Abstract:
There is disclosed a water treatment apparatus for treating stormwater, the water treatment apparatus comprising a volume of filter media, a baffle and an inlet conduit. The baffle extends upwards from the volume of filter media and defines a pre-treatment zone on one side of the baffle and a treatment zone on an opposing side of the baffle. The inlet conduit opens into the pre-treatment zone and is separated from the treatment zone by the baffle. The baffle is configured to regulate a flow of stormwater received via the inlet conduit by controlling the passage of stormwater from the pre-treatment zone to the treatment zone.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This disclosure claims priority to U.S. Provisional Patent Application No. 62/303,127 filed on Mar. 3, 2016, the disclosure of which is considered part of the disclosure of this application and is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    The disclosure relates to a water treatment apparatus for treating stormwater. 
         [0003]    Water treatment systems such as storm drains are commonly used to drain excess rain and ground water from impervious surfaces such as roads, pavements, car parks and footpaths. Stormwater planters are also known, and comprise containers located in pavements (sidewalks) having openings for receiving growing media, such as soil, and plants. The organic matter is able to absorb excess rain and ground water, thereby reducing the effects of flash flooding. Further, the organic matter acts as a filter media for filtering pollutants from the stormwater. 
         [0004]    However, it is desirable to provide an improved water treatment system for treating stormwater. 
       SUMMARY 
       [0005]    According to an aspect of the disclosure, there is provided a water treatment apparatus for treating stormwater. The water treatment apparatus comprises a volume of filter media, a baffle and an inlet conduit. The baffle extends upwards from the volume of filter media and defines a pre-treatment zone on one side of the baffle and a treatment zone on an opposing side of the baffle. The inlet conduit opens into the pre-treatment zone and is separated from the treatment zone by the baffle. The baffle is configured to regulate a flow of stormwater received via the inlet conduit by controlling the passage of stormwater from the pre-treatment zone to the treatment zone. 
         [0006]    The baffle may be arranged such the pre-treatment zone surrounds the treatment zone. 
         [0007]    The baffle may comprise a plurality of holes which allow stormwater to pass through the baffle from the pre-treatment zone to the treatment zone. 
         [0008]    The plurality of holes may be disposed above an upper surface of the volume of filter media. 
         [0009]    The plurality of holes may be spaced upwards from an upper surface of the volume of the filter media. 
         [0010]    The baffle may extend into the filter media below an upper surface of the filter media. 
         [0011]    The water treatment apparatus may further comprise a structural frame spaced upwards from the filter media with the baffle disposed between the structural frame and the filter media. 
         [0012]    The baffle may extend downwards from the structural frame. 
         [0013]    The structural frame may comprise a maintenance access hole. 
         [0014]    The water treatment apparatus may further comprise a removable cover for removably covering the maintenance access hole. 
         [0015]    The maintenance access hole may open into the pre-treatment zone. 
         [0016]    The removable cover may comprise an inlet for supplying an external source of the stormwater into the treatment zone and/or pre-treatment zone. 
         [0017]    The removable cover may form a surface of a pavement. 
         [0018]    The structural frame may comprise an opening for receiving a plant planted in the volume of filter media in the treatment zone. 
         [0019]    The inlet conduit may be formed in a curb of a road. 
         [0020]    The water treatment apparatus may further comprise a drainage tube at least partly disposed within the volume of filter media. The drainage tube may comprise a plurality of drainage holes for receiving filtered stormwater from the filter media. The drainage tube may comprise a discharge outlet for discharging the filtered stormwater from the drainage tube. 
         [0021]    The drainage tube may further comprise a bypass inlet extending above the level of the filter media in the pre-treatment zone for discharging stormwater from the pre-treatment zone and bypassing the treatment zone. 
         [0022]    The water treatment apparatus may further comprise an outlet conduit extending from the pre-treatment zone for discharging stormwater from the water treatment apparatus. 
         [0023]    The water treatment apparatus may further comprise an auxiliary conduit fluidically connected to the pre-treatment zone for receiving or discharging stormwater into or from the pre-treatment zone. 
         [0024]    The inlet conduit, outlet conduit and auxiliary conduit may be provided on different sides of the apparatus. 
         [0025]    According to another aspect of the disclosure, there is also provided a water treatment system comprising a plurality of water treatment apparatus as described above, wherein the water treatment apparatus are connected in series such that the outlet conduit of one water treatment apparatus is connected to the inlet conduit of an adjacent water treatment apparatus. 
