Effects of reactor geometry and electron donor on performance of the hybrid linear flow channel reactor

Marais, T.S.; Huddy, Robert J.; Hille, Robert P. van; Harrison, Susan T.L.

doi:10.1016/j.hydromet.2020.105462

Cited by 2 publications

(5 citation statements)

References 30 publications

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“…This was attributed to partial sulphide oxidation at the surface, whereby hydroxyl ions are released during the formation of elemental sulphur. These findings were consistent with previous investigations (Marais et al, 2020a;Marais et al, 2020b;Marais et al, 2020c).…”

Section: Effect Of Temperature On Biological Sulphate Reduction Perfo...supporting

confidence: 94%

“…After restoring optimal operating conditions at 30 °C and longer HRT, all three reactors were able to recover a high sulphate conversion efficiency. The acetate-fed reactor achieved a sulphate conversion of 72%, which was higher than previously reported when operated under similar conditions (Marais et al, 2020c). The increased abundance of Desulfobacter during operation at 10 °C may have been advantageous for increasing BSR activity.…”

Section: Sulphur-oxidising Bacterial Response To Thermal Shiftmentioning

confidence: 52%

“…A 2 L lactate-fed reactor had been operated continuously for 1,137 days since the initial laboratory-scale demonstration (Marais et al, 2020a;Marais et al, 2020b). The 8 L lactate-fed and 2 L acetate-fed reactors were operated for approximately 488 and 524 days prior to the current investigation, respectively (Marais et al, 2020c). In this study, temperature was gradually decreased in increments of 5 °C from 30 to 10 °C.…”

Section: Evaluating the Effect Of Temperature On Process Performancementioning

confidence: 99%

“…Laboratory-scale hybrid LFCRs, designed to enhance biomass retention and with a working volume of 2 and 8 L were previously described by Marais et al (2020c). The 2 L reactors were constructed with internal dimensions of 250 mm (L) × 100 mm (w) × 150 mm (h), with an aspect ratio of (l/w) of 2.5.…”

Section: Reactor Set-up and Operationmentioning

confidence: 99%

“…Previous investigations have reported on the proof-ofconcept, development and characterisation of the hybrid LFCR process under different operating parameters, such as the effect of hydraulic residence time (HRT), carbon substrate and reactor geometry (Marais et al, 2020a;Marais et al, 2020b;Marais et al, 2020c). These studies have highlighted the potential of the hybrid LFCR as an alternative semi-passive technology, achieving relatively high sulphate and sulphide removal efficiencies with the recovery of elemental sulphur as a valueadding by-product.…”

Section: Introductionmentioning

confidence: 99%

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Effect of temperature change on the performance of the hybrid linear flow channel reactor and its implications on sulphate-reducing and sulphide-oxidising microbial community dynamics

Marais

Huddy

Hille

et al. 2022

Front. Bioeng. Biotechnol.

