Field of the invention
[0001] The present invention relates to the field of façade wall washing, and more specifically
to façade wall washing using aqueous cleaning liquids.
Background of the invention
[0002] The purposes of façade wall washings are
í) to improve the esthetical appearance of the façade wall and/or to preserve the façade
wall and/or
ii) to prepare the façade wall for painting or other surface treatments in order to achieve
a satisfactory and sustainable result.
[0003] Traditionally, façade walls have been washed by applying water under high pressure,
by application of water containing chemicals and/or by blasting techniques.
[0004] The high-pressure washings entail a number of problems. The high pressure forces
water deep into pores and cavities of the façade wall which results in long drying
times, e.g. more than two days, modified moisture properties of the façade wall which
may accelerate algae growth and accumulation of dirt, and sometimes even damaging
of building materials behind the façade wall surface. As an example, the long drying
times results in long change-over times and high costs of a façade restoration project
including washing and painting. Furthermore, the force of the high-pressure water
may mechanically harm the finish of the façade wall, and excess amounts of water is
consumed.
[0005] Washing with chemicals results in a waste water which is harmful to the environment.
Further, the chemicals may also be harmful to the operator(s) performing the washing.
Also, the chemicals may retain the applied water in the façade and thereby cause longer
drying times.
[0006] Blasting techniques also harm the finish of the façade, and the dust resulting from
the blasting is a working environment problem.
[0007] Some types of dirt on façade walls have required a combination of the above-mentioned
techniques. For example, to wash away green algae, water containing environmentally
harmful algae-removing chemicals have been applied under high pressure.
[0008] In
US 5 249 326, a system for washing building windows is disclosed. The washing technique relies
on the combination of mechanical treatment with brushes and rinsing with purified
water. The system comprises a washing unit with brushes, purifying means for delivery
of purified rinsing water and cable arrangements for restraining the washing unit
against the building surface. Cleaning of "other exterior surfaces" is also mentioned.
However, the system is clearly adapted for window washing. Further, neither specific
adaptations of the system for washing façade walls nor the maximum conductivity of
the rinsing water for achieving a satisfactory washing result are discussed.
[0009] Consequently, there remains a need within the art for a method which effectively
washes different types of dirt off a façade wall without: damaging the façade or the
building materials; decreasing the resistance to future dirtying; causing harm to
the environment or operators performing the washing; or consuming large amounts of
water.
Summary of the invention
[0010] Thus, an object of the present invention is to provide a method for effectively washing
away dirt from a façade wall.
[0011] Another object of the present invention is to provide a façade wall washing method
which cause minimal harm to the façade wall and building materials.
[0012] Another object of the invention is to provide a façade wall washing method which
allows for quick drying of the washed façade wall.
[0013] Another object of the present invention is to provide a façade wall washing method
which is environmentally friendly.
[0014] Another object of the present invention is to provide a façade wall washing method
which minimizes the exposure to harmful matter when performing the washing method.
[0015] Another object of the present invention is to provide a façade wall washing method
which achieves a good washing result using limited amounts of water.
[0016] These and other objects of the present invention are achieved by means of a method,
a use and a system as characterized by the claims. According to the invention, the
method for washing away dirt from a façade wall comprises the following steps: (a)
providing a cleaning liquid, wherein said cleaning liquid consists of water having
a conductivity of 3 µS/cm or less; (b) cleaning said façade wall, wherein said cleaning
involves application of said cleaning liquid of step (a) onto said façade wall; and
(c) allowing used cleaning liquid from step (b) containing dirt to leave the façade
wall.
[0017] Preferable embodiments of the invention are characterized by the dependent claims
or itemized embodiments.
[0018] Throughout the description and the claims, a "façade wall" refers to the part of
a façade of a building not being of glass, i.e. not being windows.
[0019] Further, throughout the description and the claims, "dirt" refers to materials which
are unwanted on a façade wall, e.g. deposits, such as calcium sulfate, soot, dust,
organic material, such as rubber particles and biological material, such as, algae
and mould, comprising claudiosporium, and heavy metals.
[0020] The invention is based on the surprising finding that water having a conductivity
of 3 µS/cm or less possesses excellent properties for façade wall washing. Without
being bound to any specific theory, the inventive water has very few dissolved ions
and consequently, a high capacity of dissolving salts and hydrates. As an example,
the inventive water is very reactive towards gypsum, CaSO
4*2H
2O, which is often formed on façade walls comprising calcium carbonate, CaCO
3, such as façade wall comprising limestone, after exposure to acidic rain comprising
sulphate. Further, it is contemplated that the inventive water destroys the cells
of algae, such as green algae, by osmosis: the hypotonic purified water moves across
the cell membranes into the cells to balance the difference in salt concentrations,
which results in such a high internal pressure that the cells explodes.
[0021] In a preferred embodiment of the invention, the cleaning liquid consists of water
having a conductivity of 1 µS/cm or less, such as 0.5 µS/cm or less.
