Phytodepuration of the effluents in a closed system of fish production

Resumo

It was evaluated the feasibility of growing lettuce intercropped with Nile tilapia farming in a hydroponic system and the efficiency upon the improvement of the quality of the effluent. The experimental structure was composed of one module for fish production and other for plant production in the hydroponic system. It was used production technique NFT (Nutrient Film Technique), and the nutrient solution used was the effluent of fish farming. It was used a randomized block experimental design with four treatments and three replications, considering each repetition an 8-day cycle in hydroponics. The treatments were: 20; 40, 60 and 80 plants for the first, second, third and fourth treatments, respectively. Electrical conductivity, pH, temperature and dissolved oxygen did not change (P>0.05) in relation to the input effluent and they were not affected (P>0.05) by the number of plants. We observed a linear effect of number of plants on the parameters orthophosphate and nitrite, ie the higher the number the greater the removal of plants for these parameters in the water. The percentage of nitrogen in leaves and roots of lettuce was not influenced by the number of plants. There was a linear effect of the number of plants on the accumulation in lettuce leaves parameters dry matter, nitrogen and phosphorus. There was a linear effect of the number of plants on the accumulation of dry matter and phosphorus and quadratic effect on nitrogen accumulation in roots of lettuce.There is a technical feasibility of integrating the intensive Nile tilapia farming in a closed system of recirculating water in the production of hydroponic lettuce, with nutrients remotion such as nitrogen and phosphorus from the effluents and their incorporation in leaves and roots of lettuce.