GB2609406A

GB2609406A - Wastewater Treatment

Info

Publication number: GB2609406A
Application number: GB2110841.0A
Authority: GB
Inventors: O'brien Newbery Mark
Original assignee: Glade Holdings Ltd
Current assignee: Glade Holdings Ltd
Priority date: 2021-07-28
Filing date: 2021-07-28
Publication date: 2023-02-08
Anticipated expiration: 2041-07-28
Also published as: GB202110841D0; WO2023007120A1; GB2609406B; CA3230061A1

Abstract

Wastewater and aeration are supplied to a wastewater treatment apparatus 101 comprising a vessel 104, wherein the vessel may be configured for underground installation. A package treatment plant can comprise the apparatus, wherein the plant is for a building, such as a residential or commercial property, that may not be connected to a mains sewer. Interior and exterior zones 204, 205 of a chamber 105 of the vessel are defined by a chamber partition 203, and upper and lower regions of the interior zone are in fluid communication with the exterior zone. An inlet 106 directs wastewater into the interior zone and an outlet 107 intakes treated wastewater from the exterior zone for discharging outside the vessel. Treatment media 213 is retained within the interior zone, and air is delivered to a lower region of the interior zone by an air delivery arrangement 108. An underside (706, Fig. 7) of a humus crust (701, Fig. 7) developed at the liquid surface (702, Fig. 7) within the exterior zone is exposed to a continuous flow of oxygenated, circulating received wastewater. A growth of the humus crust depth is thereby inhibited.

Description

WASTEWATER TREATMENT

Field of the Invention

The present invention relates to the treatment of wastewater, in particular to a wastewater treatment apparatus and a wastewater treatment method, and more particularly to a package treatment plant for a building that is not connected to a mains sewer.

Background of the Invention

A building, whether residential or commercial, that has no connection to mains drainage for the disposal of sewage must have provision for treating wastewater that complies with the relevant regulations for surface and groundwater pollution control.

As a general guide for the UK (considering differences between the agencies for England, Wales, Scotland, and Northern Ireland), if the site in question is more than 30 metres from the nearest public foul sewer, then in most cases alternative options can be considered.

If pumping to the public foul sewer, checks must be undertaken to establish legal and financial aspects, (such as rights of access, obligations in perpetuity and connection fees) and to determine an appropriate specification for the technical aspects of pumping and storage; however, if a property's wastewater cannot be connected to the public foul sewer, then an alternative solution must be implemented. At the present time, available options are (under current naming conventions) a "cesspool", a "septic tank" and a 'package treatment plant".

A cesspool is a holding tank for wastewater, having no overflow, and hence has a collecting function. This option typically requires a relatively large capacity tank, to avoid needing emptying too often, which size can be impracticable for installation in areas in which space is restricted. Further, all effluent must be taken away by a licensed tanker firm, meaning that emptying costs are relatively expensive in addition to regular, suitable access for the tanker being required.

A septic tank has two or more chambers to allow some of the solids in the wastewater to settle out, and hence performs a separation function. A septic tank is much smaller than a cesspool, and the liquid part of the wastewater is polluting and may only be dispersed into a drainage field such as a sub-surface irrigation system, typically comprising a system of soakaway trenches. Appropriate soil porosity testing must be performed, and then a compliant soakaway system designed accordingly. However, the installation of a septic tank may be prohibited, such as in regions in which a prescribed minimum depth of soil between the soakaway and the water table cannot be achieved, for example if trenches would need to be constructed in low-lying, flat ground with clay soil and a high water table, or if restrictions are in place to protect a nearby environmental asset, for example, an underground region from which drinking water is extracted, or a Site of Special Scientific Interest (SSSI). Further, a septic tank should be emptied annually to avoid failure of the soakaway system.

A package treatment plant is a modern alternative to a septic tank that produces a clear effluent that is suitable for discharge into a watercourse if one is available, although if no watercourse is available, the effluent still needs to be discharged into a suitable drainage field. A package treatment plant has a treating function, and by way of comparison, the effluent from a package treatment plant is typically in the order of 20 times cleaner than that from a septic tank. A package treatment plant can offer a way of overcoming such difficulties as a high water table or nearby environmentally sensitive area, although if there is a high water table or discharge is into a watercourse that may flood, there can be a requirement to utilise an automatic effluent pumping system (with non-return valve to prevent any back flow).

Different types of package treatment plant are known; however, an older type featuring complicated mechanical and electrical components is becoming less popular and a newer type featuring an air blower for aerating the sewage is becoming increasingly commonplace; however, some of the aerated systems still have a septic settlement stage, with the risk of odours and a requirement to be emptied once or more a year, but other, superior ones aerate all the sewage received, including all solid matter, and do not require emptying as often.

