Molecular evaluation of microalgal communities in full-scale waste stabilisation ponds

ABSTRACT

Waste stabilisation ponds (WSPs) are widely used across the world as a passive wastewater treatment for domestic wastewaters, but little is known about their ecology, especially their phototrophic communities. This study uses molecular methods and flow cytometry to assess the cyanobacterial and eukaryotic communities longitudinally throughout two systems, one treating domestic wastewater and the other mixed industrial/domestic wastewaters. More variation was seen between the systems than between different stages in the treatment processes for both eukaryotic and cyanobacterial communities. Chlorella species and Planktophrix cyanobacteria dominated both treatment systems. Arthrospira cyanobacteria were detected only in the industrial/domestic system. The balance between non-photosynthetic and photosynthetic organisms is rarely considered, though both play vital roles in WSP functioning. Flow cytometry showed that the facultative and first maturation pond in the industrial system contained a lower proportion of photosynthetic organisms compared to the domestic system. This is reflected in the species richness data and low dissolved oxygen levels detected. All data indicated that both systems are significantly different from one another and that variation longitudinally throughout the systems is lower. A more systematic study is needed to determine if it is the wastewater source rather than the initial inoculum that drives community composition.

GRAPHICAL ABSTRACT

KEYWORDS:

• Ecology
• microalgae
• molecular microbiology
• waste stabilisation ponds
• wastewater
• phytoplankton

Acknowledgements

We would like to thank Prof. Vania Melo and students at Universidade Federal do Ceará, Newcastle University Flow Cytometry unit and also CAGECE for giving us access to their WSPs and providing chemical data. This work was presented at the 10th IWA specialist group conference on Ponds Technology.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Cesar R. Mota Filho http://orcid.org/0000-0002-3538-8856

Additional information

Funding

This work was financially supported by the School of Civil Engineering and Geosciences, Newcastle University, the Royal Society [grant number JP090804], and the Project Global Innovation Partnership to Investigate, Restore and Protect the Urban Water Environment, funded by the British Council and the Department for Business, Innovation and Skills, via the Global Innovation Initiative. This work also received financial backing of the Society for Applied Microbiology’s Presidents fund.