BALLAST WATER TREATMENT METHOD AND
BALLAST WATER TREATMENT SYSTEM
BACKGROUND
(a) Field of the Invention
The present invention relates to a clarification
treatment of ballast water in a ship for example. In
particular, the present invention relates to ballast water
treatment method and system for clarifying a coagulated
flocs separated from ballast water.
(b) Description of the Related Art
According to International Convention for the control
and management of Ships' Ballast Water and Sediments
adopted in 2004 by International Maritime Organization
(IMO), ships are required to include therein treatment
systems to kill planktons for example in ballast water for
the purpose of avoiding the disturbance of an ecological
system and health hazards due to the migration and
diffusion of microorganisms via ballast water. Currently,
there have been developed ballast water treatment
techniques using combinations of various water treatment
techniques such as ozonation, ultraviolet irradiation,
heating treatment, and magnetic separation.
For example, a ballast water treatment technique using
ozone is disclosed in Japanese Unexamined Patent
Application Publication No. 2008-100157. The ballast water
treatment technique disclosed in Japanese Unexamined Patent
Application Publication No. 2008-100157 mixes ozone
generated by an ozone generating system in the ballast
water transferred to a ballast tank to thereby kill
microorganisms and bacteria or the like in the ballast
water by the strong oxidizing action by ozone.
A ballast water treatment technique using ultraviolet
irradiation is disclosed in Japanese Unexamined Patent
Application Publication No. 2006-263664 for example. The
ballast water treatment technique disclosed in Japanese
Unexamined Patent Application Publication No. 2006-263664
adds hydrogen peroxide or hydrogen peroxide-generating
compound to ballast water to irradiate ultraviolet light in
the wavelength range of 240 to 300 nm to ballast water
prior to the discharge of ballast water. In this
technique, adding hydrogen peroxide or a hydrogen peroxide-
generating compound to ballast water is for the purpose of
killing microorganisms and bacteria or the like by the
strong oxidizing action or the like as in the previously-
described ozonation technique. The ultraviolet irradiation
is for the purpose of avoiding the environment pollution by
discharged ballast water by degrading hydrogen peroxide
remaining in the ballast water.
A ballast water treatment technique by a heating
treatment is disclosed in Japanese Unexamined Patent
Application Publication No. 2008-110276. The technique
disclosed in Japanese Unexamined Patent Application
Publication No. 2008-110276 performs a heat exchange
between pumped low-temperature ballast water and high-
temperature ballast water subjected to a heating treatment
in advance to thereby heat the low-temperature ballast
water to a temperature at which microorganisms and bacteria
or the like are killed.
A magnetic separation technique is disclosed in
Japanese Unexamined Patent Application Publication No. H9-
117618. The technique disclosed in Japanese Unexamined
Patent Application Publication No. H9-117618 adds magnetic
powders and coagulant to ballast water to agitate the
mixture to thereby generate magnetic flocs including
microorganisms and bacteria or the like in ballast water to
separate the magnetic flocs by a magnetic separation system
from ballast water and to collect the magnetic flocs
remaining in the ballast water by a drum-type filter.
According to this technique, microorganisms and bacteria or
the like in ballast water are physically removed. Thus, no
impact is caused on the environment by discharged ballast
water.
Under the background as described above, private
companies have developed ballast water management systems
using various techniques as described above. IMO has
provided requirements for an approval of a ballast water
management system. Such an approval is done in Japan
through Ministry of Land, Infrastructure, Transport and
Tourism as a responsible organization.
Requirements for an approval of a ballast water
management system include a discharge standard regarding
microorganisms and bacteria or the like (Toxicogenic Vibrio
Cholerae, Escherichia coli, enterococci) included in
ballast water. Thus, an approval of a ballast water
management system requires evidence that the system
sufficiently satisfies these standards.
However, when the techniques disclosed in the above
respective publications are used to perform a ballast water
treatment in a large volume, it is difficult to find an
evidence in the above respective publications that these
techniques can kill microorganisms and bacteria or the like
in ballast water. Furthermore, in the case of the
technique disclosed in Japanese Unexamined Patent
Application Publication No. 2008-110276, although
microorganisms and bacteria or the like included in ballast
water can be removed as magnetic flocs, there has been
pointed out a risk of collecting and retaining flocs of
coagulated microorganisms and bacteria or the like for
which an impact on the ecological system and health is
worried.
In view of the above, it is an objective of the present
invention to provide a method and system for a ballast
water treatment that can kill microorganisms and bacteria
or the like included in magnetic flocs so that no impact is
caused on the environment and human bodies.
SUMMARY
A ballast water treatment method according to the
present invention for achieving the above objective is
characterized in including: a step of adding magnetic
powders and coagulant to ballast water to thereby generate
magnetic flocs including microorganisms and bacteria; a
step of collecting the magnetic flocs from the ballast
water; and a step of heating the collected magnetic flocs
to a temperature at which the microorganisms and the
bacteria are killed, the temperature being determined in
advance.
In a ballast water treatment method having the above
characteristic, the heating step may insert the magnetic
flocs to a pipe path and heat the pipe path to which the
magnetic flocs are inserted.