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Semi-passive bioremediation is a promising strategy to mitigate persistent low volume mine-impacted wastewater containing high sulphate concentrations. Building on the proof of concept demonstration of the hybrid linear flow channel reactor (LFCR), capable of simultaneous biological sulphate reduction and partial sulphide oxidation with elemental sulphur recovery, the impact of key operating parameters, such as temperature, on process performance is critical to real-world application. Temperature fluctuates seasonally and across the diurnal cycle, impacting biological sulphate reduction (BSR) and partial sulphide oxidation. The process is reliant on the metabolic activity and synergistic interactions between sulphate-reducing (SRB) and sulphide-oxidising (SOB) microbial communities that develop within discrete oxic and anoxic microenvironments within the hybrid LFCR. In this study, the impact of operating temperature on process performance was evaluated by decreasing temperature with time from 30 to 10°C in each of three laboratory-scaled hybrid LFCR units operating in pseudo-steady state at 1 g/L sulphate. Using lactate as a carbon source, two reactor sizes (2 and 8 L) were considered, while the impact of lactate vs. acetate as carbon source was evaluated in the 2 L reactors. On incremental decrease in temperature from 30 to 10°C, a decrease in volumetric sulphate reduction rate was observed: from 0.144 to 0.059 mmol/L.h in the 2 L lactate-fed reactor; from 0.128 to 0.042 mmol/L.h in the 8 L lactate-fed reactor; and from 0.127 to 0.010 mmol/L.h in the 2 L acetate-fed reactor. Similarly, sulphate conversion efficiency decreased (2 L lactate-fed: 66% to 27%; 8 L lactate-fed: 61% to 20%; 2 L acetate-fed: 61% to 5%). A decrease in temperature below the critical value (15°C) led to considerable loss in metabolic activity and overall BSR performance. Sessile and planktonic microbial communities were represented by bacterial phyla including Proteobacteria, Synergistetes, Bacteroidetes, and Firmicutes. A diverse group of putative SRB (Deltaproteobacteria) and SOB, including Alpha, Beta, Gamma, and Epsilonproteobacteria phylotypes, were prevalent and shifted in relative abundance and community composition in response to decreasing temperature. Specifically, the decrease in the relative abundance of Deltaproteobacteria with decreasing temperature below 15°C corresponded with a loss of BSR performance across all three reactors. This study demonstrated the impact of low temperature on the physiological selection and ecological differentiation of SRB and SOB communities within the hybrid LFCR and its implications for real-world process performance.

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Section: Effect Of Temperature On Biological Sulphate Reduction Perfo...supporting

confidence: 94%

Section: Sulphur-oxidising Bacterial Response To Thermal Shiftmentioning

confidence: 52%

Section: Evaluating the Effect Of Temperature On Process Performancementioning

confidence: 99%

Section: Reactor Set-up and Operationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Effect of temperature change on the performance of the hybrid linear flow channel reactor and its implications on sulphate-reducing and sulphide-oxidising microbial community dynamics

Marais

Huddy

Hille

et al. 2022

Front. Bioeng. Biotechnol.

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Elemental sulphur recovery from a sulphate-rich aqueous stream in a single hybrid linear flow channel reactor is mediated through microbial community dynamics and adaptation to reactor zones

Marais

Huddy

Harrison

2022

FEMS Microbiology Ecology

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The coupled application of biological sulphate reduction (BSR) and partial sulphide oxidation to treat sulphate-rich wastewater is an effective strategy to mitigate pollution and recover elemental sulphur for re-purposing. The recent development of the hybrid linear flow channel reactor (LFCR) achieves simultaneous BSR and partial sulphide oxidation with biosulphur recovery via a floating sulphur biofilm (FSB). Here, we explore the microbial community zoning and dynamics facilitating the process. Three continuous LFCRs were used to evaluate the effect of reactor zones, hydraulic residence time (HRT), carbon source, namely lactate and acetate, as well as reactor geometry and scale on process performance and microbial community dynamics. Community composition of sessile and planktonic microbial consortia were resolved at a 5- and 2-day HRT through 16S rRNA amplicon sequencing. Preferential attachment and prevalence of specific phylotypes within the sessile and planktonic communities revealed clear adaptation of key microorganisms to different microenvironments. Key microbial taxa affiliated with sulphate reduction and sulphide oxidation as well as those implicated in fermentation and syntrophic metabolism, fluctuated in response to changes in HRT and process performance. Through understanding the relationship between microbial community dynamics and process performance this research will inform better process design and optimisation of the hybrid LFCR.

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Effects of reactor geometry and electron donor on performance of the hybrid linear flow channel reactor

Cited by 2 publications

References 30 publications

Effect of temperature change on the performance of the hybrid linear flow channel reactor and its implications on sulphate-reducing and sulphide-oxidising microbial community dynamics

Effect of temperature change on the performance of the hybrid linear flow channel reactor and its implications on sulphate-reducing and sulphide-oxidising microbial community dynamics

Elemental sulphur recovery from a sulphate-rich aqueous stream in a single hybrid linear flow channel reactor is mediated through microbial community dynamics and adaptation to reactor zones

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