         [0026]    The invention may comprise any combination of the features and/or limitations referred to herein, except combinations of such features that are mutually exclusive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    Arrangements will now be described, by way of example, with reference to the accompanying drawings, in which: 
           [0028]      FIG. 1  is a perspective view of a water treatment apparatus; 
           [0029]      FIG. 2  is a side perspective view showing a cross-section of the water treatment apparatus; 
           [0030]      FIG. 3  is a top perspective view showing a further cross-section of the water treatment apparatus; 
           [0031]      FIG. 4  is a top perspective view showing a further cross-section of the water treatment apparatus; 
           [0032]      FIG. 5  is a side cross-sectional view of another water treatment apparatus; 
           [0033]      FIG. 6  is a perspective view showing a water treatment system comprising a plurality of water treatment apparatus; and 
           [0034]      FIG. 7  is a schematic plan view showing a cross-section of the water treatment system of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0035]      FIG. 1  shows a water treatment apparatus  2  for treating stormwater. The water treatment apparatus  2  generally comprises a water treatment portion  4  and filter media (not visible in  FIG. 1 ). The water treatment portion  4  is installed in a pavement  6 , such that an upper surface of the water treatment portion  4  is level with and forms part of a pavement surface. In the arrangement shown, the water treatment portion  4  is installed next to a road  8 , such that a side surface of the water treatment portion  4  forms part of a curb  10 . 
         [0036]    The side surface of the water treatment portion  4  comprises an inlet conduit  12  for receiving stormwater collected on the upper surface of the road  8 . The inlet conduit  12  tapers laterally along its length such that its width reduces. The inlet conduit  12  is therefore funnel-shaped. The lower edge of the inlet conduit  12  is approximately level with the upper surface of the road  8  such that even under low flow conditions, stormwater is able to enter the water treatment portion  4  via the inlet conduit  12 . 
         [0037]    The upper surface of the water treatment portion  4  is provided with an opening  14  providing access to the filter media below. The filter media is a particulate medium for plant growth. The filter media may comprise a mixture of sand, gravel and organic material and may comprise a top layer of mulch. The filter media (growing media) can be used to grow plants. For example, a tree  15  may grow from the filter media and extend through the opening  14  into the space above the water treatment portion  4 . 
         [0038]      FIG. 2  shows a cross-sectional side view of the water treatment apparatus  2 . The water treatment portion  4  comprises a frame  16  disposed approximately at the level of the pavement  6 . 
         [0039]    A volume of the filter media  18  is disposed below the frame  16 . The upper surface of the volume of filter media  18  is provided at a level which is below that of the lower edge of the inlet conduit  12 . The volume of filter media  18  is surrounded by the native soil  20  at its sides and base. The filter media  18  directly contacts the native soils  20 , which are themselves permeable. As such, stormwater passing through the filter media  18  is able to permeate into the native soils  20 . 
         [0040]    The frame  16  has a rectangular upper portion. A pillar or pier  22  extends from each of the four corners of the rectangular upper portion. The distal end of each pillar  22  is supported by a concrete pad foundation  24 , which is disposed in the native soil  20 , below the filter media  18 . 
         [0041]      FIG. 3  shows a further cross-sectional view of the water treatment apparatus  2 , as viewed from above. As shown, the upper portion of the frame  16 , is formed by an outer rectangular section  26  and an inner rectangular section  28 . The inner rectangular section  28  is nested within the outer rectangular section  26  such that they are arranged concentrically. The inner and outer rectangular sections  26 ,  28  are connected by a plurality of support beams  29 , which extend between the outer section  26  and the inner section  28 . A rectangular baffle  30  extends downwards from the inner rectangular section  28  of the frame  16  to (and possibly below) the upper surface of the filter media  18 . 
         [0042]    The support beams  29  divide the area between the outer and inner rectangular sections  26 ,  28  into a plurality of maintenance access holes  32 . As shown in  FIGS. 1 and 2 , a removable maintenance cover  34  is provided over each of the maintenance access holes  32 . The outer rectangular section  26 , the inner rectangular section  28  and the support beams  29  comprise support ledges  36 , which support the maintenance covers  34  at the level of the upper surface of the pavement  6 . The maintenance covers  34  are sufficiently strong that they can be walked on, and thus form an extension of the surface of the pavement  6 . 
         [0043]    A central opening formed within the inner rectangular section  28  receives a grate  35  in which the opening  14  described previously is formed. The grate  35  allows stormwater collected on the upper surface of the pavement  6  to pass directly into the water treatment portion  4 . 
