Document Type

Dissertation - Open Access

Award Date


Degree Name

Doctor of Philosophy (PhD)

Department / School

Agricultural and Biosystems Engineering

First Advisor

Xufei Yang


The development of innovative flocculation technologies is essential for addressing the challenges of agricultural water treatment. These technologies play a crucial role in removing contaminants such as suspended solids and nutrients, thereby ensuring safer water for irrigation and livestock consumption. By enhancing water quality and wastewater management, they contribute significantly to environmental sustainability and public health in agricultural communities. This comprehensive thesis extensively explores various dimensions of flocculation, with a focused effort on methodologies and resources aimed at strengthening sustainability and efficiency. A pivotal aspect of the research involves synthesizing cationic starch (CS), a flocculant derived from an underutilized resource, potato peel waste (PPW), thus supporting a circular economy (Ag-back to Ag-process). Through precise etherification with (3-chloro-2 hydroxypropyl) trimethylammonium chloride (CHPTAC), a water-soluble cationic starch with a high degree of substitution (DS) is successfully achieved. Optimizing reaction parameters yields promising results, with substantial reductions in total suspended solids (TSS) observed in swine and dairy wastewater samples. The study also focuses on preparing another natural flocculant, cationic cellulose (CC), achieved by etherifying commercial cellulose with CHPTAC, presenting a promising alternative for agricultural water treatment. Rigorous characterization techniques validate the successful cationization process, with the optimized CS & CC sample demonstrating exceptional performance across various environmental applications, including significant advancements in algal harvesting and dye removal processes. Furthermore, the thesis introduces a DC-initiated flocculation technology designed specifically for microalgal harvesting, aiming to overcome inherent limitations (contamination and cost) in chemical flocculants. By utilizing a DC electric field across titanium plate electrodes, this method achieves unprecedented efficiency in microalgal cell aggregation without the need for foreign chemicals. The notable contrast with traditional electrocoagulation methods lies in the utilization of inert electrodes, effectively bypassing the introduction of Al+3 ions into the fresh algal biomass which poses challenges, especially in the pharmaceutical and cosmetic industries. The promising scalability of this innovative approach offers significant potential for widespread adoption in both algae harvesting and processing, further solidifying its status as a cornerstone of sustainable agricultural water treatment practices. Ultimately, this study serves as a beacon of hope that highlights the transformative impact of innovative flocculation technologies in agricultural water treatment. By promoting environmentally friendly alternatives and embracing circular economy principles, these advancements have the potential to revolutionize agricultural water management with sustainability, efficiency, and environmental stewardship.


South Dakota State University



Rights Statement

In Copyright