Uso planejado de água residuária proveniente de estação de tratamento de esgoto na irrigação em cultura de alface crespa

Abstract

For a long time it was thought the water as an unlimited natural resource. However, the industrial and technological development, and population growth, had caused the demand for this feature to increase significantly in order to cause disturbances in their natural cycle. Human activities even the simplest of daily generate wastewater that must be pretreated prior to its discharge into water bodies or infiltration systems. Such wastewater, even after treatments have right amount of nutrients and organic matter, which must follow limits imposed by law. To be dumped into natural drainage networks begins the self-purification process afforded by organisms in the environment. However, these evictions are not the only ones this stream. In its extension several evictions are incorporated, they are specific or not, making the self-purification of natural resources, increasingly difficult. In this sense arises the reuse of water, a practice used long ago. In recent years it is gaining more space in Brazil experienced by the current water crisis. Being the country's largest water demand in the agricultural sector, lower quality water reuse becomes a new theme of research and technologies to be explored. The wastewater coming from the sewage, because they have balanced amount of nutrients can be used as an economic resource value to the agricultural sector, the use of it in fertigation systems. In this context, this study aimed to evaluate the irrigation curly lettuce crop, using wastewater in a planned manner, from a Sewage Treatment Plant. The system was implemented using two treatments, CO - well water and EF - residual water with eight repetitions each. Which was conducted after the characterization of wastewater, which obtained as a result, high values for biochemical oxygen demand, chemical oxygen demand, nitrogen, phosphorus when compared to previous studies and fecal coliform count. The latter being responsible for the use of closed system for the application of the experiment. However, the parameters are within permitted by law. Later productivity tests and sanitary quality of the produced lettuce were conducted, the result being greater leaf area, leaf number, height, fresh weight of shoot and shoot dry mass in the application of irrigation with wastewater. Finally, a public perception test was performed on a sample group of 107 people related to water reuse and use of wastewater in irrigation, showing that there is wide acceptance of treated sewage used for irrigation of agricultural crops due to high confidence population in relation to sewage treatment conducted in the city.