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Ancillary Substances
Published in Robert H. Kadlec, Treatment Marshes for Runoff and Polishing, 2019
The processing of sulfur in wetland ecosystems is represented by interconversions of several sulfur compounds in the different micro-regions of the ecosystem (Figure 12.9). Oxidized forms, such as sulfite, sulfate and thiosulfate, are found in the oxygenated portion of the water column. Reduced forms, including sulfide, bisulfide, and elemental sulfur, are found in the soils and sediments under conditions of low redox potential. Ionic and molecular forms are prevalent. Hydrogen sulfide, and methylated sulfur compounds, are volatile, and may be lost from the wetland to the atmosphere. Sulfate is an essential nutrient because its reduced, sulfhydryl (-SH) form is used in the formation of amino acids. Because there is usually enough sulfate in surface waters to meet the sulfur requirement, sulfate rarely limits overall productivity in wetland systems.
Conventional Metal Recycling Techniques
Published in Hong Hocheng, Mital Chakankar, Umesh Jadhav, Biohydrometallurgical Recycling of Metals from Industrial Wastes, 2017
Hong Hocheng, Mital Chakankar, Umesh Jadhav
As seen in Equations 3.21 and 3.22, sulfate is the major product (90%); other products (1%–2%) such as sulfite, sulfate trithionate, tetrathionate, and other polythionates can be detected. The formation and regeneration of thiosulfate and/or Fe(III) occur in these reactions. In particular, tetrathionate forms from thiosulfate oxidation (Equation 3.23) across a wide range of pH due to different oxidants (Schippers et al. 1996, Schippers and Jørgensen 2002). Further, thiosulfate decomposes to sulfite and elemental sulfur, which is a very slow reaction at pH 2, and hence, tetrathionate is the main product of thiosulfate reactions. This tetrathionate decomposes to sulfate (Equation 3.24) and trithionate (Equation 3.25): 2S2O32− + 2Fe3+ + 5H2O → S4O62− + 2Fe2+S4O62− + H2O → HS3O3− + SO42− + H+S3O32− + 1.5O2 → S3O62−
Treatment of Wastes Containing Arsenic, Selenium, Thallium, and Mercury Compounds
Published in Bell John W., Proceedings of the 44th Industrial Waste Conference May 9, 10, 11, 1989, 1990
Edwin F. Rissmann, Stephen M. Schwartz
For wastewaters containing chromate ions in addition to arsenates, ion exchange may be the preferred treatment. Chemical reduction processes that might be used to treat chromates by reduction may have the undesirable effect of also reducing arsenate to arsenite. This is particularly true when stronger reducing agents such as sulfites or sulfides are used. For example, the oxidation reduction potential for the sulfite-sulfate ion couple is -0.92 volts. For the arsenite-arsenate couple, it is +0.58 volts. Theoretically, then, sulfite ion should reduce arsenate to arsenite. If iron salts are used as the reducing agent for chromates, the situation is more complicated. The oxidation reduction potential for the ferrous ferric couple varies from + 0.77 to + 0.42 volts depending on negative ions present and pH.3 Thus, in some circumstances, chromate can be theoretically reduced to trivalent chrome while arsenic is left in the desirable arsenate state.
Retrieving sulfur in thiosulfate bio-oxidation: indigenous consortium vs. its dominant isolate Ochrobactrum sp.
Published in Bioremediation Journal, 2023
Panteha Pirieh, Fereshteh Naeimpoor
Under the aerobic condition, a portion of sulfide is reported to be chemically oxidized into S2O3−2 (Eq. (4)) (Klok et al. 2013; Pirieh and Naeimpoor 2019). Sulfide/thiosulfate can completely be oxidized into sulfate when oxygen is sufficiently available (Eqs. (3) and (5)), while oxygen limitation results in partially oxidized products such as elemental sulfur by Eq. (1) (100% S0 from S−2) and Eq. (6) (50% S0 from S2O3−2) (Camiloti et al. 2019; Pirieh and Naeimpoor 2019; Marais et al. 2020). Among sulfur oxidation products, elemental sulfur is the most favorable due to its applications as a primary chemical in various industries such as plastic, paper, petrochemicals, sulfuric acid, and ore leaching processes or fertilizers in agriculture (Sharshar et al. 2020). Unlike hydrophobic chemical sulfur, biological S0 has a hydrophilic character and is dispersible in water, making it more applicable (Mu, Yang, and Xing 2021). Nonetheless, instant separation of S0 from the culture is essential since it can be swiftly oxidized into sulfite/sulfate (Eq. (2) or (7)). Formation of S0 through Eqs. (1) and (6) is supported by molar ratios of O2/(S-sulfide or S-thiosulfate) ≤ 1.0, whereas higher ratios favor sulfate formation viaEqs. (3) and (5) (Bonilla-Blancas et al. 2015; Sun et al. 2017).
Influence of inoculum selection on the utilisation of volatile fatty acid and glucose in sulfate reducing reactors
Published in Environmental Technology, 2022
Miheka Patel, Denys K. Villa Gómez, Ilje Pikaar, William P. Clarke
The measurement of biomass was based on total suspended solids (TSS) and volatile suspended solids (VSS) using standard methods [31]. Stirring minimised the establishment of biofilm on the walls of the reactor so samples of suspended solids were representative of the total biomass in each reactor. VFA (acetic acid, propionic acid, butyric acid, iso-butyric acid, iso-valeric acid and hexanoic acid) and ethanol were measured using an Agilent 7890A gas chromatograph equipped with a flame ionisation detector and a capillary column (DB-FFAP 125–3212). Formic acid and lactic acid were analysed with a HPLC (Shimadzu) equipped with a Shimadzu refractive index (RID-10A) detector using a 300 mm × 7.8 mm Phenomenex Rezex ROA-Organic Acid H+ column. pH was measured using an Orion™ Ross Ultra Electrode. Dissolved sulfur species (i.e. sulfide, sulfite, sulfate, thio-sulfate) were measured using an IC with a UV and conductivity detector (Dionex ICS-2000) [32]. sCOD was analysed using a low range (10–150 mg.L−1) Spectroquant® cell and a SQ 118 Photometer (Merck, Germany). Prior to the sCOD analysis, samples were diluted ten-fold to remove any potential interference by chloride and also acidified with 0.3 mL of 4 M H2SO4 to remove any H2S that could interfere with the sCOD analysis.
Simultaneous removal of NOx, SO2, and Hg from flue gas in FGD absorber with oxidant injection (NaClO2)– full-scale investigation
Published in Journal of the Air & Waste Management Association, 2020
Maria Jędrusik, Dariusz Łuszkiewicz, Arkadiusz Świerczok, Mieczysław Adam Gostomczyk, Mariola Kobylańska-Pawlisz
The obtained data confirms the results obtained on the laboratory scale (Heidel, Hilber, and Scheffknecht 2014; Krzyżynska and Hutson 2012b), where low pH < 7.0 of the slurry promoted the absorption of NO2 from the carrier gas in the calcium carbonate slurry. It is because nitrogen dioxide reacts with and oxidizes HSO3− and SO32- ions present in the slurry (Wang et al. 2012). For pH between 5.3 and 6.1, sulfite, sulfate, and hydrogen sulfate ions coexist with each other in the slurry (Glamser, Eikmeier, and Petzel 1989), the lower pH of the slurry effected the higher share of HSO3− (for pH around 4.0, there are mainly HSO3− ions):