Proper compliance with the activity plan for decreasing hydrogen sulphide decreases the concentration of pollutant in the ambient air and therefore the unpleasant odour in the Kehra region.
In the second half-year of 2015, the Estonian Environmental Research Centre conducted control measurements of ambient air in the manufacturing territory of AS Horizon Tselluloos ja Paber in Kehra and in the vicinity thereof. The purpose of the measurements was to assess the emissions and spread of pollutants directed into the ambient air from the air pollution sources located at the territory of the company and the quality of ambient air in the vicinity of the company.
In the measurement point located north of the territory of the company, where mainly south-west and southern winds blew during the measurement period, the concentration of hydrogen sulphide exceeded the permitted limit values of pollution level on almost all measurement days. In addition, presence of unpleasant odour which has caused discontent among the local people was also identified. Therefore, the Environmental Board ordered the company to submit an activity plan for decreasing hydrogen sulphide.
“Hydrogen sulphide is a gas with the odour of rotten eggs which in larger quantities is toxic to people and hazardous also to the environment. In Estonia, the limit value of air quality established for hydrogen sulphide is 8 µg/m3 as an average per hour and per 24 hours to protect the health of the people and the environment. In the case of lower concentrations, unpleasant odour can be smelled, but it is not hazardous,” said Dagmar Undrits, Chief Specialist of Ambient Air of the Environmental Board.
Based on the requirements of the Environmental Board, the company conducted an inventory of the ambient air pollution sources located at the territory of the mill in the summer of 2016. The results showed that the main pollution sources of hydrogen sulphide were tall oil kettle and water treatment plant which in turn causes higher concentrations of hydrogen sulphide also in the compost area of the landfill.
According to the activity plan for decreasing hydrogen sulphide, hydrogen sulphide produced in the boiling of tall oil is directed to a post-combustion plant which decreases the content of pollutant in the waste gas.
In order to decrease hydrogen sulphide produced in the water treatment plant, environmentally safe iron(III)sulphate is used which neutralises the emission of hydrogen sulphide in the water treatment plant.
The term for the implementation of the measures provided in the activity plan is the end of October of 2017, after which new measurements shall be conducted to make sure the measures are efficient and that the limit values of air quality are not exceeded. The Environmental Inspectorate shall check the compliance with the measures provided in the activity plan.
The activity plan of Kehra paper mill for decreasing hydrogen sulphide can be examined at the homepage of the Environmental Board.
Additional information:
Dagmar Undrits
Chief Specialist of Ambient Air of the Environmental Board
E-mail: dagmar.undrits@keskkonnaamet.ee
Phone: 680 7423
