Research

Recycling poultry processing wastewater back into crop irrigation

The poultry industry is a major generator of nutrient-rich wastewater. This water supply is currently being treated as a waste at a significant expense to industry—and ultimately—consumers. Repurposing this water supply for use in crop production has the potential to significantly reduce treatment costs, increase food production, and reduce the overall impact on the environment. However, there are three main challenges that need to be addressed in order to safely and efficiently use wastewater for food production: 1) The nutrients in the wastewater should be in the appropriate form for stable crop production; 2) The crops irrigated with wastewater must be free of pathogens; and 3) The negative effects of antimicrobial chemicals in the poultry wastewater must be mitigated. The goal of our project is to develop engineered biological processes that overcome these three challenges. Successful development of such processes will pave the way for recycling of wastewater back into safe and sustainable food production. We will meet our project goal by engaging in four major research activities: 1) Developing an innovative wastewater treatment reactor that uses algae and bacteria deployed together to clean the water and transform existing nutrients into forms that are usable by plants. 2) Testing the ability of the above reactor, along with other non-chemical treatment steps, to clean the water of pathogens so it is safe to use for crop irrigation. 3) Growing lettuce (a model crop that presents a “worst case scenario” from a food-safety standpoint) to test our system’s performance. And finally, 4) Developing a set of engineering models derived from our experimental data. These models will serve as the basis for scaling up our process so it can be deployed safely and effectively at commercial poultry processing plants. This project is being funded by a NIFA Foundational Grant in Water Qauntity and Quality.

Integration of anaerobic digestion with algae cultivation

Anaerobic digesters are an established technology for the treatment of high-organic wastes and wastewaters. They recover energy from this waste in the form of methane-rich biogas which can be burned for heat and power. Microbial communities in digesters can break down complex organic molecules, however, they do a poor job of removing nutrients such as nitrogen and phosphorus from wastewater. These nutrients typically leave the digester in the solid sludge or liquid effluent. Nitrogen and phosphorus in the effluent can contribute to nutrient pollution leading to eutrophication of natural waters, harmful algal blooms, and disruption of aquatic wildlife. We are investigating cultivation of algae on digester effluent as a sustainable method of treating this nutrient-rich wastewater. The algae use these nutrients along with sunlight and carbon dioxide to grow. The result is cleaner water, sequestration of carbon dioxide, and production of energy-dense biomass that can be processed into biofuels. One of the key bottlenecks to integrating digesters with algae cultivation is the presence of algal inhibitors in digestate. Such inhibitors include excess ammonia, volatile fatty acids, and phenolic compounds. We are investigating chemical (nanomaterial) and biological strategies for overcoming algal inhibition. We are also investigating the efficiency of upgrading the wastewater-grown algae by feeding it to zoonplankton. This work is funded by a NIFA Foundational Grant in Biotechnology & Bioengineering.

Investigation and modeling of taste and odor compounds in drinking water

Drinking water reservoirs across the Southeastern US often suffer from periods of muddy odor. These odors are caused by the release of certain compounds such as MIB and geosmin by cyanobacteria and actinobacteria. We are using molecular approaches (quantitative PCR and sequencing) to identify the organisms responsible for taste and odor episodes. We also are integrating this data into empirical models in order to better predict when episodes will occur. This work is being funded by the USGS, Auburn Water Works, Opelika Utilities, and Columbus Water Works.

Process modeling and life cycle assessment of a pilot-scale aquaponics system

Aquaponics repurposes the waste nutrients (mainly nitrogen and phosphorus) from fish farming in order to produce hydroponic crops. Auburn University is home to one of the largest pilot scale aquaponics facilities on a university campus, boasting four greenhouses. The system produces tilapia and a range of produce that is sold to local markets and supplies Tiger Dining, Auburn University's student dining service. Because it converts fish waste (a potential environmental pollutant) back into food, aquaponics is considered a "sustainable" method of food production. Our project aims to quantify the environmental impacts of aquaponics. To do so, we are developing a detailed mass balance model of elemental flows through the system. We then use this model to conduct a life cycle assessment which is a rigorous approach to accounting for environmental impact of human-made systems. So far, this work has been supported by the Alabama Agricultural Experiment Station but we are looking to expand our resource base to better support our student workers. In fact, we have kicked off the "Aquaponics Fund for Excellence" which aims to raise money to train students in local, sustainable food production. If you are interested in contributing, you may do so here: https://alumniq.auburn.edu/giving/to/Ag  

Algal-bacterial interaction for advanced wastewater treatment and biofuel production

Algae are very effective at removing nutrients from wastewater and many algae species accumulate lipids (oil) and starch which can be processed into biofuels. We are interested in studying biological processes that simultaneously treat wastewater and produce fuels. However, one of the key challenges and opportunities of this approach is the complex interaction that takes place between algae and bacteria in these processes. Sometimes algal-bacterial interactions are harmful (even pathogenic). However, we have shown that in many cases, bacteria can dramatically enhance algal growth, nutrient uptake, and production of biofuel precursors. We have discovered that exchange of cofactor metabolites between bacteria and algae can account for much of this beneficial interaction. We utilize advanced analytical techniques such as LCMS, GCMS, and metagenomics to better understand the complex exchange of metabolites between algae and bacteria. We have applied some of these findings to the study of interaction between algae and microbial communities found in anaerobic digester effluent. This work was funded by the NSF Energy for Sustainability Program.