Diferentes cargas hidráulicas em sistemas de aquaponia utilizando a semenente do açaí (Euterpe oleracea) na remoção de nitrogênio.

Abstract

In aquaponics systems, fish produce nutrients and organic matter that can be used in plant nutrition. Nitrifying biofilters have the function of reducing the concentration of ammonia in aquaponics systems and transforming it into nitrate NO3-, in two phases: conversion of ammonia into nitrite and conversion of nitrite into nitrate. The use of acai stone (Euterpe oleracea Mart. 1824) as a biofilter has proven its efficiency in the removal of toxic ammonia for fish farming integrated with vegetable production. This result led to the questioning of this work, to know if the hydraulic retention time can affect the efficiency of the biofilter with açaí stone and what would be the best flow rate for this type of system. The experiment took place at UFRA, in the BIOAQUAM Laboratory. The açaí seeds were collected after extraction of the pulp, washed, and distributed on 0.5 m3 and 0.13 cm high benches. Fish weighing 21.8±7.74 g and length 11.28±6.88 cm were allocated in the culture tank at a density of 20 animals/tank. After this acclimation period, water was also allowed to circulate in the stands where the açaí stones were, with flow rates of 1.4 (m³/d) m²; 5.4 (m³/d)m²; 13.6 (m³/d)m²; 23.3 (m³/d)m² in triplicate. As the hydraulic load passed through the live biofilter affected the dissolved oxygen effluent and pH of the water, at the lowest loads of 5.4 and 1.4 (m³/d)m². There was germination of the açaí stone, with better performance found for the treatments of 13.6 and 5.4 (m³/d) m². The performance of the system varied throughout the study, the removal written in mg/h is the ideal reflection of the behavior of the system over eight experimental weeks, being the hydraulic loads 23.3 and 13.6 (m³/d) m², demonstrated a higher efficiency for the system. Therefore, for a system beneficial for animals and plants we recommend the hydraulic load of 13.6 (m³/d) m².