Award Date

5-1-2022

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Civil and Environmental Engineering and Construction

First Committee Member

Erica Marti

Second Committee Member

Jacimaria Batista

Third Committee Member

Eakalak Khan

Fourth Committee Member

Jun Kang

Fifth Committee Member

Boo Shan Tseng

Number of Pages

306

Abstract

Much of the world’s population feed on grains (wheat, rice, and corn). Corn is as sensitive as it is productive. This thirsty, fast-growing plant goes into thermal shock in drought. In 2014, California lost over $2.2 billion in crop production due to drought. The Horn of Africa (in 2011) and Sahel (in 2012) faced humanitarian disasters due to food and water scarcity. The higher frequency of climate change and the erratic nature of rain, combined with underlying economic and social vulnerabilities, has meant that food and water scarcity is here to stay. To improve food and water scarcity, water reclamation and reuse is a logical option. To alleviate food production, phosphorus is necessary to increase crop yield. Apart from the affordable phosphorus rock that is expected to last for less than 80 years, the primary source of phosphorus can be wastewater. Aluminum, iron, and magnesium coagulants (AIMCs) are expended to retrieve phosphorus from wastewater and deliver clean water to communities. However, AIMCs' performance is affected by pH, making their application in wastewater a challenge. If excess phosphorus is not removed from wastewater, 1-2 mg/L of phosphorus can pollute water bodies triggering algal bloom and resource loss. Emerging lanthanide coagulants (LCs) were introduced in wastewater treatment plants to retrieve phosphorus (Task-1). LCs outperformed AIMCs, especially under extreme acidity conditions and enhanced removal of other contaminants like organic matter. LCs don’t require pH adjusters and produce less sludge which translates into cost-saving. The use of LCs in water means human/animal exposure, and there is a lack of information on lanthanide-associated health effects. Therefore, the study was extended to understand the cytotoxicity and genotoxicity of LCs (Task-2). This objective helps the World Health Organization and Environmental Protection Agency to establish exposure limits of LCs. Bioassays with human cells were used to fulfill this objective. At expected LC effluent concentrations (0.5 mg/L) from WWTP, LCs did not elicit any changes in mitochondria potential, reflective of continued cellular ability to generate energy. LCs did not activate the production of reactive species that can trigger cytotoxicity. Furthermore, no DNA damage was registered as a result of LCs exposure. Having secured that LCs are less harmful and possess a high affinity to retrieve phosphorus and treat wastewater, lanthanide-phosphorus (Ln-P) precipitates and lanthanide reclaimed wastewater (LRWW) were used to grow corn (maize), Task 3. LCs did not affect corn growth in terms of height, chlorophyll development, stomatal conductance, and electron transport rate. Lanthanides did not attenuate the availability of phosphorus to corn as anticipated. In addition, lanthanides increased calcium and magnesium uptake. Thus, full-scale implementation of LCs in wastewater treatment can help us bridge the following United Nations Sustainable Development Goals (UNSDGs): • UNSDG-6: Clean water and sanitation/public health: Treated wastewater can be recycled to communities while reducing community exposure to pathogens and emerging contaminants • UNSDG-2: No hunger: Treating wastewater and recovering vital nutrients boosts agriculture • UNSDG-1: No poverty: Boosting agriculture enhances crop yields, thus leading to poverty reduction for farmers • UNSDG-11: Sustainable communities and cities: Collecting and capturing nutrients from wastewater before they are discharged into the environment promotes community sustainability • UNSDG-14: Life below water: Removing nutrients like phosphorus protects water bodies from algae growth that affect the aquatic environment • UNSDG-15: Life on land: Preventing water contamination protects animals from toxins like cyanotoxins

Keywords

Cerium and lanthanum; Corn and food production; Rare earth elements; Toxicity; United Nations Sustainable goals; Wastewater and water treatment

Disciplines

Environmental Engineering

File Format

pdf

File Size

9900 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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