Harbour sludge removal causes marine ecosystem damage elsewhere

Large amounts of silt have accumulated in harbours near cities, making it difficult for ships to dock due to falling water levels. In addition, the sludge usually contains high levels of toxic chemicals and nutrients, resulting in poor water quality and a dangerous environment for aquatic life. In some cases, to clean up the polluted harbours, the sludge is transported to other marine environments further from the shore, causing marine pollution elsewhere and harming fish and plants in those areas.

Nº 115

1) Denmark

2) China

some attempts made
past case
Region-1
Region-2
Region-3
Region-4
ongoing case
no attempts made

None

Harbour sludge removal causes marine ecosystem damage elsewhere

Large amounts of silt have accumulated in harbours near cities, making it difficult for ships to dock due to falling water levels. In addition, the sludge usually contains high levels of toxic chemicals and nutrients, resulting in poor water quality and a dangerous environment for aquatic life. In some cases, to clean up the polluted harbours, the sludge is transported to other marine environments further from the shore, causing marine pollution elsewhere and harming fish and plants in those areas.

1) In 2022, the bottom sludge was removed from Copenhagen Harbour to allow for the construction of the artificial peninsula Lynetteholm, which will house 35,000 people and protect the city’s harbour from rising water levels. However, the removed sludge was transported to Køge Bugt in Denmark. As a result, sludge has accumulated in Køge Bugt, causing environmental damage to the area and drawing criticism from local residents.

2) In 2013, improper sludge disposal was widespread in China, with around eighty per cent of all sludge being improperly disposed of, resulting in significant secondary pollution. This is because the cost of improper disposal is significantly lower, ranging from $16 to $24 per tonne, compared to the cost of proper alternatives such as incineration, which can cost around $240 to $360 per tonne.

1. Carlson, C. (2021, June 7). Artificial island Lynetteholm to be built in Copenhagen harbour. Dezeen. Available at https://www.dezeen.com/2021/06/07/artifical-island-lynetteholm-copenhagen-harbour/

KIMO. (2022, May 12). KIMO Denmark to Danish government: Stop dumping sludge in Køge Bay. KIMO. Available at https://www.kimointernational.org/news/kimo-denmark-to-danish-government-stop-dumping-sludge-in-koge-bay/

2) Yang, G.; Zhang, G.; Wang, H. (2015). Current state of sludge production, management, treatment and disposal in China. Science Direct, 60-73. https://www.sciencedirect.com/science/article/pii/S0043135415002250?casa_token=Rw12hdQa448AAAAA:5NutK_XO-dMwwum4uK6nu2L2iR_6iQ4FCvv70MAgvepsYxxfDj8wHQkcoJS_Erf5sx3in7N6Cqg

Feng, L.; Luo, J.; Chen, Y. (2015) Dilemma of Sewage Sludge Treatment and Disposal in China. Environmental Science & Technology, 4781-4782. https://pubs.acs.org/doi/pdf/10.1021/acs.est.5b01455