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Wastewater Treatment & COVID-19 Sewage

Wastewater is the liquid sewage discharged from homes and business and is unfit for human consumption. There are four main sources of wastewaters: 1) domestic sewage, 2) industrial wastewater, 3) agricultural runoff and 4) stormwater and urban runoff. These sewage needs to be treated before going back to the environment. The degree of treatment required for a wastewater treatment plant depends mainly on discharge requirements for the effluent. The purpose of the treatment plants is to produce clean water that will not harm or pollute the surrounding environment when it is discharged into it.

In Ireland, large urban areas collectively generate 92% of the country’s urban wastewater. The European Union’s Urban Wastewater Treatment Directive sets requirements for treating wastewater from these large urban areas, aiming to protect the environment from the adverse effects of wastewater discharges.

Wastewater Tracking for COVID-19

New technologies have enabled companies and governments to use wastewater testing to identify other substances and viruses. As several companies around the globe are offering specific COVID-19 wastewater testing services, we will show you where, why, when, and how these samples are collected and preserved, and how we can help you perform the sample collection more easily.

COVID-19 Spotlight: Tracking Community Outbreaks with Autosamplers

We are more than ten months into the global pandemic. We hope we are all aware of how COVID-19 is transmitted by now. COVID-19 is primarily transmitted through close contact and droplets that come from your nose and mouth. For instance, from someone who is talking loudly, singing, shouting, coughing or sneezing. It happens when people are within 1 to 2 meters of each other.

It is important to remember, though, that there could be a virus outside the respiratory system, such as in the digestive tract. It was proven when scientists found coronavirus in human faeces, as they continued to study the pandemic. Consequently, we are now aware that the virus which causes COVID-19 can be detected by wastewater sampling. Governments and scientists can now monitor the spread of the virus almost in real-time with the analysis of these samples, enabling them to take action to suppress the rapid spread of the virus.

Where Are Scientists Collecting COVID-19 Virus Samples?

There are two main types of studies underway to detect coronavirus in wastewater – detection inside wastewater treatment facilities, and large residential buildings, like apartment complexes

Health officials can take two different approaches to sampling for COVID RNA. They can collect water samples from a wastewater treatment facility - or from a specific residential building.

In the first scenario, treatment plants collect wastewater from nearby areas and process the materials before discharging it into rivers or solid waste facilities. Recognizing the patterns of virus concentration within the entire population will enable the government to decide the steps required to reduce the further spread of the virus (e.g., the closure of businesses or limits on social gatherings). Testing has also been carried out at water treatment facilities to determine whether the COVID-19 virus can contaminate drinking water. Fortunately, so far, the response was negative and was attributed to filtration and disinfection - the treatment methods employed at these facilities.

In the second scenario, researchers collect samples directly from the pipes of individual residential facilities, like apartments, nursing homes, hospitals, and more. Samples obtained from these places can pinpoint if a single person in the building may be infected, which could help officials isolate specific viral hot spots, rather than an entire community. For example, let’s suppose samples collected outside of a dormitory indicated that a student resident tested positive for the COVID-19. In that case, the building could be quarantined to suppress the spread of infection to an entire college campus.

What are the Challenges of Collecting these Samples?

There are many challenges one can face when sampling water. In this article, we will focus on three, which are highly important in a post-COVID-19 world: location, preservation and sample integrity and security.

As mentioned above, there are two typical sampling scenarios in the COVID research arena and, sometimes, access to those facilities can be very challenging as we will explain below.

In a wastewater facility, it's critical to collect samples in the raw water before primary treatment. The Environment Protection Agency (EPA) lists 6 different locations where wastewater sampling for influent samples can be conducted, depending on the equipment at the facility. These include the upflow siphon, upflow distribution box, aerated grit chamber, flume throat, pump wet-well, or downstream of the preliminary screening. It is advised to collect samples from a very turbulent environment to ensure that the sample is well-mixed.

It’s critical to collect a representative water sample to ensure your COVID RNA analysis is as accurate as possible. It’s encouraged to collect samples from a turbulent environment to ensure the sample is well-mixed.

