To guarantee sufficient water depths for increasingly bigger ships in the port of Antwerp, Antwerp Port Authority has to dredge and dispose of large volumes of sludge and sediment every year. However, the on-shore dumps and underwater compartments currently used for the disposing of maintenance dredging spoil are slowly coming to their capacity limits.
In 2006, the Flemish Region decided to tackle the problem in a new and sustainable manner by building a mechanical dewatering installation and storing the dewatered sludge on shore in the Port of Antwerp itself. The project is called AMORAS - an acronym that stands for “Antwerpse Mechanische Ontwa¬tering, 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 falls into two phases: The first consists of the design engineering and construction of the dewatering installation, and the
second phase covers the operation of the installation for a period of 15 years. It is estimated that 500,000 tonnes of dry matter will have to be treated and stored every year.
The filtrate from the sludge dewatering has to be treated before it can be discharged. The treatment process is carried out in two stages, the first of which is a preliminary physico-chemical treatment to remove all fine suspended particles.
Organic hydrocarbons and nitrogen are then removed in the biological treatment stage. The biological water treatment plant consists of a suspended activated sludge system and is designed as two identical parallel treatment lanes that can operate entirely independently of one another. It has a hydraulic capacity of up to 250 m³ an hour.
There are four steps during the biological treatment process: pre-denitrification, nitrification, denitrification and post-aeration. This makes it possible to optimise the process to the highest degree and to remove all the nutrients from the filtrate. A final sedimentation by gravity prevents any activated sludge from being carried away with the treated water. Sand filters further limit the number of suspended particles in the effluent.
Part of the treated water is recycled as process water in the AMORAS installation, while the rest is pumped via the discharge pipe back into the B1 Canal Dock, where it is discharged in accordance with the applicable environmental standards.