Fosforets och kvävets påverkan på mikroorganismer i biorening vid Billerud Korsnäs pappersbruk i Grums

Sammanfattning

Biological treatment tanks are part of the biological purification process used in the pulp and paper industry, where microorganisms are utilized to break down organic material. The efficiency of this degradation is influenced by factors such as the availability of nutrients such as nitrogen (N) and phosphorus (P). The aim of this study was to investigate how the ratio between nitrogen and phosphorus (N:P) affects the growth of microorganisms in a biological treatment at the Billerud Korsnäs papermill in Grums. The hypothesis was that a high N:P ratio would promote microbial growth, and a low N:P ratio will reduce the microbial growth. Water samples were collected five times per day over four days. Total nitrogen (Tot-N) and total phosphorus (Tot-P) were analyzed, and bacterial colonies were cultivated onPetrifilm. The results showed a positive correlation between the N:P ratio and the number of bacterial colonies, as well as a strong positive correlation between Tot-N and the number of bacterial colonies. In contrast, Tot-P showed a weak and non-significant negative correlation with bacterial growth. The strong correlation between nitrogen and bacterial abundance suggests that nitrogen, rather than phosphorus, was the limiting factor for growth, indicating that a high N:P ratio favors microbial activity.