A comparative assessment on how molasses and CO2 gas prevent carbon limitation in the large-scale culture of freshwater macroalgae

Cole, Andrew J.; Vucko, Matthew J.; Nys, Rocky de

doi:10.1016/j.algal.2017.09.014

Cited by 5 publications

(4 citation statements)

References 38 publications

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“…While several studies have reported that carbon dioxide infusions in algal wastewater treatment systems stimulate algal productivity [ 33 , 51 , 50 , 52 ], few studies have identified the causal mechanism [see 31 for exception]. This study confirmed earlier experiments showing that carbon dioxide stimulates algal productivity in periphytic algae wastewater treatment systems.…”

Section: Discussionsupporting

confidence: 86%

“…Because carbon dioxide infusions simultaneously lower pH and raise DIC, the mechanism resulting in increased algal productivity has not often been assessed. Cole et al [31] augmented DIC in high rate algal ponds. The study's results were consistent with the carbon limitation hypothesis because experiments showed an 87% and 89% increase in Oedogonium intermedium biomass when molasses and carbon dioxide (respectively) were used as carbon sources.…”

Section: Introductionmentioning

confidence: 99%

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Carbon limitation in hypereutrophic, periphytic algal wastewater treatment systems

Furnish

Keller

2020

PLoS ONE

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Global eutrophication degrades water quality in freshwater ecosystems and limits the availability of freshwater for human consumption. While current wastewater treatment facilities (WWTF) remove pathogens and pollutants, many US WWTF continue to discharge nutrients that contribute to eutrophication. Traditional nutrient removal technologies can effectively reduce eutrophication risk, but can have unintended negative consequences on human and environmental health. Alternatives, such as algae-based treatment systems, improve the sustainability of the nutrient recovery process by producing biomass that can be converted to biofuel. However, research is needed to increase the productivity of algal treatment systems to improve their economic viability. Because algae in wastewater treatment systems are grown in wastewater rich in nutrients, the algae could become limited by dissolved inorganic carbon. This hypothesis was tested in 1.2 m long recirculating floways (n = 8 for each treatment/control) by quantifying algal dry mass and wastewater nutrient concentrations in 3 independent experiments: (1) carbon dioxide gas infused vs air infused control; (2) hydrochloric acid acidified vs neutralized solution control vs no chemical addition control; and (3) sodium bicarbonate addition vs no chemical control. Results showed increases in algal biomass after 18 days in wastewater augmented with dissolved inorganic carbon (carbon dioxide or sodium bicarbonate). In contrast, maintaining wastewater at near neutral pH with hydrochloric acid reduced algal productivity relative to controls. Nutrient reductions generally paralleled algal biomass increases except in the bicarbonate addition experiment. These findings provide evidence for the importance of carbon limitation in algal wastewater treatment floways. These results could help explain why carbon dioxide infusions stimulate algae in treatment systems. Furthermore, these results suggest that algae in nutrient enriched, sun-exposed streams (e.g., agricultural ditches or urbanized streams) may become carbon limited during peak periods of productivity. These findings could have important implications for ecosystems undergoing eutrophication as atmospheric carbon dioxide concentrations continue to rise.

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Section: Discussionsupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Carbon limitation in hypereutrophic, periphytic algal wastewater treatment systems

Furnish

Keller

2020

PLoS ONE

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“…It should be noted however, that the gains achieved on provisioning CO 2 are relatively modest, and will need to be balanced by the likely expense of providing CO 2 to cultures at scale, although there are opportunities to integrate with CO 2 waste streams at some sites [10,29]. A 10% increase in bioremediation efficiency and biomass production as measured in this study may not be sufficient to offset the significant capital expense associated with provisioning CO 2 to large-scale cultures [10], although cheaper alternative carbon sources are available [28]. Regardless, a positive outcome of this study is that effective bioremediation of Al can be achieved without the need to provide supplemental CO 2 .…”

Section: The Effect Of Co 2 On the Productivity Of Oedogonium And Thementioning

confidence: 81%

“…A similar rationale can be found for linking biomass production of algae for liquid biofuel production with waste water utilisation or treatment [22,23], including marine algae for coastal systems [24] Oedogonium is also a source of carotenoids with strong anti-oxidant properties [25] which, given that other commercially important algae containing bioactives have been cultured in diverse waste waters [26,27], provides further potential for high-value application. With a mean productivity of 12.1 g DW m −2 day −1 , which is the same annualised productivity when this species is cultured at large-scale integrated with waste water at industry sites [28], annual biomass yields of 44 tonnes ha −1 could be expected at scale, offering a significant source of biomass for regional applications in agriculture and bioenergy production.…”

Section: Productivity Of Oedogonium and Al Sequestration In Giru Wastmentioning

confidence: 93%

Bioremediation of Aluminium from the Waste Water of a Conventional Water Treatment Plant Using the Freshwater Macroalga Oedogonium

Roberts

Shiels²,

Tickle³

et al. 2018

Water

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Abstract:Conventional water treatment processes use aluminium sulphate (alum) as a coagulant in the production of potable water. While alum is an inexpensive and reliable means of treating water, the process generates waste water containing dissolved Al. This waste water is primarily dealt with via on-site retention. In this study we investigate the cultivation of the freshwater macroalga Oedogonium as a means to sequester dissolved Al from waste water from a conventional water treatment plant. Furthermore, we examine the use of CO 2 to manipulate the pH of cultivation as a means of enhancing the sequestration of Al by either increasing the productivity of Oedogonium or increasing the bioavailability of Al in the waste water. The relative bioavailability of Al under conditions of CO 2 and no-CO 2 provision was contrasted by comparing Al uptake by Diffusive Gradients in Thin Films (DGTs). Oedogonium was able to grow rapidly in the waste water (12 g dry weight m −2 day −1 ) while consistently sequestering Al. The Oedogonium-treated waste water had a sufficiently low Al concentration that it could be used in unrestricted irrigation in the surrounding region. When CO 2 was added to the waste water containing concentrations of Al up to 8 mg L −1 , there was a slight increase (~10%) in the rate of sequestration of Al by Oedogonium relative to waste water not receiving CO 2 . This was due to two concurrent processes. The provision of CO 2 increased the productivity of Oedogonium by 15% and the bioavailability of Al by up to 200%, as measured by the DGTs. Despite this strong effect of CO 2 on Al bioavailability, the increase in Al sequestration by Oedogonium when CO 2 was provided was modest (~10%). Al was sequestered by Oedogonium to concentrations below permissible limits for discharge without the need for the addition CO 2 . The cultivation of Oedogonium in waste water from conventional treatments plants can simultaneously treat waste water for re-use and provide a biomass source for value-added applications.

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Hot and bright: Thermal and light environments for the culture of Oedogonium intermedium and the geographical limits for large-scale cultivation in Australia

et al. 2018

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A comparative assessment on how molasses and CO2 gas prevent carbon limitation in the large-scale culture of freshwater macroalgae

Cited by 5 publications

References 38 publications

Carbon limitation in hypereutrophic, periphytic algal wastewater treatment systems

Carbon limitation in hypereutrophic, periphytic algal wastewater treatment systems

Bioremediation of Aluminium from the Waste Water of a Conventional Water Treatment Plant Using the Freshwater Macroalga Oedogonium

Hot and bright: Thermal and light environments for the culture of Oedogonium intermedium and the geographical limits for large-scale cultivation in Australia

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