It is desirable to provide improvements in the treatment of wastewater by a package treatment plant

Summary of the Invention

According to a first aspect there is provided a wastewater treatment method, comprising: supplying wastewater and aeration to a wastewater treatment apparatus; the wastewater treatment apparatus comprising: a vessel defining a chamber having a lower end and an upper end, a chamber partition disposed within the chamber to define an interior zone of the chamber, inside the chamber partition, and an exterior zone of the chamber, outside the chamber partition, wherein a lower region and an upper region of the interior zone of the chamber are in fluid communication with the exterior zone of the chamber, treatment media retained within the interior zone of the chamber, an inlet for receiving wastewater to be treated within the chamber, the inlet comprising an exit port arranged to direct liquid into the interior zone of the chamber, an outlet for discharging treated wastewater from the chamber, the outlet comprising an entrance port arranged to intake liquid from the exterior zone of the chamber, and an air delivery arrangement for delivering air to the lower region of the interior zone of the chamber; wherein an underside of a humus crust developed at the liquid surface within the exterior zone is exposed to a continuous flow of oxygenated, circulating received wastewater, and growth of a depth of the humus crust is inhibited by a degradation of the underside of the humus crust being maintained by said continuous flow of oxygenated, circulating received wastewater.

According to a second aspect there is provided a wastewater treatment system, comprising: a wastewater treatment apparatus, the wastewater treatment apparatus comprising: a vessel defining a chamber having a lower end and an upper end, a chamber partition disposed within the chamber to define an interior zone of the chamber, inside the chamber partition, and an exterior zone of the chamber, outside the chamber partition, wherein a lower region and an upper region of the interior zone of the chamber are in fluid communication with the exterior zone of the chamber, treatment media retained within the interior zone of the chamber, an inlet for receiving wastewater to be treated within the chamber, the inlet comprising an exit port arranged to direct liquid into the interior zone of the chamber, an outlet for discharging treated wastewater from the chamber, the outlet comprising an entrance port arranged to intake liquid from the exterior zone of the chamber, and an air delivery arrangement for delivering air to the lower region of the interior zone of the chamber; in which a humus crust is developed at the liquid surface within the exterior zone of the chamber, an underside of the humus crust is exposed to a continuous flow of oxygenated, circulating received wastewater, and growth of a depth of the humus crust is inhibited by a degradation of an underside of the humus crust being maintained by said continuous flow of oxygenated, circulating received wastewater.

Sewage/wastewater first enters the interior zone of the chamber (which may also be termed the "central chamber"), where air is continuously diffused in at the base (lower region). The sewage rapidly mixes with the contents of the central chamber. The continuous supply of air creates an environment that is right for naturally occurring microorganisms to grow in the liquor and degrade the sewage. The process is aided by the treatment media, which provides both a means of physical degradation and a high surface area for the growth of micro-organisms.

The continuous air supply also drives recirculation from the central chamber into the exterior zone of the chamber (which may also be termed the "outer settlement chamber") due to what is known as the "air lift effect". This happens due to the interior and exterior zones being in fluid communication, allowing flow from the central chamber into the outer settlement chamber, and from the outer settlement chamber into the central chamber. The recirculation flow is out at the top of the central chamber and back in at the bottom of the outer settlement chamber.

The process in the outer settlement chamber is very three dimensional but includes the continuous recirculation of oxygenated liquor from the top of the central chamber to all around the base, with the majority of solids returning to the central chamber. Additionally, there is a contra-flow of some solids moving upwards to form a humus crust on the surface of the outer settlement chamber. The humus crust of solids is further degraded by the continuous flow of oxygenated recirculating liquid to the underside.

Specific examples may vary in features of design but provide the same treatment processes.

In an example, a lower portion of the chamber partition defines a lower transfer arrangement comprising a lower aperture arrangement that comprises at least one opening.

In a specific example, the lower aperture arrangement comprises a plurality of openings distributed around the circumference of the chamber partition.

In an example, an upper region of the chamber partition is provided with an upper transfer arrangement that incorporates a baffle and an upper aperture arrangement that comprises at least one opening.

In an example, the interior and exterior zones of the chamber are arranged concentrically about a central axis of the chamber.

In an example, the chamber partition and the chamber each define a cross-section shape that is one of: substantially cylindrical, substantially oblong.

In an example, the chamber partition defines a cross-sectional shape that is substantially constant along a depth direction of the chamber.

In an example, the entrance port of the outlet is closer to the bottom end of the chamber than the exit port of the inlet In an example, the exit port of the inlet is closer to the central axis of the chamber than the entrance port of the outlet In an example, the inlet is provided by an inlet pipe that comprises a straight piece.

In an example, the outlet is provided by an outlet pipe that comprises a T-piece.

In an example, the air delivery arrangement comprises an air diffuser arrangement that comprises at least one air diffuser.

In an example, the air diffuser arrangement is connected to an air blower by air line. In an application, the air blower is sited at or above ground level.