[0022] In a particularly preferred embodiment of the invention, the cleaning liquid consists
of water having a conductivity of 0.1 µS/cm or less, such as 0.08 µS/cm or less. It
was noted by the inventors that water having such low conductivity has unexpectedly
good washing properties. The washing effect increased significantly when the conductivity
of the cleaning liquid was brought down to 0.1 µS/cm or less.
[0023] Water can have a theoretical minimum conductivity of about 0.055 uS/cm. Consequently,
in one embodiment, the cleaning liquid consists of water having a conductivity of
0.055 - 3 µS/cm, such as 0.055 - 1 µS/cm, such as 0.055 - 0.5 µS/cm, such as 0.055
- 0.1 µS/cm, such as 0.055 - 0.08 µS/cm.
[0024] In one embodiment of the invention, the application of cleaning liquid of step (b)
comprises continuous application of the cleaning liquid in the form of a mist for
a period of 3 hours or less. Using the cleaning liquid of the invention, a good washing
result is obtained already after less than 3 hours when the cleaning liquid is applied
in the form of a mist. For example, the period may be as short as 10-60 minutes. For
example, the mist may be provided by nozzles, which are well known to the person skilled
in the art. Shorter application times are beneficial because they lead to lower costs
due to lower water consumption and lower labor and construction costs.
[0025] In one embodiment of the invention, step (b) comprises a first application of the
cleaning liquid, and, after a predetermined period of time, a second application of
the cleaning liquid. For example, the predetermined period of time may be 1-24 hours,
such as 1-12 hours. When using two separate applications, the water from the first
application is given time to dissolve the dirt on the façade wall, and subsequently,
the water from the second application washes away the dirt-containing water from the
first application. Two separate applications are beneficial because they require less
water than one, corresponding continuous application. As an example, a brushing of
the façade wall is performed between the first and the second application of cleaning
liquid. Alternatively, or as a complement, brushing may be performed simultaneously
with the first or second application. Brushing further facilitates the removal of
dirt from the façade wall. Appropriate brushes are well known to the skilled person.
[0026] In one embodiment of the invention, the cleaning liquid is applied to the façade
wall with a flow of at least 20 liters/minute.
[0027] In one embodiment of the invention, the method for washing away dirt from a façade
wall further comprises the steps of: (d) collecting the used cleaning liquid of step
(c); and (e) purifying the collected, used cleaning liquid of step (d). Collecting
and purifying the used cleaning liquid prevents hazardous components comprised in
the dirt from the façade wall to be released to the surroundings, such as the surrounding
nature or the sewage system. For example, step (d) may involve collecting the used
cleaning liquid in a storm drain or street inlet located in the vicinity of the façade
wall and step (e) may involve purifying at the washing site. Collecting the used cleaning
liquid in a nearby storm drain is very convenient, because the water leaving the façade
wall is naturally directed to such storm drain and no extra water directing means
are required. By purifying the collected, used cleaning liquid at the washing site,
no transportation of used cleaning liquid is needed and the purified liquid may be
discharged at the washing site, for example in the same storm drain as in which the
used cleaning liquid was collected.
[0028] In one embodiment of the invention, step (a) involves providing the cleaning liquid
at the washing site by continuous processing of inlet water. Normally, the inlet water
is having a conductivity of more than 3 µS/cm. By "at the washing site" is meant in
the vicinity of the façade wall, such as within 100 meters of the façade wall, such
as within 50 meters of the façade wall, such as within 30 meters of the façade wall.
By providing the cleaning liquid at the washing site by continuous processing of inlet
water, the cleaning liquid does not have to be transported to the washing site. Rather,
for example, municipal water available at the washing site may be used as inlet water
avoiding all transportations of water. Transportations are costly and inconvenient
and further, transportations of the cleaning liquid may impair its quality, i.e.,
increase the amount of dissolved matter in the cleaning liquid and thus the conductivity.
[0029] In one embodiment of the invention, step (a) involves providing the cleaning liquid
at the washing site by continuous processing of inlet water and, in a further step
(f) recycling at least part of the purified, used cleaning liquid of step (e) such
that it constitutes at least part of the inlet water of step (a). By recycling at
least part of the purified, used cleaning liquid, the water consumption of a façade
wall washing is decreased.
[0030] In one embodiment of the invention, the dirt includes one or more of the following:
algae, green algae and calcium sulphate compounds.
[0031] As an example, the dirt includes algae. The inventors have found that the washing
method of the invention effectively removes algae, which are one of the most frequent
types of dirt also, traditionally, being very difficult to wash away.
[0032] As another example, the dirt includes calcium sulphate compounds, such as gypsum,
CaSO
4*2H
2O. The inventors have found that the washing method of the invention effectively removes
calcium sulphate compounds, which are also one of the most frequent types of dirt
on façade walls. Calcium sulphate compounds are mainly formed on the surface of façade
walls comprising calcium carbonate, such as façade walls comprising sandstone, limestone,
travertine, marble, calcareous sandstone, cement, concrete, and rendering or facing
plaster.
