Environmental, Water Resources, and Coastal Engineering Seminar Series

Fitts-Woolard Hall 2331

An Engineer Talks About Poop (Alternatively, Challenges and Opportunities in Global Sanitation)

Abstract: Most people don’t think about or don’t want to think about what happens to human waste- fecal material. Where do we poop, where does it go? This is a big, global problem: 2020 WHO/UNICEF data show that 3.6 billion people- 46% of the global population- don’t use a toilet or latrine where the fecal material is safely treated and disposed. This is a wicked problem that touches on engineering, public health, social and cultural dimensions, and has economic impacts in less developed countries. This presentation will discuss a systems view of the sanitation “value” chain- from the user interface, the toilet or latrine, to the collection and transport of fecal material, to treatment and disposal. Key factors for addressing this global challenge will be discussed, including how to re-think sanitation technologies.

One major project is developing a hygienic and dignified way of emptying pit latrines. Every day, pit latrines receive an estimated 0.6 billion kg of faeces and 2.1 billion kg of urine from 1.77 billion people around the world. Once pits are full, fecal sludge has to be removed, before being transported and treated/reused. Manual emptying of pit latrines using buckets and shovels still exist today – a high-risk, unsanitary, and undignified job. One of the biggest challenges in this field is developing a single pit emptying technology that can empty trash-filled pits at a competitive cost. Our NC State University team has developed the innovative pit-emptying device, the Flexcrevator. This device removes fecal sludge even in the presence of trash in pits. The Flexcrevator system has been developed over 6 years with extensive field testing in South Africa, Zambia, Malawi, Kenya, and India, with funding from the Bill & Melinda
Gates Foundation, and has recently been patented. Our overall goal is to demonstrate how the Flexcrevator can scale-up to meet global demand for hygienic and profitable pit emptying, thereby improving sanitation practices and access world-wide. The presentation includes the design evolution of the trash exclusion head, lab testing results with faecal sludge simulants and trash, and field testing results from Zambia, Kenya, Madagascar, and Rwanda. The challenges and lessons learned in designing this technology will be discussed.

Biography: Francis de los Reyes is the Glenn E. and Phyllis J. Futrell Distinguished Professor #2 of Civil, Construction, and Environmental Engineering, Alumni Distinguished Undergraduate Professor, and University Faculty Scholar at North Carolina State University. He is also an Associate Faculty of Microbiology and Training Faculty of Biotechnology. He has also worked in water and sanitation issues in developing countries, and has collaborations in the Philippines, India, China, South Africa, Pakistan, Ghana, and Malawi. Current and past research projects include: competition between filaments and floc-formers in activated sludge, ecophysiology of nitrifiers and denitrifiers in microbial floc, N removal from swine waste, fate of bioagents in landfills, microbial characterization of landfills, molecular techniques for groundwater remediation sites, foam control methods, factors affecting fats, oils, and grease deposits in sewers, wastewater treatment for rural areas, water reuse systems, novel molecular techniques for detecting denitrifiers, energy from co-digestion, and solutions for pit latrine emptying problems.