In an example, the treatment media comprises a plurality of objects that provide a substrate for microbiological colonisation. In a specific example, the treatment media is fabricated from a plastics material.

In an example, the vessel is fabricated from glass fibre reinforced plastic (GRP).

In an example, the vessel is configured for underground installation.

In an example, the vessel is provided with an anchor arrangement comprising at least one anchor element for use in facilitating secure installation of the vessel. In a specific example, one or more wet ground anchor elements are provided for facilitating secure installation of the vessel in wet ground.

In an example, the vessel is provided with a lifting arrangement comprising at least one lifting element, for use in facilitating controlled positioning of the vessel for installation.

In an example, the vessel defines an access port, providing access into the chamber, the access port positioned to provide access into the chamber from the upper end of the chamber.

A third aspect comprises the use of a wastewater treatment method according to the first aspect or a wastewater treatment system according to the second aspect, to treat wastewater a residential property or a commercial property.

A wastewater treatment method according to the first aspect or a wastewater treatment system according to the second aspect may be used to treat wastewater from a permanent, semi-permanent, temporary or transportable building or structure.

In an example, wastewater from a plurality of buildings is treated. In a specific example, wastewater from more than one building is treated by the same wastewater treatment system.

A fourth aspect comprises a package treatment plant installation incorporating a wastewater treatment system according to the second aspect Further particular and preferred aspects of the invention are set out in the accompanying dependent claims.

IC

Brief Description of the Drawings

The present invention will now be more particularly described, with reference to the accompanying drawings, in which: IS Figure 1 is a side section schematic of a package treatment plant installation; Figure 2 shows a cut-away section of a wastewater treatment apparatus; Figure 3 is a side section of the wastewater treatment apparatus of Figure 2; Figure4 is a plan view of the wastewater treatment apparatus of Figure 2; Figures 5 & 6 are a side section and a plan view respectively of the wastewater treatment apparatus of Figure 2, during use, with a first component of circulation indicated; Figures 7 & 8 are a side section and a plan view respectively of the wastewater treatment apparatus of Figure 2, during use, with a second component of circulation indicated; Figure 9 is a plan view schematic of the wastewater treatment apparatus of Figure 2, during use, with a humus crust indicated; and Figure 10 shows steps in a method of treating wastewater using the wastewater treatment apparatus, the method according to a process of the present disclosure.

Description

Illustrative embodiments and examples are described below in sufficient detail to enable those of ordinary skill in the art to embody and implement the apparatus described herein.

It is to be understood that embodiments and examples can be provided in many alternate forms and the invention should not be construed as limited to the embodiments and examples set forth herein but by the scope of the appended claims.

Unless otherwise defined, all terms (including technical and scientific terms) used herein are to be interpreted as is customary in the art. In addition, features referred to herein in the singular can number one or more, unless the context clearly indicates otherwise. Similarly, the terms "comprises", "comprising", "includes", "including", "has" and/or "having" when used herein, specify the presence of the stated feature or features and do not preclude the presence or addition of one or more other features, unless the context clearly indicates otherwise.

In the following description, all orientational terms, such as upper, lower, radially, and axially, are used in relation to the drawings and should not be interpreted as limiting on the invention, unless the context clearly indicates otherwise.

The drawings are not necessarily drawn to scale, and in some instances the drawings may have been exaggerated or simplified for illustrative purposes only.

A wastewater treatment method and a wastewater treatment system will now be described. The wastewater treatment method and the wastewater treatment system may be usable to treat wastewater from, for example, a residential property or a commercial property.

A package treatment plant installation is illustrated in Figure I, in which a wastewater treatment apparatus 101 is provided for treating wastewater 102, from a building 103. The wastewater treatment apparatus 101 comprises a vessel 104 defining a chamber 105, an inlet 106 for receiving wastewater 102 to be treated within the chamber 105, and an outlet 107 for discharging treated wastewater from the chamber 105. The wastewater treatment apparatus 101 further comprises an air delivery arrangement 108 for delivering a flow of air to the chamber 105. Wastewater 102 flows from the building 103 to the inlet 106 of the wastewater treatment apparatus 101 in the direction indicated by arrow 109 and treated wastewater flows from the outlet 107 of the wastewater treatment apparatus 101 in the direction indicated by arrow 110. As shown, the vessel 104 of the wastewater treatment apparatus 101 is installed subsurface, so most of the vessel 104 is disposed below ground level III. Effluent from the vessel 104 may be discharged to a watercourse (not shown) or to a drainage field/soakaway system (not shown); however, with the latter arrangement a sample chamber 112 is required to enable the effluent quality to be checked periodically.

The wastewater treatment apparatus 101 will now be described in further detail, with reference to Figure 2.