By the characteristics as described above, magnetic
flocs as a heating target can be heated securely. This
eliminates such magnetic flocs that are treated while being
unheated due to short pass for example.
In the ballast water treatment method having the above
characteristics, the heating of the magnetic flocs is
desirably performed by double-boiling the pipe path.
By the characteristics as described above, scale is
suppressed from adhering to the interior of the pipe path.
In the ballast water treatment method having the above
characteristics, an exit temperature of the pipe path may
be measured to investigate a heating status of the magnetic
flocs.
By the characteristics as described above, whether
bacteria or the like included in the magnetic flocs are
killed or not securely can be confirmed empirically.
In the ballast water treatment method having the above
characteristics, a pressure in the pipe path may be
measured to investigate a status of the pipe path.
By the characteristics as described above, the damage
or clogging of the pipe path through which magnetic flocs
are sent can be detected.
A ballast water treatment system of the present
invention for achieving the above objective includes: a
coagulation section for agitating magnetic powders and
coagulant added to ballast water to generate magnetic
flocs; a magnetic separation section for collecting the
magnetic flocs generated by the coagulation section; a pipe
path through which the magnetic flocs collected by the
magnetic separation section is sent; and a heating section
for heating the pipe path.
In the ballast water treatment system having the above
characteristics, the heating section may be a tank in which
water is stored and the pipe path may be immersed in the
tank.
By the configuration as described above, the pipe path
can be heated by double-boiling, thus suppressing scale
from adhering to the interior of the pipe path.
In the ballast water treatment system having the above
characteristics, the tank includes a steam supply opening
through which steam from a ship machine for heating water
in the tank is supplied.
By the configuration as described above, heating can be •
performed economically. Furthermore, the steam jetting can
agitate water in the tank to thereby provide a uniform
temperature distribution in the tank.
In the ballast water treatment system having the above
characteristics, an exit of the pipe path may have a
temperature sensor.
By the configuration as described above, the heating
status of magnetic flocs can be known through the detection
of the temperature, thus confirming whether bacteria or the
like included in the magnetic floc are securely killed.
In the ballast water treatment system having the above
characteristics, the pipe path may have a pressure sensor.
By the configuration as described above, the status of
the pipe path such as damage or clogging can be detected.
The ballast water treatment system having the above
characteristics is characterized in that the pipe path is
structured to have an inlet and an exit provided at an
upper part and to extend from the inlet to the lowest part
and draw an oval helical shape from the lowest part thereof
so as to extend to the exit.
By the configuration as described above, the machining
is simplified and a necessary and sufficient length can be
secured. Even when a magnetic floc includes air, air can
be naturally removed from the magnetic floc.
According to the ballast water treatment method having
the characteristics as described above, microorganisms and
bacteria or the like included in a magnetic floc can be
killed so as to eliminate an impact on the environment and
human bodies.
According to the ballast water treatment system having
the above characteristic, the ballast water treatment
method having the above characteristics can be carried out
to kill microorganisms and bacteria or the like included in
a magnetic floc so as to eliminate an impact on the
environment and human bodies.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 illustrates the configuration showing a ballast
water treatment system according to an embodiment.
Fig. 2A illustrates the top configuration of a heat
sterilization section according to an embodiment.
Fig. 2B illustrates the front configuration of the heat
sterilization section according to an embodiment.
Fig. 2C illustrates the side configuration of the heat
sterilization section according to an embodiment.
Fig. 3A illustrates the top configuration of an
insertion tube constituting the heat sterilization section
according to an embodiment.
Fig. 3B illustrates the front configuration of the
insertion tube constituting the heat sterilization section
according to an embodiment.
Fig. 3C illustrates the side configuration of the
insertion tube constituting the heat sterilization section
according to an embodiment.
Fig. 4 illustrates the relation between the retention
time of magnetic flocs in an insertion tube and an
achieving temperature according to an embodiment.
Fig. 5 illustrates the flow of a startup preparation
step in the heat sterilization section according to an
embodiment.
Fig. 6 illustrates the flow of a magnetic floc heat
sterilization step in the heat sterilization section
according to an embodiment.
Fig. 7 illustrates the flow of a heat sterilization
ending step in the heat sterilization section according to
an embodiment.
Fig. 8A illustrates the top configuration of a heat
sterilization section according to the first modification
example.
Fig. 8B illustrates the front configuration of the heat
sterilization section according to the first modification
example.
Fig. 9A illustrates the top configuration of a heat
sterilization section according to the second modification
example.
Fig. 9B illustrates the front configuration of the heat
sterilization section according to the second modification
example.
Fig. 10A illustrates the top configuration of a heat
sterilization section according to the third modification
example.
Fig. 10B illustrates the front configuration of the
heat sterilization section according to the third
modification example.
DETAILED DESCRIPTION OF EMBODIMENTS
The following section will describe in detail an
embodiment according to a ballast water treatment method
and a ballast water treatment system of the present
invention with reference to the drawings.
First, with reference to Fig. 1, the entire
configuration of a ballast water treatment system 10
according to an embodiment will be described. The ballast
water treatment system 10 has: a coagulation section 20, a
magnetic separation section 30, a filter separation section
40, and a heat sterilization section 50.
