What we do


With the ever-increasing size of vessels, guaranteeing sufficient draught for shipping traffic is essential for the Port of Antwerp to prosper and grow, now and in the future. To make sure it can accommodate the new giants, Antwerp Port Authority needs to dredge and store large volumes of siltation material every year. However, the available onshore and underwater deposit areas for dredged spoil were reaching capacity.

Therefore in 2006, the Flemish Government decided to build a mechanical, silt dewatering plant in the port area as a long-term, sustainable and innovative solution for the treatment and storage of dredged spoil. This ambitious project is known as AMORAS, which stands for ‘Antwerpse Mechanische Ontwatering, Recyclage en Applicatie van Slib’ (Antwerp Mechanical Dewatering, Recycling and Application of Sludge). The total investment in the AMORAS project is in the region of €120 million.

The project was divided into two phases: the first consisted of the detailed design, engineering and construction of the dewatering installation and should be executed in a period of 30 months. And Phase 2 covers the actual exploitation of the installation for a period of 15 years. Some 500,000 tonnes of dry material are expected to be treated and stored every year.


This huge and complex project was awarded to the SeReAnt joint venture company. DEME and the other partners of SeReAnt have extensive and specialised experience with all the diverse aspects of the AMORAS project, such as the exploitation of various silt treatment centres, dredging and transport of dredged spoil, de-sanding and mechanical dewatering including storage of dredged spoil, as well as having a lot of environmental expertise.

In terms of sustainability, the new, silt dewatering installation met all the contemporary ecological demands and aims to maximise efficiency of energy use in every phase of the process. The plant also has a reliable and user-friendly design because of far-reaching automation, in-depth control systems and optimal use of available capacity.

Used technology:

Six major steps of the AMORAS project:

Underwater cell

The maintenance dredging material from the harbour docks was temporarily stocked by the Antwerp Port Authority in an underwater cell (with a capacity of 300,000 m³) created in the Canal Dock B1. A dredging unit pumped the dredged spoil to the shore for the treatment process to start. Heavily contaminated spoil was not stocked temporarily but pumped ashore directly using a barge unloading dredger.

Sand separation

The material that had been pumped ashore was diverted to a sieving installation to remove all the coarse elements. Depending on the environmental quality of the material and/or the sand fraction percentage, the decision was taken to de-sand the material in a sand separation plant.

Consolidation and Dredging gantry

Next, the material was pumped by booster pumps through a discharge pipeline to the dewatering plant on the ‘Bietenveld’ site, 4 km away. Here, the material was temporarily deposited in four consolidation ponds, with a capacity of 120,000 m³ each. In the consolidation ponds, the process water required for sieving, de-sanding and pumping the material was separated again. Less contaminated spoil was deposited in three consolidation ponds, whereas more contaminated material went to the fourth pond.

An innovative dredging system with a rotating gantry spanning the consolidation ponds enabled fully automated steering of the process. The dredging gantry is equipped with two mobile dredge pumps that can move along the entire span and that are able to work independently from each other.

Dewatering plant using filter presses

In the dewatering hall (140 m x 25 m) the sediment is collected and kept in suspension by 12 mixing units in a large conditioning tank (2,400 m³). Conditioning is done with either lime or polyelectrolyte to improve the sediment’s dewaterability. Twelve membrane chamber filter presses dewater the material, pressing the water through a filter cloth, at a rate of approximately 10 tonnes of dry material per hour per filter press, with a maximum capacity of 3,000 tonnes of dry material per day (24 h). The resulting filter ‘cakes’, with a dry matter content of at least 60 %, are transported to the deposit site by a series of conveyor belts. Two ventilators, each with a capacity of 120,000 m³/h, extract air from the dewatering hall and blow the air into two acid scrubbers, removing any potential ammonia nuisance.

Water Treatment Plant

The filter process water and other effluent water is gathered in the buffer pond for wastewater and subsequently pumped to a water purification plant. There the particles in suspension are removed through a physico-chemical process. In a second step the organic material and nitrogen is removed by means of biological cleaning.

Deposit site

The controlled deposit of the filter cakes is located on the ‘Zandwinningsput’ site. Here, a stack of filter cakes of over 50 m high can be deposited on top of an existing 10 m layer of medium consolidated silt that was previously deposited there.

Related jobs

All jobs