MIL-HDBK-1005/9A
The optimum use of carbon columns as a treatment process
requires the development of design parameters from a detailed
laboratory pilot-scale treatability investigation with the
wastewater under consideration. Pilot scale studies should
determine the necessary design parameters for sizing of a carbon
contact system. The design parameters include type of carbon,
breakthrough and head loss characteristics, and pretreatment
requirements.
The main components of an adsorption system, as shown in
Figure 25, include two or three adsorption columns packed with
activated carbon, liquid transfer pumps, valves, basic
instrumentation for pressure and liquid flow monitoring, and
backwashing provisions. Periodic backwashing is required to
remove accumulated suspended solids. To minimize backwashing, the
column influent should be pretreated to maintain suspended solids
at less than 50 mg/L. These levels of suspended solids are
normally achieved by polishing in multimedia filters prior to
carbon adsorption.
Periodic regeneration of activated carbon is necessary
at the exhaustion of adsorption capacity. For most oily waste
treatment plants, a vendor-provided regeneration service should be
investigated. Onsite regeneration is economical for very large
industrial or domestic wastewater plants where carbon usage is
more than 1,000 pounds/day. For oily wastewater plants with
continuous operation, supplying two or more columns instead of one
large column capable of handling the entire flow should provide
adequate redundancy. For batch operated plants, redundant
capacity is not needed as maintenance or carbon replacement can be
scheduled during plant shutdown. The contacting system can be
pressurized or operated under gravity. The pressurized systems
are generally more flexible and can be operated at a higher head
loss.
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