Ports host companies that deal with transport, manufacturing, chemicals and oil refining, and the storage of chemicals, solvents, mineral oils, pulp and paper and food. Port areas also manage toxic waste and non-ferrous material. Consequently, harbours and coastal areas throughout Europe have deposits of sediment that are contaminated with heavy metals and organic substances such as hydrocarbons and polyaromatic hydrocarbons.
Dredging of harbours is done periodically for maintenance. The dredged sediments are most commonly dumped in nearby marine waters. Over time, contaminants in the sediment build up to concentrations that degrade the marine environment around the port. The volume of dredged material Europe-wide is very roughly estimated at 200 million m3/yr, about 60% of which is contaminated.
As a consequence of heavy industrial activity and commercial and passenger maritime transport, the Port of Livorno has been listed in Italy as a Polluted Site of National Relevance. The environmental site assessment showed that a thick layer (up to 3 metres) of the port seabed is polluted by heavy metals. The total volume of sediments to be treated is 218 000 m3. Contaminants include cadmium (Cd), mercury (Hg), lead (Pb), copper (Cu), zinc (Zn), arsenic (As) and polyaromatic hydrocarbons (PAH).
The project will demonstrate, through several actions, that sediment dredged from port waters, and characterised by heavy metal and hydrocarbon concentrations above acceptable standards, can be treated in a specifically equipped Confined Disposal Facility using electrokinetic remediation (EKR). The project will demonstrate the environmental and economic benefits of this solution over landfilling.
The project will construct an EKR demonstration plant in the Port of Livorno to treat approximately 150 m3 of dredged sediment.
The project expects to achieve the following results:
- Decontamination through EKR of dredged polluted harbour sediments containing heavy metals and hydrocarbons: 80% of Cd, Hg and Pb will be removed, and up to 95% of Ni, Zn, As, Cu and PAH will be removed, resulting in full compliance with legislation;
- Reduction of sediment volume using innovative electro-osmosis techniques; these will reduce the volume of sediment by 50%, meaning a reduction in the volume of sediment to be stored in the Confined Disposal Facility; and
- Sediments will be disposed of in a Confined Disposal Facility that could be converted either into a port industrial/commercial facility or into a recreational area, or be reused for one of the following activities - habitat restoration/enhancement or beach nourishment, aquaculture, parks and recreation, forestry, agriculture and horticulture, or construction and industrial activities - with a substantial reduction of overall project costs.
The expected economic impact of the new sediment management approach for construction and maintenance works will be at least €15 million on a triennial basis, on the basis of the Livorno Port Authority 2010-2012 Operative Plan. Furthermore, the energy cost will be reduced by 70% in comparison with previous EKR applications and experiments.