Bioremediation of coal-fired power station waste water using freshwater filamentous algae from the genus Oedogonium

Ellison, Michael Brian (2013) Bioremediation of coal-fired power station waste water using freshwater filamentous algae from the genus Oedogonium. Masters (Research) thesis, James Cook University.

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The bioremediation of industrial waste water by macroalgae is a sustainable and renewable approach to the treatment of waste water produced by mining and mineral processing industries. The cultivation of live algae for metal bioremediation has simultaneous benefits as a form of biological carbon capture, particularly if algal growth is supported by carbon dioxide emitted from industrial facilities that also produce waste water, such as coal-fired power stations. However, few studies have tested the bioremediation of complex multi-element waste streams from coal fired power stations by live algae.

Application of algal bioremediation at scale requires an algal species that can grow in waste water while sequestering multiple contaminants. This thesis investigates the ability of multiple species of freshwater green macroalgae from the widely distributed ("cosmopolitan") genus Oedogonium to grow in waste water as a means of metal bioremediation. The Oedogonium genus is comprised of multicellular filamentous green macroalgae with an ability to grow rapidly in intensive monocultures. This thesis will expand this existing knowledge base by investigating the general ability of multiple species of Oedogonium to grow in industrial waste water and sequester metals. The experiments used Ash Dam water produced in the washing of residual ash from the power stations flue stacks and is contaminated by multiple regulated metals (Al, Cd, Ni and Zn) and metalloids (As and Se) in excess of Australian and New Zealand Environmental Control Council (ANZECC) guidelines.

The first experiment tested three species of Oedogonium for their growth and concentration of 18 elements from waste water from Tarong power station, a 1400 MW coal-fired power station in Queensland, Australia. All species had consistent growth rates in Tarong Ash Dam water, despite significant differences in their growth rates in "clean" water. While there were differences in the temporal pattern of metal uptake by the three species, over the course of the experiment all three species accumulated the same elements preferentially and to a similar extent. These results demonstrate that the genus has a consistent ability to grow in waste water and concentrate elements. ANZECC trigger values for the key elements of Al, As, Cd, Ni, Se and Zn initially exceeded guidelines, and all three study species of the genus Oedogonium were able to concentrate these elements. There was, however, a much higher bioconcentration of the metals Cu, Mn, Ni, Cd and Zn, with slower accumulation of the metalloids defined here as As, Mo and Se. Bioremediation would therefore be most rapid and complete for metals.

The second experiment investigated the effect of nutrient addition on the growth of the three species of Oedogonium in Ash Dam water. The maintenance of high productivity is essential to a successful remediation program as growth is positively correlated with metal sequestration. Tarong Ash Dam water is a complex effluent that contains many of the constituents of commercial growth media, particularly Zn, Cu, Mn, Mo and Fe, and so the additional nutritive requirements of algae grown in Ash Dam water are not clear. I contrasted the growth of three species of Oedogonium in Ash Dam water and "clean" water amended with nitrogen and phosphorus, both in isolation and simultaneously, with control cultures receiving no nutrients and f/2 media.

The addition of nutrients enhanced the growth rate of all species of Oedogonium; however, the response was specific to each nutrient. The two nutrient regimes that coincided with the highest productivity were the addition of f/2 and the addition of phosphate, regardless of species of Oedogonium. The addition of nitrogen alone did not increase the growth rate of any species. Interestingly, the least variation within growth rates was demonstrated in phosphate treatments in Ash Dam water. There was little additional benefit in terms of increased growth by adding the more complex f/2 media. The three species had mean specific growth rates of 2.9 – 7.5% in the no nutrient treatment, increasing to 9.5-10.9% in the P treatment, and 7.6-14.8% in the f/2 treatment. Overall, these results strongly suggest that P is the most limiting nutrient in both Ash Dam water and, furthermore, that there are no clear differences in the nutritive requirements of the three species of algae in Ash Dam water and dechlorinated town water.

The results show that the species of Oedogonium evaluated in this study all have an ability to grow in complex waste water and deliver similar rates of remediation. Consequently, due to its widespread distribution, high growth rates in intensive culture and, through this study, proven ability to grow in and remediate waste water, Oedogonium is a key target for scaled bioremediation applications. Macroalgal bioremediation can clearly remediate a complex suite of pollutants, providing an innovative and sustainable bioremediation process. The scope for remediation is greatest for metals (Al, Cd, Cu, Mn, Ni and Zn), with slower remediation of metalloids (As, Mo and Se). These data provide a predictive context to determine the ability of live algae to remediate complex waste waters containing multiple targets of remediation.

Item ID: 42249
Item Type: Thesis (Masters (Research))
Keywords: bioremediation; effluent; filamentous green algae; industrial wastewater; macroalgae; Oedogonium; treatment; waste water
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Publications arising from this thesis are available from the Related URLs field. The publications are:

Chapter 2: Ellison, Michael B., de Nys, Rocky, Paul, Nicholas A., and Roberts, David A. (2014) Growth and metal bioconcentration by conspecific freshwater macroalgae cultured in industrial waste water. PeerJ, 2. pp. 1-17.

Date Deposited: 13 Jan 2016 07:16
FoR Codes: 10 TECHNOLOGY > 1002 Environmental Biotechnology > 100203 Bioremediation @ 100%
SEO Codes: 96 ENVIRONMENT > 9609 Land and Water Management > 960912 Urban and Industrial Water Management @ 100%
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