23 JULY 2003
summarized below may not be applicable in every case and additional "site-specific"
requirements may also need to be addressed. In addition to the information that follows
in this paragraph, a summary of design calculations is presented in Chapter 3, and
design examples that illustrate use of these calculations and the following sizing criteria
are presented in Chapter 5.
Concentration Related. Several preliminary steps should be completed to
ensure adequate sizing. The first step in the initial design phases is doing a mass
balance around process units that generate sludge. This step will only provide a basis
for the anticipated volume of solids that should be used for equipment sizing. The next
step should confirm the anticipated quantities of sludge generated following conditioning
and treatability testing because the sludge volume may increase following the addition
of conditioning chemicals such as lime.
Flow Related. Several flow related factors that affect sizing criteria should be
considered. Flow related factors can be categorized into two separate categories: peak
and minimum flows and equipment concerns.
2-7.2.1 Peak and Minimum Flows. Because the filter press is a batch operation, the
sizing of the filter press and associated supporting system is primarily based on an
average daily flow of liquid sludge and the percent concentration of solids in the sludge
feed. To compensate for peak flows, storage may be required prior to the dewatering
system as described in Subparagraph 2-7.2.2. Because the process is a batch opera-
tion, storage should also be provided for low flows to ensure an adequate amount of
sludge is present to complete the sludge dewatering cycle.
2-7.2.2 Equipment Concerns. Flow related equipment concerns associated with siz-
ing criteria include those related to sludge pumping, piping, and storage. The following
paragraphs provide recommended requirements from the "Ten States Standards"
2-220.127.116.11 Sludge Pumping. A detailed discussion of sludge transport (i.e., pumps)
equipment is presented in Paragraph 2-4.4 of this chapter. The following minimum
sizing criteria and requirements should be considered for sludge pumps.
a. Capacity. The volumetric capacity for the sludge pumps will be based pri-
marily on the filter press size or required length of the associated filtration (filling) cycle
period. The sludge pumps should be adequately but not excessively sized and should
be equipped to handle varying capacities and pressures through the filter press cycle.
b. Number of Units. Duplicate units or standby units should be provided for
each type of sludge transfer pump used. The duplicate units should be sized with suffi-
cient capacity to handle peak flows with the largest unit out of service.
c. Type. A positive displacement pump, such as a diaphragm, progressive
cavity, or piston-type pump, should be used for this sludge dewatering application. A
general application guide is presented in Table 2-7.