SECTION VI REVIEW OF SLUDGE DEWATERING （第六部分对污泥脱水）.pdfVIP

SECTION VI REVIEW OF SLUDGE DEWATERING TECHNIQUES SECTION VI REVIEW OF SLUDGE DEWATERING TECHNIQUES Introduction Dewatering is a physical (mechanical) unit operation used to reduce the moisture content of sludge so that it can be handled and/or processed as a semi-solid instead of as a liquid. Devices commonly used for dewatering include: - Rotary Vacuum Filters - Centrifuges - Drying Beds - Lagoons - Filter Presses - Continuous Belt Filter Presses (CBFPS) - Thermal Drying Drying beds, lagoons and thermal drying were not considered suitable dewatering methods for this particular application, and therefore are not discussed in detail in this section. Both drying beds and lagoons require a fair amount of suitable acreage for proper installation and operation. Such acreage is not available nearby the treatment facility. This would not only have an impact on land acquisition costs, but on transportation and handling costs. Thermal drying was not considered suitable on the basis of its high energy input requirements. In addition, the use of the dried AMD sludge as a supplemental fuel in the thermal process is precluded due to its inert nature. Following is a detailed description of those dewatering devices considered capable of achieving the AMD sludge disposal objectives. However, the final selection will be based on the economic evaluation performed in Section VII of this report. A. Rotary Vacuum Filtration 1. Conventional Rotary vacuum filtration basically consists of a cylindrical drum covered with a filter media which rotates partially submerged in a vat of sludge. The physical mechanisms which take place during vacuum filtration may be divided into three phases (see Figure V