As already described, the wastewater treatment apparatus 101 comprises a vessel 104 defining a chamber 105. The chamber 105 has a bottom end 201 and a top end 202. A chamber partition 203, which in the shown arrangement is a generally tubular partition, is disposed within the chamber 105 to define an interior zone 204 of the chamber 105, inside the chamber partition 203, and an exterior zone 205 of the chamber 105, outside the chamber partition 203. The interior zone 204 of the chamber 105 is in fluid communication with the exterior zone 205 of the chamber 105.

In this example, and as will be described further, a lower region 206 of the interior zone 204 of the chamber 105 is in fluid communication with the exterior zone 205 of the chamber 105. In this specific illustrated example, a lower portion of the chamber partition 203 defines a lower transfer arrangement comprising a lower aperture arrangement that comprises at least one opening, such as the opening indicated at 207, the lower transfer arrangement allowing fluid flow from one side of the chamber partition 203 to the other, and by means of which the interior zone 204 is in fluid communication with the exterior zone 205. An opening of the lower aperture arrangement may be formed in any suitable way. An opening may be provided by a missing portion of material along, or spaced inwardly from, an edge of an end of the chamber partition 203. It is to be appreciated that various factors will affect the flow between the interior zone 204 and the exterior zone 205 of the chamber 105, such as the: size of each opening, the shape of each opening, the positioning of each opening. Aspects of the flow between the interior zone 204 and the exterior zone 205 that may be affected include flow rate and degree of turbulence.

In a preferred example, the lower aperture arrangement comprises a plurality of openings that are distributed all around the lower region of the interior zone. In the specific illustrated example, the lower portion of the chamber partition 203 defines a plurality of openings distributed around the circumference thereof.

In this example, and as will described further, an upper region 208 of the interior zone 204 of the chamber 105 is in fluid communication with the exterior zone 205 of the chamber 105. In this specific illustrated example, an upper portion of the chamber partition 203 is provided with an upper transfer arrangement that incorporates a baffle, indicated at 209, and an upper aperture arrangement that comprises at least one opening, such as the opening indicated at 210, the upper transfer arrangement allowing fluid flow from one side of the chamber partition 203 to the other, and by means of which the interior zone 204 is in fluid communication with the exterior zone 205. The baffle and the at least one opening of the upper aperture arrangement may have any suitable configuration, and an opening of the upper aperture arrangement may be formed in any suitable way.

As already described, the wastewater treatment apparatus 101 comprises an inlet 106 for receiving wastewater 102 to be treated within the chamber 105, and an outlet 107 for discharging treated wastewater from the chamber 105. The inlet 106 comprises an exit port 211 that is arranged to direct liquid into the interior zone 204 of the chamber 105.

The outlet 107 comprises an entrance port 212 arranged to intake liquid from the exterior zone 205 of the chamber 105. The interior zone 204 of the chamber 105 may be termed, a "treatment area" and the exterior zone 205 of the chamber 105 may be termed a "settlement area".

Also indicated is treatment media 213 (only a portion of a typical actual amount is shown, to avoid obscuring other illustrated features), which is retained within the interior zone 204 of the chamber 105 when the wastewater treatment apparatus 101 is in use.

In this example, the treatment media 213 comprises a plurality of objects that provide a substrate for microbiological colonisation, and a means of physical degradation of solids. In this specific illustrated example, the treatment media 213 comprises a plurality of "beads", for example bead 214, which may be a HDPE (high-density polyethylene) bead. It is to be appreciated that beads or other objects may be fabricated from any suitable material or combination of materials, may have any desired property, and may have a regular or an irregular profile for providing surface area for supporting bacteria/biofilm.

In an example, the treatment media 213 is secured in a desired position within the interior zone 204 of the chamber 105. In a preferred example, and in this specific illustrated example, the treatment media 213 is held on, or along, an inner wall 215 of the chamber partition 203. In such an example, the treatment media 213 may be attached to the chamber partition 203 in any suitable way, for example using strings.

Controlling the distribution of the treatment media 213 within the chamber 105 can improve the water treatment process and efficiency.

It is further to be understood that the treatment media may be tethered or otherwise restrained within the chamber, to prevent undesired release from the vessel.

As already described, the wastewater treatment apparatus 101 comprises an air delivery arrangement 108 for delivering air to the chamber 105. In this example, the air delivery arrangement 108 comprises an air diffuser arrangement that comprises at least one air diffuser, such as the air diffuser indicated at 216. In this example, the air delivery arrangement 108 is arranged to deliver air to the lower region 206 of the interior zone 204 of the chamber 105. Hence, in this specific illustrated example, the air diffuser 216 is shown located in the lower region 206 of the interior zone 204 of the chamber 105. The or each air diffuser may be located within the interior zone, upon an internal base surface. In this specific illustrated example, the air diffuser arrangement is connected to an air blower 217 by air line 218. In an application, the air blower is sited at or above ground level.

