EVALUATION OF REUSE PRACTICE WITH SEWAGE TREATED IN STABILIZATION LAGOONS IN THE SEMI-ARID RIO GRANDE DO NORTE.
Reuse of treated sewage in irrigation. Semi-arid. Stabilization ponds.
The Brazilian semi-arid region covers 88% of the municipalities of the state of Rio Grande do Norte. This region is marked by long periods of drought and irregular rains, constantly living with water stress, one of the alternatives to minimize the effects of lack of is the use of domestic sewage treated in agricultural irrigation, producing food for the animals and for the general population. But for this it is important to know the characteristics of the raw sewage (affluent) and treated sewage (effluent). Based on this need, a monitoring plan was formulated for four sewage treatment plants (ETE) in the state of Rio Grande do Norte, three of them located in cities located in the semi-arid region (Caiçara do Rio do Vento, Parelhas and Santana do Seridó) and one installed in a transition region between the tropical and semi-arid region (Pedro Velho), all with the main reactor being a facultative lagoon. The monitoring plan counted on 12 months with one monthly in each station, in each station two collections were collected one of the affluent and another one of the effluent. Laboratory analyzes were carried out to quantify BOD, COD, suspended solids, electrical conductivity, pH, nitrogen, phosphorus, sodium, calcium, magnesium and thermotolerant coliforms, sodium, calcium and magnesium analyzes were only performed in the effluent. The field views subsidize, apart from the sampling of the samples, operational data on the reuse of the effluent in the field, at which time we sought to understand the use of this effluent. During the field activities, high-definition aerial images of the systems with a drone were also collected, making it possible to understand the reuse area as a whole. With this data in hand we created a profile for each municipality, where we understood the practice of reuse and quantified the parameters of the samples, searching in the literature and national and international laws, parameters that subsidize a reuse of the effluent with environmental and sanitary safety. We conclude that the systems studied, even promoting good efficiency in the removal of BOD and COD, in the order of 81% and 69%, respectively, according to the TEE configurations, do not present adequate effluent to the agricultural reuse.