The coagulation section 20 has a flash mixer 22 and a
flocculator 24 and generates magnetic flocs F out of raw
water (ballast water) sent via a pump 12. To realize this,
a piping path for sending raw water to the flash mixer 22
includes a magnetic powders addition section 14 and a
coagulant addition section 16. Furthermore, a path through
which water is sent from the flash mixer 22 to the
flocculator 24 includes a organic flocculant addition
section 18. Magnetic powder may be preferably torriron
tetraoxide for example. Coagulant may be preferably
aqueous inorganic coagulant such as polyaluminum chloride,
ferric chloride, and ferric sulfate. Organic flocculant
may be preferably anionic and nonionic ones.
The flash mixer 22 has mixing paddle 23 that rotates
with a high speed to agitate raw water and magnetic powders
and coagulant added to the raw water. The raw water to
which magnetic powders and coagulant are added is subjected
to the high-speed agitation by the mixing paddle 23 to
thereby generate minute magnetic flocs (magnetic micro
flocs) having a size of about tens of µm. When magnetic
micro flocs are generated, microorganisms and bacteria or
the like in raw water are absorbed to surround magnetic
powder as a core and are taken into magnetic micro flocs
because the microorganisms and bacteria or the like in raw
water are electrically-charged.
The flocculator 24 is configured as a continuous multi-
stage flocculator having multiple stages (three stages in
this embodiment). The flocculator tanks 24A to 24C at the
respective stages have agitating paddles 25A to 25C,
respectively. The flocculator 24 having the configuration
as described above is set so that the agitation speed is
decreased in a stepwise manner from the upstream-side
flocculator tank 24A to the downstream-side flocculator
tank 24C. The flocculator 24 receives ballast water
including magnetic micro flocs and organic flocculant added
to this ballast water sent from the flash mixer 22. Thus,
the low-speed agitation is performed in a step-wise manner
from the flocculator tank 24A to the flocculator tank 24C
to thereby grow magnetic micro flocs. Furthermore, since
the agitation speed is decreased in a step-wise manner,
there is a small risk where the grown magnetic flocs F are
broken by the collision with the agitating paddles 25A to
25C.
In this embodiment, as shown in Fig. 1, the flash mixer
22 and the flocculator 24 constituting the coagulation
section 20 are provided in an integrated structure.
However, another structure also may be used in which the
flash mixer 22 and the flocculator 24 are separated and are
connected by a piping through which water is sent from the
flash mixer 22 to the flocculator 24.
In the coagulation section 20 having the configuration
as described above, air is removed from the flash mixer 22,
the flocculator 24, and the path connecting them so that
the spaces thereof are completely filled with water. By
doing this, even when a ship including the ballast water
treatment system 10 swings, no wave is caused in the
ballast water (ballast water including magnetic micro flocs
or the like) in the coagulation section 20, thus providing
a smooth water delivery.
The magnetic separation section 30 collects, from the
ballast water, the magnetic flocs F grown by the
coagulation section 20 to have a predetermined size. The
magnetic separation section 30 includes: a magnetic
separator 32, magnetic discs 34, scrapers (not shown), and
a conveyor 36. The magnetic separator 32 receives the
ballast water including the magnetic flocs F sent from the
coagulation section 20. The magnetic discs 34 are attached
to rotating drums for example and at least a part thereof
is immersed in the ballast water in the magnetic separator
32 to rotate the rotating drum. This consequently attracts
and collects the magnetic flocs F floating in the magnetic
separator 32. The magnetic flocs F absorbed and collected
by the magnetic discs 34 are raised by the screw rotation
from the magnetic separator 32 and are scraped by the
scrapers from the magnetic discs 34. Then, the scraped
magnetic flocs F are transferred by the conveyor 36 to the
magnetic flocs storage tank 38.
The filter separation section 40 collects dusts and
minute magnetic flocs for example that could not be
collected by the magnetic separator 32. In the filter
separation section 40, the water being treated is supplied
via a water supply pipe 44 to the inner side of a filter
drum 42. The water being treated supplied to the filter
drum 42 is filtered by being flowed from the inner side of
the filter drum 42 to the outer side. During this,
collected matters such as magnetic flocs and dusts
remaining in the water being treated adhere to the inner
side of the filter drum 42. This consequently removes the
contamination substance such as magnetic flocs and dusts
remaining in the water being treated. Thus, the water
being treated is turned into purified treated water.
The contamination substance adhered to the inner side
of the filter drum 42 is washed away by water jetted from a
spray nozzle 46 provided above the filter drum 42. The
contamination substance washed away by water jetted from
the spray nozzle 46 to the filter drum 42 drops into a
hopper 4 8 (an inlet of the contamination substance
discharge pipe) provided in the filter drum 42 and is
discharged via the contamination substance discharge pipe
48a. It is noted that the treated water purified by the
filter drum 42 may be partially used as water jetted
through the spray nozzle 46. In this case, as shown in
Fig. 1, the treated water may be partially sent by the
circulation pump 45 to the spray nozzle 46. The
contamination substance and water jetted through the spray
nozzle 46 are returned to the previous stage of the pump 12
via a pump 4 9 provided in the contamination substance
discharge pipe 4 8a.