As shown, the vessel 104 defines an access port 219, providing access into the chamber 105. An access port cover 220 is provided, which is usable to selectively close and open the access port 219. In this specific illustrated example, the access port 219 is positioned to provide access into the chamber104 from the top end 202 of the chamber 105.

According to this example, the vessel 104 is provided with an anchor arrangement comprising at least one anchor element, such as the wet ground anchor element indicated at 221, for use in facilitating secure installation of the vessel 104, in particular in wet ground.

According to this example, the vessel 104 is provided with a lifting arrangement comprising at least one lifting element, such as the lifting element indicated at 222, for use in facilitating controlled positioning of the vessel 104 for installation.

The liquid surface 223 is indicated in Figure 2. The maximum volume of liquid containable within the chamber 105, is determined by the size of the chamber 105 and the relative positioning of the outlet 107, by means of which liquid exits the vessel 104; the maximum liquid level within the interior zone 204 of the chamber 105 is also affected by the relative positioning of the upper aperture arrangement, by means of which liquid can flow between the interior and exterior zones 204, 205 of the chamber 105.

Referring now to Figure 3, the chamber 105 of the vessel 104 has a depth direction Dp, and a central axis Ac.

According to this specific illustrated example, the chamber partition 203 and the chamber each define a cross-sectional shape (in a plane to which the depth direction Dp is normal) that is substantially circular.

According to this illustrated example, the interior zone 204 and the exterior zone 205 of the chamber 105 are arranged concentrically, providing radial symmetry about the central axis Ac.

It is to be appreciated that the chamber partition 203 and the chamber 105 may define a different cross-sectional shape. In another specific example, the cross-sectional shape of the chamber partition 203 and of the chamber 105 is substantially oblong, having parallel long sides and semi-circular ends. The interior zone 204 and the exterior zone 205 of the chamber 105 may be arranged concentrically about the central axis Ac, providing bilateral symmetry about the central axis Ac.

In an example, and in this example, the cross-sectional shape of the chamber partition 203 is substantially constant along the depth direction Dp. In this specific illustrated example, the chamber partition 203 is substantially cylindrical, having a diameter Di. The size of the cross-sectional shape is substantially constant, so that the diameter at a lower end of the chamber partition 203, towards the bottom end 201 of the chamber 105 is substantially equal to the diameter of an upper end of the chamber partition 203, towards the top end 202 of the chamber 105. Also, the cross-sectional shapes of the ends of the chamber partition 203 are aligned (in each of perpendicular directions along a plane to which the depth direction Dp is normal). The chamber partition 203 may be termed as having "straight" walling.

It is to be appreciated however that the chamber partition may comprise a portion that does not have a diameter that is substantially constant along the depth direction Dp, for example an upper portion that tapers inwardly towards the central axis Ac in the direction from a lower end to an upper end of the chamber partition. A "non-straight" portion may be provided above the maximum liquid level of the chamber.

In an example, and in this example, the cross-sectional shape of the chamber 105 changes along the depth direction Dp. In this specific illustrated example, the chamber 105 has a substantially circular cross-section shape, the size of which decreases along the depth direction Dp from the top end 202 to the bottom end 201 of the chamber 105. According to this specific illustrated example, the chamber 105 is generally crucible-shaped, and has a maximum diameter Dm. As shown, the diameter of the chamber 105 changes along the depth direction Dp, so that the diameter of the bottom end 201 of the chamber 105 is less than the diameter of the top end 202 of the chamber 105. The chamber 105 may be termed as having "inwardly tapering" walling. It is to be appreciated however that reduction in the size of the cross-sectional shape may be continuous, or in discrete steps, involving either a straight or a curved profile, and the rate of reduction of the diameter may be regular, or irregular.

According to this example, the inlet 106 is provided by an inlet pipe 301, and the outlet 107 is provided by an outlet pipe 302. According to this specific example, the inlet pipe 301 comprises a straight piece. According to this specific illustrated example, the inlet pipe 301 extends substantially normal to the depth direction Dp, in a radial direction Dr of the chamber 105. According to this specific example, the outlet pipe 302 comprises a T-piece having a first, stem section 303 that extends substantially normal to the depth direction Dp, and a second, cross section 304 that extends substantially parallel to the depth direction Dp.

The second, cross section 304 includes a portion that extends generally downwardly of the first, stem section 303 and provides the entrance port 212. Thus, as shown, the T-piece is oriented with the "T" shape rotated 90 degrees from the usual orientation of the letter According to the shown arrangement, inlet pipe 301 extends into the chamber 105 (interior zone 204) from one side of the vessel 104 and the outlet pipe 304 extends into the chamber 105 (exterior zone 205) from the opposite side of the vessel 104.