         [0044]    As shown, the inlet conduit  12  is provided in one side of the frame  16 . Two further openings  38 ,  40  are provided in two of the other sides of the frame  16 , the purpose of which will be described below. 
         [0045]      FIG. 4  shows a further cross-sectional view of the water treatment apparatus  2  as viewed from above. As shown, the rectangular baffle  30  divides a space above the filter media  18  into a pre-treatment zone  42  outside of the baffle  30  and a treatment zone  44  within the baffle  30 . The pre-treatment zone  42  surrounds the treatment zone  44 . 
         [0046]    The baffle  30  comprises a plurality of orifices  46 , which extend through the baffle  30 . The orifices  46  are circular and are provided in all four sides of the baffle  30 . The orifices  46  are of a uniform profile and size. The orifices  46  are equally spaced from each other, and spaced an equal distance from the upper surface of the filter media  18 . The lower edges of the orifices  46  are disposed above the upper surface of the filter media  18 . 
         [0047]    In use, after a period of rainfall, stormwater collected on the road  8  passes through the inlet conduit  12 , into the water treatment portion  4 . The stormwater initially enters the pre-treatment zone  42 . The baffle  30  prevents stormwater from passing through into the treatment zone  44  from the pre-treatment zone  42 , such that the stormwater pools within the pre-treatment zone  42 . 
         [0048]    The filter media  18  is permeable, and, accordingly, the stormwater contained in the pre-treatment zone  42  percolates downwards through the filter media  18 . The stormwater contains small particles of solid material, for example small particles of organic matter and grit, that are able to penetrate into the filter media  18 . As these small particles pass through the filter media  18 , they are retained by the filter media  18  such that the stormwater is filtered. The stormwater entering the water treatment portion  4  also contains larger pieces of solid material such as litter that are unable to penetrate into the filter media  18  and thus collect above the filter media  18  in the pre-treatment zone  42 . 
         [0049]    Under very low flow conditions, the stormwater is adequately drained via the filter media  18  such that the level in the pre-treatment zone  42  does not rise above the lower edge of the orifices  46  of the baffle  30 . Accordingly, the stormwater is unable to pass into the treatment zone  44 . Under higher flow conditions, stormwater accumulates in the pre-treatment zone  42  to such a level that it is able to pass from the pre-treatment zone  42 , into the treatment zone  44  via the orifices  46 . As the orifices  46  are equally spaced from each other, and spaced an equal distance from the upper surface of the filter media  18 , the flow of stormwater into the treatment zone  44  is approximately equal around the entire perimeter of the baffle  30  for any given flow condition. 
         [0050]    The orifices  46  may also perform a screening function by preventing debris which cannot pass through the orifices  46  from entering the treatment zone  44 . 
         [0051]    Under high flow conditions, stormwater enters the pre-treatment zone  42  through the inlet conduit  12  at a high velocity. Typically, this would result in the stormwater scouring away a top layer of the filter media  18  and/or causing channeling of the filter media  18 . The baffle  30  impedes the flow of the stormwater as it enters the pre-treatment zone  42 . This not only reduces the speed of the stormwater and thus the problems described above, it also helps to distribute the stormwater evenly around the entire pre-treatment zone  42 , and thus the treatment zone  44 . This leads to improved filtration, and increased length of service between maintenance events. Further, the baffle  30  acts to reduce the lateral rate of flow through the treatment zone  44 , thereby protecting the plant  15  located therein. 
         [0052]    As shown in  FIG. 3  and as previously described, the maintenance covers  34  are removable from the maintenance access holes  32 . The grate  35  can also be removed. Accordingly, maintenance personnel are able to access both the pre-treatment zone  42  and the treatment zone  44  for removal of solid material that has collected on the upper surface of the filter media  18 . Some or all of the filter media  18  may also be replaced, if necessary. These processes may be carried out either manually or using a machine such as a vacuum pump. Once the maintenance process has been completed, the maintenance covers  34  can be replaced. 
         [0053]    The baffle  30  may reduce the amount of solid matter that collects in the treatment zone  44  sufficiently such that the grate  35  need not be removable. 
