Why use mechanical dewatering instead of geotubes?
When cleaning a pond or lagoon, one approach often considered is using geotubes or geotextile bags. This approach requires pumping the sludge or sediment from the pond to the geotubes which work as filters to contain the solids and drain the liquid. Press Rentals has performed work dredging ponds into geotubes at customer's requests. However we have found the following occurrences to encourage our customers to use a mechanical dewatering approach.
- Blinding: The filter fabric can often blind off from smaller particles and cease any dewatering from continuing- leaving the operator a large bag of wet sludge.
- Bursting: The bags can burst spilling the sludge back to the pond or all around the dewatering site.
- Footprint: Most customers do not have the acreage to set up bags the size of football fields (100 yards X 50 yards). If the dewatering occurs successfully, it can take weeks for the solids to be dry enough to cut the bags open for disposal.
- Filling: The geotubes are designed to be filled to a certain level. Press Rentals has found dewatering does not occur fast enough to maximize their designed capacity and projects require more bags than originally estimated.
Value of using mechanical dewatering (belt filter presses, plate & frame filter presses, & centrifuges):
- Blinding: If belt blinding is occuring from flocculant or smaller particles, operator can actively see this and make appropriate changes to facilitate dewatering.
- Bursting: When using mechanical dewatering, the sludge is contained using mixer tanks & HDPE fused pipe.
- Footprint: Often the footprint needed for a belt press dewatering system is 50' X 50'
- Faster: Belt filter presses are a faster dewatering approach vs. geotubes as the filter cake is immediately ready for disposal after it has been dewatered.