Continuous biological sulfate reduction from phosphogypsum waste leachate

Salo, Marja; Mäkinen, Jarno; Yang, Jason; Kurhila, Matti; Koukkari, Pertti

doi:10.1016/j.hydromet.2018.06.020

Cited by 29 publications

(22 citation statements)

References 20 publications

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“…Our previously published works have focused on BSR in different operative conditions, by varying either sulfate loading rate (Salo et al 2018 ) or influent pH (Salo et al 2020 ). With a steady increase in sulfate loading rate, the BSR bioreactors continued to increase their sulfate removal rate, reaching a maximum of 15,000 mg/L*d (Salo et al 2018 ), which is among the highest achieved in a BSR bioreactor (Liamleam and Annachhatre 2007 ; Qian et al 2019 ). When testing the limits of acidity tolerance of a BSR bioreactor, the influent pH could be decreased down to 1.6 – 1.8 while maintaining an efficient sulfate removal rate (Salo et al 2020 ).…”

Section: Introductionmentioning

confidence: 99%

Sulfate-reducing bioreactors subjected to high sulfate loading rate or acidity: variations in microbial consortia

Salo

Bomberg

2022

AMB Expr

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Sulfate-reducing bioreactors are used in e.g. the mining industry to remove sulfate and harmful metals from process waters. These bioreactors are expected to be run for extended periods of time and may experience variations in the influent quality, such as increasing sulfate loading rate and decrease in pH, while being expected to function optimally. In this study we followed the sulfate removal rate and variation in microbial communities over a period of up to 333 days in three different up-flow anaerobic sludge blanket (UASB) bioreactors being submitted to increasing sulfate loading rate or decreasing pH. Sodium lactate was used as the sole carbon source and electron donor. All three bioreactors contained highly diverse microbial communities containing archaea, fungi and bacteria. Sulfurospirillum and Desulfovibrio were the most prominent bacterial genera detected in the bioreactors receiving the highest sulfate loading rates, and the greatest relative abundance of methanogenic archaea and the fungal genus Cadophora coincided with the highest sulfate reduction rates. In contrast, Sulfuricurvum was dominant in the bioreactor receiving influent with alternating pH, but its relative abundance receded in response to low pH of the influent. All bioreactors showed excellent sulfate removal even under extreme conditions in addition to unique responses in the microbial communities under changing operational conditions. This shows that a high diversity in the microbial consortia in the bioreactors could make the sulfate removal process less sensitive to changing operational conditions, such as variations in influent sulfate loading rate and pH.

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Section: Introductionmentioning

confidence: 99%

Sulfate-reducing bioreactors subjected to high sulfate loading rate or acidity: variations in microbial consortia

Salo

Bomberg

2022

AMB Expr

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“…Simultaneously, insoluble calcium sulfate, called phosphogypsum waste, is generated and stacked in the vicinities of phosphoric acid plants [7,8]. If not properly managed, it can cause negative environmental effects by releasing contaminated run-off and seepage waters [9][10][11]. The fate of impurities in the wet processes vary.…”

Section: Introductionmentioning

confidence: 99%

Sequential Bioleaching of Phosphorus and Uranium

et al. 2019

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Phosphorus and uranium are both vital elements for society. In recent decades, fears have arisen about the future availability of low-cost phosphorus and uranium. This has resulted in pressure to de-centralize production of both elements by utilizing lower-grade or complex deposits. The research presented here focused on phosphorus-containing apatite ores with uranium impurities; in order to separate uranium by selective and sequential bioleaching before phosphorus leaching. This would create an alternative process route for solvent-extraction, used to remove/recover uranium from the phosphorus acid product of apatite H2SO4 wet process. In this work, it was seen that the used fluorapatite ore required 24 h leaching at pH 1 by H2SO4 to result in 100% leaching yield for phosphorus. As this ore did not contain much uranium, an artificial fluorapatite-uranium ore was prepared by mixing standard uranium ore and fluorapatite. The research with this ore showed that 89% of uranium dissolved in 3 days at pH > 2 and leaching was improved by applying Fe3+ oxidant. In these conditions only 4% of phosphorus was leached. By prolonged (28 days) leaching 95% uranium yield was reached. According to the experiments, the iron in the uranium leach solution would be mainly Fe3+, which allows the use of H2O2 for uranium recovery and then direct use of spent leachate for another uranium leaching cycle. After the dissolution of uranium, 90% of phosphorus was dissolved by decreasing the pH to 1.3. This was done by bioleaching, by utilizing biogenic sulfur oxidation to sulfuric acid.

