Francis de los Reyes

This project is to provide an 8-week international research experience for NC State students to work in Malawi, with partners from Malawi University of Science and Technology and Mzuzu University. The research will focus on research gaps in Water, Sanitation, and Hygiene (WaSH).

The goal of the project is to develop a low-cost, portable auger-based technology that can reliably and hygienically empty a wide variety of pit latrines and septic tanks containing wastes with a range of moisture and trash contents. After extensive field and lab testing, we have finalized an EV design that was successful in emptying pit latrines in the field while successfully excluding trash. Two technologies have been developed: a mechanized trash excluder that actively rejects trash in a pit while allowing emptying of the fecal sludge, and a complete, low-cost system that uses a vacuum and an excluder to empty the de-trashed fecal sludge to pit-side containers (currently called ????????????????Flexcrevator???????????????). We also recently finished a generalized market/business analysis for both technologies. NC State??????????????????s focus during this part of the project will be to coordinate work with potential commercial partners and contractors to design, build, and test Design Validation (DV) trash excluders. The primary outcomes and results will be: ??????????????? Design, build a minimum of five (5) DV trash excluder units and create the necessary documentation for Design Validation with an outside contract manufacturer (per New Product Development Guideline) ??????????????? Testing a minimum of two units (2) units in Ghana with an interested commercial partner (iDE Ghana/Sama Sama) over the course of at least 7 months as a means to understand the performance of the unit and collect commercialization data. This information will be used to develop business model documentation in Ghana, including supply chain, marketing, financing, sales plan. ??????????????? Testing of the two (2) units will also include a study led by NC State on gender impacts: how the trash excluder operation, access, ownership/business operation, and the how the business of pit emptying is affected by gender. The goal is to identify barriers to inclusive use of the device and define explicit ways to remove these barriers.

In the continuing quest to relate microbial communities in bioreactors to function and environmental and operational conditions, engineers and biotechnologists have adopted the latest molecular and ???????????????omic methods. Despite the large amounts of data generated, gaining mechanistic insights and using the data for predictive and practical purposes is still a huge challenge. This project will use a methodological framework to guide experimental design to improve the operation, start-up, and resilience and resistance of anaerobic bioreactors co-digesting food and FOG wastes. This research represents leading edge work to combine molecular microbial methods, bioreactor experiments, and modeling to identify and exploit the underlying factors that govern microbial community assembly in anaerobic co-digestion systems.

While significant research has been conducted to date on the benefits and process limitations of co-digestion of GIW with municipal biosolids in a traditional anaerobic digestion process, there is very little knowledge on the benefits and limitations of co-digestion of GIW with municipal biosolids in a process that includes thermal hydrolysis pretreatment process (THP) upstream of the anaerobic digestion process. The proposed study would focus on understanding the benefits and process limitations of co-digestion of GIW with municipal biosolids that have been pretreated with THP. This study will also consider how GIW addition shifts the nutrient concentrations in the anaerobic digestion process and how the reduction in nutrient concentrations impacts microbial population and kinetics in the anaerobic digestion process (i.e., does reduced nutrient content result in less stress on the microbial population in the anaerobic digestion process). This research will benefit the City of Raleigh and other utilities that are considering implementing THP to enhance their digestion process to understand the benefits and limitations of GIW co-digestion with this process. This research will also help to provide much needed information for full-scale implementation of GIW co-digestion in a THP + MAD process, which would ultimately result in an additional outlet option for GIW.

Wastewater treatment with Anaerobic Ammonium Oxidation (Anammox) holds the promise of significantly reducing energy and chemical costs associated with nitrogen removal from wastewater The Anammox process involves the anaerobic conversion of nitrite to nitrogen gas with ammonium as the electron donor. While used more regularly in side-stream applications, the use of mainstream Anammox is still limited. Most of the challenges associated with widespread application of Anammox for mainstream nitrogen removal involve the Anammox bacteria being outcompeted by other, more robust organisms commonly found in wastewater and utilized for conventional nitrogen removal. However, in addition to process challenges there are also significant costs associated with a change in infrastructure. One novel possibility that may address both challenges would be to convert existing filter infrastructure into tertiary Anammox filters for mainstream nitrogen removal. For the past two years our research team operated a preliminary pilot Anammox filter at the Neuse River Resource Recovery Facility in Raleigh, NC. While the filter showed exciting promise (> 90% TIN removal in some cases), the controlled nature of the influent into our preliminary pilot filter limited the applicability of the results. This study would build on our experience, and push the frontier of research on sustainable nitrogen removal in wastewater treatment. The primary objective of this study is to compare a pilot scale tertiary Anammox filter to a traditional denitrification filter, under a range of realistic operating conditions. We hypothesize that the Anammox filter will lead to significant cost savings while achieving similar or superior results to a traditional denitrification filter.