How to treat the coronavirus in the water cycle?
As the corona virus is spreading around the globe water treatment professionals need to know how this virus behaves in drinking water and wastewater systems. Are water treatment filtration and disinfection processes sufficient for coronavirus removal and inactivation? According to international experts coronaviruses are not a major threat for wastewater and water industries due to their low concentrations in municipal wastewater and high susceptibilities to degradation in aqueous environments.
Canadian experts Nicole McLellan, David Pernitsky and Arthur Umble recently published a whitepaper for water treatment professionals on the website Stantec. They state the virus can be removed easily if water treatment professionals take proper precautions and risk considerations. The coronavirus (COVID-19) is a new variety of a coronavirus like Sars and Mers. It is an enveloped virus and these viruses do not survive easily in water (like the Noro- en Adenovirus) and they can be removed and inactivated efficiently.
According to a scientific article in the Lancet there is a possibility of faecal–oral transmission of the new coronavirus, especially in areas with poor sanitation. But coronaviruses are susceptible to antiseptics containing ethanol, and disinfectants containing chlorine or bleach. Sewage from hospitals should be properly disinfected. Wastewater treatment plants receiving sewage from hospitals and isolation centers treating coronavirus patients—and domestic sewage from areas of known large contamination—may have elevated concentrations of viruses. Wastewater from these sources should treated by a variety of processes to reduce the pollution impacts on nearby receiving surface waters.
Use of chemicals
According to the Canadian experts secondary wastewater treatment is credited with removing 90% of viruses, though broad studies suggest the level of virus removal is highly variable, ranging from insignificant to greater than 99% percent. Because of this variability, the primary process for the inactivation of viruses in wastewater treatment is chemical disinfection, like chlorination or ultraviolet light.
Drinking water treatment is an effective barrier
Surface-water treatment plants with upstream wastewater impacts are the most susceptible to having coronavirus contamination in the raw water supply during, and after, an outbreak. Viruses are exposed to several potentially inactivating stresses in surface waters, including sunlight, oxidative chemicals, and predation by microorganisms. Generally, enveloped viruses are more susceptible to common drinking water disinfectants than non-enveloped viruses, so drinking water treatment should be effective.
According to the Canadian experts wastewater and drinking water treatment industries would face increased scrutiny if a major virus pandemic occurs. Utilities would need to respond rapidly to minimize occupational and public health risks based on the available evidence. Wastewater effluents would possibly impact recreation, irrigation, and drinking waters. While wastewater treatment does reduce virus levels, infective human viruses are often detected in wastewater treatment plant effluent.