The heat sterilization section 50 subjects the magnetic
flocs F collected by the magnetic separation section 30 to
a heating treatment to thereby kill microorganisms and
bacteria or the like included in the magnetic flocs F. The
magnetic flocs F collected by the magnetic separation
section 30 are temporarily stored in a collected flocs
receiver tank 52 and is sent via a pump 54 to the heat
sterilization section 50. It is noted that the magnetic
flocs F are in the form of slurry and thus the pump 54 used
for transfer may be a positive displacement pump such as a
tube pump or a uniaxial screw-type pump.
The magnetic flocs F subjected to the heat
sterilization by the heat sterilization section 50 is sent
to a collected flocs storage tank 56. The collected flocs
storage tank 56 includes a circulation mechanism 58 (pump)
and an agitation mechanism (not shown) for the purpose of
preventing the precipitation and separation of the magnetic
flocs F. The reason is that, if the magnetic flocs F are
separated from water and is precipitated, it is difficult
to take out the magnetic flocs F by suction but the
circulation and agitation as described above can prevent
the separation and precipitation of the magnetic flocs F.
The collected flocs storage tank 56 includes a sampling
system 59 of the magnetic flocs F. By confirming that the
sampled magnetic flocs F includes no microorganisms or
bacteria or the like, the safety of the magnetic flocs F in
the collected flocs storage tank 56 can be confirmed.
The following section will describe a specific
configuration of the heat sterilization section 50
according to an embodiment in detail with reference to Fig.
2A, Fig. 2B, Fig. 2C, Fig. 3A, Fig. 3B, and Fig. 3C. The
heat sterilization section 50 according to an embodiment
includes a heat exchanger tube 60 and a tank 70.
The heat exchanger tube 60 is a pipe path for the
pneumatic transportation of the magnetic flocs F sent from
the collected flocs receiver tank 52 via the pump 54. The
heat exchanger tube 60 is desirably configured by a hollow
material having heat resistance and corrosion resistance.
A specific example may include a titanium piping for
example.
As shown in Fig. 3A, Fig. 3B, and Fig. 3C, the heat
exchanger tube 60 includes, at the upper part thereof, an
inlet 62 and an exit 64. The piping extends from the inlet
62 to the lowest part and is bent from the lowest part to
have an oval shape (so-called track shape). The bent heat
exchanger tube 60 upwardly extends to draw an oval and
helical shape to reach the exit 64. The reason is that the
configuration as described above can be machined more
easily than in the case of a hairpin curve shape having a
bent section with a smaller radius for example and can
secure a necessary and sufficient length. Furthermore, by
the configuration in which the heat exchanger tube 60
having the inlet 62 at the upper part thereof is caused to
extend to the lower side and then is caused to extend to
the exit 64 provided at the upper part, even when the
magnetic flocs F includes air, air can be removed naturally
and no risk is caused where lifted air inhibits the
pneumatic transportation of the magnetic flocs F. It is
noted that the heat exchanger tube 60 formed by bending is
longitudinally bound and retained by a support 69, thereby
preventing the deformation of the pipe path due to the
deadweight.
The inlet 62-side of the heat exchanger tube 60 is
connected to the pump 54. The exit 64-side is connected to
the collected flocs storage tank 56. The inlet 62-side of
the heat exchanger tube 60 has a pressure gauge 66, thus
providing a configuration where the pressure in the heat
exchanger tube 60 can be measured. By the configuration as
described above, damage of the heat exchanger tube 60 and
the clogging of the interior of the insertion tube can be
known. When the heat exchanger tube 60 is broken for
example, the magnetic flocs F subjected to pneumatic
transportation is caused to leak, thus causing a decrease
of the pressure in the heat exchanger tube 60. The
clogging of the interior of the heat exchanger tube 60 on
the other hand causes an increase of the pressure in the
heat exchanger tube 60. The exit 64 of the heat exchanger
tube 60 has a thermometer 68. By the configuration as
described above, it is possible to know whether the heating
status of the magnetic flocs sent by pneumatic
transportation into the heat exchanger tube 60 is
appropriate or not.
The tank 70 is a tank to contain and heat the above-
described heat exchanger tube 60. The tank 70 stores
therein water. Thus, the heat exchanger tube 60 is
immersed in water stored in the tank 70. Water stored in
the tank 70 may be soft water used in the ship. The reason
is that the use of soft water can prevent chlorinated lime
for example from adhering to the interior of the tank 70 or
the heat exchanger tube 60, thus providing a longer
maintenance cycle.
The tank 70 includes a steam supply opening 72 for
supplying steam as a heat source for heating water and a
condensed water discharge opening 74 for discharging
excessive water caused by the steam supply. The steam
supply opening 72 and the condensed water discharge opening
74 may be provided in the following layout. Specifically,
the steam supply opening 72 is provided at the lower part-
side of the tank 70 (or at least at the lower-half part)
and the condensed water discharge opening 74 is provided at
the upper part-side of the tank 70 and at least at a
position higher than the upper part of the heat exchanger
tube 60 immersed in water. By the layout as described
above, the high-temperature steam jetted through the steam
supply opening 72 moves upward while heating the water in
the tank 70 to thereby cause an agitation action, thus
providing a uniform temperature distribution in the tank
70. Furthermore, the condensed water discharge opening 74
provided at a position higher than the upper part of the
heat exchanger tube 60 can maintain the water level at a
position higher than the heat exchanger tube 60.
