Date of Award
12-2025
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Environmental Engineering and Earth Science
Committee Chair/Advisor
Dr. Sudeep Popat
Committee Member
Dr. Shanna Estes
Committee Member
Dr. Elizabeth Carraway
Abstract
Rendering is a resource recovery technique commonly utilized to recover fats and proteins from unused animal parts discarded during meat processing and slaughter. Resource recovery involves converting waste products into valuable products. Rendering generates large volumes of heavily polluted wastewater. Pollutant concentrations can vary significantly, although rendering wastewater (RW) has extremely high concentrations of fats, oils, and greases (FOG). To remove pollutants, first chemicals called coagulants are added to RW to encourage pollutants to clump together to form flocs. The flocs are then floated to the surface and removed through the addition of air in a process called dissolved air flotation (DAF). However, pH impacts coagulant effectiveness, so RW often requires chemical addition to adjust pH prior to coagulation. Additionally, DAF breaks down fats in RW, ruling out the possibility for additional fat recovery.
Prior research conducted by Ao Xie through Clemson University developed an alternative to traditional RW treatment, known as electrocoagulation – electrofloatation (EC – EF). In EC – EF, metal electrodes are submerged in the water, and an electrical current is passed through them. The negatively charged electrode, anode, dissolves to form coagulant while the positively charged electrode, cathode, splits water to make hydrogen bubbles. EC – EF showed potential as an alternative RW treatment, achieving comparable pollutant removal without breaking down fats. The EC – EF method previously developed was replicated for this project, with a larger volume and a greater number of RW samples tested. This project assessed differences in pH as well as iii pollutant concentrations in RW samples then analyzed the impacts of these variables on pollutant removal during EC – EF.
Initial pH in this study varied between samples, ranging from 7 to 9.5. Superior pollutant removal was achieved when initial pH was closest to 7, a neutral pH, with declining performance for increasing pH. Pollutant concentration had no clear impacts on pollutant removal overall. However, it was determined that different types of pollutants were removed to varying levels. EC – EF was much more successful in removing fats than proteins. Overall, this research demonstrated several limitation of EC – EF for the treatment of RW, as sufficient pollutant removal was not achieved for all RW conditions observed.
Recommended Citation
Hardison, Katie L., "Impact of Rendering Wastewater Variability on Electrocoagulation - Electroflotation" (2025). All Theses. 4783.
https://open.clemson.edu/all_theses/4783