tht growth of SRB, 2) to estimate the reduction of TCE by ferrous iron generated due to oxidation of hydrogen sulfide, and 3) to illuminate the interaction between SRB and ferrous iron. Mixed bacteria was cultivated from the sludge of the sewage treatment plant. Increasing hydrogen sulfide and decreasing sulfate confirmed the existence of SRB in mixed culture. Although hydrogen sulfide lonely could reduce TCE, the concentration of hydrogen sulfide produced by SRB was not sufficient to reduce TCE directly. With hematite as ferric iron, hydrogen sulfide produced by SRB was consumed to reduce ferric ion to ferrous ion and ferrous iron produced by hydrogen sulfide oxidation decreased the concentration of TCE. Tests with seawater confirmed that the activity of SRB was dependent on the carbon source concentration.

title: Removal of heavy metals using a novel sulfidogenic AMD treatment system with sulfur reduction: Configuration, performance, critical parameters and economic analysis.
abstract: A novel sulfidogenic acid mine drainage (AMD) treatment system with a sulfur reduction process was developed. During the 220 d operation, >99.9% of 380 mg/L ferric, 150 mg/L aluminum, 110 mg/L zinc, 20 mg/L copper and 2.5 mg/L lead ions, and 42.6 44.4% of 100 mg/L manganese ions in the synthetic AMD were step by step removed in the developed system with three pre posed metal precipitators and a sulfur reduction reactor. Among them, zinc, copper and lead ions were removed by the biogenic hydrogen sulfide that produced through elemental sulfur reduction; while ferric, aluminum and manganese ions were removed by the alkali precipitation. Compared with the reported sulfate reduction reactors, the sulfur reduction reactor significantly reduced the chemical cost by 25.6 78.9% for sulfide production, and maintained a high sulfide production rate (1.12 g S2 /L d) The pH level in the sulfidogenic reactor driven by sulfur reducing bacteria posed a significant effect on the sulfide production rate. Under a nearly neutral condition (pH 7.0 7.5) elemental sulfur dissolved into polysulfide to increase the bioavailability of S0. At acidic conditions (pH 6.0) polysulfide formation was limited and sulfate reduction became dominant. Therefore, maintaining the sulfidogenic reactor driven by sulfur reducing bacteria at neutral condition is essential to realize high rate and low cost AMD treatment. Moreover, the escape of residual hydrogen sulfide from the system was eliminated by employing a 17% recirculation from effluent to the sulfidogenic reactor.

title: Research progress in prevention and control technology of hydrogen sulfide from urban sewer
abstract: The hydrogen sulfide from urban sewer does increasingly serious harm to the environment.The common treatment agents for hydrogen sulfide removal include oxygen,hydrogen peroxide,sodium hypochlorite,ferric chloride and ferrous sulfate,etc.The shortcoming of the control method of sewer hydrogen sulfide is high cost.The treatment of hydrogen sulfide in the sewage treatment system by using chemical and biological methods has made some important progress in recent years.The research status of current and new technology of hydrogen sulfide emission control in sewer systems was introduced in this paper.Microbial fuel cells and bacteriophage for the treatment of hydrogen sulfide from urban sewer will play an important role in the future.

title: Hydrogen sulfide and turbidity control using catalysed oxidation coupled with filtration for groundwater treatment
abstract: The presence of hydrogen sulfide in drinking water supplies can result in odour complaints, sulfur induced corrosion and black water problems in distribution systems. Conventional approaches for hydrogen sulfide control are based on either air stripping to remove nonionized H 2 S or oxidation to form sulfate. Residual hydrogen sulfide can react with chlorine or chloramines resulting in the generation of turbidity in the distribution system, potentially compromising disinfection effectiveness. A promising alternative is to employ hydrogen peroxide oxidation catalysed by iron to form elemental sulfur that can be removed by filtration. Bench and pilot scale tests were conducted on a Florida groundwater to evaluate reaction kinetics and process efficiency. The use of in line hydrogen peroxide oxidation catalysed by low dosages of ferric sulfate coupled with two stage upflow filtration was capable of complete removal of hydrogen sulfide and associated turbidity. Additional benefits of this physical/chemical treatment approach include elimination of odour generation, reduction of chlorine demand and improved stability of the finished water.

