Phosphorus recovery - why is it so important?

May 21, 2018 | By Barbara Grzebulska

In the magazine of Water Supply and Sewerage and on the website you will find articles devoted to the BEST project carried out by REC Poland (Btter Efficiency for Industrial Sewage Treatment).

The text is available at:

BEST project is divided into a series of stages, each of which will address a different issue affecting the quality of water in the Baltic Sea. The first one concerns the issue of zero waste economy and the recovery of phosphorus from sewage sludge. Other issues are: management of hazardous substances in industrial wastewater, management of wastewater from food production and dairy products with high content of organic components and BOD, possibility of preliminary treatment for various industrial wastewater, methods of work for further capacity building, development of cooperation between industry representatives and the treatment sector wastewater. The recovery of phosphorus is a frequently indicated aspect of the circular economy that can be implemented in the water and sewage industry.

Why is the reduction of phosphorus load in sewage sludge crucial?

Nutrient concentrations are the most important factors of eutrophication, because they affect other indicators, for example primary production and the development of plant organisms in the marine environment.

In the sea, phosphorus occurs in organic compounds that are an element of dead organic matter and in inorganic compounds - phosphates. Plants can take these two elements mainly in the form of water-soluble ions of inorganic phosphorus compounds. Their highest concentrations are recorded in estuaries, coastal waters and upwelling regions.

The fact that the main supplier of nutrients to the sea is land causes that the most and the quickest effects of eutrophication are observed in the coastal zone of the sea. However, due to the possibility of good oxygenation, this zone has the greatest potential to neutralize the negative effects of eutrophication. The most difficult conditions are created at greater depths where anaerobic masses of water constitute a constantly replenished warehouse of variously degraded organic matter, producing increasingly large amounts of hydrogen sulphide.

A separate problem is the ever more frequent occurrence of toxic phytoplankton blooms.

About 30 species of toxin-producing algae have been recorded in the Baltic. The blooms are formed primarily of cyanobacteria. This is due to their ability to capture nitrogen from the atmosphere, which gives them an advantage over other plant organisms.

To sum up - changes in the environment caused by eutrophication are mainly:

- increasing the areas and intensity of phytoplankton blooms,

- increase in primary production,

- increase of zooplankton biomass,

- decrease of water transparency,

- reducing the range of resident algae and flowering plants,

- increasing the inflow of organic matter and its deposition in bottom sediments,

- increase of secondary production: zoobenthos and fish in the bottom and in the water depth

above the halocline,

- increase in frequency and expansion of areas with periodic or permanent lack


- reduction of secondary production: zoobenthos and fish in the bottom and in the water depth below


- changing the species composition of the reservoir - lowering its biodiversity.



1. Morze Bałtyckie - o tym warto wiedzieć, "Zeszyty zielonej akademii", Gdynia 2008

2. Wstępna ocena stanu środowiska wód morskich polskiej strefy Morza Bałtyckiego, Raport do KE, IMGW-PIB, Główny Inspektorat Ochrony Środowiska 2013.


Partnership: The flagship involves 16 partners from Estonia, Finland, Latvia, Poland and Russian Federation. Lead partner is the City of Helsinki from Finland. 

Budget: c. EUR 3.6 million, of which BSR Programme co-financing c. EUR 2.9 million.