Aquaculture America 2021

August 11 - 14, 2021

San Antonio, Texas

AN INNOVATIVE WASTE-TO-FOOD RECIRCULATING AQUACULTURE SYSTEM FOR WASTEWATER REUSE AND ANTIBIOTIC-FREE AQUAFEED PRODUCTION

 
Fahad Asiri* and Kung-Hui Chu
 
Zachry Department of Civil and Environmental Engineering
Texas A&M University
College Station, TX 77843
fmasiri@tamu.edu
 

Recirculating aquaculture system (RAS) plays a vital role in the  sustainability and commercial viability of aquaculture that  provides a significant protein source to human nutrition. Despite that  RAS  reduces  water  demand  and allows  for year-round intensive production , intensive aquaculture leads  to common challenges such as wastewater /waste management, high  feed cost, and most importantly, the widespread use of antibiotics and the increasing ineffectiveness of antibiotics against aqua species pathogens. Therefore, there is an urgent  need for  a cost- effective  approach to overcome these challenges for sustainable aquaculture .

This study developed  a novel  RAS-polyhydroxybutyrate  (PHB) system ( called RAS-PHB) to address the challenges described above.  The RAS-PHB  system can produce  PHB-rich biomass (single-cell proteins, SCPs) as healthy aquafeed from aquaculture wastewater/wastes .  The PHB-rich SCPs  are rich in protein and contain high PHB  as a biocontrol agent and immunostimulant , eliminating the need for antibiotics and  improving the survival and growth of aquatic species. The configurations of RAS-PHB  system  and conventional RAS are illustr ated in Figure 1. Briefly, the sand filter in conventional RAS  (Figure 1A)  is replaced with a zeolite sorbent unit to recover nutrients (particularly ammonia). T he biofilter is  also substituted with a nonsterile bioreactor for cultivating PHB-producing SCPs  using nutrients  recovered  from the sorbent unit  and  supplemental  carbon sources like agro-industrial wastes. Finally, chitosan as a nontoxic , healthy bioco agulant  was used to harvest PHB-rich SCPs as  an aquafeed (Figure 1B). The composition of the PHB-rich SCPs produced from  various wastes was analyzed and compared to conventional aquafeed s.  A simple analysis was  performed  to compare the  economic  advantage of using the proposed RAS-PHB over the traditional RAS system.