Hem > About Gryaab > Gothenburg Regions’s future WWTP

The Nya Rya Project will guarantee sustainable wastewater treatment in the Gothenburg region

Increased population, higher water flows and demands for stricter effluent limits are some of the challenges that Gryaab handles in the Nya Rya project.

Major expansion of the existing WWTP

The existing Rya WWTP in Gothenburg, Sweden, with 800 000 connected inhabitants (2021), is about to expand to a much larger WWTP with 1.35 million connected inhabitants in 2055. This is equivalent to an increase of the average influent flow from 4.5 cubic meter per second to 6.5 cubic meter per second. In addition to new water treatment processes this project also includes a new huge pumping station and considering a new tunnel for effluent wastewater. The project, called Nya Rya, started in 2021 and will be finalized in 2036.


Choosing the most sustainable technology

The prerequisites are set: the most sustainable technology is to be chosen. So how do we decide what is most sustainable? By performing a full multicriteria analysis developed by Gryaab’s industrial phD student. Considering 16 different criteria, we will be able to make a conscious choise of process technology, that will last for a long period of time.

This year we investigate and design three different possible technical solutions, either on activated sludge, aerobic granular sludge or membrane biofilm reactors.



Pilot trials in 2022-2023

The investigations during the first year of the project, 2021, led to the decision to test three different technologies in pilot scale:

  • The first pilot is a drum filter unit where we study the possibility to pre-filter the influent wastewater (after 2 mm bar screens) compared to conventional primary settlers. This pilot will run for one year.
  • The second pilot is a biological process unit with aerobic granular sludge instead of conventional activated sludge. We will run this pilot during one year both with pre settled and crude wastewater and study how low effluent concentrations we can acheive.
  • The third pilot consists of two lines of granulated activated carbon (GAC) filters. They are placed after the existing 15 um disc filters. The purpose of these pilots are to investigate the reduction of particles and micropollutants. Two filters operate with different retention times, but both are filled with the same type of re-activated GAC from coconut shells. These pilots will run for two years.