Thiosulfate Removal Research Articles

Treatment of complex sulfur-containing solutions in ammonia desulfurization ammonium sulfate production by ultrasonic-assisted ozone technology

In this work, the cause of abnormal color in ammonium sulfate products formed by flue gas desulfurization is revealed by investigating the conversion relationship between different sulfur-containing ions and their behavior in a sulfuric acid medium. Both thiosulfate (S2O32−) and sulfite (SO32− ＆ HSO3−) impurities affect the quality of ammonium sulfate. The S2O32− is the main reason for the yellowing of the product due to the formation of sulfur impurities in concentrated sulfuric acid. To address the yellowing of ammonium sulfate products, a unified technology (US/O3), using ozone (O3) and ultrasonic waves (US) simultaneously, is exploited to remove both thiosulfate and sulfite impurities from the mother liquor. The effect of different reaction parameters on the degree of removal of thiosulfate and sulfite is investigated. The synergistic effect of ultrasound and ozone on ion oxidation is further explored and demonstrated by the comparative experiments with O3 and US/O3. Under the optimized conditions, the thiosulfate and sulfite concentration in the solution is 2.07 and 5.93 g/L, respectively, and the degree of removal is 91.39 and 90.83%, respectively. The product obtained after evaporation and crystallization is pure white and meets the national standard requirements for ammonium sulfate products. Under the same conditions, the US/O3 process has apparent advantages, such as saving reaction time compared with the O3 process alone. Introducing an ultrasonically intensified field improves the generation of oxidation radicals ·OH, 1O2, and ·O2– in the solution. Furthermore, the effectiveness of different oxidation components in the decolorization process is studied by adding other radical shielding agents using the US/O3 process supplemented with EPR analysis. The order of the different oxidation components is O3(86.04%) > 1O2(6.53%) > •OH(4.45%) > •O2–(2.97%) for the oxidation of thiosulfate, and it is O3(86.28%) > •OH(7.49%) > 1O2(4.99%) > •O2–(1.25%) for the oxidation of sulfite.

Impact of sulfamethoxazole and organic supplementation on mixotrophic denitrification process: Nitrate removal efficiency and the response of functional microbiota

Recirculating aquaculture systems (RAS) effluent is characterized by low COD to total inorganic nitrogen ratio (C/N), excessive nitrate, and the presence of traces of antibiotics. Hence, it urgently needs to be treated before recycling or discharging. In this study, four denitrification bioreactors at increasing C/N ratios (0, 0.7, 2, and 5) were started up to treat mariculture wastewater under the sulfamethoxazole (SMX) stress, during which the bioreactors performance and the shift of mixotrophic microbial communities were explored. The result showed that during the SMX exposure, organic supplementation enhanced nitrate and thiosulfate removal, and eliminated nitrite accumulation. The denitrification rate was accelerated by increasing C/N from 0 to 2, while it declined at C/N of 5. The decline was ascribed to which SMX reduced the relative abundance of denitrifiers, but improved the capability of dissimilatory nitrogen reduction to ammonia (DNRA) and sulfide production. The direct evidence was the relative abundance of sulfidogenic populations, such as Desulfuromusa, Desulfurocapsa, and Desulfobacter increased under the SMX stress. Moreover, high SMX (1.5 mg L−1) caused the obvious accumulation of ammonia at C/N of 5 due to the high concentration of sulfide (3.54 ± 1.08 mM) and the enhanced DNRA process. This study concluded that the mixotrophic denitrification process with the C/N of 0.7 presented the best performance in nitrate and sulfur removal and indicated the maximum resistance to SMX.

