The global water sector mobilizes to investigate the use of wastewater surveillance of the genetic signal of SARS CoV-2 as an indicator of the distribution of COVID-19 in communities.
By Col. Bhaskar Tatwawadi (Retd)
Sewage Surveillance and COVID-19 Monitoring in Communities
The COVID-19 pandemic pervading the entire globe has brought urban wastewater management into sharp focus. In this backdrop, the Water Research Foundation (WRF) based in Denver, Colorado (USA) had convened the International Water Research Summit on Environmental Surveillance of COVID-19 Indicators in Sewersheds in April 2020. This was in response to the overwhelming need for information regarding the distribution and prevalence of COVID-19 in sewage. The global water sector had mobilized to investigate the use of wastewater surveillance of the genetic signal of SARS CoV-2 as an indicator of the distribution of COVID-19 in communities. The research recommendations of global experts who contributed to the Summit, including potential uses of wastewater surveillance for tracking COVID-19, sampling design, analytical tools, and communication of results to public health decision-makers, the public, and other key stakeholders were presented in a paper by the foundation in July 2020.
The summit had four focal points as under:
- Develop best practices and standardized procedures for the collection and storage of wastewater samples
- Develop best practices for the use of tools to identify the genetic signal of SARS-CoV-2 in wastewater samples
- Develop recommended approaches for the use of data on the genetic signal of SARS-CoV-2 to inform trends and estimates of community prevalence, and
- Develop strategies to communicate the implications of wastewater surveillance results with the public health community, elected officials, wastewater workers, and the public.
Among other important findings recorded during the summit, the following are very important:
- Current studies have demonstrated little success in recovering infectious SARS-CoV-2 virus from stool samples. Therefore, although there is a genetic signal for the presence of the virus, there may not be infectious virions present in wastewater.
- Wastewater surveillance could offer valuable information to public health decision-makers on the potential prevalence of community disease. This includes the identification of “hot spots” within a community, provided that an appropriate spatial sampling approach is implemented, as well as identifying areas that are not currently impacted by the virus.
- With respect to risk assessment, the importance of occupational health and safety was emphasized; specifically the protection of in-sewer operators and laboratory staff at wastewater treatment utilities. The general risk assessments for worker safety could be conducted now using information from other well-characterized viruses and exposure routes.
- Surveillance can also be conducted across the treatment regime for other purposes if different sample types are collected and analyzed. For example, monitoring at different stages of the wastewater treatment process can provide information on the effectiveness of the specific treatment process in removing or damaging the viral genetic material.
- The methods of analysis typically include sample concentration followed by extraction of the genetic material using molecular techniques to amplify, detect, and quantify the presence of one or more target gene sequences.
- The critical importance of engaging early and proactively with health officials regarding the types of analyses to be undertaken and how the results are going to be communicated to ensure successful collaboration, sharing of information, and support of complementary health outcomes was stressed.
- From available case studies, wastewater surveillance is an effective leading indicator of COVID-19 emergence but may be a lagging indicator of subsidence, at least relative to clinical data.
It was concluded that the implementation of wastewater surveillance at a scale to meaningfully inform health practitioners and decision-makers will require significantly increased capacity for analysis from utilities and researchers, some of whom will be new to wastewater surveillance. While the commercial laboratories may be able to support these activities. The local analytical laboratories will need mentoring to implement the new methods.
Identifying the intensity and duration of the genetic signal through wastewater surveillance will only be possible if there is a high-quality genetic signal in the community. Focus on the link between the genetic signal and clinical information on infection prevalence within the community will be needed.
The relationships between the water sector, clinical health practitioners, and policy and decision-makers, information- and knowledge-sharing to proactively assess other potential threats to human health will have to be defined. As surveillance becomes widespread, the tracking of different strains of the virus across geographic areas, providing details of the spread of COVID-19, and the effectiveness of control measures and intervention strategies will be gauged.
So far, the global response to the COVID-19 pandemic has been reactive. However, the wastewater surveillance data can develop a more proactive state of pandemic preparedness.
Sanitation and Sewage Treatment in India
Going back in history, the first big push to the aspects of water supply and sanitation came in the form of the International Drinking Water Supply and Sanitation Decade 1981-1990. This decadal program was implemented under the Ministry of Works and Housing, Govt. of India. The decadal goals were modest and provided for sanitation coverage of about 25% population in India. The emphasis was however on the drinking water supply. Later the urban development projects of water supply and sanitation were sought to be realized through firstly the JnNURM till 2014 and later the AMRUT missions (now underway). Several water supply and wastewater management projects are in different stages of execution under the mission mode.
Urban Sewage/ Wastewater Management in India
The urban sewage generation in India was estimated at about 62,000 million liters per day in 2019 by the Min. of Housing and Urban Affairs. Of this generated sewage, about 23,277 million liters was treated in sewage treatment plants. As per the CPCB Report updated in December 2016, the number of operational sewage treatment plants in India was 920. The installed treatment capacity was pegged at 23,277 MLD as per the MoEF and CC as updated in May 2018. While the number of sewage treatment plants and their cumulative treatment capacity can be arrived at from data published by the implementing agencies, the exact quantity of municipal sewage actually treated in them is not known. It has been experienced that the quantity of sewage actually flowing through the sewerage networks and reaching the STPs is much less than the installed capacities of plants. The Swachchha Bharat Abhiyan has however pushed up significantly the sanitation coverage in the urban and rural sectors. The sewage collection and treatment systems however lag in planning and execution.
Sewage Surveillance for Better Management in the COVID-19 Era
Very recently (July 2020) the Ministry of Housing and Urban Affairs, Government of India has issued an Advisory on On-Site and Off-Site Sewage Management Practices for the guidance of the urban administrators, planners, and engineers to develop and manage municipal sewage. The advisory might consider including some of the aspects of sewage surveillance and monitoring of SARS-Cov2 as outlined above. This will ensure that a very vital and contemporary aspect of sewage management is adequately covered in the Indian context.
About the Author
Col. Bhaskar Tatwawadi (Retd) is the Technical Director at Tandon Urban Solutions Pvt. Ltd., Mumbai. An army veteran and a Civil Engineer from VNIT Nagpur with a Master’s degree in Environmental Engineering (with Honors) from IIT Roorkee, he has over 45 years of professional experience. He has led design teams for several industrial wastewaters to recycle projects for automobiles and textiles industries.
His 22 years stint in the Army, Corps of Engineers, included the construction of water treatment plants and the design of several sewerage and sewage treatment projects for military, naval, and air stations. Later, he has worked on many projects in water and wastewater management including design and execution of rural and urban water supply and sanitation schemes, the Visakhapatnam Industrial Water Supply Project (1998), construction of the BWSSB Water Treatment Plant of 300 MLD (2000 -01) and the ﬁrst Chennai Metro-water Seawater Reverse Osmosis Plant of 100 MLD (2007).
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