In the case of COVID-19 virus research, it is crucial to note that although the chances for the transmission of the virus from wastewater to scientist are very low, airborne transmission is, indeed, possible, if droplets of water or aerosols containing the virus are suspended in the air. Due to this safety concern, you should consider where to collect the samples while sampling for airborne viruses in water.

Likewise, in the second scenario, where wastewater samples are collected outside of highly populated facilities, it is necessary to enter a manhole or infiltrate pipes. In this case, there is the potential for direct exposure to concentrated waste when collecting water samples, and again, the chance of contracting the virus is slim but still possible. Suppose the sample collection needs to occur in a location where the virus could be suspended in the air. In that case, the scientists or technicians collecting the sample should wear proper personal protection equipment (PPE) to best ensure their safety.

However, to alleviate some of the threat of these airborne droplets affecting your teams, you can incorporate automatic samplers, such as the ProSample, into your sampling regime. These samplers allow for a one-time exposure to the possibility of virus contraction during the initial instrument setup. But the exposure is minimised afterwards with proper barriers installed between the sampler and sample source. For example, you can install an automatic sampler above a drain or near a pipe access point, and the sample tubing would feed directly into the raw water. In this case, barriers such as drains covers or walls protect the scientist. At wastewater facilities, operators can position samplers underneath or adjacent to the primary treatment location. The  is portable, so as the hot spots move throughout a region, so can the sampler. 

Manual water sampling can introduce many safety hazards for technicians. Autosamplers prevent direct contact with potentially dangerous sampling environments and reduce the risk of infection while sampling.

The second challenge of collecting water samples for COVID-19 testing is the preservation of the sample itself. Many environmental samples require preservation of the sample before it is analysed to hold the sample in its current state. Examples of preservation methods include acidifying samples to be processed for nitrate+nitrite with sulphuric acid, acidifying samples for lead with nitric acid, or simply using ice to cool samples to be assessed for faecal coliform content.

But what preservation technique should scientists use with SARS-CoV-2 samples? Like with bacteria, virus samples are best preserved when held at 4°C or lower. Studies have shown that SARS-CoV-2 is stable for at least fourteen days if kept at these cold temperatures. When collecting these samples manually, it is essential to remember to immediately put the sample on ice or in a refrigerator after collection.

Alternatively, an autosamplerlike the ProSample makes things much more manageable. With this instrument, you can fill the sampling chamber with ice to ensure that all samples collected are held at the proper temperature for preservation until someone can obtain them. The ProSample has a double-walled and insulated chamber that allows for longer ice retention, allowing a user some flexibility in scheduling their sample pick-up timing. Since most COVID samples will require a quick turnaround within 24 hours for processing, the sampler housing with ice is perfect for keeping these critical samples cool.

It is critical to preserve water samples at the proper temperature to maintain data integrity. An autosampler can be packed with ice to maintain a cool environment inside the instrument, regardless of whether you collect discrete or composite samples.

The final challenge every sample program must consider is sample integrity, which goes together with sampler security. While most scientists will never have to consider the possibility of vandalism, when a sampler is being deployed near residential facilities or in high population areas, this is an important consideration. It costs a substantial amount of money to deploy a sampler correctly or to send individuals out to collect them and process the samples in the lab. The last thing anyone wants is for samples to be discarded due to contamination or improper preservation.

The ProSample provides many protective measures to protect the instrument (and water samples) from vandalism.

The ProSample can help you keep your samples safe and sound using a variety of mechanisms. Not only is the sample chamber able to be locked with locking latches, but the lid above the pump head can also be locked, ensuring that the sample and program are safe. Operators can even password-protect the instrument's user interface to avoid vandals from poking around and changing the device setup.

For added security, an  group from YSI also offers a wide variety of housing options to protect your sampler, from fibreglass to metal materials. Using housing will allow for the addition of other measurement devices and data loggers so that any continuous data that needs to be collected can be stored and transmitted via cellular or satellite telemetry. As a final note, the ProSample is also a compact and portable size when compared to other autosamplers on the market. It can be hidden relatively easy and can also fit into small places – like inside drains when suspended with a harness.