According to the specific illustrated arrangement, the inlet pipe 301 extends through a wall of the vessel 104, through the exterior zone 205 of the chamber 105, and is suitably positioned relative to the chamber partition 203 for delivering liquid to the interior zone 204 of the chamber 105; the outlet pipe 302 extends through a wall of the vessel 104, through the exterior zone 205 of the chamber 105, and is suitably positioned relative to the chamber partition 203 for intaking liquid from the exterior zone 205 of the chamber 105. It can be seen from Figures 3 and 4 that the inlet pipe 301 extends into the chamber so that it meets a relatively near side of the chamber partition 203, in this specific example meeting it at a tangent, but the outlet pipe 301 extends into the chamber 105 so that is passes alongside the chamber partition 203 to a relatively far side thereof. Thus, the exit port 211 of the inlet 106 and the entrance port 212 of the outlet 107 are disposed in the same half of the chamber 105, albeit with the former being directed to the interior zone 204 and the latter being directed to the exterior zone 205.

In Figure 4, a lateral direction is indicated by arrow Dlt and a transverse direction that is normal to the lateral direction Dlt is indicated by arrow Dtr.

According to the shown arrangement, the inlet and outlet pipes 301, 302 are spaced in the lateral direction Dlt, and extend substantially parallel to each other.

According to the shown arrangement, the exit port 211 of the inlet 106 and the entrance port 212 of the outlet 107 are displaced in the transverse direction Dtr, and the exit port 211 of the inlet 106 is closer to the central axis Ac than the entrance port 212 of the outlet 107.

Also according to this example, exit port 211 of the inlet 106 and the entrance port 212 of the outlet 107 are displaced in the depth direction Dp, and the entrance port 212 of the outlet 107 is closer to the bottom end 201 of the chamber 105 than the exit port 211 of the inlet 106.

Further according to this example, the exit port 211 of the inlet 106 is generally diametrically opposite the openings of the upper aperture arrangement Use of a wastewater treatment apparatus according to the present disclosure will now be discussed.

Figures 5 to 8 illustrate flow patterns within chamber 105 of the wastewater treatment apparatus 101 during use. A first flow pattern is illustrated in, and discussed with reference to Figures 5 & 6, and a second flow pattern is illustrated in, and discussed with reference to Figures 7 & 8.

IS

As indicated in each of Figures 5 to 8, wastewater 102 enters the chamber 105 through the inlet 106, as indicated by arrow 109, and leaves the chamber 105 through the outlet 107, as indicated by arrow 110. As already mentioned, the interior and exterior zones 204, 205 of the chamber 105 are in fluid communication at upper and lower regions of the chamber partition 203. It should be noted that as a way of visually differentiating aspects of flow hereinafter described with reference to Figures 5 & 6 and Figures 7 & 8 respectively, in Figures 5 & 6 arrows are shown with unbroken line and in Figures 7 & 8 arrows are shown with broken line.

Referring to Figure 5, as indicated by arrow 501, liquid entering the chamber 105 through the inlet 106, leaves the exit port 211 of the inlet 106 into the interior zone 204. From there, the sewage can mix with liquor already in circulation. As already described, a lower aperture arrangement is present at a lower portion of the chamber partition 203, allowing a flow between the interior and exterior zones 204, 205, and an upper aperture arrangement is present at an upper portion of the chamber partition 203, also allowing a flow between the interior and exterior zones 204, 205. More specifically, during normal operation, liquid flows from the interior zone 204 to the exterior zone 205 through the upper aperture arrangement at the upper end of the chamber 105 and liquid flows from the exterior zone 205 to the interior zone 204 through the lower aperture arrangement at the lower end of the chamber 105.

As indicated by arrow 502, liquid within the chamber 105 can flow downwardly, for example when initially entering the interior zone 204 from the inlet 106. However, as indicated by arrow 503, liquid can flow upwardly within the chamber 105.

Due to the "air lift effect" present within the interior zone 204 of the chamber 105, liquid can flow from the interior zone 204 into the exterior zone 205, via the upper aperture arrangement, as indicated by arrow 504. Then, as indicated by arrow 505, liquid can flow downwardly within the exterior zone 205. As indicated by arrow 507, liquid can flow from the exterior zone 205 into the interior zone 204, via the lower aperture arrangement From there, the sewage can mix with liquor already in circulation. It is to be appreciated that, under the influence of the "air lift effect" established when the interior zone 204 of the chamber 105 is provided with aeration, indicated at 508, a continuous transfer of liquid from the interior zone 204 to the exterior zone 205 can be established. In simple terms, the encircling flow may be described as going up-over-down-under, or upwards-outwardsdownwards-inwards.

Referring to Figure 6, as indicated by arrow 601 and similarly by arrow 602, liquid within the chamber, can flow in a circular direction. The liquid may flow in a clockwise or an anticlockwise direction and may flow in a swirling or spiralling motion.

