Wastewater and its role through the eyes of an expert

Wastewater, even if it is a “stinky” topic in many respects, should be within our circle of interest. An estimated 80% of wastewater from developed and developing countries enters the environment worldwide in an untreated state. In Poland, this percentage is lower, although the amount of 300 million^{cubic meters} per year is also no small problem. However, this issue is not the only one worth noting. Also, what we discharge with wastewater after treatment is not fully investigated, and standards still need to be defined. We must be aware that through technological development we continue to “enrich” our wastewater with new substances that can be, despite multi-million dollar investments in wastewater treatment plants, very harmful to us and the environment in which we live.

I spoke with Dr. Eng. about the challenges of daily work, as well as investigations based on the composition of wastewater. Edyta Łaskawiec – a water and wastewater technologist, assistant professor in the Department of Environmental Biotechnology at the Faculty of Environmental Engineering and Energy at Silesian University of Technology.

Agnieszka Hobot: Topics related to water and wastewater should be of great interest – after all, this water goes into our bodies and the environment in which we live. Is this really the case? Or does this subject matter have a narrow industry audience?

Edyta Łaskawiec: I think interest in this topic is growing all the time, although indeed, popular science channels with trivia have a much larger reach and audience than social media profiles that focus on specific topics, much narrower issues. On the other hand, I am pleased that we have a response from people who are interested in this topic.

They write that they would never have thought that sewage could be so interesting. This shows that it is worth the time to popularize this knowledge about the water and wastewater environment. I observe that people’s awareness has been increasing significantly in recent years. We are beginning to see that we have a huge problem with water, with quality and with quantity, and we are looking for information. This is very important and shows that it is worthwhile to bring this subject matter to a wider audience, not only from the water and wastewater industry, in a more accessible way.

AH: You are a water and wastewater technician. So let’s start briefly with the topic of water. Some people are afraid to drink tap water, which water companies are urging in their campaigns. What does it look like from your point of view? Should we avoid it and when? For example, when it smells bad?

E£: Indeed, our senses are such a major indicator in determining the quality of water. Organoleptic analysis, which determines smell and taste, is important to how we perceive water. There are many myths circulating around the subject, concerning, for example, the hardness of water. We have to refute them. We should remember that water sometimes travels quite long distances, and although it sets off on its way to the consumer treated, it flows through kilometers of water mains and through different quality installations in buildings. It is exposed to various factors and disruptions during this time, such as problems associated with aging infrastructure. Lingering sediments, even if they are not pathogenic, can adversely affect the taste and smell of water.

Sometimes the installation materials are mixed, some older, others newer, and thus further problems pile up as the pressure of the water being transferred changes. Stagnation can also be a problem. In installations that have been unused for too long, microorganisms go about their business and multiply. In addition, any process related to corrosion of materials can cause a disturbing condition of the water. Microorganisms can use both plastic carbon and metals for growth, the result can be corrosion, the appearance of deposits or metal filings. The water then turns brown or yellow.

The bottom line is that tap water is safe and drinkable, and water companies are doing everything in their power to make this quality the best it can be. On the other hand, it is often the case that local problems reduce its parameters, but if they are not continuous, do not involve intense coloration of the water or very strong chemical odor, then temporary changes should not worry us.

AH: Technological development in the 21st century. is occurring at a tremendous pace, it also involves the discharge of more and more new substances into the ecosystems, which are more or less researched and can have a huge impact on our health. Not all have established standards and not all are tested. Where are we now with this knowledge?

E£: I think there are still very many substances that are discharged into the environment that we don’t know. We are constantly doing our business and producing new compounds. Though starting with over-the-counter medications, antibiotics and illegal substances, as well as industrial ones. Each of them must find an outlet somewhere in the environment.

The group of substances that are being analyzed by scientists and included one by one in the Water Directive as controlled in the water or wastewater environment will continue to grow all the time, as our knowledge and analytical skills continue to develop. On the other hand, it can be very difficult to set a point where we say we have the situation under control and are controlling most of the substances that pose a threat to our health or the environment.

