Skip to main content

Novel disinfection system with recyclable magnetic nanoparticles and metal ions: Evaluation with bacteria, algae, and virus

Qian Gao, PhD Candidate, Bren School

Dec 2 2021 | 9:00 am PST Bren Hall 3526

Qian Gao stands in front of a bridge
Qian Gao



Advisor: Arturo Keller
Committee: Patricia Holden, Helene Gardner

This defense will take place in person at Bren. Join in Bren Hall 3526/Pine (masks required) or watch online using this link and passcode water


Water pollution with pathogenic microorganisms is one of the serious threats to human health, particularly in developing countries. Although traditional disinfection technologies are effective to control microorganism contamination in water and have been widely applied in wastewater treatment plants, the disadvantages, such as disinfection byproducts or high energy consumption, are major concerns when considering sustainable use. Thus, this dissertation proposed a novel disinfection system with an optimization of the traditional methods, by using metal ions as disinfectants and aided by magnetic nanoparticles to achieve sustainable treatment. Various microorganisms, including bacteria, toxic cyanobacteria, and waterborne viruses were used for case studies to evaluate the efficacy of this novel method, and the reusability of disinfectants and magnetic nanoparticles were explored for long term application. Chapter 1 demonstrated the feasibility of this novel disinfection method with a case study on E. coli. Chapter 2 optimized the disinfection method for cyanobacteria contamination and achieved the simultaneous removal of both residual metal ions and the cyanotoxins, making the system suitable for a complicated environment. Chapter 3 shortened the time needed for operating the system by using the magnetic nanoparticles with adsorbed metal ions as the disinfectants, and evaluated the disinfection effectiveness on waterborne viruses.


Qian graduated from Peking University, China, with two Bachelor’s degrees in Environmental Science and Laws (Intellectual Property), and a Master’s degree in Environmental Science. She has a strong interest in solving water pollution problems with nanotechnology. For her masters, she finished the research about removing the surfactants with carbon nanotubes, and authored two manuscripts in high-impact journals such as Water Research. During her PhD program, Qian focuses on developing a novel disinfection method with high efficiency, easy operating conditions, and reduced environmental effect. This novel disinfection method has been evaluated with various target microorganisms including bacteria, algae and virus, and performs well under a wide range of environmental conditions, which is very promising for the practical application in the future.

arrow up icon