Separation of phosphorus uptake and carbohydrate storage for intensive algal treatment processes

Microalgal systems have the potential to be an effective tertiary treatment step to lower effluent nitrogen and phosphorus levels discharged from secondary clarifiers at water resource recovery facilities. This work leveraged a tubular photobioreactor (PBR) system to evaluate the effect of a natural microalgal consortium on amended secondary clarifier effluent from the Urbana, IL water resource recovery facility. The photobioreactor is critical to ensure algae dominance over heterotrophic bacteria, but phosphorus uptake has been shown to be achieved in a dark mix tank. The objective of the work was to determine whether the system could use light time in the photobioreactor for carbohydrate storage and still achieve the adequate nutrient removal in the dark. The system was cycled between light and dark conditions, on the timescale of hours, with the goal of creating phosphorus-deplete conditions in the light, to see if phosphorus removal occurred when fresh influent was added in the dark. Different experimental conditions were evaluated with the goal to achieve complete phosphorus removal, but ultimately, the system was unable to achieve the level of removal necessary for full-scale implementation under these conditions. Since complete phosphorus removal was not achieved, carbohydrates were not stored in the light and no phosphorus removal occurred in the dark. Many different troubleshooting steps were attempted (e.g., increased solids and liquids residence times, cycle time, light exposure, aeration and pH control) but even under the less conservative conditions, the removal was not achieved, presumably because the limiting factor was not identified. The results of this study will still be able to help inform full-scale design and operation of algal treatment processes, as insight was gained into the laboratory reactor setup.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Environ Engr in Civil Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2019

Author dc:creator

• Ackerman, Courtney Anne

Contributors dc:contributor

• Guest, Jeremy S

• Wastewater treatment
• algae
• phosphorus
• light
• photobioreactor

Statement dc:rights

• © 2019 Courtney Anne Ackerman

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/105939

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F105939