How to make ecological fertiliser from municipal waste? [Experts’ panel]

Since the number of sewage treatment plants in Poland is growing, the amount of sludge produced there is increasing as well. Sooner or later, each and every plant faces a dilemma what to do with the sludge. Storage is the cheapest but the least environment-friendly solution. The best option would be to process and reuse the sludge (e.g. as fuel or fertiliser). ”Instead of asking if to process the sludge we should rather think how to process that” - claims Prof. Maciej Zalewski, Director of the European Regional Centre for Ecohydrology who called for changing attitude to the management of resources.  ”If we don’t start to recycle resources now, we may run out of them by 2030. As simple as that.”  

Experts’ panel on the use of sewage sludge

Use of sewage sludge

The neighbours of Poland achieve much better results as regards using the sludge for agricultural purposes. Estimates show that Germany uses 25 percent of the sludge and Sweden as much as 90 percent. Also in Poland - in line with initial findings of the NIK audit - less and less sludge goes to landfill sites. More and more frequently it is processed by means of environment-friendly methods, like composting or anaerobic digestion. The panel participants underscored, though, that the use of the processed sludge in the Polish agriculture is still too low. ”The point is that the sludge should become an ecological fertiliser, not waste” - says  Cezary Kołodziejski from the Municipal Sewage Treatment Plant in Łowicz.

According to specialists, farmers are afraid of potential harmfulness of fertilisers made from the sewage sludge because they do not know much about them. At the same time, the data quoted by Wojciech Stępień, PhD from the Department of Agricultural Chemistry at the Warsaw University of Life Sciences reveal that because of restrictions imposed by the European Union the amounts of heavy metals in the sewage sludge in Poland are decreasing.

An expert on contamination of sewage sludge with heavy metals

Contamination of sewage sludge

The research presented by Prof. Lidia Sas-Paszt from the Department of Agricultural Engineering at the Institute of Horticulture in Skierniewice proves that the fruit and vegetables grown on biofertilisers improve people’s well-being and taste better. In 2003-2012, production of biopesticides in Poland went up twice. Although forecasts point to its continued growth, it is still only a fraction as compared with chemical fertilisers.

The panel participants also mentioned drawbacks of Polish regulations in that matter. Legal norms for laboratories examining sludge (e.g. for parasites, heavy metals or pathological bacteria) are so high that it is almost impossible to meet them. Maybe this is the reason why the instances of forging test results are so frequent. It also happens that sewage treatment plants choose the laboratories that will produce ”proper” results for them. According to Prof. Tomasz Cencek, Head of the Department of Parasitology and Invasiology in Puławy, supervision of laboratories has to be implemented.  

”We’re very satisfied with this debate, we’ve learnt a lot” - admits Jan Kołtun, Director of the NIK Branch in Poznań. ”We should take advantage of the potential of nature. We can now do that with  the sewage sludge thanks to modern methods based on good microorganisms. Environment-friendly solutions are our future” - Kołtun leaves no doubt about that.

The final report on the functioning of national sewage treatment plants should be ready in three months. It will also include the most interesting fragments of the experts’ debate organised by NIK.