Photochemically produced reactive species generation by extracellular organic matter sensitizers from Chlamydomonas reinhardtii

Microalgae biotechnologies have shown promise as tertiary wastewater treatment processes capable of reducing nitrogen and phosphorous to meet increasingly stringent regulatory limits and as producers of biofuel feedstock. During growth and respiration, microalgae excrete extracellular organic matter (EOM) as metabolic byproducts which have the potential to act as photosensitizers for the generation of reactive species, including singlet oxygen (1O2), hydroxyl radicals (•OH), and triplet excited dissolved organic matter (3DOM). These reactive species can play an essential role in the mineralization of dissolved organic matter, nutrient cycling and bioavailability, attenuation of toxic pollutants, and inactivation of pathogens. Recent studies observed enhanced transformation of organic micropollutants in UV and visible light irradiated algae suspensions where photogenerated 1O2 and •OH were detected. The photochemistry in EOM matrices is still largely unknown as well as the impacts of reactive species on cultivation including EOM mineralization, protective extracellular reactive species generation, and nutrient availability. This study reports on reactive species production in EOM solutions separated from pure batch cultures of Chlamydomonas reinhardtii under solar irradiation. Results show increasing steady-state levels of 3DOM, 1O2, and formation rates of •OH under sunlight irradiation as EOM levels increase with batch culture growth. Changes in reactive species levels were compared with changes in culture characteristics such as volatile suspended solids (VSS) and nutrient availability as well as EOM properties including dissolved organic carbon (DOC) and specific UV absorbance (SUVA). EOM-sensitized reactive species photogeneration in comparison to other DOM sources was also discussed along with implications for the fate of contaminants, EOM, and culture stability in photobioreactors.

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

2015

Author dc:creator

• Tenorio, Raul

• Reactive oxygen species
• algae cultivation
• algal organic matter

Statement dc:rights

• Copyright 2015 Raul Tenorio

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/78791

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/78791