Integrated dredging solutions

Drying of sludge and sediments

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At Dragage Maroc, we specialize in the dewatering and ecological management of sludge and sediment through the use of geotextile tubes. Ce système innovant permet une élimination efficace de l’eau contenue dans les boues, facilitant leur manipulation, leur transport et leur réutilisation avec un faible impact sur l’environnement.

Why choose sludge dewatering with geotextiles?

The use of geotubes for sludge dewatering has become one of the most effective and sustainable solutions for managing dredging sludge in rivers, ports, and coastal areas. Here are some of its main advantages:

  • Efficient separation of solids and liquids in sludge
  • Sludge volume reduction of up to 90%.
  • Minimal environmental impact in the treatment of sludge and sediment
  • Reduced operating and energy costs
  • Ease of transport and disposal of dewatered sludge
  • Possibility of recycling treated sludge for reuse in agriculture or construction

How does sludge dewatering using geotextiles work?

The process of mechanical dewatering of sludge using geotextile tubes follows the following steps:

1. Removal of contaminated sediments

The first step is sludge extraction. Sediment, for example, can be extracted using a suction dredger. Further sludge can be continuously generated as a by-product.

Advantages of geotextile

  • Extremely high processing speed.
  • Direct processing without the need for temporary storage.
  • Online system without intermediate steps.

2. Packaging

The sludge is conditioned by a chemical flocculating agent, responsible for the agglomeration and clumping of fine particles suspended in the water into groups of larger particles, forming what are called “flocs”.

Advantages of geotextile

  • Low mechanical loads acting on the flocs (lower rupture potential).
  • Reduction (or elimination) of mechanical equipment required for the process.

3. Drying

The gravity drainage process ensures a constant flow of water from the mud mixture into the geotextile tube. The pore size of the woven geotextile ensures the retention of the solid fraction, while allowing water to escape through the geotextile, which acts as a filter element.

Advantages of geotextile

  • Possibility of water recirculation.
  • Large storage capacity.
  • Possibility of arranging the tubes at different levels.
  • Simple capacity expansion (adding new modules)

4. Final withdrawal

During the continuous dewatering (consolidation) process, the moisture content of the sludge inside the pipes gradually decreases to a level suitable for its removal, transportation and final disposal, and the dried sludge can also be reused for other specific purposes.

Advantages of geotextile

  • Encapsulating the sludge prevents its rehydration.
  • Geotextile tubes also allow for permanent containment of sludge.
  • It requires little space.

Applications of sludge dewatering using geotextiles

The disposal of sludge, sediment and various wet wastes from mines, industrial plants, construction sites and water treatment systems is generally laborious and expensive.

For these reasons, drying these materials before their final disposal appears to be the most economical solution.

Geotextile tubes offer a fast, cost-effective and viable dewatering solution for different types of materials.

Our sustainable sludge dewatering technology is ideal for:

  • Removal of contaminated sediments in rivers and ports
  • Restoration and recovery of beaches and marine ecosystems
  • Waste and environmental management in infrastructure projects
  • Treatment of sewage sludge and industrial effluents
  • Recycling of dredged sediment for construction applications
  • Sustainable management of contaminated dredging sludge
Sediments
Sediments sometimes contain some degree of contamination with substances such as TBT, PCBs, and/or heavy metals like mercury and lead.
Mining Waste
Mining processes continuously generate a significant volume of residues which, depending on their composition, can pose an environmental risk.
Industrial Sludge
Industrial processes produce organic and mineral sludge that becomes easier to store, transport, or dispose of in the form of dried “cakes.”
Construction sludge
Sludge from construction sites (excavations, drilling, etc.), with limited disposal space.
Sewage sludge
Sewage sludge (a by-product of biological processes in wastewater treatment plants). Smaller facilities generally lack mechanical sludge dewatering equipment.

Geotextile tubes for sludge dewatering

Geotextile tubes offer a fast and economical way to dewater sludge and sediment. The large modules offer high operational capacity combined with optimal drying performance, while occupying a relatively small footprint.

Made from geotextiles, high-tech fabrics specifically designed for this application, the tubes can be stacked on multiple levels to further enhance the system’s storage capacity. Significant cost savings can be achieved in terms of energy consumption, fuel, and maintenance costs associated with sludge transportation and dewatering, which are typical of other systems.

Geotextile tubes can also be used for the permanent containment of dried and consolidated materials without risk of rehydration (e.g. by rain), even during extended periods of operation.

As a result, a greater amount of dry solid residue is obtained compared to drying beds, for example. Geotextile tubes not only act as a durable and reliable containment system, but they also minimize to some extent the emission of the characteristic sludge odor.

Advantages of geotextile tubes

Three decisive factors

There are several factors to consider when choosing the best sludge dewatering and disposal system for a specific application.

Decision criteria include the required dewatering capacity and operating speed, water quality, reuse (sludge or percolate), available space, and maintenance requirements. In addition to the above, and with equal importance, the capital investment associated with implementing the system must be considered. Overall, system efficiency is the most decisive factor in most projects. It is important that sludge removal from problem areas is carried out as quickly as possible, thus reducing the volume of sludge very quickly to facilitate its disposal, while also contributing to the reduction of overall project costs.

These three crucial factors are illustrated by the following project example for a sludge volume of 100,000 m3 and a dredged volume of 345,000 m3.

Operational capacity

Indicates the volume of sludge that can be processed by the dewatering method in a given period (here, in a ten-hour workday). This stage involves the highest costs of the process due to the labor and facilities it requires. Generally speaking, the faster the extraction, the lower the total cost of the drying process.

Duration of the operation

In addition to the filling operation, the drying process also includes the subsequent volume reduction phase. With the development of the “cake” (dried sludge mass), the material becomes suitable for final disposal.

Geotextile bag modules allow this entire process to be carried out in a short period of time, comparable only to the use of mechanical means. Thus, the use of geotextile bags is equivalent to the operation of 12 centrifuges, 22 chamber filter presses or 30 belt filter presses.

The diagram shows the comparison based on the use of a single centrifuge or a filter press.

Project cost

In addition to the operational efficiency of a dewatering system, assessing its economic viability is essential. There are substantial cost differences between different systems related to labor, installation, energy requirements, accessories, and consumables.

Commitment to the environment

At Dragage Maroc, we are committed to implementing sustainable sludge drying processes to ensure responsible and environmentally friendly waste management. Our low-impact sludge dewatering systems comply with current regulations and contribute to the preservation of aquatic ecosystems.

Contact us today!

If you are looking for effective and sustainable solutions for the maintenance and restoration of marine and coastal environments, don’t hesitate to contact us. Our team of experts is ready to help you protect and revitalise our precious coasts and oceans.

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