[0033] In one embodiment of the invention, the façade wall comprises calcium carbonate,
such as at least 5 % calcium carbonate (w/w), such as at least 10 % calcium carbonate
(w/w), such as at least 15 % calcium carbonate (w/w), such as at least 20 % calcium
carbonate (w/w), such as at least 25 % calcium carbonate (w/w), such as at least 30
% calcium carbonate (w/w), such as at least 35 % calcium carbonate (w/w), such as
at least 40 % calcium carbonate (w/w), such as at least 45 % calcium carbonate (w/w),
such as at least 50 % calcium carbonate (w/w), such as at least 55 % calcium carbonate
(w/w), such as at least 60 % calcium carbonate (w/w), such as at least 65 % calcium
carbonate (w/w). Due to above-mentioned reasons, the invention is particularly suitable
for washing façade walls comprising calcium carbonate.
[0034] In one embodiment of the invention, the method for washing away dirt from a façade
wall further comprises the steps of: (g) determining if after-treatment is needed;
and, if after-treatment is needed, (h) applying an after-treatment liquid selected
from a silicate liquid, a silicone hydride liquid and a fungicide liquid to the façade
wall, wherein step (h) is performed after step (c). A fungicide liquid may be needed
if the dirt comprises algae. In one example, the after-treatment liquid is selected
from a silicate liquid and a silicone hydride liquid. The silicate liquid may be a
liquid comprising potassium silicate. The silicone hydride liquid may be a liquid
comprising silane or a combination of silane and siloxane. Such after-treatment liquid
is particularly suitable if the façade wall comprises calcium carbonate, such as at
least 5 % calcium carbonate (w/w).
[0035] Without being bound to any specific theory, the following description of the effect
of an after-treatment with a silicate liquid or a silicone hydride is provided. A
façade wall comprises pores. Generally, the diameter of such pores should be smaller
closer to the surface of the façade wall and larger further into the façade. As long
as the pores have such shape, capillary forces "sucks" water from the inner parts
of the surface because water is drawn from a larger cavity to a smaller. However,
over time, the material surrounding the small-diameter part of the pores close to
the surface is transformed. For example, façade wall material comprising calcium carbonate
may be transformed to gypsum as described above. Then, when the façade wall is cleaned,
the formed gypsum is washed off and the shape of the pores is altered. Also, the shape
of the pores may be altered because the material surrounding the small-diameter part
of the pores is worn off. With the altered shape of the pores, water is no longer
"sucked" out and the water properties of the façade wall is impaired. Applying an
after-treatment liquid selected from a silicate liquid and a silicone hydride liquid
reforms the original shape of the pores by building up a silicon-containing material,
such as SiO
2, in the part of the pores closest to the surface. Such silicon-containing materials
resist many of the most common stresses on façade walls, such as mechanical and chemical
stress from wind and rain.
[0036] In one embodiment, step (g) may comprise at least one measurement of the water absorption
capacity of the façade wall. For example, the water absorption capacity may be measured
by measuring the amount of water absorbed by a limited area of the façade wall during
a limited period of time. If the water absorption capacity is high, after-treatment
is considered to be needed. A "high" water absorption capacity refers to a water absorption
capacity which is higher than desired. The person skilled in the art is aware of desired
water absorption capacity levels. Desired water absorption capacity levels may vary
with weather conditions, i.e. geographical location. Further, desired water absorption
capacity levels vary between different façade wall materials. In an alternate or complementary
example, step (g) may comprise measuring the drying time of the façade wall. The drying
time may be measured by applying water to a limited area of the façade wall and then
measuring the amount of time required for that area to reach a certain degree of dryness.
If the drying time is long, after-treatment is considered to be needed. A "long" drying
time refers to a drying time which is longer than desired. The person skilled in the
art is aware of desired drying times. Further, the person skilled in the art understands
how to perform such measurement.
[0037] As an example, step (g) may comprise two water absorption capacity measurements,
wherein the first measurement is performed before step (b) and the second measurement
is performed after step (c). The difference in water absorption capacity between the
second and the first measurement may then be used to determine: i) if after-treatment
is needed; and/or
ii) the composition of the after-treatment liquid, such as the components of the after-treatment
liquid, e.g. silicate(s) and/or silicone hydride(s), and their concentration(s). For
example, if the difference is considered to be large, an after-treatment liquid with
a high concentration may be used and/or the period of application according to step
(h) may be long. The person skilled in the art understands what, during the circumstances,
is considered to be a "high concentration" or a "long period". The first measurement
may be performed during an initial step determining the status of the façade wall.
In addition to a water absorption capacity measurement, such status-determining may
comprise visual inspection of the façade wall and analysis of the dirt on the façade
wall.