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“…This study evaluated the optimal conditions for nickel (Ni) and cobalt (Co) 7.1.1.2 Implications Phosphate can be found widely in many waste streams containing organics such as municipal wastewater or phosphogypsum waste leachate (Salo et al, 2018;Sanchez-Andrea et al, 2012). The use of these waste streams as an electron donor for SRB can provide phosphate, and ultimately, enhance metal recovery.…”

Section: Discussionmentioning

confidence: 99%

“…Phosphate can be found widely in many waste streams containing organics such as municipal wastewater or phosphogypsum waste leachate (Salo et al, 2018;Sanchez-Andrea et al, 2012;Yeoman et al, 1988). Therefore, the use of these waste streams as an electron donor for BSR can provide phosphate, and ultimately, enhancing metal recovery (Reis et al, 2013;Salo et al, 2018;Villa-Gomez et al, 2012).…”

Section: Ni/co Sulfide Precipitation In the Batch Experimentsmentioning

confidence: 99%

“…Phosphate was found to be one of the main compounds in biogenic sulfide that can significantly enhance Ni and Co sulfide precipitation efficiency and particle settling properties (Chapter 3). To reduce the cost of phosphate, it is worthwhile to assess the cotreatment of mine-impacted water and municipal wastewater that contain higher amount of phosphate (Salo et al, 2018;Sanchez-Andrea et al, 2012;Yeoman et al, 1988). Such cotreatment also have other advantages: (1) this can dilute the mine-impacted water to reduce the toxicity of high metal concentrations on SRB;…”

Section: Co-treatment Of Mine-impacted Water and Municipal Wastewatermentioning

confidence: 99%

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Strategies for nickel and cobalt recovery from mine-impacted water using sulfate-reducing bacteria

Liu¹

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With the increasing world demand and price of valuable metals such as nickel (Ni) and cobalt (Co), it has become more attractive to recover these metals from secondary streams such as mine-impacted water. Biogenic sulfide produced through a biological sulfate reduction process is a promising approach compared with the traditional hydroxide or chemical sulfide precipitation for metal recovery, as it can be produced on site and utilize the substances that already exist in the waste streams. Moreover, it is effective even with low metal concentrations and low pH solutions due to the low solubility products of the metal sulfides. However, the generation of fine particles in the sulfide precipitation process is a challenge and usually results in poor settling, which deteriorates the metal recovery efficiency. Despite this, the compositions of biogenic sulfide solutions from different sources are various depending on the electron donors and the influent characteristics, which may affect the metal precipitation reactions and particle settling properties. Therefore, the effect of using chemical sulfide and four biogenic sulfide-containing solutions for Ni and Co precipitation and settling was evaluated in this thesis. Results showed that phosphate was the main component enhancing particle settling whereas acetate and sulfate exhibited a smaller influence. The Ni and Co recovery were also assessed in a novel single-stage upflow fixed-bed sulfidogenic bioreactor treating metal and sulfate-containing wastewater (0-200 mg/L Ni and 0-10 mg/L Co). Over 99% of Ni and Co precipitated and settled in the bioreactor regardless of the initial metal concentration. Bacterial communities attached on the carrier materials and metal precipitates collected from the bioreactor bottom were also characterized. These findings helped describe the simultaneous treatment of sulfate-and metal-containing wastewater in a sulfidogenic bioreactor and provided information on how to scale up the reactor and to optimize the metal recovery efficiency. Ni and Co often co-exist in ores and the associated mine waste; however, their similar chemical behaviors have made the selective recovery of both metals a challenge. The addition of chemicals and energy in hydrometallurgy are common practices for Ni-Co concentrates that allows selective separation through precipitation, ion exchange and solvent extraction. Although these options are economically feasible for concentrates, the same technologies may not necessarily be attractive for secondary sources with lower, but still significant metal concentrations. Therefore, a new approach to separate Ni and Co using sulfate-reducing bacteria (SRB) based on the different microbial responses to metal stress was proposed in this thesis. Results show that Ni displayed higher solubility (52-99%) than Co (0.6-15.5%) in the presence of SRB and sulfide. This could be partially explained by the higher Ni stress to SRB that induced the production of extracellular proteins that can selectively complex Ni and stabilize it in th...

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Continuous biological sulfate reduction from phosphogypsum waste leachate

Cited by 29 publications

References 20 publications

Sulfate-reducing bioreactors subjected to high sulfate loading rate or acidity: variations in microbial consortia

Sulfate-reducing bioreactors subjected to high sulfate loading rate or acidity: variations in microbial consortia

Sequential Bioleaching of Phosphorus and Uranium

Strategies for nickel and cobalt recovery from mine-impacted water using sulfate-reducing bacteria

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