Adaptation of domestic effluent for agricultural reuse by biological, physical treatment and disinfection by ultraviolet radiation

Abstract

Domestic effluent reuse is an alternative for irrigated agriculture in situations of reduced water availability. However, as there is the presence of pathogens in wastewater, the disinfection process is necessary before use. This research evaluated the sanitary and agricultural viability of treated wastewater at a pilot-scale station composed of a septic tank, Wetlands and an ultraviolet radiation (UV) disinfection system. The Sewage Treatment Station (STS) is installed in the Agricultural Sciences Center, UFSCar, in Araras city, SP, and receives 2000 L of sewage daily, which was monitored in terms of pH, turbidity, electrical 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 (E. coli) and Sodium Adsorption Ratio (SAR).The removal efficiency of the parameters was calculated based on the input and output means of each treatment unit. Results indicated removal efficiency for K (68.2%), TN (54.1%) and TP (36.1%). The levels of Na (26.7%) and Ca (22.9%) demonstrated the contribution of these salts to the wastewater; however, SAR did not present any risks for soil sodification. Microbiologically, the STS presented removal efficiency of 4 and 5 log-cycles for TC and E. coli, respectively. Therefore, results of monitoring indicate that the treated wastewater presents sanitary and agricultural viability, and conforms with the current legislation.

Esterilizador ultravioleta em estação de tratamento de esgoto visando reúso agrícola

“…Como resultado do acúmulo de sais na dissolução do solo, a salinidade aumenta o potencial osmótico impedindo ou dificultando a absorção de água pelas raízes. Segundo Almeida (2010), a condutividade elétrica em águas de irrigação possui um intervalo usual que varia de 0 a 3000 µS cm -1 , no entanto, elevadas concentrações salinas podem comprometer a cultura e o solo caso a irrigação não seja feita de maneira adequada (Oliveira et al, 2019).…”

“…Esta redução ocorre inicialmente pela função do tanque séptico e então é estabilizada pela wetlands Souza et al (2015). observaram redução significativa na turbidez após a passagem do efluente pela wetlands, bem comoOliveira et al (2019) ao também avaliarem a mesma ETE nos anos seguintes (2016 e 2017).…”

Effect of turbidity on ultraviolet disinfection of domestic wastewater for agricultural reuse

“…Increases in world population, urbanization, and water use for irrigation have led to irregular and disordered water supply, hence limiting water availability. This has promoted indirect reuse of wastewater without prior planning or treatment (Oliveira et al, 2019). However, after proper treatments, the reuse of effluents is an alternative to meet water demands of the agricultural sector, in which large amounts of freshwater are used (Zewde et al, 2019).…”

“…The Center for Agricultural Sciences of the Federal University of São Carlos (CCA-UFSCar) manages a Pilot Effluent Treatment Station (ETE), in which a UV sterilizer was used to remove microbial loads; however, the equipment has not performed steadily due to variable wastewater turbidity (Oliveira et al, 2019). Thus, in this study, we assessed at a bench scale the effect of wastewater turbidity and radiation dose on microbial inactivation using a UV sterilizer for effluent treatment.…”

Study of the performance of disinfection with sodium hypochlorite on a full-scale sewage treatment plant

“…Sewage treatment plants can remove these indicators by 90-98%, and an effective additional removal of up to 99.999% can be achieved by a final disinfection process. Currently the most advanced treatment plants use strong disinfectant agents such as ozone, UV rays, peracetic acid, and others (Castro Ribas and Fortes Neto, 2008;de Oliveira Pereira et al, 2011;Amin et al, 2013;Verma et al, 2015;Barreto Camilo Junior et al;de Almeida Soares Oliveira et al, 2019;) but the traditional sodium hypochlorite is still the most widely used all over the world due to its low cost and ease of use. We investigated a full-scale sewage treatment plant located in an area north of Milan, Italy.…”