[0038] In one embodiment of the invention, the method for washing away dirt from a façade
wall further comprises the steps of: (i) applying an after-treatment liquid selected
from a silicate liquid and a silicone hydride liquid to the façade wall, wherein step
(i) is performed after step (c). In such embodiment, the method comprises steps (a),
(b), (c) and (i), and step (i) has the same benefits as described above with regard
to application of a silicate liquid or a silicone hydride liquid.
[0039] In one embodiment of the invention, the after-treatment liquid comprises the cleaning
liquid. An after-treatment liquid comprising silicate(s) and/or silicone hydride(s)
may, for example, preferably be prepared by mixing a silicate or silicone hydride
solution with water with a low or substantially no concentration of calcium carbonate,
e.g. deionized water. The calcium carbonate concentration of normal municipal water
is, at many locations, too high. Consequently, it is beneficial to mix the silicate
or silicone hydride solution with the cleaning liquid having a conductivity of 3 µS/cm
or less. For example, the silicate solution may have a water to potassium silicate
ratio of about 30:1 (w/w), such as commercially available KEIM Fixativ. As an example,
the water to potassium silicate ratio of the after-treatment liquid may be about from
250:1 to 45:1 (w/w), depending on the condition of the façade wall and the desired
result. As an example, if the façade wall is very porous, an after-treatment liquid
having a high such ratio, such as 180:1, may be applied during a first application,
followed by a second application with an after-treatment liquid having a ratio of
about 120:1 and a third application with an after-treatment liquid having a ration
of about 60:1. The person skilled in the art understands how to adapt the ratio of
the after-treatment liquid to the needs of a specific façade wall.
[0040] One embodiment of the invention relates to use of a cleaning liquid consisting of
water having a conductivity of 3 µS/cm or less, such as 1 µS/cm or less, such as 0.5
µS/cm or less, such as 0.1 µS/cm or less, such as 0.08 µS/cm or less, for washing
away dirt from a façade wall. For above-mentioned reasons, use of such cleaning liquid
is particularly suitable for washing a façade wall.
[0041] One embodiment of the invention relates to a façade wall washing system comprising:
a cleaning liquid apparatus for providing a cleaning liquid, wherein the cleaning
liquid consists of water having a conductivity of 3 µS/cm or less, such as 1 µS/cm
or less, such as 0.5 µS/cm or less, such as 0.1 µS/cm or less, such as 0.08 µS/cm
or less; and cleaning liquid application means. The person skilled in the art understands
what appropriate cleaning liquid application means are. In one example, at least part
of the cleaning liquid application means are of such materials that do not considerably
increase the ion content of the cleaning liquid. Especially, it may be important that
the parts of the cleaning liquid application means being in contact with the cleaning
liquid during a longer time is made of such materials.
[0042] In one embodiment of the invention, at least one of the cleaning liquid apparatus
and the cleaning liquid application means contains conductivity measurement means
for measuring the conductivity of the cleaning liquid. Such conductivity measurement
means may serve to assure the operator that the cleaning liquid has a sufficiently
low conductivity to obtain the desired washing result.
[0043] In one embodiment, the system further comprises a waste water apparatus for purifying
used cleaning liquid. Traditionally, the waste water resulting from façade wall washings
have been let out to the drainage system without purification. However, such waste
water commonly contains contaminants which are harmful to humans, such as the to operator(s)
performing the washing, and to the environment. For example, the waste water may contain
heavy metals, such as heavy metals resulting from the pigments of eroding façade paint,
such as linoleum based paint. Examples of pigments comprising heavy metal compounds
are cadmium yellow (cadmium sulfide), cadmium red (cadmium selenide) and cadmium orange
(an intermediate cadmium sulfoselenide), chrome green, lead white, zinc white, cobalt
blue, uranium yellow and copper sulfate. Further, the waste water resulting from façade
walls which have been exposed to exhaust gases from vehicular traffic, such as façade
walls in urban environments, may contain particularly high levels of lead and lead
compounds. Further, the used cleaning liquid may contain organic compounds being harmful
to humans and the environment. Accordingly, in one embodiment, the waste water apparatus
comprises a purification device for removing particles, organic compounds and heavy
metals from the used cleaning liquid. As an example, the purification device comprises:
a prefilter for removing particulate matter; an organic compounds removing device
comprising activated carbon; and and an ion exchange filter for removing heavy metals,
wherein: the prefilter is arranged upstream the organic compounds removing device
and the ion exchange filter; and the organic compounds removing device and the ion
exchange filter may be the same or different. As an example, the purification device
further comprises a chelating ion exchange filter for removing heavy metals arranged
downstream the prefilter. The chelating ion exchange filter further reduces the amount
of heavy metal to very low levels, which may be necessary to fulfill environmental
policy requirements.
