About the author

Name and title(s): 

Jiri Wanner, MSc. (Eng.), Ph.D., DSc., full professor of water technology. IWA Distinguished Fellow.

Areas of expertise:

Biological wastewater treatment; activated sludge process; bulking and foaming control; nutrient removal; wastewater reuse and reclamation.

Jiri Wanner is co-editor of the forthcoming book Activated Sludge Separation Problems: Theory, Control Measures, Practical Experiences – Second Edition.



This year, the UN’s World Water Day is dedicated to topics in wastewater. What do you think/hope this will achieve?

I hope the dedication of 2017 World Water Day to the topic of “wastewater” will bring public attention to and raise public awareness of wastewater related issues, namely:

The role of proper wastewater collection and treatment in guaranteeing safety in steadily growing town agglomerations; a lack of reliable services in densely populated areas causes risks to human health.
People in more developed countries will understand that safe wastewater collection and treatment is still not a standard in many less developed countries and that waterborne diseases are still killing people in some parts of the world.
People will realize that efficient wastewater collection and treatment is quite a complicated and demanding engineering challenge and therefore it cannot be provided free of charge. It will also be an opportunity for people to ask questions like “How much we are willing to pay for a safe and sound environment, for unpolluted rivers and lakes?” or “Are we willing to pay the same amount of money for water services as we do for mobile phones or internet connection?”
Common people, but also politicians, will learn the lesson that development in the area of wastewater collection and treatment is not possible without continuous research, information exchange and also training and education of new professionals.

Why is the topic of wastewater important?

Wastewater is a natural environment for the transportation and spreading of waterborne diseases. Therefore it must be quickly and safely collected and transported from inhabited areas to prevent contamination of soil and of local water resources.

When untreated or insufficiently treated wastewater is discharged to receiving waters it can be a source of serious problems, e.g., bacterial contamination, oxygen depletion or eutrophication. This complicates the recreational use of surface waters and also the production of good drinking water.

Experience from countries traditionally suffering from lack of water has proved that wastewater can be considered a reliable source of water. This was also demonstrated in 2014–2015 in the Czech Republic when we experienced extremely long period of drought. In the summer months of 2015, effluents from wastewater treatment plants were the only water resources with unchanged flow in contrast to many creeks and smaller rivers. Also the effluent quality was rather stable while surface waters suffered from DO deficit and eutrophication. Wastewater can be also considered as a source of energy (energy bound in organic compounds, for instance) or of phosphorus which is a nutrient only obtainable from limited resources on the Earth.  

What do you think is the most significant change or development in wastewater research/treatment in recent years?

I think that the most significant change in the modern history of wastewater collection and treatment (over 150 years) is the paradigm shift in the whole wastewater sector that has taken place in the last 20 years. Wastewater is no longer understood as a kind of waste, which is reflected in the change of name from wastewater to “used water”. The main task is now not just to collect, treat and discharge wastewater, but to reuse it (after the appropriate treatment) for various purposes. Wastewater can be considered as a source of water in addition to groundwater, surface water or desalinated sea water. The role of wastewater treatment plants today is not just to “remove pollution” but to reclaim water, phosphorus, energy, etc. And this is also the direction in which most current wastewater research is oriented. In many countries (including the EU) this rapid development is now being hindered by missing legislation.

How might you suggest people get involved and/or learn more about the significance of wastewater?

I think that this is a great opportunity for mass media to attract the attention of common people to these questions. Press on wastewater usually focuses on situations where something has gone wrong (leakage from broken sewers, fish dying downstream from treatment plant discharge, extreme water blooms, etc.). Now the media have the chance to show people the journey of wastewater, from house to treatment plant, explain what happens there and how effluents can be (re)used. 

World Water Day’s focus on this topic is also a good opportunity for politicians to explain to people that they care about issues related to wastewater not only during election campaigns, but that they deal with these issues systematically.

Finally, it will be a good occasion for water companies to demonstrate how they use the money collected from the people to deal with sewage.


To learn more about World Water Day, visit the website.

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