         [0054]      FIG. 5  shows another water treatment apparatus  102 . The water treatment apparatus  102  of  FIG. 5  substantially corresponds to the water treatment apparatus  2  of  FIGS. 1 to 4 . However, the water treatment apparatus  102  is provided with a drainage tube  48 . The drainage tube  48  has a bypass inlet  50  which is located in the pre-treatment zone  42 . The drainage tube  48  extends from the bypass inlet  50  into the filter media  18 . The section of the drainage tube  48  within the filter media  18  comprises a plurality of drainage holes  54  for receiving filtered stormwater from the filter media  18 . Under high flow conditions, for example where the rate of absorption of stormwater into the surrounding native soils  20  is less than the rate of stormwater being produced by the filter media  18 , the drainage tube  48  is able to convey filtered stormwater away from the filter media  18 . Further, when stormwater pools above the surface of the filter media  18  in the pre-treatment zone  42 , the drainage tube  48  acts as an overflow device. Specifically, once stormwater in the pre-treatment zone  42  reaches the level of the bypass inlet  50 , it passes directly into the drainage tube  48 , thereby bypassing the treatment zone  44  and the saturated filter media  18 . The bypass inlet  50  is positioned above the lower edge of the orifices  46 . Accordingly, it is only possible for stormwater to bypass the filter media  18  if stormwater is already being filtered by the filter media  18  contained in both the pre-treatment zone  42  and the treatment zone  44 . 
         [0055]      FIG. 6  shows a water treatment system comprising a plurality of water treatment apparatus as described previously. In the example shown, three water treatment apparatus  2 ,  202 ,  302  are joined in series to form a modular array, however any number of apparatus may be used. As previously mentioned with reference to  FIG. 3 , additional openings  38 ,  40  may be provided. These openings  38 ,  40  can be used when forming a modular array as shown. 
         [0056]    As shown in  FIG. 7 , the opening  38  forms an outlet from the first water treatment apparatus  2  and is disposed adjacent the opening  240  of the second water treatment apparatus  202 , which forms an inlet to the second water treatment apparatus  202 . Accordingly, stormwater that accumulates in the pre-treatment zone  42  of the first water treatment apparatus  2  is able to pass out of the opening  38  and into the pre-treatment zone  242  of the second water treatment apparatus  202 . Similarly, the opening  212  forms an outlet from the second water treatment apparatus  202  and is disposed adjacent the opening  340  of the third water treatment apparatus  302 , which forms an inlet. Stormwater that accumulates in the pre-treatment zone  242  of the second water treatment apparatus  202  is therefore able to pass out of the opening  212  and into the pre-treatment zone  342  of the third water treatment apparatus  302 . 
         [0057]    In this arrangement, the sides of the second and third water treatment apparatus  202 ,  302  not having openings are disposed adjacent the road  8 , such that stormwater from the road  8  has a single point of entry into the water treatment system. In alternative arrangements, the water treatment apparatus  202 ,  302  may be arranged such that an opening of one or both water treatment apparatus  202 ,  302  are disposed adjacent the road  8 , to provide additional entry points. 
         [0058]    The modular arrangement may also be in the form of a matrix of columns and rows of apparatus. 
         [0059]    In some arrangements, the baffle  30  may be replaceable. The baffle  30  may be replaced during a maintenance event for a variety of reasons. For example, the orifices  46  may have become blocked to such an extent that in-situ repair is not possible. Accordingly, the baffle  30  may be removed, unblocked, and then reinstalled. A similar process may be carried out for any type of maintenance that needs to be carried out on the baffle  30 . Alternately, the baffle  30  may be removed and replaced by a new baffle  30 . The new baffle  30  may have a geometry that differs from that of the original baffle  30 . For example, the height, spacing, diameter and/or shape of the orifices  46  may differ from those of the original baffle  30 . This may allow the characteristics of the apparatus to be customized for the specific installation. Replacement may be carried out seasonally, so as to account for expected changes in local climate throughout the course of the year. The same effect may also be achieved using a baffle  30  which has a geometry that can be adjusted, either in-situ or following a temporary removal of the baffle  30 , such that, while the entire baffle  30  is not replaced, it functions as a new baffle  30 . 
         [0060]    The orifices  46  may differ from those shown and described above. The baffle plate could also act as a weir rather than having discrete orifices. A weir may also be provided in addition to orifices to provide a bypass function during high flow conditions. 
         [0061]    Although the baffle  30  has been described as being rectangular, it may be of any shape. In particular, the baffle may be formed as a single wall which extends laterally across the frame  16 . Accordingly, the pre-treatment zone  42  may be adjacent the treatment zone  44 , but not surround it. 
         [0062]    Although it has been described that the filter media  18  directly contacts the surrounding native soils  20 , it may instead be housed within a container.