Vegard Nilsen

IMAG0002PhD Candidate


Foundation Subject, Psychology (UiO 2003)
MSc Water and Environmental Engineering (UMB 2008)

Mathematical modeling, filtration theory, quantitative microbial risk assessment, hydrology, storm water

Professional background
Norconsult AS (2008 – ): Consultant working with design of water, wastewater and storm water networks. Involved in the expansion of Oslo Airport Gardermoen since 2009.
UMB/NMBU (2005 – ): Teaching assistant and internal examiner in mathematics courses

Research background
* «Urban Drainage in the Face of Climate Change – Adaptation of Regional Climate Model Output for Rainfall-Runoff Simulations in Oslo, Norway» MSc Thesis.
* For the project BIVUAC – Building and Infrastructure Vulnerability and Adaptive Capacity to Climate Change (NORKLIMA): Development of high temporal resolution rainfall time series for climate scenarios, with methodology from MSc-thesis
* VISK: Virus i vatten – Skandinavisk Kunskapsbank. Coauthor of report from WP5 (case studies on virus risk assessment).

Project title (PhD)
Some aspects of filtration in microbial risk assessment

Project aim
Contribute to the fundamental understanding of the role of conventional deep bed filtration processes in quantitative microbial risk assessment for drinking water

Project description
The aim of the PhD-project is twofold. The first part is a theoretical study of dose-response models for microbial infection, focusing in particular on how such models may be affected by pathogen clustering/aggregation (conventional water treatment is designed to aggregate particles). The second part of the project takes a closer look at how dose-response models may be integrated with models for conventional water treatment, in particular deep bed filtration. Traditional sand filters are able to remove a significant proportion of microorganisms, but the filtration process is dynamic and the removal capacity may vary significantly throughout the filtration cycle. We will characterize this variation experimentally, using virus as an example microorganism, and analyze mathematically the effect of this variation on risk calculations. A sub-goal is to investigate whether there exists an optimal backwash strategy, with respect to microbial risk, when several filters are operated in parallel.

Arve Heistad
John Wyller
Mette Myrmel

Selected publications
Nilsen, V., Wyller, J. (2014). QMRA for drinking water: 1. Revisiting the mathematical structure of single-hit dose-response models. Risk Analysis. Submitted.

Nilsen, V., Wyller, J. (2014). QMRA for drinking water: 2. The effect of pathogen clustering in single-hit dose-response models. Risk Analysis. Submitted.

Nilsen, V., Wyller, J. A., & Heistad, A. (2012). Efficient incorporation of microbial metabolic lag in subsurface transport modeling. Water Resources Research, 48(9), W09519.

Nie, L., Li, P., Nilsen, V., Hem, L., Sægrov, S. (2012). Modelling Climate Change and Urbanization Impacts on Urban Stormwater and Adaptation Capacity. In: Urban Drainage Modelling: extended abstracts of the Ninth International Conference on Urban Drainage Modelling, Belgrade, Sep 2012.

Nilsen, V., Lier, J. A., Bjerkholt, J. T., & Lindholm, O. G. (2011). Analysing urban floods and combined sewer overflows in a changing climate. Journal of Water and Climate Change, 2(4), 260-271.

Nilsen, V., Lier, J. A., Bjerkholt, J., Nie, L., Lindholm, O. (2009) Impact of Climate Change on Urban Flooding and Combined Sewer Overflows – Case from Oslo. In: Road Map Towards a Flood Resilient Urban Environment, Proceedings of COST C22, Paris, Nov. 2009