Keywords

Chlamydomonas reinhardtii; microalgae; salinity stress; copper stress; bioremediation; wastewater

Abstract

Microalgae offer a sustainable approach to wastewater treatment by removing pollutants such as excess nutrients, CO₂, and heavy metals. Among various species, Chlamydomonas reinhardtii shows strong potential in removing Cu(II) ions from wastewater. In addition, salinity stress in C. reinhardtii has been linked to morphological and metabolic changes that enhance lipid and phytochemical production. While salinity stress has been studied for enhancing biofuel production, its impact on microalgal removal of heavy metals, particularly Cu(II), remains largely unexplored. Understanding how varying salinity conditions affect both algal growth and the efficiency of Cu(II) remediation could provide critical insights for improving integrated wastewater treatment and resource recovery systems. This thesis investigated the effects of 3,000 mg L-1 NaCl, a slight salinity stress, on Cu(II) removal by C. reinhardtii. Algae cultures with a standard starting concentration were grown under controlled light, temperature, and mixing requirements. Experiments tested salinity (0 - 5,000 mg L-1 NaCl) and Cu(II) (0 - 40 mg L-1) in various combinations. Algal growth and Cu(II) concentrations, if applicable, were monitored over 72-hour periods, and morphological changes were observed via microscopy. The Cu(II) removal efficiency with starting concentrations of 5 and 10 mg L-1 Cu(II) varied across experiments from 6.7-20%, with no significant differences between salinity-stressed and unstressed conditions. These results suggest that moderate salinity levels (~3,000 mg L-1NaCl), commonly found in industrial and municipal wastewaters, do not inhibit the Cu(II) uptake ability of C. reinhardtii. However, variability in algal growth rates, possible bacterial contamination, and limitations in sampling frequency contributed to inconsistent data trends. Future studies should include more rigorous controls, replicate trials, and extended monitoring to confirm statistical significance. Overall, this study contributes valuable insights into the combined effects of salinity and heavy-metal stress on C. reinhardtii and advances the broader goal of sustainable microalgal wastewater treatment.

Thesis Completion Year

2025

Thesis Completion Semester

Fall

Thesis Chair

Woo Hyoung Lee

College

College of Engineering and Computer Science

Department

Civil, Environmental, and Construction Engineering

Thesis Discipline

Environmental Engineering

Language

English

Access Status

Open Access

Length of Campus Access

None

Campus Location

Orlando (Main) Campus

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Rights Statement

In Copyright