The tank 70 may include a thermometer 80 and a water-
level gauge 82. The reason is that, by measuring by the
thermometer 80 the temperature of the water in the tank 70
and maintaining the temperature in the tank 70 at a set
value, a favorable heating status of the heat exchanger
tube 60 can be maintained. The existence of the water-
level gauge 82 can prevent water level from being lower
than the upper part of the heat exchanger tube 60 immersed
in water. The reason is that the heat exchanger tube 60
cannot maintain a favorable heating status, if the heat
exchanger tube 60 is not completely immersed in water.
In the heat sterilization section 50 having the
configuration as described above, the heat exchanger tube
60 may have such a diameter that prevents the precipitation
or clogging of the magnetic flocs F. Whether the
precipitation of the magnetic flocs F is caused or not has
a relation with the delivery speed of the magnetic flocs F
sent by pneumatic transportation into the heat exchanger
tube 60 and the precipitation speed of the magnetic flocs
F. Whether the clogging is caused or not has a relation
with the diameter of the heat exchanger tube 60 and the
viscosity and property of the magnetic flocs F. The
delivery speed of the magnetic flocs F sent by pneumatic
transportation has a relation with the discharge flow rate
of the pump 54 connected to the inlet of the heat exchanger
tube 60 and the diameter (area) of the heat exchanger tube
60.
The heat exchanger tube 60 may have any length so long
as the temperature at which microorganisms and bacteria or
the like included in the magnetic flocs F can be killed can
be maintained for a predetermined time when the magnetic
flocs F is delivered at a predetermined delivery speed. It
is noted that an example according to the invention uses a
temperature of 75 degrees C and the time of 3 minutes
required to kill microorganisms and bacteria or the like by
heating.
The pump 54 has a variable discharge flow rate. The
heat exchanger tube 60 has a diameter of 34 mm, a thickness
of 1.2 mm, and a length of 57.4 m. This means that, when
the magnetic flocs F are delivered at a speed of 7.3 m/min,
the magnetic flocs F are retained in the heat exchanger
tube 60 for about 7 minutes and 50 seconds.
When the heat sterilization section 50 in the above
configuration has the tank 70 including therein water of a
temperature of about 80 degrees C, the achieving
temperature of the magnetic flocs F changing with the
retention time shows the tendency as shown in Fig. 4. As
shown in Fig. 4, the temperature of the magnetic flocs F
increases to 75 degrees C after about 3 minutes and 40
seconds during the time for which the magnetic flocs F are
retained in the heat exchanger tube 60. Then, the
temperature of the magnetic flocs F requires about 4
minutes and 10 seconds while maintaining the temperature of
75 degrees C or more until a fixed temperature of about 80
degrees C is reached. As described above, in order to kill
microorganisms and bacteria or the like in the magnetic
flocs F, the time of 3 minutes and the temperature of 75
degrees C are required. According to an experiment, when
the heat exchanger tube 60 in the above configuration is
used to deliver the magnetic flocs F at the above delivery
speed, the magnetic flocs F can be retained at the
temperature of 75 degrees C or more for 3 minutes or more,
thus securely killing microorganisms and bacteria or the
like included in the magnetic flocs F. The diameter and
length of the heat exchanger tube 60 are determined based
on various parameters including a flow rate and thus cannot
be set to a fixed value. However, the heat exchanger tube
60 may have any diameter and length, in consideration of
the time during which the temperature of the magnetic flocs
F sent by pneumatic transportation into the pipe path
increases, so long as the magnetic flocs F can be retained
at a temperature of 75 degrees C or more for the time of 3
minutes or more. In order to prevent the precipitation of
the magnetic flocs F, the pneumatic transportation speed
(flow rate) of the magnetic flocs F is set to 1.2 m/min or
more.
In the heat sterilization section 50 having the
configuration as described above, the heat sterilization of
the magnetic flocs F is carried out through three steps of
a startup preparation, a heat sterilization, and a heat
sterilization ending.
First, in the startup preparation step, as shown in
Fig. 5, the water level in the tank 70 is measured by the
water-level gauge 82 (Step S100). When it is determined by
the measurement of the water level that the water level is
lower than a predetermined water level (i.e., the water
level is lower than the water level at which the heat
exchanger tube 60 can be completely immersed in water),
water is filled into the tank 70 (Step S110) . When it is
determined by the measurement of the water level by the
water-level gauge 82 that the water level is equal to or
higher than the predetermined water level, the temperature
of water stored in the tank 70 is measured by the
thermometer 80 (Step S120). When it is determined that the
measured value by the thermometer 80 is lower than a set
temperature (e.g., 80 degrees C to 95 degrees C), steam is
supplied from the steam supply opening 72 into the tank 70
(Step S130). When the steam supply causes the temperature
measured by the thermometer 80 to reach the set
temperature, the magnetic flocs F can be taken into to the
heat exchanger tube 60, thus stopping the steam supply
(Step S140). Then, the storage amount (water level) of the
magnetic flocs F in the collected flocs receiver tank 52 is
detected (Step S150). When the water level of the
collected flocs receiver tank 52 does not reach a standard
value, there is a possibility where, during the pneumatic
transportation of the magnetic flocs F by the pump 54, the
fluid sent by pneumatic transportation may include therein
air for example. Thus, a stand-by status is maintained
until the water level reaches the standard value (Step
S160). Thereafter, when the water level of the collected
flocs receiver tank 52 reaches the standard value, the heat
sterilization of the magnetic flocs F is enabled, thus
completing the startup preparation (Step S170).