[0044] In one embodiment of the system according to the invention, the waste water apparatus
and the cleaning liquid apparatus are functionally connected so that purified used
cleaning liquid from the waste water apparatus can be recycled and used as input to
the cleaning liquid apparatus for providing cleaning liquid. Such recycling reduces
the water consumption of a façade washing operation.
[0045] In one embodiment, the waste water apparatus comprises: a collecting device for collecting
used cleaning liquid, wherein the collecting device is adapted for being arranged
in a storm drain; and a pump device for pumping collected, used cleaning liquid from
the collecting device to the purification device. The benefits of arranging a collecting
device in a storm drain are mentioned above. As an example, the collecting device
comprises a trough and a flange for maintaining the trough in a storm drain.
[0046] In one embodiment, the system according to the invention further comprises means
for routing purified, used aqueous cleaning liquid obtainable from the purification
device to a storm drain, thereby by-passing the collecting device. Such arrangement
is very convenient because the same storm drain may be used for both collecting and
drainage purposes.
[0047] Further objects and advantages of the present invention will be discussed below by
means of exemplifying embodiments.
[0048] Even though the embodiments of the invention described above are adapted for a washing
of a façade wall, they may also be applicable to a washing of an interior surface,
not being glass, or a floor.
[0049] In one embodiment, the cleaning liquid apparatus for providing a cleaning liquid
is comprising: a water inlet; a prefilter for removing particulate solids, the prefilter
having an inlet and an outlet; means for routing water from the water inlet to the
prefilter; a pump having an inlet and an outlet; means for routing water from the
prefilter to the pump; a recycling water inlet arranged between the water inlet and
the pump; a reverse osmosis device comprising an inlet, a drainage outlet and a deionized
water outlet; means for routing water from the pump to the reverse osmosis device;
an ion exchange device comprising at least one ion exchange filter, the ion exchange
device having an inlet and an outlet; means for routing water from the deionized water
outlet to the ion exchange device; a purified water tank comprising an inlet, a purified
water outlet and a recycling water outlet, wherein the recycling water outlet is arranged
at the top of the purified water tank; means for routing water from the ion exchange
device outlet to the purified water tank inlet; and means for routing water from the
recycling water outlet to the recycling water inlet; wherein water having a conductivity
of 3 µS/cm or less is obtainable from the purified water outlet.
[0050] An arrangement "at the top of the purified water tank" refers to an arrangement so
as to eliminate substantially all air from the purified water tank when the flow in
through the inlet of the purified water tank is bigger than the flow out of the purified
water outlet of the purified water tank. In a preferred embodiment, the purified water
tank is substantially air-free.
[0051] In one embodiment of the invention, step (a) involving providing the cleaning liquid
at the washing site by continuous processing of inlet water comprises: (a1) prefiltering
inlet water for removal of particulate solids; (b1) pumping water obtained from step
(a1) and optionally step (f1); (c1) subjecting water obtained from step (b1) to reverse
osmosis, thereby generating a drainage flow and a deionized water flow; (d1) subjecting
the deionized water flow from step (c1) to ion exchange treatment; (e1) collecting
water resulting from step (d1) in an air-free tank; (f1) recycling water from the
tank of step (e1) by subjecting it to at least steps (b1)-(e1); and (g1) obtaining
water having a conductivity of 3 µS/cm or less from the tank of step (e1).
[0052] The cleaning liquid apparatus for providing a cleaning liquid entails a number of
advantages. The apparatus requires only one pump. By starting the only pump required,
which is arranged upstream the reverse osmosis device, the complete purification process
is started. Consequently, only one on/off switch is required on the apparatus, which
makes it easy to operate. The pumping action of the pump is also sufficient for maintaining
an overpressure in the purified water tank (the air free tank). Consequently, water
from the purified water tank can be recycled to the recycling water inlet arranged
upstream the pump, without the aid of a second pump. In contrast, recycling of water
from the purified water tank to a recycling water inlet arranged downstream the pump
would require a second pump which makes the apparatus more complex and expensive.
Arranging the recycling water outlet at the top of the pressurized purified water
tank results in a tank substantially free from air. Minimizing the amount of air in
the purified water tank is essential for maintaining the conductivity of the water
at a low level. Further, the continuous recycling of water allows for continuous removal
of impurities resulting from the components of the apparatus. The man skilled in the
art understands that the same benefits also concerns to the corresponding method.
Brief description of the drawings
[0053] In the following detailed description, reference will be made to the accompanying
drawings, of which:
Fig 1 schematically shows an embodiment of an apparatus for the provision of water
having a conductivity of about 0.08 µS/cm or less;
Fig 2 schematically shows an embodiment of an ion exchange device;
Fig 3 schematically shows another embodiment of an apparatus for the provision of
water having a conductivity of 0.08 µS/cm or less;
Fig 4 shows a schematic representation of an embodiment of a waste water apparatus
for purifying used cleaning liquid, including a cross-sectional view of an embodiment
of a collecting device;
Fig 5 schematically shows a cross-sectional view of an embodiment of a used cleaning
liquid collecting device for arrangement in a storm drain; and
Fig 6 schematically shows a cross-sectional view of another embodiment of a used cleaning
liquid collecting device for arrangement in a storm drain.
