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Physicochemical and biological methods for treatment of municipal solid waste incineration ash to reduce its potential adverse impacts on groundwater
Published in Manish Kumar, Sanjeeb Mohapatra, Kishor Acharya, Contaminants of Emerging Concerns and Reigning Removal Technologies, 2022
Basanta Kumar Biswal, Umesh U. Jadhav, Deeksha Patil, En-Hua Yang
The pH of the leaching medium should be appropriately maintained to attain the maximum growth and activity of leaching organisms which facilitate metal mobilization/immobilization. For metal solubilization, pH ranging between 2.0 and 3.0 is suitable for optimum growth of inorganic acid producing bacteria namely Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans (Bosecker, 1997; Xu et al. 2014). However, under strong acidic conditions, i.e., pH less than 1.4, biological activities of these bacteria are significantly declined. The fungal species can grow under both acidic and alkaline conditions, i.e., a broad pH, ranging from 1.5 to 9.8 (Xu et al. 2014). The acidic metabolites produced due to metabolism of substrates by leaching organisms could change the pH of the leaching environment.
Microbiologically Influenced Corrosion Mechanisms
Published in Richard B. Eckert, Torben Lund Skovhus, Failure Analysis of Microbiologically Influenced Corrosion, 2021
Jason S. Lee, Treva T. Brown, Brenda J. Little
Several species of bacteria produce inorganic acids such as nitric, nitrous, sulfuric, sulfurous or carbonic acids. Acidithiobacillus ferrooxidans, an acidophilic FeOB, oxidizes Fe2+ to Fe3+ and reduced inorganic sulfur compounds to H2SO4 under aerobic conditions. Under acidic conditions (pH < 3.5) Fe3+ is soluble (Feaq3+), leading to the rapid corrosion of some alloys, with Feaq3+ acting as an oxidant (Inaba et al. 2019). A study measuring the corrosion rate of C1010 steel with and without A. ferrooxidans reported that corrosion increased 3–6 times in the biotic medium over that of an abiotic acidic medium (Wang et al. 2014). The accelerated corrosion did not require biofilm formation or direct cell contact with the corroding steel. Feaq3+ continuously produced by A. ferrooxidans was responsible for the increased corrosion. Dong et al. (2018) attributed corrosion of a super austenitic stainless steel to acid production by A. caldus. Thiobacillus, capable of growth at pH 1, produces sulfuric acid as a result of sulfide oxidation. Sulfuric acid is associated with concrete deterioration and iron rebar corrosion in sewer systems (Islander et al. 1991).
Kinetic, Isotherm, and Thermodynamic Studies for Batch Adsorption of Metals and Anions, and Management of Adsorbents after the Adsorption Process
Published in Deepak Gusain, Faizal Bux, Batch Adsorption Process of Metals and Anions for Remediation of Contaminated Water, 2021
Deepak Gusain, Shikha Dubey, Yogesh Chandra Sharma, Faizal Bux
The process of recovery of metals similar to the nutrient cycle can be achieved by biohydrometallurgical methods. The bacteria and fungi used for the metal solubilization in biohydrometallurgical methods are positively enhanced by the generation of the acidic media or oxidizing media during their growth in the medium (Akcil et al. 2015). Bioleaching can be achieved by Acidithiobacillus thiooxidans, Acidithiobacillus ferrooxidans (Yu et al. 2020), or Aspergillus nomius (Liu et al. 2018). The recent rise of LED (light emitting diode) has led to increased gallium, copper, and nickel waste in recent times. These metals can be bioleached with the help of Acidithiobacillus ferrooxidans (Pourhossein and Mousavi 2018). The bioleaching process has the advantages of low energy requirement and low operation and maintenance costs. However, the longer time period required for operation and the dependency on atmospheric conditions are certain limitations.
Chemical and Biological Leaching of Chalcopyrite- Elemental Sulfur Reaction Products
Published in Mineral Processing and Extractive Metallurgy Review, 2023
Leticia Maria de Melo Silva Cheloni, F. L. Martins, L. Moreira Pinto, M. L. Marques Rodrigues, V. A. Leão
Bioleaching experiments were performed with a mesophilic culture of Acidithiobacillus ferrooxidans. The microorganisms were cultivated in Norris growth medium (0.2 g/L (NH4)SO4, 0.4 g/L MgSO4.7 H2O, and 0.1 g/L of K2HPO4) in the presence of 2.5 g/L of Fe2+ (as ferrous sulfate). The tests were carried out in 250 mL Erlenmeyers flasks containing 100 mL of a 1% (w/v) pulp density, at 32ºC and the stirring rate was 120 min−1 in the presence of 15% (v/v) of inoculum. When necessary, the solution pH was corrected to 1.8 by using either 1 mol/L sulfuric acid or 6 mol/L sodium hydroxide. Redox potentials (Eh) were also periodically measured. It must be stressed that the strains were previously adapted to a pulp containing 1% (w/v) chalcopyrite, with experiments performed weekly to promote an adequate bacterial concentration adapted to chalcopyrite. The abiotic tests were carried out in the presence of 2% (w/v) of thymol (C10H14O), as bactericide. Aliquots were collected periodically, from the bioleaching experiments to analyze copper concentration by ICP-OES.
Changes in the fractionation profile of Al, Ni, and Mo during bioleaching of spent hydroprocessing catalysts with Acidithiobacillus ferrooxidans
Published in Journal of Environmental Science and Health, Part A, 2018
Ashish Pathak, Mark G. Healy, Liam Morrison
In recent years, a biotechnological leaching technique called ‘bioleaching’ has gained attention as an efficient and eco-friendly method for the recovery of metals from spent catalysts.[7] The bioleaching technique exploits the oxidization potential of acidophilic bacteria such as Acidithiobacillus ferrooxidans (At. ferrooxidans) and Acidithiobacillus thiooxidans (At. thiooxidans) to transform insoluble metallic species to soluble entities. Many studies have reported the potential of bioleaching in the recovery of different metals (Al, Mo, Ni, and V) from spent catalyst.[7–9] In most of these studies, the bioleaching yield of the metal was reported based on the total metal content of individual metals. However, it is now widely recognized that determining the total content of metals does not adequately quantify their bioavailability and mobility, or their potential environmental risks.[10] This is because toxicity depends not only on total concentrations but also on the bioavailable fraction of a given metal.[11] The metals present in the spent catalyst are therefore likely to exist in different chemical fractions, which will eventually affect their mobility and bioavailability.[8] In addition, the efficiency of the bioleaching process will also be largely dependent on the fractionation of metals, as each metal exhibits different energy states in the spent catalysts.
The coupling reaction of Fe2+ bio-oxidation and resulting Fe3+ hydrolysis drastically improve the formation of iron hydroxysulfate minerals in AMD
Published in Environmental Technology, 2021
Yongwei Song, Linlin Yang, Heru Wang, Xinxin Sun, Shuangyou Bai, Ning Wang, Jianru Liang, Lixiang Zhou
Acidithiobacillus ferrooxidans (A. ferrooxidans), an acidophilic chemoautotrophic Fe2+-oxidizing bacterium existing ubiquitously in AMD and/or AMD-impacted natural environment, is intentionally used in practical engineering [6, 7]. A. ferrooxidans can effectively facilitate the oxidation of Fe2+ to Fe3+ in acidic AMD, which is further hydrolyzed to form a series of secondary iron hydroxysulfate minerals, such as schwertmannite and jarosite (Equations 1–3) [8, 9].