AH: So which known substances should we start urgently testing in wastewater? For which standards should be introduced from now on?

E£: At the moment, microplastics have almost entered the standard, a while more and a group of compounds called perpetual chemicals, namely poly- and perfluoroalkyl compounds (PFAS), will also be expanded. These are groups with many problems, if only because of their sustainability and the way they gather. Still, we don’t fully know how they can affect living organisms.

Other compounds that may concern us are new groups of antibiotics to which microorganisms will become resistant, and this is something we need to watch and analyze in particular, because the effects of antibiotic resistance may coincide with further large-scale health problems, if only related to a pandemic. This is another consequence of climate change. Problems will pile up.

AH: In that case, are we prepared in terms of technology to treat wastewater with new substances? What can current treatment technologies fail to deal with?

E£: This is the main problem with getting these compounds into the environment, because the available technologies that focus on removing nitrogen compounds are not sufficient for a whole range of micropollutants, microplastics or antibiotic resistance genes. The development and modification of wastewater treatment technology is certainly inevitable, although we are aware that it is not an easy road. A difficult hurdle to jump over is the huge cost of new investments.

I think the lack of water and sewage infrastructure is still a significant problem. More than 80% of the world’s wastewater is not treated at all and ends up in the environment in this form. It is necessary to expand sewage systems and attempt to collect and treat wastewater from as much of the world’s catchment area as possible, including reaching places where people have sanitation problems. This could reduce the scale of pathogens entering the water, spreading diseases. In the developed world, we are doing a great job of dealing with these problems and are investing in more technology all the time, meanwhile, much of the world is still without even the basics in terms of wastewater treatment.

It is estimated that it may take 10 to 15 years to change and upgrade systems to improve wastewater quality and remove more micropollutants, and only then will we be able to say that we have partially solved the problem. On the other hand, the already more advanced resource recovery processes, hydrogen production and factories, which we often talk about in the context of wastewater treatment plants, are already a 30-year perspective. We would like to speed up these processes, if only because of climate change, but unfortunately everything takes time and implementation. We are pleased that analytical methods and molecular biology technology, which allows us to capture problems, have significantly accelerated in recent years. This allows us to exert a certain pressure both on those who legislate and on those who later, already in practice, implement these technologies.

AH: In one of your speeches, I heard about the traceability of illegal substances in wastewater and the European report that was produced on this topic. Please tell us about it. What can such research be used for in practice?

Indeed, the branch of wastewater-based epidemiology is very broad at the moment, but it began with observing public behavior in 2001. First from tracking the drugs consumed, and just four years later, the first study was conducted that looked at the cocaine consumption of Italian residents. This branch of epidemiology has developed in a very interesting way, because today there are such studies on many European countries. This allowed tracking people’s behavior in terms of consumption of selected and legal drug substances and showing some trends.

With this, selected public health objectives can be realized. Wastewater-based epidemiology not only identifies the scale of selected substances in a wastewater treatment plant, but also narrows the search for the source of pollution to specific neighborhoods or even streets. Wastewater monitoring is not something we do as a standard for healthcare, and here we see that this information can be very valuable.

AH: And now, looking a little bit into the future, what do you see as the three main challenges for the water and wastewater industry?

E£: I think the most important challenge for the next few years is to save water resources. We are doing a lot about the closed-loop economy, but we need to intensify these activities to reduce water waste as much as possible. In the future, we need to put into practice the idea of combining wastewater treatment plants with raw material factories, whether fertilizer or biogas. And in terms of the aforementioned wastewater-based epidemiology – we have great potential in terms of tracking antibiotic resistance genes and detecting more potentially dangerous microorganisms.

In summary, the three main challenges are to save water, increase Polish production of raw materials, and prepare for more health challenges, which we will be able to read from wastewater in the near future.