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Waste Treatment for the CIP System 325
From this tank, they are metered in with the plant effluent so that large surges
of concentrated BOD waste streams are not sent to the receiving POTW at
one time.
SEGREGATING AND TREATING THE VIABLE ORGANISMS
When a CIP system is used to clean equipment and piping that has been
exposed to living cells, the effluent may need to be inactivated using a
specialized waste treatment system before it is sent to waste neutralization for
pH treatment. These biowaste systems are sometimes referred to as “kill
systems.” They use heat or chemicals to kill the active cell cultures in either
batch mode or continuous mode.
Steam heat is the preferred method of inactivating any viable organisms in the
waste stream. The goal of 6-log reduction in the number of microorganisms is easily
obtainable using steam directly injected into the waste stream or using aheat
exchanger. Most designers use direct steam because of its heating efficiency as well
as it being less likely to foul from the waste stream getting “baked on.” The steam
injector is well suited for both the batch systems as well as the continuous flow
systems (Fig. 7).
Acontinuous biowaste inactivation system will include, but not be limited to,
the following components:
& Steam eductor(s) for direct steam heating
& Receiver tanks for both biowaste and high BOD waste streams
& Heat recovery exchanger on discharge line
& Additional cooler for reducing discharge temperature
How does biowaste inactivation affect the CIP system designer? First, the
designer needs to be aware of the need to treat the CIP waste streams that
potentially contain viable organisms from the process. Then system drains at the skid
and each low point will need to be grouped so that they can be sent in the
dedicated biowaste drain system to the inactivation system. In large CIP
systems, it may be beneficial to install a divert valve on the common drain
of the CIP skid that sends the pre-rinse and caustic wash, which will carry the
biological material to the biowaste system and then diverts the remaining cycles
directly to the pH neutralization system. The divert valve is an inexpensive way
to save money on the energy required to heat alarge quantity of biowaste. If a
batch system is used for inactivation, a divert valve can save a significant
amount of the capital cost for larger equipment.
CONCLUSION: IN THE FUTURE, HOW MIGHT CIP SYSTEMS BE
IMPROVED WITH RESPECT TO WASTE TREATMENT?
The design features that improve aCIP system’s ability to efficiently clean acircuit
with less water and chemicals will also reduce the waste effluent load from each CIP
circuit. Minimizing the amount of water used is the first step in reducing the waste
volume that afacility sends to the POTW. The reduced volume of water directly
corresponds to areduced chemical and heat load from each circuit. As phosphate
discharge becomes morerestricted in the United States and aroundthe world, other
cleaners with little or no phosphates should be chosen early in the process cleaning