Analysis of lettuce (Lactuca sativa) production in different substrates in an aquaponic system using an IBC container

Aquaponics is amethod of food production that integrates two types of cultivation in one unique place. Fishes and plants can be cultivated in this system, where the fish are maintained in recirculating aquaculture system and the plants in hydroponics (cultivation of vegetables without soil). In order to demonstrate that aquaponics is an alternative for the cultivation of vegetables and also a possibility of water treatment, the objective of the present study was to evaluate the water quality of an aquaponic system composed by lettuces (Lactuca sativa) and lambari fishes (Astyanax bimaculatus). Additionally, we evaluated which is the best civil construction residue (gravel, brick and expanded clay) for lettuce cultivation. The microbiological and physical - chemical monitoring of the system was carried for 42 days, and water from the fish tank was analyzed every 15 days, in the decanter, in the sump tank and in the cultivation bed. The microbiological analyzes consisted in total and thermotolerant coliforms and heterotrophic mesophilic count. For physical – chemical parameters, we analyzed pH, Dissolved oxygen (DO), Toxic Ammonia and Nitrite. Additionally, the development of lettuce in the three different civil construction residues was determined by the average total weight, average leaf mass and average root mass of the plants. We concluded that there was total and thermotolerant coliforms in all the stages of the collection. There was a better growth of the lettuce in the substrate of broken brick, followed by expanded clay and finally by crushed stone.