Next, in the heat sterilization step, the pump 54 is
started as shown in Fig. 6 to send the magnetic flocs F by
pneumatic transportation to the heat exchanger tube 60
(Step S200). After the start of the pneumatic
transportation of the magnetic flocs to the heat exchanger
tube 60, the counting of the time required for the magnetic
flocs to be discharged from the heat exchanger tube 60 is
started (Step S210) . The pneumatic transportation and
heating of the magnetic flocs F cause the heat exchange
between the water in the tank 70 and the magnetic flocs F.
Thus, the temperature of the water in the tank 70 is
measured by the thermometer 80 (Step S220) . When it is
determined by the temperature measurement that the water
temperature is lower than a set temperature, the feeding of
steam is performed (Step S230). Then, the processing
returns to Step S220 and the water temperature is measured
again. When it is determined in the measurement of the
water temperature in Step S220 that the water temperature
is equal to or higher than the set temperature, it is
determined whether the steam supply (feeding) is performed
or not (Step S240) . When no steam supply is performed,
then the storage amount (water level) of the magnetic flocs
in the collected flocs receiver tank 52 is measured (Step
S260). When steam supply is performed, the steam supply is
stopped (Step S250) and then the processing proceeds to
Step S260.
When the water level in the collected flocs receiver
tank 52 is lower than the standard value, then the driving
of the pump 54 is stopped and the magnetic flocs F are
stored in the collected flocs receiver tank 52 (Step S270).
During this, the pump 54 for sending the magnetic flocs by
pneumatic transportation is stopped and thus the count for
calculating the discharge of the magnetic flocs is also
stopped (Step S280) . When the water level in the collected
flocs receiver tank 52 is equal to or higher than the
standard value on the other hand, the operation status of
the pump 54 is determined (Step S290). When the pump is
not stopped, the pressure gauge 66 provided at the inlet 62
of the heat exchanger tube 60 detects the pressure in the
heat exchanger tube 60 (Step S300). When it is determined
in Step S290 that the pump 54 is stopped, then the
processing returns to Step S200 and the pump 54 is started.
An abnormal value detected by the pressure gauge 66 shows
that the heat exchanger tube 60 has a trouble such as
breakage or clogging. In this case, an emergency stop is
carried but where the pump 54 for sending the magnetic
flocs F by pneumatic transportation and steam supplied to
the tank 70 for example are stopped (Step S320). When a
value obtained by the pressure gauge 66 is normal on the
other hand, the temperature measurement by the thermometer
68 provided at the exit 64 of the heat exchanger tube 60 is
performed (Step S310). When the measured value by the
thermometer 68 is lower than the temperature determined in
advance at which microorganisms and bacteria or the like
are killed, it is determined to be abnomal and an emergency
stop is carried out (Step S320). When the measured value
by the thermometer 68 is equal to or higher than the
temperature at which microorganisms and bacteria or the
like are killed on the other hand, it is determined as
normal and then whether the count is completed or not is
confirmed (Step S330). When the count is completed, the
magnetic floc heat sterilization step is completed (Step
S340) . When the count is not completed on the other hand,
then the processing returns to S220 and the steps after the
measurement of the temperature of water in the tank 70 are
performed again.
After the completion of the magnetic floc heat
sterilization step, the processing proceeds to the heat
sterilization ending step as shown in Fig. 7 (Step S400).
First, cleaning water is taken into to the heat exchanger
tube 60 (Step S410) . After the taking of cleaning water
(or simultaneously with the of taking cleaning water), the
count of the time required for the magnetic flocs F
remaining in the heat exchanger tube 60 to be substituted
with cleaning water is started (Step S420) . Thereafter,
the thermometer 80 measures the temperature of water in the
tank 70 (Step S430) . When the temperature measured by the
thermometer 80 is lower than the set temperature, steam is
supplied from the steam supply opening 72 (Step S440).
Then, the processing returns to Step S430 and the
temperature measurement is performed again. When the
measured temperature in Step S430 is equal to or higher
than the set temperature on the other hand, then whether
steam supply is stopped or not is determined (Step S450).
When steam supply is stopped, then whether the count is
completed or not is determined (Step S470). When steam
supply is not stopped in Step S450, steam supply is stopped
(Step S4 60). Then, the processing proceeds to the
determination of the completion of the count in Step S470.
When the count is completed in Step S470, then the pump is
stopped (Step S480). As a result, the taking of cleaning
water into the heat exchanger tube 60 is also stopped.
