Background

Nitrogen removal, reduced emissions, and climate neutrality are central goals for modern wastewater treatment plants. Stricter discharge requirements from the EU and Swedish authorities are placing increasing demands on efficient and sustainable wastewater treatment processes. The project Kall-PN (funded by FORMAS and several municipal water and wastewater organizations in northern Sweden) aims to develop a resource-efficient wastewater treatment process with the lowest possible climate impact, adapted to northern Swedish conditions, where low water temperatures and fluctuating flows during snow melting periods present particular challenges.

Historically, wastewater treatment plants in northern Sweden have been exempt from nitrogen removal requirements, partly because nitrogen removal has traditionally been considered difficult to achieve at low temperatures and high flow rates. However, with the new EU Urban Wastewater Directive, this is likely to change.

Kall-PN will test technical solutions for removing nitrogen and phosphorus from wastewater, model these processes, and optimize them to reduce resource consumption and nitrous oxide emissions. The project builds on the experience from a previous project, where good nitrogen reduction was achieved at temperatures as low as 5 °C using MBBR (Moving Bed Biofilm Reactor) technology in a pilot at the Fillan wastewater treatment plant in Sundsvall. The process solutions studied in this project, focusing on biological removal of phosphorus and nitrogen, are based on the MBBR technology, combined with sludge hydrolysis to produce an internal carbon source.

About the master thesis

The master’s thesis focuses on biological phosphorus removal in the innovative SB-MBBR (Sequencing Batch – Moving Bed Biofilm Reactor) treatment process, with particular emphasis on treatment performance at low water temperatures and high flow rates. The study will be carried out in one of the two process lines in the pilot at the Fillan wastewater treatment plant in Sundsvall.

The work includes literature review, monitoring and operation of the pilot treatment line, water sampling, and chemical analyses. Laboratory-scale experiments and activity tests at the pilot will also be conducted to gain a deeper understanding of the process performance.

The purpose of the thesis is to evaluate the performance of the SB-MBBR process and to investigate how low water temperatures affect biological phosphorus removal, as well as how the use of internally produced carbon source from primary sludge impacts treatment performance.

Location

The workplace will be at MittSverige Vatten & Avfall and the pilot at the Fillan wastewater treatment plant in Sundsvall.

Duration

The thesis is planned to start in January 2026.

Contact

For questions, please contact: Malin Tuvesson, malin.tuvesson@msva.se or Linda Kanders, linda.kanders@ivl.se

Interested?

Submit your interest by clicking on "Registration of interest".