Comparative efficiency of three advanced oxidation processes for thiosalts oxidation in mine-impacted water

Grinding and flotation of sulfide-containing ores produce metastable, partially oxidized sulfur compounds known as thiosalts, which are notorious contributors to receiving water bodies’ toxicity by producing delayed acidity. Thus, the continuous optimization of thiosalts oxidation into sulfate is required before treated mine water is discharged into natural streams, as thiosalts oxidation slows down at low temperatures and in the absence of UV. With this aim, the present study evaluated the treatment of thiosalts at initial concentrations of 100 mg/L, 290 mg/L and 630 mg/L using three advanced oxidation processes (AOPs): (1)wet ferrates Fe(VI), 65 mg/L; (2)ozone microbubbles (O3-microbubbles), 75 g/h sparging rate; and (3)hydrogen peroxide (H2O2), 2:1 (H2O2:thiosalts) molar ratio, at 8 °C and 22 °C. All treatability tests were performed on synthetic effluents, while H2O2 efficiency was also assessed with a real effluent, a leachate of non-desulfurized tailings collected at a flotation plant. Results showed that O3-microbubbles gave better efficiency (99%) than wet Fe(VI) (82%) after 2 h of thiosulfate treatment. Similar trends were observed with synthetic and real effluents for treatment with H2O2. Efficient removal of thiosalts in the real effluent required several days of reaction at 8 °C (98%), whereas efficient removal at 22 °C (90%) was reached after 1 h of treatment. All three AOPs tested proved promising for thiosalts removal. The O3-microbubbles showed the best efficiency in terms of thiosalts removal and treatment time. Moreover, H2O2 allowed for better thiosulfate removal than wet Fe(VI), but proved inefficient at oxidizing other intermediate S species and required longer treatment time.

Multiple versus single response optimization in thiosulfate bio-removal and its products formation and function of optimum point in bioreactor

Sulfur oxidizing bacteria have been widely exploited to remove thiosulfate with adverse effects on human health and environment. Since formation of elemental sulfur among other thiosulfate oxidation products is advantageous in industrial applications, we tend to statistically screen (fractional factor design) and optimize (response surface methodology) the operating conditions in this study so that the final thiosulfate removal (Y1) and the highest sulfur production (Y2) become maximum along with the appropriate final sulfate formation (Y3). Optimum conditions were then examined in a stirred bioreactor. Screening results showed the definite effectiveness of six factors on all responses however level modification and optimization were necessary due to significant P-value of curvature. Single response optimizations (maximization of each response) resulted in dissimilar sets of optimal conditions. Multiple response (Y1 = 100 %, Y2 and Y3 = 50 %) optimization, using desirability function, was therefore used and resulted in agitation speed: 44 rpm, pH: 6.07, temperature: 24.7 °C, time: 2.64 day, inoculum ratio: 19.5 % and thiosulfate level: 2.87 mg l−1 as optimal conditions. Bioreactor experiments (agitation speeds: 30−90 rpm) under optimal conditions led to the highest S0 formation of 46 % and complete thiosulfate removal at 60 rpm and 40 h. Therefore, multiple response optimization followed by minor scale modifications can productively enhance industrial elemental sulfur formation from wastewater plants.

Study on the Removal of Thiosulfate from Wastewater by Catalytic Oxidation

Study on the Removal of Thiosulfate from Wastewater by Catalytic Oxidation

Study on the Removal of Thiosulfate from Wastewater by Catalytic Oxidation

Wastewater streaming from industrial plants, including petroleum refineries, chemical plants, pulp and paper plants, mining operations, electroplating operations, and food processing plants, can contain offensive substances such as cyanide, sulfides, sulfites, thiosulfates, mercaptans and disulfides that tend to increase the chemical oxygen demand (COD) of the streams. In the present work, removal of thiosulfate from wastewater by catalytic oxidation using aluminum oxide as a catalyst was studied. Four main factors were considered, namely the initial thiosulfate concentration, the hydrogen peroxide concentrations, the amount of the catalyst and the operating temperatures. The analysis of thiosulfate and sulfate was carried out by using UV Visible Spectrophotometer. An empirical rate equation was developed.

