Tratamento e desinfecção por radiação UV de efluente doméstico para uso agrícola

Abstract

In the face of the water crisis, aggravated by climate change, population growth and increased demand for food, effluents reuse have been presented as an alternative to irrigate agricultural areas. However, it is common the presence of pathogens in wastewater, and disinfection step becomes fundamental to adequate the effluent to the reuse, with emphasis on the application of ultraviolet (UV) radiation. Therefore, the research sought to evaluate the agricultural and sanitary viability of the domestic effluent treated in the pilot sewage treatment station composed by septic tank, wetlands and Ultraviolet radiation system (UV), through physical-chemical and microbiological monitoring. The Pilot Sewage Treatment Station is installed in the Center of Agricultural Sciences, UFSCar, Araras city, SP, and receives 2000 L of sewage daily. The research included the biweekly and monthly monitoring of the following parameters: pH, turbidity, conductivity (EC), dissolved oxygen (DO), sodium (Na), Potassium (K), calcium (Ca), total nitrogen (TN), total phosphorus (TP), magnesium (Mg), total organic carbon (TOC), total coliforms (TC), Escherichia coli and Sodium Adsorption Ratio (SAR). After data collection, the removal efficiency of each index was evaluated, based on the input and output of each treatment unit. The results showed removal efficiency for K (68.2 %), TN (54.1 %) and TP (36.1 %), for Na (26.7 %) and Ca (22.9 %), the effluent presented these salts, however, RAS did not present any risks regarding soil sodification by irrigation water. Microbiological parameters showed a reduction of 4 to 5 log cycles for total coliforms and E. coli. The results indicated that the effluent treated pilot station presents agricultural viability and, in terms of microbiological aspects, is in compliance with the relevant legislation, presenting no health risks to farmers and final consumers.