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

Tenorio, Raul

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https://hdl.handle.net/2142/78791 Copy

Description

Title

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

Author(s)

Tenorio, Raul

Issue Date

2015-04-30

Department of Study

Civil & Environmental Eng

Discipline

Environ Engr in Civil Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Reactive oxygen species
• algae cultivation
• algal organic matter

Abstract

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.

Graduation Semester

2015-5

Type of Resource

text

Permalink

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

Copyright and License Information

Copyright 2015 Raul Tenorio

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