Isolation, identification, and characterization of a novel chemolithoautotrophic bacterium with high potential in biodesulfurization of natural or industrial gasses and biogas

ABSTRACTBiological processes of hydrogen sulfide removal are extensively used as a result of their health, safety, and environment (HSE), efficiency, and economy. The most significant aspect in microbial desulfurization of natural or industrial gasses and biogas is the utilization of effective bacteria that have the ability to remove sulfur compounds particularly hydrogen sulfide. The recent research is aimed at isolating and applying the bacterium for the removal of H2S. Therefore, the bacterium which has the ability to oxidize thiosulfate was isolated from contaminated soil with sulfur compounds and identified by physiological, biochemical, morphological, and genetic techniques. Phylogenetic identification of the 16S rRNA gene sequence indicates that ISOB 14 is closely connected with the Halothiobacillus neapolitanus DSM 581. The isolated bacterium which was named Halothiobacillus sp. ISOB 14 is Gram negative, motile, and non-spore forming. Cells of ISOB 14 were small, rod-shaped, and 0.45–0.64 µm in size. This strain is strictly aerobic and obligately chemolithoautotrophic and can use thiosulfate as an electron donor. This bacterium grew faster in Postgate medium with 0.7% thiosulfate than in sulfur and sodium sulfide. The removal of thiosulfate and production of sulfate were measured by ion chromatography, a sensitive method, with conductivity detection. ISOB 14 can remove thiosulfate 100% after 18–24 h and produce sulfate up to 89.14% and 93.14% after 24 h and 72 h, respectively, under the optimum conditions of bacterium growth. These findings introduce the unique ability and high potentiality of this efficient bacterium for usage in the removal of hydrogen sulfide.

Improvement of desulfurizing activity of haloalkaliphilic Thialkalivibrio versutus SOB306 with the expression of Vitreoscilla hemoglobin gene.

To construct efficient transformation and expression system and further improve desulfurizing activity of cells through expression of Vitreoscilla hemoglobin (VHb) in haloalkaliphilic Thialkalivibrio versutus SOB306. We transferred plasmids pKT230 and pBBR-smr into T. versutus SOB306 via a conjugation method. We identified four promoters from among several predicted promoters by scoring for streptomycin resistance, and finally selected tac and p3 based on the efficiency of expression of red fluorescent protein (RFP). Expression of RFP when regulated by tac was more than three times that of p3 in SOB306. Further, we expressed VHb under the control of tac promoter in SOB306. Expression of VHb was verified using CO-difference spectra. The results showed that VHb expression can boost sulfur metabolism, as evidenced by an increase of about 11.7±1.8% in the average rate of thiosulfate removal in the presence of VHb. A conjugation transfer and an expression system for Thialkalivibrio, has been developed for the first time and used for expression of VHb to improve desulfurizing activity.

Study on Haloalkaliphilic Sulfur-Oxidizing Bacterium for Thiosulfate Removal in Treatment of Sulfidic Spent Caustic

Due to the disadvantages of physiochemical methods for sulfidic spent caustic treatment, attentions are drawn to the environmental-friendly biotreatments including sulfur-oxidizing halo-alkaliphiles. Thioalkalivibrio versutus DSM 13738 was grown at alkaline (pH10) autotrophic medium with sodium carbonate/bicarbonate as the sole source of carbon and amended with sodium thiosulfate as the electron and energy source. The effect of various parameters including temperature (25-40 °C), pH (8-11), NaCl concentration (0.5-5 % w/v) and sodium thiosulfate concentrations (100-750 mM) was evaluated on bacterial growth and thiosulfate removal. This strain could eliminate sodium thiosulfate at very high concentrations up to 750 mM. The results showed that the highest specific growth rate was pH 9.5 and thiosulfate removal of Thioalkalivibrio versutus occurred at pH 10.5. The optimum salt concentration for thiosulfate removal was 2.5 % w/v and 5 % NaCl and specific growth rate elevated 2.5% w/v. It was also specified that this strain thrives occurred in 37 °C and at 35 and 37 °C higher removal of thiosulfate. Following chemical oxidation of sulfide to thiosulfate, application of Thioalkalivibrio versutus could be promising for spent caustic treatment. Since thiosulfate is utilized as an energy source, highest removal efficiency occurred at marginally different conditions compared to optimal growth.