Thus, the interior of the heat exchanger tube 60 is filled
with cleaning water. When the count is not completed in
Step S470 on the other hand, the processing returns to Step
S430 where the temperature measurement of water in the tank
70 and the introduction of steam are repeated.
By using the heat sterilization section 50 performing
the heat sterilization treatment as described above, the
heat exchanger tube 60 is heated by an indirect heating
(double-boiling) by hot water of 100 degrees C or less.
Thus, scale can be prevented from adhering to the interior
of the heat exchanger tube 60. Furthermore, by the
structure in which water in the tank 70 is heated by jetted
steam and excessive condensed water is discharged, there is
no part where a high pressure is caused in the tank 70,
thus providing high safety. Furthermore, water and steam
stored in the tank 70 can be both obtained from those used
for the ship including the ballast water treatment system
10, which is economic. Furthermore, water stored in the
tank 70 is prevented from having a contact with
contamination substance such as the magnetic flocs F.
Thus, discharged condensed water can be reused in a
machinery such as ship.
Furthermore, by using the ballast water treatment
system 10 having the heat sterilization section 50 as
described above, microorganisms and bacteria or the like
can be physically collected from ballast water to purify
the ballast water and the magnetic flocs F obtained by
coagulating microorganisms and bacteria or the like can be
sterilized. This can consequently solve not only an impact
on the environment by the discharge of ballast water to
other sea areas but also an impact on the environment and
human bodies by the storage of collected magnetic flocs F
for a long period.
In the above embodiment, a configuration has been
described in which the collected flocs receiver tank 52 is
provided in the previous stage of the heat sterilization
section 50 to temporarily store magnetic flocs. However,
another configuration also may be used where the magnetic
flocs storage tank 38 constituting the magnetic separation
section 30 is used as a temporary storage means, thus
omitting the collected flocs receiver tank 52. The
configuration as described above can reduce the
installation space and equipment cost.
Furthermore, although a cylindrical pipe was shown as a
pipe path in the embodiment, the present invention is not
limited to a cylindrical pipe. Any pipe path can be used
so long as a narrow slit-like flow path is provided and
magnetic floc passing therethrough can be securely heated
by double-boiling.
The following section will describe a modification
example of the heat sterilization section 50 according to
an embodiment. First, with reference to Fig. 8A and Fig.
8B, the first modification example will be described. Fig.
8A is a block diagram illustrating a top configuration of a
heat sterilization section. Fig. 8B is a block diagram
illustrating a front configuration.
A heat sterilization section 50b according to this
modification example is characterized in that the form of a
heat exchanger tube 60a is different from that in the above
embodiment. Specifically, as is clear from Fig. 8A, the
planar shape is formed as a hairpin curve shape instead of
an oval shape and this shape is superposed in a multiple
stages. By forming the heat exchanger tube 60b in the
manner as described above, the volume of the tank 7 0 can be
effectively used, thus increasing the length of the heat
exchanger tube 60. This can consequently increase the time
during which the magnetic flocs F are retained in the heat
exchanger tube 60, thus securely killing microorganisms and
bacteria or the like included in the magnetic flocs F. The
other configurations are the same as those in the heat
sterilization section 50 according to the above-described
embodiment.
Next, with reference to Fig. 9A and Fig. 9B, the second
modification example for a heat sterilization section will
be described. Fig. 9A is a block diagram illustrating the
top configuration of a heat sterilization section. Fig. 9B
is a block diagram illustrating the front configuration.
The heat sterilization section 50b according to this
modification example is also characterized in the form of
the heat exchanger tube 60b. Specifically, the heat
sterilization section 50b according to this modification
example is characterized in that the two insertion tubes
60b are provided in the tank 70. Each of the insertion
tubes 60b is formed by forming an oval roll to have a
helical shape. By the heat exchanger tube 60b having the
form as described above, this is section can have a doubled
capacity for heat sterilization of the magnetic flocs F
and, even when one of the insertion tubes 60 is damaged or
clogged, the heat sterilization treatment of the magnetic
flocs F can be continued. The other configurations are the
same as those in the heat sterilization section 50
according to the above-described embodiment.
Next, with reference to Fig. 10A and Fig. 10B, the
third modification example for a heat sterilization section
will be described. Fig. 10A is a block diagram
illustrating the top configuration of a heat sterilization
section. Fig. 10B is a block diagram illustrating the
front configuration.
A heat sterilization section 50c according to this
modification example is characterized in the relation
between the heat exchanger tube 60 and the tank 70. Thus,
the heat exchanger tube 60 according to this modification
example may have the same form as that of the insertion
tube in the heat sterilization section 50 according to the
above-described embodiment and the heat sterilization
sections 50a and 50b according to the above first and
second modification examples. The heat sterilization
section 50c according to this modification example is that
a structure 76 is provided in the dead space in the tank 70
configured by the roll or turning of the heat exchanger
tube 60. The configuration as described above can exclude
water in the dead space, thus reducing the time required
for to increase the water temperature by steam. The
structure 7 6 provided in the dead space desirably has a
thermal conductivity higher than that of water. The other
configurations are the same as those in the heat
sterilization section 50 according to the above-described
embodiment.
