The Role of Photochemical Processes for Pathogen Inactivation in Non-Conventional Wastewater Treatment Systems

EPA Grant Number: FP917488
Title: The Role of Photochemical Processes for Pathogen Inactivation in Non-Conventional Wastewater Treatment Systems
Investigators: Mostafa, Simon A
Institution: University of Colorado at Boulder
EPA Project Officer: Lee, Sonja
Project Period: August 27, 2012 through August 26, 2015
Project Amount: $126,000
RFA: STAR Graduate Fellowships (2012) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Environmental and Water Science


Several studies have been dedicated to learning more about the impact of photochemical processes on pathogens present in NC-WWT systems. This research attempts to provide a better understanding of the impact of natural and effluent organic matter (NOM, EfOM) in the formation of reactive oxygen species (ROS), such as singlet oxygen, and their potential impacts on pathogen concentrations via indirect photolysis processes.


Water samples from various sources will be collected and analyzed with respect to their organic matter content (using size exclusion chromatography [SEC] and fluorescence techniques) and the steady-state concentrations of ROS (particularly singlet oxygen) generated under sunlight conditions. Known concentrations of microbes will be introduced and their inactivation measured after exposure to conditions that enable photolysis to take place (i.e., irradiation under a solar simulator or natural sunlight) to establish the relationship between ROS dose (steadystate concentration time, CT) and pathogen indicator inactivation rates. Analysis of the organic matter, ROS concentrations and microbe concentrations within working systems can be conducted, and the correlations established in the previous project components can be measured against parameters found in units working under real-world conditions.

Expected Results:

This research will lead to a better understanding of sunlight-mediated photochemical processes within NC-WWT systems, their relation to the NOM/EfOM found within such systems and their role in pathogen inactivation. Such results should lead to better estimations on systems performance based on the OM present and inform future designs that take advantage of such oft-ignored indirect photolysis processes.

Potential to Further Environmental/Human Health Protection
Because of the high microbial concentrations present in raw sewage, the removal of pathogens is one of the primary objectives in WWT. Without it, soil, crops and water sources (both ground water and surface water bodies) may become contaminated when coming into contact with untreated water streams, leading to detrimental health and environmental impacts. Thus, it becomes clear that the development, optimization and introduction of decentralized NC-WWT systems that do not rely on high energy, chemical and labor inputs and that are sound socially and environmentally would be highly beneficial to those communities that do not have access to conventional treatment technologies common in more developed regions.

Supplemental Keywords:

wastewater treatment, waste stabilization ponds, constructed wetlands

Progress and Final Reports:

  • 2013
  • 2014
  • Final