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The 5th IWAMA Capacity Development workshop was organized on 13-15 June 2018 in Kalmar, Sweden. The workshop focused on the topic recently trending: nutrient reduction and recovery in the wastewater treatment sector. Over 70 participants representing academia, research institutions, wastewater treatment utilities and private companies participated in the event.

The workshop started with the warm welcome by the hosts – representative of the City Council Kalmar Municipality Mr. Roger Kaliff and Professor William Hogland from Linnaeus University. Both highlighted the importance of circular economy in the water sector focusing on reducing water use and consumption and promoting local actions towards reuse, restoration and recovery of water resources. Further, the speakers stressed the importance of collaboration between different sectors – universities, water practitioners and private sector through international projects like IWAMA.


Wastewater and sewage sludge are a reach source of nutrients, in particular phosphorus and nitrogen

Nutrients recovery is very important from the circular economy perspective. Opening the day with the expert presentation, Jyrki Laitinen from Finnish Environment Institute provided a thorough overview of nutrient recycling. Among most crucial circular economy activities, Mr. Laitinen mentioned “No waste” principle and closing the loops in as many areas of production and consumption as possible, for instance with renewable energy and phosphorus recovery. Further, he pointed out that the international legislative framework and its national implementations affect greatly recycling, processing and usage of nutrients. In addition, many countries have their own national regulations. These regulations are nationally implemented in very different ways, leading to different kinds of solutions and situations on organic fertilizer markets.

European and national policies driving nutrient recycling were presented by Ludwig Hermann, President of European Sustainable Phosphorus Platform. It is expected that the upcoming revised EU Fertilisers Regulation will open the EU market for recycled nutrients and for various recycling technologies. In preparation is also definition of criteria for EU Fertilisers Regulation for struvite and phosphate salts, ashes chemically processed to produce fertilisers or used directly as fertilisers, biochars and pyrolysis products. Several success stories on technological solutions and national regulations on nutrient recycling from sludge in Switzerland, Germany and Finland were discussed in the session.

“We need incentives for efficient reuse of phosphorus, harmonization of EU and national policies and awareness raising” says Mr. Hermann.


Wastewater typically contains a large amount of nutrients – particularly phosphorus – that can pose a harmful threat to infrastructure and the environment, causing problems such as eutrophication in waterbodies and a build-up of struvite in mechanical systems. By utilizing nutrient recovery, wastewater plants can mitigate these challenges while improving water quality and meeting stringent phosphorus discharge limits. The advantages of WWTP with phosphate recycling by struvite precipitation and recovery from sludge were introduced in the presentation from P.C.S. Pollution Control Service GmbH in Germany. Economic drivers for P-recovery process and struvite production were presented as potential good practices to be used on the larger scale in the region. The solution of recovery of struvite as a mineral phosphorus fertilizer offers more advantages in comparison to the application of sewage sludge in agriculture. Struvite is significantly cleaner than the sewage sludge in terms of heavy metals.

Phosphorus is a scare natural resource vital for the health and growth of humans, animals, and all plants in particular agricultural crops. It is most important plant nutrient and significant plant fertilizer. In most European countries phosphorus import dependency rate is 100%. Excavation of geogenic deposits is not sustainable and limited to some 150–350 years. Therefore, it is of outmost importance to find sustainable alternative solutions.

German new sludge strategy for P-recovery „Klärschlammverordnung“ clearly states that big and medium WWTPs have to recover phosphorus after a transition period of respectively 12 and 15  years. Also direct use of sewage sludge as fertilizer is not allowed after the transition period. Exception was done for small and medium WWTPs where agricultural use is still possible. Strategy sets clear objective for phosphorus recovery: at least 50 % extraction efficiency, lowering the P-Content < 20 g P/TDS and no co-incineration of sludge containing > 20 g P/TDS. Matthias Barjenbruch from Technical University of Berlin presented various technological aspects and processes of P-recovery from municipal wastewaters. Many of the processes are still in development or only applicable at laboratory scale for the moment, however, there are around 50 WWTPs with proper operation of P-recovery to serve as good examples. Feasibility of P-recovery processes has to be examined and developed further, and wastewater utilities and companies are actively working on finding even more efficient and economically sound processes.

Introduced general political and technical aspects of the nutrient recycling discussed in the beginning of the project workshop resulted in a panel discussion on the nutrient reduction and recovery in WWT in the Baltic Sea Region with participants from varied backgrounds: local authority, environmental institute, technical university, wastewater treatment facility and private company. Rich professional background allowed a discussion formulating complex approach to the challenge of nutrient recycling, as well as solutions to it.

The event continued with the afternoon session of selected case studies familiarizing the participants with practical examples of implementing said reduction and recovery. Speakers from Germany, Finland and Latvia introduced the ways of recovering nitrogen with thermal chemical hydrolysis and phosphorus – with thermal treatment of sludge. Further, an example of phytoremediation of a site with the use of sludge was brought up in the context of a piloted case in Latvia. Nutrients in sludge further led to discussing sludge treatment as soil improver for agricultural purposes.

Apart from the extensive discussions in the heart of Kalmar, participants had a chance to visit several sites in and around the city to combine theoretical knowledge with practical examples of operating the water sector with the smart and sustainable approach. As a crucial part of the IWAMA workshop, the event involved a study visit to the local wastewater treatment plant operated by Kalmar Vatten. Further, participants visited the Malmfjärden site dealing with the sediment uptake and lake remediation, as well as a desalination plant in Sandvik in the northern part of the Öland island.


The last capacity development workshop of the IWAMA project will be organized in Gdansk, Poland, already in September 2018.