Abstract

Human activities generate surplus nutrients which may lead to algal bloom events in water resources along with serious ecological problems and thus substantial economic losses. Particularly, harmful algal blooms (HABs) represent toxic cyanobacterial blooms which produce cyanotoxins. The primary concerns of HABs are the exposures to a wide variety of cyanotoxins via ingestion of contaminated drinking water, inhalation during recreational activities, and consumption of contaminated fish and shellfish. However, conventional physical and chemical methods are not always possible to efficiently handle these HABs events. It is urgent to develop viable and rapid solutions to control HABs in field and mitigate the effects of HABs in fresh water, particularly in those that serve as sources of drinking water supply. Quaternary ammonium compounds (Quats) represent a wide range of cationic compounds with different formulation that constitutes products for agriculture, domestic and medical and industry. As organic antimicrobial compounds, Quats can be used as alternatives to existing chemical-based technique for HABs control due to its less toxicity and its affinity to variety of surface. In this study, recycled concrete aggregate (RCA) from a regional construction and demolition (C&D) waste recycling facility was used as a sustainable and environmentally friendly substrate and coated with a composite of silica-quaternary ammonium compounds (Fixed-Quat). Then, the algistatic capabilities of imparting antimicrobial properties of Quats to the RCA surface, which involve the covalent attachment of the biocides to the surfaces (sol-gel technique), were evaluated with HABs-causing algal species, Microcystis aeruginosa. Chlorophyll-a was measured to determine the efficiency of HABs mitigation using Fixed-Quat coated RCA in terms of photosynthetic inactivation of the selected algae. OD660 and pH were measured as key parameters to monitor algal cell growth and cement hydration. Notably, a 61% reduction of chlorophyll-a within 6 hours and complete removal of chlorophyll-a within 8 hours were achieved, indicating that Fixed-Quat coated RCA would be efficient in growth inhibition of Microcystis aeruginosa. Overall, with an appropriate design for field application and further evaluations like lifetime of Quat coating and potential recovery of treated algae, the Fixed-Quat antimicrobial coated RCA would be a promising and sustainable alternative to conventional HABs mitigation methods in various aquatic systems.

Notes

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Graduation Date

2018

Semester

Spring

Advisor

Lee, Woo Hyoung

Degree

Master of Science in Environmental Engineering (M.S.Env.E.)

College

College of Engineering and Computer Science

Department

Civil, Environmental, and Construction Engineering

Degree Program

Environmental Engineering

Format

application/pdf

Identifier

CFE0007400

URL

http://purl.fcla.edu/fcla/etd/CFE0007400

Language

English

Release Date

November 2019

Length of Campus-only Access

1 year

Access Status

Masters Thesis (Open Access)

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