The above embodiment has been mainly exemplarily
described where the heat sterilization section 50 is
structured so that magnetic flocs are sent by pump to the
interior of the heat exchanger tube 60 immersed in the tank
70 and the heat exchanger tube 60 is heated by double-
boiling. However, the technical scope of the ballast water
treatment method of the present invention also includes a
case where a drying machine is used as a heat sterilization
section for killing microorganisms and bacteria or the like
coagulated in magnetic flocs. Any form of drying machine
may be used. Thus, a drying machine herein may be,
although not shown, the one that uses the steam heat
generated and used by machines used for a ship including
the ballast water treatment system to evaporate water
included in a magnetic flocs.
One example of a drying machine may be the one that
pushes magnetic flocs to the surface of a rotary drum
heated by the above heat to evaporate water to subsequently
scrape the magnetic flocs (in the dry form) from the
surface of the rotary drum.
Even when the drying machine having the configuration
as described above is used as a heat sterilization section,
no risk is caused where magnetic flocs have a short path to
reach the collected flocs storage tank 56. Furthermore, in
this embodiment, the rotary drum is directly heated by
steam. Thus, the surface temperature (heating temperature)
can be increased than in the case of where the heat
exchanger tube 60 is heated by double-boiling. Thus,
bacteria or the like can be securely killed within a short
time. Furthermore, when a drying machine is used as the
heat sterilization section, water included in magnetic
flocs can be evaporated, thus reducing the volume of
substances (dried magnetic flocs) stored as contamination
substances.
we claim:-
1. A ballast water treatment method, comprising the steps
of:
adding magnetic powder and coagulant into ballast water
to thereby generate magnetic flocs including microorganisms
and bacteria;
collecting the magnetic flocs from the ballast water;
and
heating the collected magnetic flocs to a temperature
at which the microorganisms and the bacteria are killed,
the temperature being determined in advance.
2. The ballast water treatment method according to claim 1,
wherein: the step of heating comprises inserting the
magnetic flocs to a pipe path and heating the pipe path to
which the magnetic flocs are inserted.
3. The ballast water treatment method according to claim 2,
wherein: the heating of the magnetic flocs is performed by
double-boiling the pipe path.
4. The ballast water treatment method according to claim 2,
further comprising the step of measuring an exit
temperature of the pipe path to investigate a heating
status of the magnetic flocs.
5. The ballast water treatment method according to claim 3,
further comprising the step of measuring an exit
temperature of the pipe path to investigate a heating
status of the magnetic flocs.
6. The ballast water treatment method according to claim 2,
further comprising the step of measuring a pressure in the
pipe path to investigate a status of the pipe path.
7. The ballast water treatment method according to claim 3,
further comprising the step of measuring a pressure in the
pipe path to investigate a status of the pipe path.
8. The ballast water treatment method according to claim 4,
further comprising the step of measuring a pressure in the
pipe path to investigate a status of the pipe path.
9. A ballast water treatment system, comprising:
a coagulation section for agitating magnetic powder and
coagulant added to ballast water to generate magnetic
flocs;
a magnetic separation section for collecting the
magnetic flocs generated by the coagulation section;
a pipe path through which the magnetic flocs collected
by the magnetic separation section is sent; and
a heating section for heating the pipe path.
10. The ballast water treatment system according to claim
9, wherein: the heating section is a tank in which water is
stored and the pipe path is immersed in the tank.
11. The ballast water treatment system according to claim
10, wherein: the tank includes a steam supply opening
through which steam from a ship machine for heating water
in the tank is supplied.
12. The ballast water treatment system according to claim
9, wherein: an exit of the pipe path has a temperature
sensor.
13. The ballast water treatment system according to claim
10, wherein: an exit of the pipe path has a temperature
sensor.
14. The ballast water treatment system according to claim
11, wherein: an exit of the pipe path has a temperature
sensor.
15. The ballast water treatment system according to claim
9, wherein: the pipe path has a pressure sensor.
16. The ballast water treatment system according to claim
10, wherein: the pipe path has a pressure sensor.
17. The ballast water treatment system according to claim
11, wherein: the pipe path has a pressure sensor.
18. The ballast water treatment system according to claim
12, wherein: the pipe path has a pressure sensor.
19. The ballast water treatment system according to claim
13, wherein: the pipe path has a pressure sensor.
20. The ballast water treatment system according to claim
9, wherein: the pipe path is structured to have an inlet
and an exit provided at an upper part and to extend from
the inlet to the lowest part so as to draw an oval helical
shape from the lowest part thereof to the exit.

A ballast water treatment system is provided that can
kill microorganisms and bacteria or the like included in
magnetic flocs so as to eliminate an impact on the
environment and human bodies. The ballast water treatment
system includes a coagulation section for agitating
magnetic powder and coagulant added to ballast water to
generate magnetic flocs; and a magnetic separation section
for collecting the magnetic flocs generated by the
coagulation section. The ballast water treatment system is
characterized in having a pipe path to which the magnetic
flocs are taken and a heating section for heating the pipe
path. The heating section may be provided as a tank
and the pipe path may be immersed in the tank.