ONE OF Europe's busiest ports is seeking approval to build a prototype dewatering plant that will squeeze dredged material dry.
Antwerp Port Authority is hoping to reap huge benefits by mechanically dewatering dredged material which currently has to be dried in huge lagoons.
Mechanised drying of the 350,000t dry matter (TDM) of dredgings arising each year from maintenance work is expected to be quicker and need less space.
Antwerp wants to free up nearly 100ha of lagoons containing dredged material so it can develop a massive new container handling yard.
'The dewatering plant is critical to port expansion, ' said Liv Duerinckx, project engineer with MWH, which is designing the plant and handling the port's planning application.
MWH and Belgian partner Seghers Kappel Group estimate the Authority's land take can be reduced from around 120ha to 20ha by using mechanised dewatering.
Dredged material has historically been dumped either at sea or in landfill sites.
New environmental regulations are making disposal at sea more difficult.
Land disposal requires drying the dredgings to make them easier to handle and to reduce landfill costs. Water content is typically reduced from 80%-85% to 70%-60%.
In lagoons this can take up to a year.
The prototype mechanical process will use a combination of centrifugal tanks to settle out sand and heavy fines, chemical flocculation, and a series of chamber filters, which will sieve silts from the water.
Drying will take a matter of hours. Total project cost is expected to be £19M.
Even though the mechanical process is energy-intensive, MWH predicts it will reduce treatment cost to £17.5-£20/TDM compared to £20-£30.5/TDM for lagoons.
Because the mechanical process will produce material with engineering properties the port also stands to sell dry material on to the construction industry.