Study on Haloalkaliphilic Sulfur-Oxidizing Bacterium for Thiosulfate Removal in Treatment of Sulfidic Spent Caustic

Due to the disadvantages of physiochemical methods for sulfidic spent caustic treatment, attentions are drawn to the environmental-friendly biotreatments including sulfur-oxidizing halo-alkaliphiles.Thioalkalivibrio versutusDSM 13738 was grown at alkaline (pH10) autotrophic medium with sodium carbonate/bicarbonate as the sole source of carbon and amended with sodium thiosulfate as the electron and energy source. The effect of various parameters including temperature (25-40 °C), pH (8-11), NaCl concentration (0.5-5 % w/v) and sodium thiosulfate concentrations (100-750 mM) was evaluated on bacterial growth and thiosulfate removal. This strain could eliminate sodium thiosulfate at very high concentrations up to 750 mM. The results showed that the highest specific growth rate was pH 9.5 and thiosulfate removal ofThioalkalivibrio versutusoccurred at pH 10.5. The optimum salt concentration for thiosulfate removal was 2.5 % w/v and 5 % NaCl and specific growth rate elevated 2.5% w/v. It was also specified that this strain thrives occurred in 37 °C and at 35 and 37 °C higher removal of thiosulfate. Following chemical oxidation of sulfide to thiosulfate, application ofThioalkalivibrio versutuscould be promising for spent caustic treatment. Since thiosulfate is utilized as an energy source, highest removal efficiency occurred at marginally different conditions compared to optimal growth.

Autotrophic and heterotrophic denitrification for simultaneous removal of nitrogen, sulfur and organic matter

ABSTRACTThe aim of this investigation was to assess the startup and operation of a laboratory-scale hybrid UASB-Anaerobic Filter Reactor (UASFB) of 1 L volume, kept at 30°C, in order to carry out a simultaneous autotrophic and heterotrophic denitrification process. First, the heterotrophic and autotrophic populations were separately enriched, with specific cultures and subsequently the UASFB was inoculated with 2 g L−1 of volatile suspended solids (VSS), with a ratio of 1.5:1 (autotrophs: heterotrophs). The influent or synthetic wastewater used was composed of: Na2S2O3·5H2O, CH3COOK, NaNO3, NaHCO3, K2HPO4, NH4Cl and saline solution. The concentrations varied depending on the organic loading rate (OLR), nitrogen loading rate (NLR) and sulfur loading rate (SLR) applied. In the UASFB reactor, two experimental conditions were tested and assessed: (i) COD/N ratio of 3.6 and SLR of 0.75 kg S m−3 d−1; and (ii) COD/N ratio of 5.8 and SLR of 0.25 kg S m−3 d−1. The results obtained demonstrated that an inoculum coming from an anaerobic reactor was able to carry out the process, obtaining a maximum nitrate removal of 85.3% in the first stage of operation and 99.5% in the second stage. The recovery of sulfur in form of sulfate in the effluent did not present a tendency to stabilize during the measured time, with a maximum thiosulfate removal of 32.5%, when the SLR was lowered to 0.25 kg S m−3 d−1. The maximum organic matter elimination, measured as COD, was 75.8%, which indicates the relatively good performance and behavior of the heterotrophic microorganisms.

Selective removal of thiosulfate from thiocyanate-containing water by a three-dimensional structured adsorbent: a calcined NiAl-layered double hydroxide film

NiAl-layered double hydroxide (NiAl-LDH) platelets were uniformly grown on a porous Ni foam substrate by a facile in situ hydrothermal method.

