David Blersch1, Jarrod Litton1, Jesse Chappell2, Terry Hanson2, Mollie Smith2, Daniel Wells3
1 Biosystems Engineering Department, Auburn University, USA
2 School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, USA
3 Department of Horticulture, Auburn University
Aquaponics polyculture production facilities are based on the concept of utilizing multi-trophic relationships to support multiple species of plants and animals for food production. Inherent in the aquaponics production perspective is the design of production yield systems around recovery of nutrients in the water stream into useful production streams. Controlled cultivation of benthic algae for recovery of nutrients from agricultural wastewaters has been investigated for decades, but little investigation has been done for its application in aquaponics systems. One of the challenges of algal cultivation in aquaponics wastewater is the low and variable pH of the water, which often negatively impacts algal growth. The purpose of this research is to investigate the optimization of benthic algal cultivation for nutrient recapture from an aquaponics production system in Auburn, Alabama. Two Algal Turf Scrubber (ATS) flow lanes were constructed at the North Auburn Fisheries Unit in conjunction with a pilot-scale tilapia-cucumber aquaponics production system to assess the performance in terms of algal growth, nutrient recovery, and biomass production rates. The flow lanes receive their source water from tilapia fish waste routed as the plant effluent. Each ATS flow lane acts as a tertiary treatment of the wastewater for the entire aquaponics system. Biomass was harvested weekly, and analyzed for growth rate, ash content, and nutrient content. Results show seasonal growth rates that strongly correlate with temperature. Investigation into novel growth substratum materials and configurations show potentially increased algal productivity rates over standard substrata that promise to increase overall biomass yield. These results will be useful to determine operational parameters for algal cultivation in an integrated aquaponics scenario.
