Decoupled aquaponics is a strategy that allows combining the culture of animals and plants in a disruptive way. These systems present several advantages in using water, space, and residuals. In the same line, Biofloc technology (BFT) has shown to be a beneficial technique implemented in this production activity. It represents low-cost equipment and a versatile way to transform aquaculture waste into valuable products used in horticulture. Despite the favorable attributes of BFT, the typical combination was heterotrophic BFT and aquaponic, but the description of the strategies for integrated aquaponics and photoautotrophic BFT with Chlorella microalgae has not been completely explained. Diversifying the production system is a necessity in developing countries, which is why this investigation focus on the characterization of residuals from O. niloticus BFT in a photoautotrophic, heterotrophic, and control, and their relationship and strategies implemented to integrate these residuals with the NFT hydroponic horticulture using five green leaf plant species: lettuce (Lactuca sativa), pak-choi (Brassica rapa subsp. chinensis), rocket (Eruca sativa), spinach (Spinacia oleracea), and basil (Ocium basilicum). This experiment was performed in five weeks; it evaluated plant growth, production, parameters, the size, elements content in biofloc, and the diverse strategies to integrate these residuals (mineralization, flocculation, and filtration). During the experimental period, the photoautotrophic treatments showed the highest levels of micro and macronutrients among all treatments. According to growth percentage, lettuce and pak-choi did not show significant differences (p > 0.05), while for basil and spinach, the best results were obtained with photoautotrophic treatment (p < 0.05). The best combination was with spinach and/or pak-choi and/or lettuce. The relationship between N:P was suitable in the photoautotrophic treatments compared with hydroponic solutions. The ideal integration process was the combination of flocculation and filtration before adding the liquid fraction from BFT to NFT system. The aerobic-anaerobic reactor allows the attaining of essential micronutrients.
Therefore, O. niloticus BFT rearing in the photoautotrophic mode and its integration with decoupled aquaponics system is beneficial in arid coastal zones where water is scarce. It is necessary to improve aquaculture performance, reuse water, BFT nutrients, and increase profits.