Studies on the Oxidative Removal of Sodium Thiosulfate from Aqueous Solution

Thiosulfate is generated from various process industries, such as petrochemical, metallurgical, photography processing, pharmaceutical, pigment and dye manufacturing units, etc. Thiosulfate-bearing wastewater is also produced during the anaerobic treatment of wastewater. In the present work, oxidative removal of thiosulfate in the presence of UV light from aqueous solution has been investigated. The effect of thiosulfate concentration, oxygen partial pressure, UV light intensity and air flow rate on the kinetics of thiosulfate removal has been explored, and suitable rate equations were developed for the oxidation processes. 67 % of thiosulfate was removed from the aqueous solution by carrying out aerial oxidation for one hour. Using photooxidation by UV light, 1,200ppm thiosulfate could be oxidized by one hour. Overall reaction by aerial oxidation followed the second-order kinetics, whereas by photooxidation, it followed third-order kinetics.

Isolation of sulfide remover strain Thermithiobacillus tepidarius JNU-2, and scale-up bioreaction for sulfur regeneration

A sulfur removing bacterium named JNU-2 was isolated from an industrial anaerobic sludge pool. Its 16S rRNA phylogeny showed high homology to the species Thermithiobacillus tepidarius. The strain Thermithiobacillus tepidarius JNU-2 was initially cultivated for removing sulfide from sulfate-containing waste water for recycling sulfur. Thiosulfate removal and elemental sulfur production ratios reached 98.0 % and 83.06 %, respectively, after incubating for 24 h. Furthermore, based on the traits of JNU-2, a novel sulfur regeneration reactor—an internal airlift loop reactor (IALR)—was constructed and applied successfully. The key operating conditions of ventilatory capacity (VC) and hydraulic retention time (HRT) were also investigated. The production ratio of elemental sulfur was about 60.0 % and the maximal yield was 75 mg L−1 h−1 at 60 mL min−1 VC and 10 h HRT. All results indicated that the strain JNU-2 and the novel reactor would be of great potential for producing sulfur sources at industrial sites.

Potential Application of Halothiobacillus Neapolitanus for Hydrogen Sulfide Removal in Biogas

Biogas has been extensively used for many applications. The amount of carbon dioxide and hydrogen sulfide in the biogas directly affects its energy content and corrosive property. Many processes were used to remove these gases from the biogas stream. The current research aimed to isolate a pure bacterial strain capable of simultaneous removal both gases, and apply it in the biotrickling filter designed for carbon dioxide and hydrogen sulfide removal. Pure isolate of bacteria capable of thiosulfate oxidation was isolated from an activated sludge seed, and was identified by 16S rDNA method. The isolated microbe was closely related to Halothiobacillus neapolitanus (HTN), an obligately chemolithoautotrophic bacteria able to utilized carbon dioxide as a carbon source, and oxidize sulfide as a energy source. Optimum buffer concentration for thiosulfide oxidation activity was evaluated by varying phosphate buffer concentration in the range of 26 - 78 mM (pH 7.3). The optimum buffer concentration for the growth and thiosufate oxidation was 52 mM. At this buffer concentration, HTN can remove thiosulfate up to 69.8% within 36 h, and maximum thiosulfate removal was 79.1% after 120 h incubation at the initial concentration of 10 g/L thiosulfate. The sulfate production rate was 147.7 ± 9.76 mg/L·h. The current findings indicate the potential use of HTN in a biological process of hydrogen sulfide and carbon dioxide removal to upgrade biogas quality.

Kinetics and Thermodynamics Study of Thiosulfate Removal from Water by Calcined MgAl-CO<sub>3</sub> Layered Double Hydroxides

Layered double hydroxides (LDHs) are potential scavengers for anionic contaminants due to their “memory effect”. Here we report the removal of thiosulfate anion from contaminated water by calcined MgAl–CO3 LDH (CLDH). The results indicate that CLDH exhibits a good performance in adsorption of thiosulfate.We studied the kinetics and thermodynamics of adsorption of thiosulfate from water. The equilibrium isotherm showed that the uptake of thiosulfate anion well agrees with the Langmuir equation, the positive value of △HӨ demonstrates the endothermic feature of the adsorption, the pseudo-second order kinetics model can be uItalic textsed to describe the uptake process and the value of Ea was calculated to be 75.898 kJ/mol. Our results suggest that the process of thiosulfate uptaking was controlled by the reaction rate of thiosulfate with the CLDH rather than diffusion.

