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Literature Review & Summary Report Design Basis Memorandum St. Johns River Water Management District Contract # SK940AA

BCI Project No. 19-15089 September 2007 Page 5

Table 1 Dewatering Technologies

Classification

Vendor

Type

PASSIVE

Miratech

Geo-textile

Tubes

PHYSICAL

Veolia Environmental Services

Centrifuge

PHYSICAL

Linatex Tennessee

Hydrocyclone

PHYSICAL

Waste Technologies of Australia Environmental Biotechnology CRC Pty Ltd

Electrodewatering

CHEMICAL

NALCO

AIDS

Ciba

SNF

Polymers

Description

Geotextile tubes are comprised of high-strength polypropylene fabric and are fabricated to the project’s requirements. The tube is filled by a system pumping sludge material. The tube retains fine-grain fill material while allowing effluent water to exit through the tube wall. Chemical formulations used to coagulate and flocculate dredged slurries. Polyacrylamide polymers are currently most widely used for this purpose. Chemicals may be used in conjunction with confined settling/dewatering areas, or they may be used as conditioning agents for integrated systems such as the Phoenix or Genesis systems. Flocculated sludge is pumped into the feed port of the centrifuge where it is immediately subjected to high centrifugal forces (in excess of 2800 G’s). The high “g” force takes advantage of the difference in specific gravity and thus separates the solids from the liquids. A hydrocyclone is a high- throughput, particle-size classifier that can accurately separate sediments into coarse and fine- grained portions. A direct current voltage is applied to the biosolids mixture. The application of current in the initial stages of dewatering causes particles to migrate to the electrode of opposite charge (i.e., electrophoresis). Once a cake is formed, electroosmosis occurs as ions migrate to the appropriate electrode to compensate for particle charges.

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