Avaliação da ocorrência e decaimento de vírus entéricos e SARS-CoV-2 no tratamento de esgoto em reator UASB e da persistência de rotavírus A em lodo de UASB dessecado em leito de secagem

Abstract

This research aimed to evaluate the occurrence of SARS-CoV-2, rotavirus A, and norovirus viruses in sewage, treated sewage, sludge and scum from a UASB reactor-type treatment system. Additionally, the persistence of rotavirus in the sludge in the drying bed for 63 days was evaluated. The study was carried out at the Sanitation Research and Training Center (CePTS) UFMG/COPASA, located at the Arrudas Sewage Treatment Station in the city of Belo Horizonte/MG. The UASB-type compacted system used has a treatment capacity of 80 m³/day and 3 m³ of sludge anaerobic volume were discarded in the drying bed. Nine samplings were carried out for each matrix during the months of September to December 2020. For the detection and quantification of the viruses, the RT-qPCR technique was used. The concentration of SARS-CoV-2 in sewage varied between 2.00x104 and 3.76x104 gc/l, with amplification of 67% of the samples. In contrast, rotaviruses A amplified in 100% of the samples and ranged from 9.09x103 gc/l to the maximum concentration, 6.5x103 cg/l. In the treated sewage, the SARS-CoV-2 varied between 6.73x103 gc/l with an average removal of 0.66. Rotavirus A had a concentration of 4.65x103 and 4.63x104 gc/l, with a reduction of 0.27 log10. The positive sample rated were 66.67% and 100% for SARS-CoV-2 and rotavirus A, respectively. In the UASB reactor bottom sludge, SARS-CoV-2 concentrations ranged from 7.84x103 to 8.98x104 gc /gTS while rotavirus A ranged from 3.35x104 to 5.91x104 gc /gTS. The viruses left the reactor through the disposal of sludge in the proportion of 29% and 17% for the new coronavirus and rotavirus A, respectively. The positivity rate of the samples for SARS-CoV-2 and rotavirus A was 89% for both viruses. The scum showed SARS-CoV-2 concentration values ranging from 2.67x103 and 2.39x104 gc /gTS. Rotavirus concentrations in the range of 1.3x104 and 7.40x104 cg/gTS were detected. Sample positivity rates were 67% and 100% for SARS-CoV-2 and rotavirus A respectively. It was not possible to quantify noroviruses due to its low concentration in the environmental. However, the presence of this virus was observed in 44% of the raw sewage samples, 56% in the treated effluent, in 22 % of the sludge samples and 56% in the scum samples. The persistence of rotavirus A in the waste sludge from the UASB reactor after dewatering in the drying bed was evaluated. The virus was found in 100% of the samples after the 63-day monitoring.