Woven Fabric Dewatering Technology

Veolia Separations has successfully completed several large-scale dewatering projects using Woven Fabric Dewatering Tubes. This technology is often the most inexpensive if it is appropriate for the specific sludge stream and the client has the necessary conditions (time and real estate) to employ it in a safe and environmentally responsible manner.

Veolia can supply the Fabric Tubes, all of the necessary dredging/pumping/piping systems, the polymer and necessary management and labor to establish/maintain a Woven Fabric Tube dewatering process.

The Polymer system and Fabric Tubes must be carefully monitored during the tube filling operation. The sludge flow to the Tubes must be controlled through a series of manifolds and valves while closely monitoring and controlling the following:

• Feed solid content
• Proper application of polymer
• Equal distribution of sludge/solids in each tube
• Clear, free-flowing filtrate from each tube
• Tube cloth condition and water release
• Tube height and inflation rates
• Underlying tube stability (if filling a second layer tube)
• Basin stability and drainage
• Safe location of personnel with respect to potential hazards (e.g., tube rupture and/or rolling)

Veolia can manage/supervise the installation of each row of Tubes using Onyx provided labor.

The tubes are filled to 85% capacity and then allowed to consolidate. Once consolidation has taken place the geo-tubes are refilled and the cycle continues until the capacity has been reached with consolidated solids (85% of geo-tube capacity).

Drainage ditches in and around the lay down area will direct the water from each tube back to the sludge pond(s) or to a filtrate treatment process.

The full/consolidated geo-tubes can be left in-place to dewater over a prolonged period of time to maximize volume reduction.

Veolia can also provide a proposal/price for opening the tubes, loading the solids and transporting them to the client’s designated landfill (if/as appropriate).

Advantages of Woven Fabric Tube Technology

• Requires much less dewatering equipment
• Requires less labor/operator effort
• Very basic, low-tech operation
• Usually the most inexpensive dewatering approach (if it works)

Disadvantages of Woven Fabric Tube Technology

• Typically requires expensive polymer addition to pre-condition sludge
• Dewatered tube solids are not as “dry” as filter press, belt press or centrifuge “cake”, therefore, much less waste volume reduction
• Does not meet the required PFT and/or dryness/compaction specs on many sludge streams
• Susceptible to cloth blinding by many sludge streams (oil and/or high biological content are most difficult)
• Requires a large amount of real-estate
• Requires a long period of time to dewater
• Can be adversely impacted by local climate conditions (high humidity/rain)
• Relatively “sloppy” and not feasible on hazardous sludge streams
• Requires extensive preparation/construction of tube lay-down and drainage area/system