AMORAS -
Mechanical Dewatering of Sediment
Port of Antwerp, Belgium
Region: Europe
/ Middle East / Africa
Service
Offering: Engineering
& Design, Environmental Planning & Management
Market
Sector: Natural
Resources & Mining, Ports Waterways & Costal
Client Type: Private
Sector
Status: Complete
Description:
The Port of Antwerp needed to dispose of 2,000,000 m³ of polluted
harbour sediment (600,000 tons of Dry Matter) each year, to maintain and improve
the port’s navigation system for large vessels. Lagooning the sediments was no
longer an acceptable solution: scarcity and cost of land in Antwerp forced
the Port to seek a new and sustainable way to deal with its huge amount of
harbor sediment.
MWH tested the feasibility of the approach through a pilot test of
sand separation and sediment dewatering with chamber filter presses. During
these tests extensive screening (environmental and geotechnical) of the incoming
(i.e. sediment) and outgoing products (i.e. filter cakes, filtrate, sand) was
performed, as well as a mass balance of the pollutants in the incoming sludge,
filter cake, filtrate and sand.
This screening showed the following important results:
·
Filter cake dry matter content : 62 %
·
Filter cake strength parameters :
·
- Cohesion c : ± 20 kPa
·
- Internal friction angle φ : ± 22 kPa
·
Filter cake permeability : 1.10-9 m/s
After conditioning with lime and ferric chloride the filter cakes
could be processed easily. Because the sand fraction was clean, filtrate and
filter cakes contained majority of the pollutants
MWH was then selected as part of a joint venture to design a
process and plant for the mechanical separation, conditioning and dewatering of
this sediment.
This process is an cost-efficient, sustainable solution for the
treatment of these harbour sediment and includes the separation, conditioning
and dewatering of the sediment using membrane chamber filter presses. The plant
will treat harbour sediment equivalent to 600,000 tons of Dry Matter annually.
The project represents a total value of 100,000,000 Euro (design
and construction of the installation) and is the largest mechanical dewatering
plant worldwide that uses this technique. MWH was responsible for the following
activities: basic design, detailed engineering, drawing up of the tender
documents, selection of the contractor(s), supervision of the execution of the
works, start-up assistance and process optimisation.
Project Highlights
The mechanical separation and dewatering of the sediment and
inorganic industrial sludges is technically feasible for the huge amount of
sediment. The risk to the environment is limited and controlled as a
result of the separation of ‘dirty’ and ‘clean’ flows. Additionally the
excellent compaction properties of the filter cakes ensures an impermeable
layer, which also decreases possible environmental risks. Reuse of the
produced filter cakes is possible and research on this is ongoing as more and
more applications for the reuse of the filter cakes become available.
Services Provided
·
Acceptance of the harbour sludge
·
Dredging unit
·
Sand separation unit
·
Sludge transport (4 km) with booster pumps 1500 m³/h
·
Mechanical dewatering plant (12 membrane filterpresses 2,0 m x 2,0
m)
·
Water treatment installation (fysico chemical and biological
treatment)
·
Disposal site included geotechnical contructions
·
Disposal plan
·
Management of the sediment quality/ Acceptance Plan /
Monitoring Plan