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Norra Djurgårdsstaden
Husarviken in Norra Djurgårdsstaden, Stockholm. Photo: Holger Ellgaard (wikimedia) View original picture , opens in new tab/window

Master's thesis on greywater treatment and resource recovery from sorting sewer systems

Published: 22 April 2021

Nutrition recovery from sorting systems in Norra Djurgårdsstaden, Stockholm

Background

In collaboration with the City of Stockholm, Stockholm Vatten och Avfall (SVOA) plans to implement a sorting system for drainage of sewage and food waste in a residential area in Norra Djurgårdsstaden (NDS). As part of this work, SVOA participates in the MACRO 3 project (food in circular robust systems) together with several other actors including Luleå University of Technology and RISE. The aim is to utilize and reuse nutrients and energy in a resource-efficient way.

exempel på sorterande system
Example of a sorting system (Image source: NSVA Helsingborg).

In NDS, black water (from toilets), greywater (bath, wash, shower) and food waste (food waste disposers) will be diverted in separate lines to the resource extraction plant. Black water and food waste contain energy that can be converted to biogas as well as phosphorus, nitrogen and other plant nutrients that can replace artificial fertilizers.

Greywater that counts for the biggest flow contains heat and water that can be recovered. Moreover, treating greywater on the spot and either reusing it for watering plants or discharging it to surface waters will also reduce the flows in the sewer system.

There are currently a few areas in Sweden and Europe with sorting systems in urban environments. In Sweden there is H+ in Helsingborg that recently has been put into operation. Most projects actually focus on nutrients and energy from blackwater and kitchen waste. Therefore, we want to focus on technologies for treatment and resource recovery from greywater in this project.

Assignment

The aim of the project is to develop a new approach for a suitable treatment process for greywater in an urban environment. The process solution must include heat recovery, treatment to a quality that allows irrigation during the summer and discharge to recipients during the winter, as well as handling sludge and other possible by-products. The project includes:

  • Investigation of greywater composition and temperature (literature, reference plants)
  • Comparison and analysis of possible technologies and technology combinations where energy, chemical and areal needs are included, as well as possible costs
  • Potential for energy recovery
  • Suggestion of approach of a process solution for NDS in Stockholm, including an estimate of area requirements, energy balance and overall investment and operating cost calculation

The focus will be on technologies and process solutions. The results are to be presented orally in a final report and in writing in a clear and well-founded report.

The master's thesis project (30 hec) is to be carried out at Luleå University of Technology during the autumn term 2021. The supervisor at Luleå University of Technology is Inga Herrmann and the examiner is Elisabeth Kvarnström. Supervisors at SVOA are Sofia Andersson and Kristina Stark Fujii.

Application

If you are interested in the master's thesis project send an application or your queries to Kristina Stark Fuji (kristina.stark.fuji@svoa.se , phone 08-522 133 52) no later than June, 1 and do not forget to describe why you are interested in the project and what makes you a good candidate.