Dewatering sediments

Belt filter presses are common dewatering choices in Europe and the United States. They can dewater sediment rapidly and do not take as large an area as the air drying processes. Belt filter presses are, thus, often used in confined locations (such as cities) and where large volumes of sediment must be dewatered. They do not dewater as completely as air drying processes, however, and may be limited by the percent solid demands of the treatment to be used. Furthermore, if the sludge is very gritty, the belts may wear out rapidly. 

Gravity Thickening Thickeifiiu of sediments slurries to produce a concentrate tliat can then be dewatered using filtration or dewatering lagoons. Able to produce a thickened product with a solids concentration of 15-20%. Least effective method for dewatering sediment slurries. Requires use of a substantial amount of land. Potential for localized odor and air pollution problems. Low to Medium... 

Theoretical studies (30) comparing the abihty to dewater compressible sohds by sedimenting and filtering centrifuges to pressure filters, have shown that at high G levels, scroU decanters produce drier cakes than pressure filtration. 

Settling/sedimentation (followed by separation and additional dewatering of the sludge)... 

If river cleanup is involved, including dredging, the first estimate of the costs likely to be incurred is on the order of 6.6 Million per kilometer. This includes dredging the bottoms, cleaning and excavating the sides, and thermally treating the sludges after they are dewatered. The sediments will be pumped out at about 2% solids and have to be put into a contained area, the liquid treated, and the solids dried and excavated. 

In most countries, solid waste containing metals such as neutralization sludge from the plating industry and flue dust from the metal and steel industries is currently collected and dumped in landfill, where it constitutes a perpetual toxic threat to the environment and a waste of resources. The alternatives to this landfill disposal are either to reduce the rate of discharge at source by an individually designed recovery process or to separate and recover the metals from the collected waste in a centrally located facility. A presumption for a centrally located facility would be that companies with metals in their effluents require treatment of their total wastewater streams. This could be accomplished through the relatively simple process of neutralization, which requires minor investment in sedimentation tanks and dewatering equipment and involves relatively modest operation costs. 

According to the vendor, costs for sediment removal, dewatering, water treatment, and segregation by particle size are approximately 250/m or less. For removal only, costs are 100/m or less. These estimated costs do not include mobilization and demobilization and/or supplying temporary enclosures (used in pretreatment) if none are available at the site (personal communication Roger Carr, Eriksson Sediment Systems, Inc., May, 1997). 

The Mini-Miser dewatering system uses hydraulic pressure to mechanically extract liquids from sludges, sediment, and solids. The system incorporates a patented press design that has previously... 

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