PSTP effective in removing SARS-CoV-2 RNA: Study

The Pagla Sewage Treatment Plant (PSTP) was found to be effective in removing the Covid-19 virus (SARS-CoV-2) from the raw sewage, according to a new study.

The findings of the study were disseminated at a seminar, jointly arranged by icddr,b and the Dhaka Water Supply and Sewerage Authority (DWASA), at Buriganga Hall, WASA Bhaban in the capital.

The study was conducted to determine the presence of SARS-CoV-2 in sewage and other contaminated surface water sources in and around Dhaka city, an icddr,b press release said.

The shedding of the SARS-CoV-2 virus through human faeces begins within three days of infection, which ultimately goes into the sewerage system and contaminates the environment if the sewage is not properly treated and discharged.

Accordingly, between September 2020 and January 2021, the researchers collected samples from 22 sewage and 23 sludge from the DWASA’s Narinda, Basabo sewage pumping stations and PSTP.

Additionally, two composite water and two sediment samples were collected from the Mitford point of the Buriganga River and under the Abdullahpur bridge of the Turag River. A total of six samples (three water and three sediment samples) were also collected from three ponds around the capital as well.

All these samples were tested for the presence of SARS-CoV-2 by RT-qPCR assay and different physicochemical parameters, said Dr Sirajul Islam, Emeritus Scientist at icddr,b and the Principal Investigator of the study, while presenting their findings.

“We found that among the raw sewage and sludge samples, about 57.1 per cent and 53.3 per cent samples were found to have SARS-CoV-2 RNA, respectively.”

“There was no presence of SARS-CoV-2 in the samples collected after treatment by the PSTP,” he concluded.

The SARS-CoV-2 RNA wasn’t found in the water and sediment samples collected from the river and pond ecosystems. The difference in physicochemical parameters such as pH, temperature, total dissolved solids, dissolved oxygen, conductivity, and dissolved solid in river and pond water samples were not prominent.

However, variation was observed in treated and untreated sewage samples collected from different sampling sites of the PSTP.