The National Board of Waters in Finland has proposed a study on the joint treatment of industrial and municipal wastewaters of the City of Kotka. This study is of great interest due to the large forest products industry and food industry in Kotka. All of the wastewaters from the forest products and the food industry and the municipal sewage have been found to be suitable for biological treatment, which makes the joint treatment applicable. An activated sludge process is selected because it takes advantage of the large amount of nutrients in the municipal sewage and it has proved to be the most efficient treatment method for forest industry wastewaters.
However, municipal wastewater contains more nutrients than needed for the biological process, which can cause eutrophication problems in the watercourse. To reduce the pollution caused by the nutrients, chemical treatment of the wastewater is also proposed in the joint treatment. It was concluded that the joint treatment of wastewater is economically, technically and environmentally the best way to arrange wastewater treatment for the industry and the city.
The Effect of Wood Forest Products Import on Pollution Emissions: Evidence from China’s Forest Products Industry