How Else Can the ProSample be Useful for COVID-19 Sampling?

One of the pitfalls of manual sampling is that the collection timing is not always the same for each sample. With manual sampling, it isn't easy to collect samples at the same time interval. Your technician may not arrive on time; it takes time to prepare to take a sample and equipment calibration time; you may need samples outside of regular working hours, etc. While modelling techniques may account for the time difference, if a scientist wants to ensure their samples are collected consistently, an autosampler is a fantastic solution.

In today’s busy world, there are many factors that can prevent a technician from taking manual grab samples at a consistent time each day.

An autosampler, like the ProSample, minimizes the risk of these extenuating circumstances surrounding sample collection. For example, maybe a residential building is more populated in the morning, so it is ideal for collecting water samples as residents are preparing for their day.

The ProSample can be programmed to collect samples based on time or flow pacing, meaning that scientists who deploy it do not have to worry about being physically present to collect a sample at the perfect time. In time-paced sampling events, you can program the autosampler to collect samples at certain times or specific time intervals, such as one sample every six hours. In flow-paced sampling, you can trigger sample collection every time the water flow rates hit a certain threshold at the collection site. This is possible by connecting third-party sensors to the ProSample to measure flow or gauge height converted to flow – such as the SonTek IQ, YSI Amazon bubbler, or . Flow-paced sampling does not occur at regular time intervals, making it hard to have someone on-site to collect these samples.

The ProSample can capture water samples at a specific time interval (e.g. every hour), or it can be connected to third-party sensors and collect samples based on water flow rates or gauge height.

The ProSample will sample 24 hours a day, 7 days a week; All you need is for someone to pick up the samples!

Manual sampling is also a challenge because the sampling technique between technicians may not be the same, and sampling locations may differ. While we are all typically trained to follow similar sampling protocols within an organization, each individual tends to find one or two minor deviations from the standard protocol that "makes their job easier." These deviations could include collecting a sample from the water's edge instead of wading into the middle to collect a sample per protocol. While this situation is more reminiscent of stream sampling, similar issues happen when different technicians pull samples in pipes or treatment facilities.

Not all technicians pull water sample in the same way. Even with standard operating procedures (SOPs) in place, it’s impossible to ensure samples are captured in a consistent manner without using an autosampler like the ProSample.

Is the sample collected at the proper depth? Was it the correct portion of the system sampled to maintain consistency? Was the sample in a well-mixed location, or was the sample poorly mixed and not representative? 

Adding an autosampler unit like the ProSample, to a system ensures that the depth and horizontal location of the collected samples are the same every time that a sample is collected. This consistency in sample location eliminates some of the errors associated with sampling by removing location bias. However, it is paramount to pick the correct place to install an autosampler. You need to evaluate potential locations (such as shallow filled pipe versus full pipe) to ensure that the sampler will collect representative samples no matter what the channel or process conditions are.

Finally, different studies will require separate bottles of sample water for analysis, while others may prefer to composite the collected samples into a single, large container. There is no right or wrong reason for choosing either of these options, and the ProSample has a wide variety of bottle choices to use as well. Researchers typically want HDPE containers for sample collection, and the ProSample can be equipped with 1 to 24 of these different sized containers. The material used as pump tubing can also be changed from plastic tubing to a Teflon-lined tubing at the user's discretion. The tubing setup depends on if additional analyses are going to be performed on the samples besides SARS-CoV-2 tracking.

Once a sample is collected and properly preserved, many scientists can perform a PCR reaction in-house while others prefer to send the samples to an outside agency for analysis. Regardless of the samples' final destination, the YSI ProSample autosampler can certainly positively augment your current sampling program in many ways.  It can provide a safe environment for employees, consistent samples based on time and location, and properly preserving specimens until they are picked up for processing.

Like to know more?

If you have any questions about ProSample and how it could benefit your organization or about sampling for COVID-19 in general, contact Environmental Sales Specialist.