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Design Guidelines — Building FAST® Systems Into Ships’ Tanks
Scope
These design guidelines are intended to assist naval architects and
engineers in determining the feasibility of and the requirements
for building FAST® sewage treatment systems into ship’s tanks.
The guidelines are general in nature, are subject to change without
notice and shall not be used for design without prior review and
written approval by FAST® Systems specific as to each case.
General
The FAST® process is unique in that its application is relatively
independent of tank shape. Therefore, the process can usually be
built into ship’s tanks.
For most marine applications, the process requires two tanks:
1. A Media Tank to convert raw sewage into water and
2. A Wet Well to provide chlorine contact volume and/or to
act as a sump for automatic control of discharge pumps.
The Media Tank is sized by the organic load and the Wet well is
sized by the hydraulic load. The sizing and other requirements for
these tanks depend upon:
1. The effluent standard to be met.
2. Whether or not long term sludge storage will be required
and the length of the storage period required.
3. The types of domestic wastewater to be treated.
4. The number of persons to be served.
5. Whether vacuum or conventional toilets will be
employed.
6. Whether chlorine or UV disinfection will be employed.
USCG and IMO Requirements
1. These certifications are based upon a ten day test.
2. The regulations do not require performance testing of
the individual system after installation and the question
of performance after the ten day period is not addressed.
3. These regulations also incorporate a loophole which
permits a system to meet the requirements using dilution
rather than removal of BOD5 and TSS.
Secondary Treatment
1. Based upon a 30 day average, EPA defines secondary
treatment as removal of 85% of applied BOD5 and TSS
and effluent containing an average of not more than 30
mg/l of either parameter (45 mg/l average during a 7 day
period).
2. In industrial applications where diluting water might be
added to the water for process purposes, the required
effluent parameters must be adjusted for the dilution.
That is, if 2 gallons of seawater are added to 1 gallon of
wastewater to produce chlorine or for any other reason,
the diluted effluent must contain not more than 10 mg/l
BOD5 and TSS.
3. Achieving this performance requires separation of
residual sludge from the effluent.
Sludge Storage
1. Residual sludge is a byproduct of the FAST® process, as
it is of any process capable of removing BOD5 and TSS.
2. The sludge comprises non-biodegradable materials and
those biodegradable materials which have not been fully
oxidized to CO2 and water.
3. Process tanks of practical size will produce a residual
sludge and that sludge can be separated from the effluent
and stored for separate disposal.
4. A system designed to meet minimum USCG and IMO
requirements does not require long term sludge storage.
5. Many FAST® units incorporate internal sludge storage
for periods ranging from 90 days to one year. Such long
storage periods can be useful to vessels which never leave
controlled waters.
6. If the vessel does leave controlled waters from time to
time, the stored sludge can be discharged at sea.
Types of Domestic Wastewater to be Treated
1. Marine regulations define sewage as human waste and
the water which transports that waste (black water). Gray
water and ground food waste from the galley are not
included in that definition.
SMITH & LOVELESS INC.
® FAST® Process
www.marinefast.com
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