Thus, when the wastewater treatment apparatus 101, liquid received within the chamber circulates between the interior zone 204 and the exterior zone 205, flowing this way and that up, down and around, within a complex flow pattern. Liquid can exit the chamber 105 by flowing into the entrance port 212 of the outlet 107 to a sufficient level.

It is important to understand that solids within the circulating liquid sink to the bottom end 201 of the chamber 105 and are transferred from the exterior zone 205 to the interior zone 204 via the lower aperture arrangement at the lower portion of the chamber partition 203.

However, as will be discussed further below, a portion of the solids within the circulating liquid form a humus crust, indicated at 701 in Figure 7, at the surface, indicated generally at 702.

Once liquor has transferred to the exterior zone 205 from the interior zone 204, a flow pattern within the exterior zone 205, indicated by arrows 703, 704 and 705, which indicate circulation within the chamber 105, causes part of the solids content to accumulate at the surface 702, thus creating the humus crust 701. It is to be appreciated that physical surfaces within the chamber 105 may facilitate the formation of the humus crust 701.

By virtue of the aforementioned "air lift effect" within the chamber 105, there is a continuous circulation of oxygenated liquid within the chamber 105, and to the underside 706 of the humus crust 701. The growth of the depth of the humus crust 701 is inhibited by a degradation of the underside 706 of the humus crust 701 being maintained by the flow of oxygenated, circulating wastewater received within the chamber 105. Two mechanisms for the degradation of solids can be identified: the first being a mechanical interaction, involving such a physical process as erosion, and the second being a chemical interaction, involving such a biological process as aerobic digestion.

An advantageous feature of the wastewater treatment apparatus during use will now be described with reference also to Figure 7. Over time, a humus crust 701 develops at the liquid surface within the exterior zone 205 of the chamber 105. In accordance with the present disclosure, wastewater 102 and aeration is supplied to the interior zone 205 of the chamber 105 and an underside of the humus crust 701 developed at the liquid surface within the exterior zone 205 of the chamber 105 is exposed to a flow of oxygenated, circulating received wastewater, wherein growth of the depth of the humus crust 701 is inhibited by a degradation of the underside of the humus crust 701 being maintained by the flow of oxygenated, circulating received wastewater.

The flow of wastewater 102 within the chamber 105 restraining the thickness of the humus crust 701 beneficially prolongs the period that the wastewater treatment apparatus 101 can be used for, before the chamber 105 of the vessel 104 requires emptying. This not only reduces maintenance cost and inconvenience but serves to improve consumer perception of a package treatment plant comprising the wastewater treatment apparatus 101.

The continuous circulation and mixing processes are driven by the already mentioned "air lift effect". Air is continuously blown and diffused into the interior zone, at the bottom end, by the aeration arrangement, and the lower aperture arrangement at a lower portion of the chamber partition and the upper aperture arrangement at an upper portion of the chamber partition allows the liquid within the chamber to continuously mix and circulate, ensuring the supply of oxygen to the liquid surface and hence to the underside of the humus crust formed from secondary solids that are produced during the treatment process.

Importantly, the aeration and degradation is of all the sewage and not only the liquid fraction.

Advantageously, the wastewater treatment system operates (subject to correct loading and maintenance) without producing any odour.

Notably, the degradation of the humus layer during operation of the wastewater treatment system described herein is to such a degree that the emptying interval is significantly extended when compared to prior art systems that need to be emptied regularly. It is anticipated that the depth of the humus layer may be managed by the wastewater treatment process to such an extent that an emptying interval of at least 3 years can be achieved. It is however envisaged that a wastewater treatment system as described herein may perform so effectively that the vessel never needs to be emptied.

It is to be appreciated that the flow or circulation pattern established within the chamber is three-dimensional and may incorporate a plurality of distinguishable components of flow or circulation. Each component may involve linear and/or rotational motion, and may be distinguished by using one or more features, for example the degree of linear and/or circular flow along a flow path and whether the flow path forms a loop or has distinct start and end points.

In an example, a sub-pattern of flow may be identified as involving predominantly circular flow along a path extending from a start point at the exit port of the inlet to an end point at the entrance port of the outlet, another may be identified as involving predominantly linear flow along a path forming a loop traversing the chamber partition, and yet another may be identified as involving predominantly circular flow along a path forming a loop within the exterior zone.

The humus crust 701 is shown in Figure 9, formed within the exterior zone 205 of the chamber 105 of the vessel 104 of the wastewater treatment apparatus 101.

Figure 10 shows steps in a method of treating wastewater using the wastewater treatment apparatus, the method according to a process of the present disclosure. According to wastewater treatment method 1001, at step 1002, wastewater and aeration are supplied to the chamber of a vessel of a wastewater treatment apparatus described herein (such as wastewater treatment apparatus 101, and such as into the interior zone 204 of the chamber 105), and at step 1003, the underside of a humus crust developed at the liquid surface within the chamber of the vessel of the wastewater treatment apparatus (such as in the exterior zone 205 of the chamber 105 of wastewater treatment apparatus 101) is exposed to an oxygenated, circulating flow of received wastewater.