Example embodiments
[0054] The embodiments presented below are provided as examples and are not limiting to
the invention.
1. Apparatus for the provision of water having a conductivity of about 0.08 µS/cm or less
[0055] To obtain the cleaning liquid of the invention, an apparatus as described below may
be used. For example, municipal water may be used as inlet water.
[0056] With reference to figures 1 and 2, the apparatus comprises the following components:
a water inlet 1; a prefilter 2 for removing particulate solids, the prefilter 2 having
an inlet and an outlet; means for routing water from the water inlet 1 to the prefilter
2; a prefiltered water tank 9, the prefiltered water tank containing a recycling water
inlet 4 and further containing a prefiltered water inlet, and an outlet; means for
routing water from the prefilter 2 to the prefiltered water tank 9; a pump 3 having
an inlet and an outlet; means for routing water from the prefiltered water tank 9
to the pump 3; a reverse osmosis device 5 comprising an inlet, a drainage outlet and
a deionized water outlet; means for routing water from the pump 3 to the reverse osmosis
device 5; an ion exchange device 6 comprising a first and second ion exchange filter
61, 62 arranged parallel to each other and upstream a third ion exchange filter 63,
the ion exchange device 6 having an inlet and an outlet; means for routing water from
the deionized water outlet to the ion exchange device 6; a purified water tank 7 comprising
an inlet, a purified water outlet and a recycling water outlet 8, wherein the recycling
water outlet 8 is arranged at the top of the purified water tank 7; means for routing
water from the ion exchange device 6 to the purified water tank 7; and means for routing
water from the recycling water outlet 8 to the recycling water inlet 4; wherein water
having a conductivity of about 0.08 µS/cm or less is obtainable from the purified
water outlet.
[0057] An arrangement "at the top of the purified water tank" refers to an arrangement so
as to eliminate substantially all air from the purified water tank when the flow in
through the inlet of the purified water tank is bigger than the flow out of the purified
water outlet of the purified water tank.
[0058] An "ion exchange filter" refers to any ion exchange means comprising ion exchange
material, including ion exchange columns. For example, the ion exchange filters may
comprise an anionic exchanger bed, an cationic exchanger bed and/or a mixed bed.
[0059] Conductivity measuring means 64 are arranged at two positions: i) downstream the
first and second column 61, 62, but upstream the third column 63; and
ii) downstream the third column 63.
[0060] The purification grade of the prefilter 1 is 1 µm with a β-value of 80-90 %. The
pump is made of acid-proof stainless steel.
[0061] The inlet 1 is adapted for being connected to a fire hydrant. Municipal water provided
by a fire hydrant in Stockholm, Sweden has a conductivity of about 200-300 µS/cm.
After passing the reverse osmosis device 5, the conductivity of the water is about
1-5 µS/cm. After the first or second ion exchange filter 61, 62, the conductivity
is about 0.1 µS/cm, and after the third ion exchange filter, about 0.06 - 0.07 µS/cm.
The final conductivity depends e.g. on the temperature of the water.
[0062] The purified water outlet of the purified water tank 7 is connected to hose 10. To
minimize the hose's 10 contribution of ions to the cleaning liquid, i.e., the purified
water, the inside of the hose 10 is made of PVC, which is a beneficial hose material
in that aspect. At least one pump 11 is arranged on the hose 10 to pressurize the
cleaning liquid for application on a façade wall. For example, additional hoses may
be connected to the purified water outlet. Additional pumps may be arranged on these
hoses, providing water at different pressures. The hose 10 is connected to application
means for application of the cleaning liquid to a façade wall, such as nozzles.
2. Apparatus for the provision of water having a conductivity of about 0.08 µS/cm or less
[0063] To obtain the cleaning liquid of the invention, an apparatus as described below may
be used. For example, municipal water may be used as inlet water.
