Literature Review & Summary Report Design Basis Memorandum St. Johns River Water Management District Contract # SK940AA
BCI Project No. 19-15089 September 2007 Page 25
Increasing the settling rate of solids
Reducing sensitivity to temperature & flow fluctuations
Efficient use of disposal areas due to improved thickening and dewatering
Substantially increased clarity of recovered water
The cost of Polymer application must be considered in the choice of a dewatering system. Additionally, the disposition of released water must be considered. For water returning to a lake or stream environment, polymers should be investigated for wildlife toxicity.
Solid Bowl Centrifuge
The solid bowl centrifuge is a continuous feed operation typically requiring reduced labor and operator effort. This technology is also noted as being the best technology for most oil, water, and latex sludge streams. Filter cake is produced at sufficiently high solids content to truck or convey to a reuse or final disposal site.
As with most mechanical dewatering systems, the need for settling basins, return water systems, and containment area restoration, as well as the piping and pumps to the settling area is eliminated.
The solid bowl centrifuge cake is not as dry as a more conventional filter press cake. The result is less waste volume reduction. Operation of a centrifuge requires a higher skill level and a more experienced operator, as well as a greater amount of electric power compared to filter press and belt press technology.
The solid bowl centrifuge functions as a secondary dewatering step, necessitating a pre- thickening step; usually accomplished by a conventional thickener or clarifier. This technology must be considered a step in a more complex process and is not applicable as a stand-alone dewatering system. Additionally, return water will likely need treatment to remove dissolved phosphates prior to reintroduction to the lake
A hydrocyclone is a high-throughput, particle-size classifier that can accurately separate sediments into coarse and fine-grained portions and is particularly effective at removing the sand sized fraction. As such, this device would be used primarily to remove large amounts of coarse