In a joint project between SU “St. Kliment Ohridski”, through the ‘Clean & Circle’ Center of Competence, and Sofiyska Voda, operated by the international VEOLIA Group, world leader in resource management, a method was developed for examining the quantity of SARS-CoV-2 in the wastewater of Sofia city. Following the example of a number of countries /France, Germany, Austria, Greece/, which determine morbidity levels not only according to the data from clinical samples, but also by the domestic wastewater, now this measure will also be applied in Sofia. The information about the presence of the virus in wastewater could be used in three main ways:  

As a preventive tool for early warning - anticipation of potential new waves and detection of disease outbreaks.

As a tool to manage and control the spread of coronavirus.

As a precautionary measure, if the local population test is negative but the virus is found in the wastewater, potential sources of infection should be investigated.
The introduction of the method is the result of one year’s work of scientists and specialists from the ‘Clean & Circle’ Center of Competence and Sofiyska Voda, operated by the international VEOLIA Group. It has been developed following an Austrian model, where a Covid-monitoring program has been implemented covering over 100 residential areas. The Bulgarian team developed its own approach, which allowed achievement of efficient results over a short period of time.
The project covers assessment of the water in Sofia. In the next stage of the project regular monitoring has been planned of SARS-CoV-2 in the wastewater arriving at the treatment plant and spots of the sewer system of the city of Sofia. The monitoring will allow morbidity rates in the city to be assessed. The most important thing is that after the treatment of the wastewater, viral fragments do not survive and the treated water is safe for the water recipient bodies (in this case Iskar river) and the people.

The obtained results would be useful for application and monitoring in other cities and water cycles as well, especially in areas with pronounced winter and summer tourism.

Chief Assistant Professor Mihaela Beluhova and Chief Assistant Professor Slavil Petkov – the creators of the modification of the method for isolating and determining SARS-CoV-2 in wastewater. 

Niya Stoyanova and Elena Ivanova from the Laboratory Testing Complex of Sofiyska Voda AD are applying the method in real samples with modern automated system for extracting and isolating nucleic acids and subsequent PCR detection in real time. 
Experimental setups of the most difficult element of the method – isolating and concentrating native viral RNA from the complex set of pollutants in wastewater.