Removing Toxic Micropollutants from Wastewater

Interview conducted by Beth EllisonDec 16 2015

Dr. Michael Cimbritz, a lecturer at Lund University, has extensive experience working in the wastewater treatment industry. He spoke to AZoCleantech about the environmentally damaging micropollutants found in wastewater, his research into their removal and why he is using ozone supplied by Primozone to do so.

Can you tell us about the work that you do on the removal of micropollutants from wastewater?

I am managing a project supported by the Swedish Agency for Marine and Water Management with Primozone being one of the project partners. The goal is to establish guidelines for the implementation of advanced wastewater treatment at a Swedish wastewater plant whilst considering existing plant configurations.

In practice this means that we focus on the implementation of using ozonation or activated carbon to remove micropollutants. If (or when) the removal of micropollutants is required, we should be prepared to say how different wastewater treatment plants could or should be upgraded.

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Some plants are large, others are small. Some plants have relatively large inflows due to leakage in the sewer system. Some plants are designed for nitrogen removal, others for the removal of phosphorus and organic matter (BOD). All of these differences mean the plants have different process solutions.

All these factors could be of great importance when deciding how a specific treatment plant should be upgraded. In addition, in Sweden, there is a national ambition that sludge should be returned to farmland. This is an important difference with respect to many other countries which may call for different solutions.

We are mainly working with large-scale pilot tests in close cooperation with municipal wastewater treatment plants and companies such as Primozone. When it comes to ozonation we are interested in the applicability of ozone following various process configurations. Post-treatment of the wastewater following its ozonation is another very important question that needs to be addressed.

What are micropollutants?

Micropollutants is an umbrella term for a variety of different substances which have adverse environmental effects. Some of these substances are pharmaceuticals, metals, endocrine disruptors (compounds which interfere with hormones in humans and animals) and biocides (compounds that are toxic to living organisms).

Several studies have shown that wastewater treatment plants are significant point sources for many of these substances. If we have combined sewer systems, that is pipes collecting both waste- and stormwater, we could also find, for example, biocides flushed off roofs and other surfaces during heavy rainfalls. More diffuse sources such as these are important for several compounds. However, our research is more focused on the elimination of these substances present in wastewater rather than their origins.

What kind of products contain micropollutants?

They can be found in pharmaceutical drugs, in cosmetics and in many chemicals that are frequently used in our homes and in the manufacturing industries.

Image Credits: Kaesler/shutterstock.com

Are there any safe alternatives to micropollutants?

Yes and no. In some cases we can find alternatives that are less harmful but in other cases it is much harder and replacing them can be problematic. This is especially true if we consider, for example, serious diseases. We simply need certain medicines and they cannot be easily replaced.

What are the main reasons people should be concerned about micropollutants?

There are several issues, one is their negative effects on the aquatic environment. There are several negative effects that have been reported, with the feminization of fish being one of the most well-known effects.

In some areas the protection of drinking water sources is another issue. In this case it is not easy to foresee effects but with precautionary principles in mind it could be justified to take measures in cases where there is a drinking water plant downstream from a wastewater treatment plant.

In general, we see an increasing pressure on water resources in many parts of the world, not least in densely populated regions like for example the Ruhr area in Germany. Furthermore, if water is to be reused for different purposes, which can be expected, elimination of micropollutants will be a necessity.

Why has this become an important topic recently?

Our wastewater treatment plants are designed for the removal of organic matter and nutrients, and not for the removal of micropollutants, although some of these compounds can be removed using conventional treatment processes.

Such processes include biological treatment processes like the activated sludge process or biofilm processes. In these processes microorganisms either degrade or transform various nutrients and to some degree even certain micropollutants. However, tests have shown that even when these processes are modified, for example with longer retention times, a broad spectrum of micropollutants cannot be eliminated. There is ongoing research also on this topic.

In Switzerland there is a new law coming to force in 2016 regarding micropollutant levels and in the EU we will see this question being raised. Also, the number of scientific publications on both the advanced treatment and the ecotoxicological effects of micropollutants is increasing. This research is demonstrating both the seriousness and the complexity of the problem.

What changes will this lead to in wastewater treatment in the near future?

We have already seen treatment plants being upgraded, mostly in Switzerland and Germany but also in other countries. In practice this means that we will see more wastewater treatment plants with post-treatment steps.

The energy input and the complexity of wastewater treatment as a result of this will increase even further. At the same time we will hopefully see improved water quality!

What methods can be used to remove micropollutants from wastewater?

There are several possibilities but ozonation and activated carbon, either granulated or powdered, are often mentioned as feasible solutions, both technically and economically.

Full-scale installations are, up to now, based on these technologies. There is one important difference between the two methods. Removal by ozonation is based on the degradation of micropollutants by oxidation whereas the removal of micropollutants with activated carbon is based on the principle of adsorption.

This means that the activated carbon, with the adsorbed micropollutants, needs to be removed and further treated to clean the filter. This is obviously not the case with ozonation, however the oxidation of complex substances can result in formation of potentially toxic products which may require additional post-treatment.

There could be several reasons to choose either ozonation or activated carbon and our research project will hopefully provide some guidance.

In the project you are involved in you have chosen to use ozone. Why? Why Primozone?

We are looking at both activated carbon and ozone from different suppliers.

Primozone is a partner showing both commitment and transparency, which is absolutely crucial for academic credibility.

Primozone has recently launched a website on the topic – why is it important to spread knowledge about the problem?

In the case of micropollutants we can see that multidisciplinary approaches are necessary. Analytical chemists and environmental engineers need to cooperate. The interpretation of ecotoxicological effects is another critical issue to consider. Which treatment plants should be upgraded and why?

Treatment of micropollutants is the next big question for the wastewater business. All stakeholders need to learn more!

The new micropollutants website released by Primozone aims to spread knowledge regarding the problems, solutions and research surrounding micropollutants.

About Dr. Michael Cimbritz

Michael Cimbritz, works at the Faculty of Engineering at Lund University, as Associate Senior Lecturer in Sanitary Engineering with specialization in separation processes, particle separation and micropollutants.

Mr Cimbritz has an extensive experience in wastewater engineering working at companies like SWECO and Veolia and has a PhD in water and environmental engineering from Faculty of Engineering, Lund University.