Graduation Year


Document Type




Degree Granting Department

Civil Engineering

Major Professor

Noreen Poor, Ph.D.

Committee Member

Scott Campbell, Ph.D.

Committee Member

Elaine Howes, Ph.D.

Committee Member

Maya Trotz, Ph.D.

Committee Member

Michael VanAuker, Ph.D.


parasite, diarrhea, chemotherapy, excreta reuse, soybean, nutrition, predator – prey, Solar Latrines, Paquila, Guatemala, Finite Element Method, STELLA®, COMSOL®


Parasitic infections, inadequate sanitation, and poor nutrition represent major etiologies that operate in synergy to cause some of the world's most disabling diseases. Citizens of developing nations, especially children living in rural areas, are the most affected. Current research and subsequent interventions have attempted to solve these issues using vertical interventions aimed at minimizing specific health outcomes. This approach does not consider the interaction among causes and the interrelationship between human beings and their environment. Challenges solved in this manner often fail to produce sustainable results or worse, create new problems.

This project proposed the systems approach framework to address these challenges. The systems thinking dynamical modeling software, STELLA®, was used to model the conditions that promoted and/or hindered Ascaris lumbricoides and other gastrointestinal parasitic diseases in the rural developing community of Paquila, Guatemala. The interventions chosen were: administration of anti - helminthic drugs, supplying protein nutrition, and an excreta management system that allowed for effluent recycling to crop production. A new design for a Solar Latrine was proposed and the solar heating and microbial deactivation processes were modeled using the commerically available, Finite Element Method software COMSOL®.

From the simulations, disease eradication was most likely to occur when at least 50% of the host population were treated every 3 months for 2 years or more with an anti - helminthic drug of 94% efficacy or better, latrine coverage and usage were at least 70%, and nutrition was provided at about 1.1 g protein per kg (human mass) per day. Given the climatic conditions in Paquila and the proposed latrine design, sustained treatement temperatures of up to 65°C were possible in the fecal materail and with a minimum of 1 month (4 months maximum) retention time, it was concluded that the resulting humanure would meet US EPA Class A Biosolids microbial requirements.