[0064] With reference to figure 3, water is provided at the inlet (not shown) and downstream
the inlet are arranged in series: an activated carbon filter 20, such as a filter
from Norit; a particle filter 2, such as a 5 µm particle filter, such as a filter
from Osmonics; an anti-scalant dosing device 21, such as Nalco 191; a flow regulator;
and an open tank 9, such as a tank essentially made of polyethylene. Downstream an
outlet of the open tank 9 are arranged in series: a flow regulator; a pump 3, such
as a pump made out of stainless steel, such as SS316; a reverse osmosis device 5,
such as a RO-filter unit having 99 % rejection, such as DOW BW30; two parallel ion
exchange filters 61, 62, such as ion exchange filters comprising a mixed bed, such
as Rohm & Haas MB20 filters, each having a flow regulator arranged at their inlet
and outlet; a conductivity measuring device 64; an ion exchange filter 63, such as
an ion exchange filter comprising a mixed bed, such as a Rohm & Haas MB20 filter;
a conductivity measuring device 64; and a closed tank 7, such as a tank made essentially
of reinforced polypropylene. Downstream a waste water outlet of the reverse osmosis
device 5 is arranged a waste water return. Between two flow regulators arranged on
the waste water return is a connection to a point upstream the pump 3, but downstream
the flow regulator downstream the open tank 9. A closed tank outlet arranged at the
top of the closed tank 7 is connected to a recycling water inlet 4 of the open tank
9 through a recirculation pipe 24. Downstream an outlet arranged at the lower part
of the closed tank 7 are arranged two separate pipes, wherein one is having a flow
regulator and downstream of that, a low pressure pump 22, such as a pump from Grundfos,
and the other is having a flow regulator and downstream of that, a high pressure pump
23, such as a Cat pump.
[0065] Water pipes leading clean water, such as water pipes arranged downstream the reverse
osmosis device, are made of polypropylene. Other water pipes are made of PVC.
3. A waste water apparatus for purifying used cleaning liquid
[0066] With reference to figure 4, an embodiment of a waste water apparatus for purifying
used cleaning liquid comprises a collecting device 300 adapted to being arranged in
a storm drain 400. As an example, used cleaning liquid leaving a façade wall is naturally
directed the storm drain 400 and collected in the collecting device 300 being arranged
therein. The apparatus comprises a pumping device 200 comprising a pump 201 which
is arranged inside the collecting device 300. A regulator starting the pump 201 when
at least the inlet of the pump 201 is covered with water may be arranged at the pump.
A purification device 100 is arranged downstream the pumping device 200 such that
collected, used cleaning liquid may be pumped from the collecting device 300 to the
purification device 100. The purification device 100 comprises, arranged in series:
a prefilter 101, such as a particle filter, such as a 10-500 µm particle filter, such
as a 50-150 µm particle filter, preferably a 50 µm particle filter, or alternatively,
a 100 µm particle filter; an organic compounds removing device, such as a device comprising
activated carbon, such as a device comprising activated carbon and ion exchange material
102, such as a device comprising activated carbon and ion exchange material for removal
of heavy metals; and an ion exchange filter, such as a chelating ion exchange filter
103 for removing heavy metals. An outlet of the purification device 100 is connected
to discharge means 303 arranged on the collecting device 300. The discharge means
303 may route purified, used aqueous cleaning liquid from the purification device
100 through a storm drain 400 to the sewer, thereby by-passing the collecting device
300 arranged in the storm drain 400.
4. Used cleaning liquid collecting device for arrangement in a storm drain
[0067] With reference to figures 5 and 6, an embodiment of the collecting device 300 comprises
a trough 301 and a flange 302 for maintaining the trough 301 in a storm drain 400.
When the collecting device 300 is arranged in the storm drain 400, the flange 302
rests upon the same surface (the contact surface) as a storm drain lid or grating
does when covering the storm drain 400. The flange has a lower part 305, wherein at
least part of the lower part is being in contact with the contact surface when the
collecting device 300 is arranged in a storm drain 400. A packing, such as a rubber
packing, (not shown) may be provided on the lower part for preventing that water leaks
into the storm drain. A pump (not shown) for pumping used cleaning liquid collected
in the trough 301 to a purification device (not shown) may be arranged inside the
trough 301. At least one pipe 303 is arranged at the flange 302 or trough 301 so that
liquids can flow through the collecting device 300 down the storm drain 400 to the
sewer. Each pipe 303 has a upper and lower opening, wherein the lower opening, when
the collecting device 300 is arranged in a storm drain 400, is facing the inside of
the storm drain 400 and the upper opening is opposite to the lower opening facing
open air. A connecting means 304 for connecting a pipe 303 to a hose (not shown) is
arranged at the upper opening of the pipe(s) 303. For example, the hose(s) may, at
its (their) other end, be connected to the purification device (not shown) and/or
another apparatus producing discharge water.
[0068] While the invention disclosed herein has been described by means of specific embodiments
and applications thereof, numerous modifications and variations could be made therein
by those skilled in the art without departing from the scope of the invention, which
is defined by the appended claims.
ITEMIZED LISTING OF EMBODIMENTS
[0069]
101. A method for washing away dirt from a façade wall, comprising the following steps:
- (a) providing a cleaning liquid, wherein said cleaning liquid consists of water having
a conductivity of 3 µS/cm or less, such as 1 µS/cm or less, such as 0.5 µS/cm or less,
such as 0.1 µS/cm or less, such as 0.08 µS/cm or less;
- (b) cleaning said façade wall, wherein said cleaning comprises application of said
cleaning liquid of step (a) onto said façade wall; and
- (c) allowing used cleaning liquid from step (b) containing dirt to leave the façade
wall.
