Grab sampling from on-site wastewater treatment facilities: variability and correlations (2019-2022)

In this project we evaluate results from grab sampling of package plants to study the variability among grab samples as well as potential correlations between different parameters. The project is funded by the Swedish Agency for Marine and Water Management, the European Regional Development Fund and Norrbotten County Council (Region Norrbotten).

To assess the relevance of results from grab sampling repeated sampling from the same facilities is needed. In this project we take a series of samples (n = 10) of the influent and effluent from seven package plants. The sampling period covers different seasons to assess seasonal variations. Different types of package plants are included, e.g. both continuous flow and SBR. Parameters investigated include TSS, BOD, TOC, DOC, P, N, temperature, pH, turbidity, chloride and indicator bacteria. It will be studied if there are differences between the variabilities across the different parameters.

This project investigates also pollution concentrations in the effluents of on-site wastewater treatment facilities in Sweden and Finland. Existing data is compiled, consisting of i.a. a large number of sampling results from the Finnish Environment Institute as well as results from Swedish projects. Potential correlations between the measured parameters are evaluated (e.g. turbidity and BOD or P, temperature and N, type of facility and treatment efficiency). It will be discussed if sampling occasions with low measured concentrations correlate with preceding precipitation events.

The project is a collaboration between Luleå University of Technology, Oulu University and municipalities in Norrbotten.

Inga Herrmann