Technologies for nutrient removal

Nitrogen (N) and phosphorus (P) are important nutrients known for promotion of excess growth of plants, algae and bacteria such as cyanobacteria (also named as blue-green algae). On the one hand, N and P are steadily declining natural resources. On the other hand, these elements are responsible for eutrophication of surface waters. The main nutrient sources are wastewaters, storm waters, large animal farms, arable land, waste disposal sites, contaminated sites and fish farming. Agriculture and municipal wastewater treatment plants (WWTP) are the main sources of external phosphorus load at the Baltic Sea catchment area. Utilization of the best agricultural practices and right wastewater treatment technologies are needed to cut down the nutrient load entering to the Baltic Sea.

Technologies for agricultural nutrient load reduction

Removal of nutrients in wastewater treatment plant

Mechanical Treatment
1. Screening
2. Sand Catcher / Grit chamber
3. Primary Sedimentation

Biological Treatment
4. Biological Treatment
5. Secondary Sedimentation

Advanced Treatment
6. Filtration

A. Coagulant

The relatively new biological wastewater treatment technology called aerobic granular sludge (AGS) is usually applied to sequencing batch reactor (SBR) systems. Compared with the activated sludge, AGS technology has many advantages, such as excellent settleability, short settling times for good liquid-solid separation, granules have a stronger microbial structure, good biomass retention, simultaneous phosphate and nitrogen removal, high resistance to toxicity. Due to these advantages, AGS technology has a great potential to be one of the most prospective biological wastewater treatment technologies in the future.

Validation of piloted nutrient removal technologies

During WaterChain project six nutrient reduction units were tested in field experiments in Finland and in Latvia. In addition, hydraulics of a nutrient reduction filter was tested in laboratory circumstances in Estonia. All described actions were performed on a time scale from 10/2015 to 6/2018. Demonstrated phosphorus reduction methods are presented in the report at general level with operating principles and effectivity results.