The first step in the design of a treatment or disposal process is to determine the amount of sludge that must be managed and its characteristics. Deriving a solids mass balance for the treatment system under consideration can produce a reliable estimate. The solids input and output for every component in the system must be calculated. Typical values for solids concentrations from in-plant operations and processes are reported in Table 9.1. Detailed procedures for conducting mass balance calculations for wastewater treatment systems can be found in Grady et al. (1999), Metcalf & Eddy (2003), Reynolds and Richards (1996), and USEPA (1979). The characteristics of wastewater treatment sludges are strongly dependent on the composition of the untreated wastewater and on the unit operations in the treatment process. The values reported in Table 9.2 and Table 9.3 represent typical conditions only and are not a suitable basis for a specific project design. The sludge characteristics must be either measured or carefully estimated from similar experience elsewhere to provide the data for final designs.
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