CONTENT SOURCED FROM GEORGIA TECH

Even if you do your best to eat local, chances are most of the fruits and vegetables you consume come from far away — especially if you live in a big city.

Water and land for growing crops are hard to come by in urban areas. Finding more sustainable methods for growing produce in urban areas would have enormous benefits. A pilot project by Georgia Tech’s Yongsheng Chen, a professor in the School of Civil and Environmental Engineering, aims to use wastewater from the campus to do just that.

“The overarching goal is trying to figure out a way to use wastewater nutrients to grow produce in urban areas so we can decentralize vegetable production,” Chen said. A grant provides $5 million over five years from the U.S. Department of Agriculture’s National Institute of Food and Agriculture (NIFA) to create and operate a hydroponic growing system using domestic wastewater extracted from the Georgia Tech campus sewer system. It is the largest USDA award Georgia Tech has received.

“Currently we treat wastewater by taking all the nutrients from it,” Chen said. “Then we have to use an energy-intensive process to synthesize and add fertilizer to the food production process.”

The proposed anaerobic membrane biological treatment process will transfer organic contaminants into biogas and remove pathogens such as E. coli to ensure food safety, but the nutrients (nitrogen, phosphorus and potassium, for example) will remain. By using a smart membrane or nanomaterials to extract trace contaminants like endocrine disruptors, heavy metals and pharmaceuticals, the nutrients that are left can be pumped through a vertical hydroponic system to grow produce without adding fertilizer. The project will monitor water and produce quality and measure contamination from chemicals and microbes continuously.

The overall goal, Chen said, is to show that using the nutrients and water resources from domestic wastewater (DWW) in an urban controlled environment agriculture system (CEAs) is socially, environmentally and financially sustainable and can be easily replicated in other cities. The project will closely track nutrient requirements, energy needed to produce, handle and transport the fruits and vegetables, and water needs to determine what resources are needed to support this kind of CEA system (DWW-CEAs).

Ecological network analysis for DWW-CEA coupling will track material and energy flows across components that produce, consume and recycle food. Using a geodesign approach, Chen’s team will then compare data from traditional agriculture and DWW-CEAs to see how the system performs and how it could be designed to perform better in terms of water, energy and nutrient needs.