Avaliação da piscicultura em esgoto doméstico tratado: aspectos zootécnicos, ambientais e de qualidade do pescado produzido

Abstract

The use of wastewater is an alternative widespread nowadays. One way to reuse it in fish activity, considering that the effluent from Sewage Treatment Stations, are rich sources of nutrients that could be used by fish. However, some restrictions arise regarding the quality of animals for use in human diet. Thus, this research was conducted using treated sewage, to raise Nile tilapia (Oreochromis niloticus), observing zootechnical aspects, toxicology of the culture environment, as well as qualitative sanitary conditions, nutrition, and acceptability of fish produced. The experimental unit was deployed in an area adjacent to the Sewage Treatment Station (stabilization ponds), at the east side of Teresina-PI, with eighteen of fiberglass tanks, arranged in three treatments with six repetitions. Treatment T-01 was supplied only with treated water and industrial fish feed; treatment T-02 received treated sewage from the maturation pond, without additional supply of feed or oxygen, and treatment T-03 was stocked with the same sewage effluent without feed, but received supplemental aeration. During the experimental cycle, we performed a daily renewal of 15% of the volume of water stored in experimental tanks for nutrient replacement and cleaning. In ponds stocked fingerlings of tilapia, sexually reversed for males in batches of 10 individuals per tank (about 03 fingerlings / m²). We analyzed the main parameters of water quality and sewage, fueling the tanks, with special emphasis on tests for monitoring of fish farming. To verify the productive capacity of the culture environment, we assessed the growth parameters such as growth, weight gain, feed conversion and productivity. Were also conducted microbiological testing of genotoxicity (micronuclei), acceptability and preference (sensory analysis), and the level of rigor mortis (MRI) and bioimpedance. This set of tests was used to identify the level of fish quality. Individuals undergoing treatment T-01 (productivity 118,14 kg/ha.day), had the best performance, followed of treatment T-03 (productivity 48,61kg/ha.day), and T-02 (productivity 34,90 kg/ha.day). However in tests that assessed the quality, fish health and the flavor, there was not significant difference. It is concluded that the fish farming with treated domestic sewage in stabilization ponds, it is feasible. But new studies are still needed for development of the practice.