Sediment Dewatering Services
Sevenson has dewatered contaminated sediments and other hazardous materials from lakes, rivers, industrial ponds, pits and lagoons, as well as waste streams generated by petroleum refineries, petrochemical plants, and wastewater treatment plants. Sevenson’s sediment remediation division has 20+ years of experience operating recessed-chamber filter presses, belt presses and centrifuges.
- Recessed-chamber presses have been used by Sevenson to dewater sediments/sludges from rivers, lakes, ponds, industrial basins, and process plants. To optimize liquid-solid separation, these units are generally upgraded by means of filter aids such as lime, polyamines, or diatomaceous earth. This practice shortens process cycle times and produces a low-moisture filter cake.
- Belt presses are commonly used to dewater biological wastewater treatment sludges from process treatment plants or biological wastewater settling ponds. Sludges processed from a belt press generally have relatively high moisture content.
- Two-phase high-volume centrifuges that operate at extremely high g forces are very cost-effective on large remediation projects where sludge dewatering is required. These units are normally operated at high centrifugal g forces (2,000 to 3,000 g's) and produce relatively dry filter cake and a high-quality effluent. The advantage of this technology is the elimination of the need for addition of bulking agents (only a polymer flocculent is added), resulting in reduced solids volume. Filter presses require the addition of large volumes of filter aids, but centrifugation has no such requirement. This results in the production of significantly less material as a final product.
- Three-phase horizontal and vertical disc centrifuges (8,000 to 10,000 g's) are used as process systems where specifications for oil and grease production are stringent (e.g., 0.5 - 1.0 percent Bottom Sediment and Water). These units are also widely used in the petroleum/petrochemical industry when processing oily sludges such as K048 waste streams or split-phase rag layer emulsions which can be created on large dewatering operations.