title: Influence of process variables on biooxidation of ferrous sulfate by an indigenous Acidithiobacillus ferrooxidans. Part II: Bioreactor experiments
abstract: The oxidation of ferrous iron in solution using Acidithiobacillus ferrooxidans has industrial applications in the regeneration of ferric iron as an oxidant agent for the removal of hydrogen sulfide from waste gases, desulphurization of coal, leaching of non ferrous metallic sulfides and treatment of acid mine drainage. The aim of this attempt was to increase the biooxidation rate of ferrous sulfate by using immobilized cells. Rate of ferrous iron oxidation was determined in a packed bed reactor configuration with low density polyethylene (LDPE) particles as support material in order to find the most practical system for scale up. The present work studies the influence of basic parameters on the ferrous iron biooxidation process using an indigenous iron oxidizing microorganism, namely A. ferrooxidans in a 2 L packed bed bioreactor. Effects of several process variables such as initial pH, temperature, dilution rate, initial concentrations of ferrous and ferric ions on oxidation of ferrous sulfate were investigated. Experimental results indicate that in the temperature range of 31 34 degC the biooxidation of ferrous ions to ferric ions could be resulted efficiently. A pH range of 2 2.2 was optimum for the growth of the culture and effective bacterial activity for oxidation of ferrous ions to ferric ions. The highest oxidation rate of 2.9 g Fe 2+ L 1 h 1 was obtained using a culture initially containing 25 g L 1 Fe +2 at the dilution rate of 0.4 h 1 This rate is very high compared to that achieved in other bioreactors found in the literature. In addition the biooxidation of Fe 2+ to Fe 3+ conversion could be achieved effectively in the presence of the Fe 3+ in the concentration range of 0.1 0.7 g/L.

title: H[sub 2]S removal and sulfur recovery processes using metal salts
abstract: Scrubbing a sour gas stream with a solution of copper sulfate allows the clean up temperature to be increased from ambient to the adiabatic saturation temperature of the gas. The copper ion in solution reacts with the H[sub 2]S to produce insoluble CuS. The choice of copper sulfate was set by the very low solubility of CuS and the very rapid kinetics of the Cus formation. Since the copper sulfate solutions used are acidic, CO[sub 2] will not be co absorbed. In a subsequent step the solid CuS is oxidized by a solution of ferric sulfate. The copper sulfate is regenerated, and elemental sulfur is formed together with ferrous sulfate. The ferrous sulfate is reoxidized to ferric sulfate using air. Since the copper sulfate and ferric solutions are regenerated, the overall reaction in this process is the oxidation of hydrogen sulfide with oxygen to form sulfur. The use of copper sulfate has the further advantage that the presence of sulfuric acid, even as concentrated as 1 molar, does not inhibit the sorption of H[sub 2]S. Furthermore, the absorption reaction remains quite favorable thermodynamically over the temperature range of interest. Because the reaction goes to completion, only a single theoretical stage is requiredmore for complete H[sub 2]S removal and cocurrent gas/liquid contacting may be employed. The formation of solids precludes the use of a packed column for the contacting device. However, a venturi scrubber would be expected to perform satisfactorily. The kinetics of the oxidation of metal sulfides, in particular zinc and copper sulfide, is reported in the literature to be slow at near ambient temperatures. The proposed process conditions for the oxidation step are different from those reported in the literature, most notably the higher temperature. The kinetics of the reaction must be studied at high temperatures and corresponding pressures. An important goal is to obtain sulfur of high purity, which is a salable product.

title: Cleaner Tannery Wastewater Using Chemical Coagulants
abstract: This investigation evaluated the efficiency of primary coagulants, such as Ferrous sulfate (FeSO4 7H2O) Ferric chloride (FeCl3 6H2O) and Calcium hydroxide Ca (OH)2 as a coagulant aid. These chemical coagulants were used in different doses and combinations to reach the optimization of the coagulation and precipitation process, in terms of removal of chromium and other undesirable pollutants, such as ammonia, chlorides, sulfates, Chemical Oxygen Demand (COD) Total Suspended Solids(TSS) Total Dissolved Solids (TDS) hydrogen sulfide gas(H2S) The study was conducted during October 2013 November 2014. The correlation Pearson between all indicators of raw effluents showed that Total alkalinity and ammonia ions(r 0.896) TSS and NH4 (r 0.869) TSS and Cl (r 0.883) sulfate and pH, NH4 TSS respectively, (r 0.821) (r 0. 807) (r 0.824) H2S and COD (r =0.918) were strongly positively correlated. The correlation Pearson between all indicators of treated effluents showed a very strong correlation between E.Coli and St.Faecalis (r =0.992) also Total alkalinity and COD, chromium, respectively with (r 0.918) (r =0.883) chromium and COD(r 0.947) were strongly positively correlated. FeSO4 seemed to be less effective than FeCl3, with regard to the SVI. The Sludge Volume Index was the only parameter that was weakly negatively correlated with other parameters. This study concluded that the chemical combination of FeSO4 and Ca(OH)2 at 150 mg/L and 1000mg/L was more effective than FeCl3 and Ca(OH)2 for the treatment of the tannery effluents with a high efficiency in the removal of chromium, E.Coli and St. Faecalis, ammonia ions, chloride, H2S, TSS, COD and sulfate. A small disadvantage was observed with regard to the COD and TDS.