Aqueous Phase Thiosulfate Removal Using Photo catalysis

Removal of thiosulfate (S2O32-, 200 mg/L) from simulated wastewater samples was investigated under varying co-pollutants and pH conditions employing the titanium dioxide (TiO2) mediated photocatalysis. For thiosulfate only studies higher substrate removal was noted at lower pH with a specific trend of pH 4 > pH 7 > pH 10. Furthermore, near complete thiosulfate removal was also achieved at pH 4. A similar thiosulfate removal trend was also noted for the binary thiosulfate & p-cresol and thiosulfate & thiocyanate systems at pH 4, indicating high photocatalysis process efficiency. However, thiosulfate removal from the mixed systems at pH greater than 4 was slower as compared to the respective thiosulfate only systems. Nevertheless for the binary thiosulfate & thiocyanate system, significant thiosulfate removal was noted even at pH 12 when the thiosulfate concentration was reduced to 40 mg/L.

Factors affecting the performance of microbial fuel cells for sulfur pollutants removal

A microbial fuel cell (MFC) has been developed for removal of sulfur-based pollutants and can be used for simultaneous wastewater treatment and electricity generation. This fuel cell uses an activated carbon cloth+carbon fibre veil composite anode, air-breathing dual cathodes and the sulfate-reducing species Desulfovibrio desulfuricans. 1.16gdm−3 sulfite and 0.97gdm−3 thiosulfate were removed from the wastewater at 22°C, representing sulfite and thiosulfate removal conversions of 91% and 86%, respectively. The anode potential was controlled by the concentration of sulfide in the compartment. The performance of the cathode assembly was affected by the concentration of protons in the cation-exchanging ionomer with which the electrocatalyst is co-bound at the three-phase (air, catalyst and support) boundary.

Unique presence of a manganese catalase in a hyperthermophilic archaeon, Pyrobaculum calidifontis VA1.

We had previously isolated a facultatively anaerobic hyperthermophilic archaeon, Pyrobaculum calidifontis strain VA1. Here, we found that strain VA1, when grown under aerobic conditions, harbors high catalase activity. The catalase was purified 91-fold from crude extracts and displayed a specific activity of 23,500 U/mg at 70 degrees C. The enzyme exhibited a K(m) value of 170 mM toward H(2)O(2) and a k(cat) value of 2.9 x 10(4) s(-1).subunit(-1) at 25 degrees C. Gel filtration chromatography indicated that the enzyme was a homotetramer with a subunit molecular mass of 33,450 Da. The purified catalase did not display the Soret band, which is an absorption band particular to heme enzymes. In contrast to typical heme catalases, the catalase was not strongly inhibited by sodium azide. Furthermore, with plasma emission spectroscopy, we found that the catalase did not contain iron but instead contained manganese. Our biochemical results indicated that the purified catalase was not a heme catalase but a manganese (nonheme) catalase, the first example in archaea. Intracellular catalase activity decreased when cells were grown anaerobically, while under aerobic conditions, an increase in activity was observed with the removal of thiosulfate from the medium, or addition of manganese. Based on the N-terminal amino acid sequence of the purified protein, we cloned and sequenced the catalase gene (kat(Pc)). The deduced amino acid sequence showed similarity with that of the manganese catalase from a thermophilic bacterium, Thermus sp. YS 8-13. Interestingly, in the complete archaeal genome sequences, no open reading frame has been assigned as a manganese catalase gene. Moreover, a homology search with the sequence of kat(Pc) revealed that no orthologue genes were present on the archaeal genomes, including those from the "aerobic" (hyper)thermophilic archaea Aeropyrum pernix, Sulfolobus solfataricus, and Sulfolobus tokodaii. Therefore, Kat(Pc) can be considered a rare example of a manganese catalase from archaea.

Application of ion chromatography to batchwise activated sludge process for simultaneous removal of thiosulfate, acetate and ammonium ions.

Application of ion chromatography to batchwise activated sludge process for simultaneous removal of thiosulfate, acetate and ammonium ions.