Environmental monitoring of the coastal waters of Grimstad, south Norway. Effects of wastewater treatment plant effluents in the Groosefjord and the Homborsundfjord in 2015
- Year of publication
- 2015
- Contributors
- Eivind Oug, Jarle Håvardstun, Tone Kroglund, Janne Kim Gitmark, Hilde Cecilie Trannum, Medyan Antonsen
Medyan Esam Ghareeb
Jarle Håvardstun
Janne Kim Gitmark
Summary
The present study is aimed at evaluating the environmental status in water bodies receiving treated municipal wastewater. In the municipality of Grimstad, located at the south coast of Norway, there are two treatment plants that receive wastewater amounting to 16000 and 1600 personal equivalents (measured as BOF5), respectively. The larger installation (at Groos) is a biological treatment plant. The treated wastewater is discharged through a submerged pipeline ending at about 25 m depth in the Groosefjord just south of the city of Grimstad. The fjord has a threshold of 22 m and has stagnant deep water with low oxygen content deeper than 50-60 m. The smaller installation (in Homborsund) is a SBR (‘sequence batch reactor’) treatment plant. The wastewater is discharged at about 25 m depth close to a leisure vessel harbour area in Homborsund. In the fjord there is a small deep basin (56 m) south of the leisure vessel harbour.