102. A method according to item 101, wherein said application of cleaning liquid of
step (b) comprises continuous application of said cleaning liquid in the form of a
mist for a time period of 3 hours or less.
103. A method according to item 102, wherein said time period of continuous application
is 10-60 minutes.
104. A method according any one of the previous items, wherein step (b) comprises
a first application of said cleaning liquid, pausing application for a predetermined
time period, followed by a second application of said cleaning liquid.
105. A method according to item 104, wherein step (b) further comprises brushing of
said façade wall between said first and said second application of cleaning liquid.
106. A method according to any one of the preceding items, further comprising the
steps of:
(d) collecting said used cleaning liquid of step (c); and
(e) purifying said collected, used cleaning liquid of step (d).
107. A method according to item 106, wherein step (d) involves collecting said used
cleaning liquid in a storm drain located in the vicinity of said façade wall; and
step (e) involves purifying at the washing site.
108. A method according to any one of the preceding items, wherein step (a) involves
providing said cleaning liquid at the washing site by continuous processing of inlet
water.
109. A method according to item 108, said method further comprising the step of:
(f) recycling said purified, used cleaning liquid of step (e) such that it constitutes
at least part of said inlet water of step (a).
110. A method according to any one of the preceding items, wherein said dirt includes
one or more of the following: algae, green algae and calcium sulphate compounds.
111. A method according to any one of the preceding items, wherein said façade wall
comprises at least 5-65 % (w/w) calcium carbonate or more.
112. A method according to any one of the previous items, further comprising the steps
of:
(g) determining if after-treatment is needed; and, if after-treatment is needed,
(h) applying an after-treatment liquid selected from a silicate liquid, a silicone
hydride liquid and a fungicide liquid to said façade wall,
wherein step (h) is performed after step (c).
113. A method according to item 112, wherein said after-treatment liquid is selected
from a silicate liquid and a silicone hydride liquid.
114. A method according to item 113, wherein said after-treatment liquid comprises
said cleaning liquid.
115. A method according to any one of items 113-114, wherein step (g) comprises at
least one measurement of the water absorption capacity of the façade wall, and said
after-treatment is needed if said water absorption capacity is high.
116. Use of a cleaning liquid consisting of water having a conductivity of 3 µS/cm
or less, such as 1 µS/cm or less, such as 0.5 µS/cm or less, such as 0.1 µS/cm or
less, such as 0.08 µS/cm or less, for washing away dirt from a façade wall.
121. A façade wall washing system comprising:
a cleaning liquid apparatus for providing a cleaning liquid, wherein said cleaning
liquid consists of water having a conductivity of 3 µS/cm or less, such as 1 µS/cm
or less, such as 0.5 µS/cm or less, such as 0.1 µS/cm or less, such as 0.08 µS/cm
or less; and
cleaning liquid application means.
122. A system according to item 121, wherein at least one of said cleaning liquid
apparatus and said cleaning liquid application means contains conductivity measurement
means for measuring the conductivity of said cleaning liquid.
123. A system according to any one of items 121-122, further comprising a waste water
apparatus for purifying used cleaning liquid.
124. A system according to item 123, wherein said waste water apparatus is comprising
a purification device for removing particles, organic compounds and heavy metals from
said used cleaning liquid.
125. A system according to item 124, wherein said purification device is comprising:
a prefilter for removing particulate matter (101);
a organic compounds removing device; and
and an ion exchange filter for removing heavy metals,
wherein:
said prefilter (101) is arranged upstream said organic compounds removing device and
said ion exchange filter; and
said organic compounds removing device and said ion exchange filter is the same device
or two different devices.
126. A system according to item 125, wherein said organic compounds removing device
is comprising activated carbon.
127. A system according to item 125-126, wherein said purification device further
comprises a chelating ion exchange filter (103) for removing heavy metals arranged
downstream said prefilter.
128. A system according to any one of items 123-127, wherein said waste water apparatus
and said cleaning liquid apparatus are functionally connected so that purified used
cleaning liquid from said waste water apparatus can be recycled and used as inlet
water to said cleaning liquid apparatus for providing cleaning liquid.
129. A system according to any one of items 123-128, wherein said waste water apparatus
is comprising:
a collecting device (300) for collecting used cleaning liquid, wherein said collecting
device (300) is adapted for being arranged in a storm drain (400); and a pump device
(200) for pumping collected, used cleaning liquid from said collecting device (300)
to said purification device.
130. A system according to item 129, wherein said collecting device (300) is comprising
a trough (301) and a flange (302) for maintaining said trough (301) in a storm drain
(401).
131. A system according to any one of items 130, wherein said pump device (200) comprises
a pump (201) that fits inside said trough (301).
132. A system according to any one of items 129-131, further comprising discharge
(303) means for routing purified, used aqueous cleaning liquid obtainable from said
purification device to a storm drain (400), thereby by-passing said collecting device
(300).