It is to be appreciated that a humus crust will develop over a period from the start of the wastewater treatment method 1001 and hence step 1002 may be considered an "initial" or "establishing" step and step 1003 may be considered a "steady-state" or "established" step. 10 Sewage/wastewater first enters the interior zone of the chamber (which may also be termed the "central chamber"), where air is continuously diffused in at the base (lower region). The sewage rapidly mixes with the contents of the central chamber. The continuous supply of air creates an environment that is right for naturally occurring micro-organisms to grow in the liquor and degrade the sewage. The process is aided by the treatment media, which provides both a means of physical degradation and a high surface area for the growth of micro-organisms.

The process in the outer settlement chamber includes the continuous recirculation of oxygenated liquor from the top of the central chamber to all around the base, with most solids returning to the central chamber. A contra-flow of some solids moving upwards causes a humus crust to form on the surface of the outer settlement chamber. This humus crust of solids is further degraded by the continuous flow of oxygenated recirculating liquid to the underside.

In one specific example, the wastewater treatment apparatus comprises a vessel that has: an external width of approximately 2084mm, an overall height of approximately 2370mm, an access port having a diameter of approximately 800 mm, a chamber partition having a diameter of approximately 800mm, an inlet pipe having an outer diameter 100mm a lower edge positioned approximately 600 mm below the top of the vessel, and an outlet pipe having an outer diameter 100mm and a lower edge positioned approximately 700 mm below the top of the vessel.

The surface area for development of the humus crust, within the exterior zone, is approximately 2.80 m2; and using the vessel in a 9-person system provides a humus crust surface area of approximately 0.31 m2 per person. Aeration is provided by an air blower providing an air flow in the range of 60 to 90 litres per minute.

In an example, the lower aperture arrangement comprises a plurality of openings, which are preferably substantially evenly distributed around the chamber partition and each of which has a substantially rectangular shape with a depth in the range of approximately 25 mm to approximately 35 mm and a length in the range of approximately 8.5 times to approximately 10.5 times the width.

In an example, the upper aperture arrangement comprises a plurality of openings, each of which has a substantially circular shape with a diameter in the range of approximately 15 mm to approximately 30 mm, and a baffle that extends downwardly a distance of between approximately 450 mm to approximately 550 mm.

It is to be appreciated that other specific examples of a wastewater treatment apparatus as described herein can vary in one or more aspects, and may have alternative dimensions, or alternative relative dimensions. For example, the volume of the chamber, the relative volumes of the interior and exterior zones of the chamber, the number, shape and size of openings of the lower aperture arrangement and of the upper aperture arrangement, the diameter and/or the positioning of the inlet pipe of the outlet pipes and the maximum flow level of the air diffuser arrangement may vary between examples.

It is further to be appreciated that a range of versions of the wastewater treatment apparatus can be provided, from which one version may be selected for a particular application. A range may be provided in which each version has a vessel with a different chamber capacity, so that a smaller version may be selected for use in an installation for treating wastewater from a lower number of building occupants and a larger version may be used for a higher number of building occupants.

In a specific example, the vessel is fabricated from glass fibre reinforced plastic (GRP) although any suitable alternative material or combination of materials may be used in its manufacture.

It is to be appreciated that a wastewater treatment system comprising the wastewater treatment apparatus of the present disclosure may comprise other features not yet described, including, but not limited to, an effluent sterilisation apparatus, which may utilise ozonisation, chlorination or UV light for performing a sterilisation function, an effluent pump, for example a submersible pump suitable for fitting internally, an alarm, for example an alarm, which may communicate with a remote device wirelessly, to alert of failure of an effluent pump or the presence of a high liquid level condition or failure of the air blower In addition to specific advantages already mentioned, the wastewater treatment system of the present application is beneficial for reducing carbon footprint and costs. The wastewater treatment apparatus treats all the sewage and requires infrequent emptying, as described previously, and also requires only simple and inexpensive routine maintenance, which an owner may be able to carry out themselves. These aspects serve to reduce the use of heavy polluting tankers for site visits, and the volume of sewage/sludge taken to major treatment plants. Further, the wastewater treatment apparatus does not require adjustment, which serves to reduce the need for service engineer visits.

It is to be appreciated that the present application provides a wastewater treatment system in which wastewater is aerated and circulated within a vessel containing a filter media that supports a microbiological colonisation, and further in which the depth of a humus crust formed within the vessel is constrained. Degradation also occurs in the mixed liquor or activated sludge. The degradation of the humus crust controls the depth of the humus crust sufficiently to significantly delay, or even overcome, the need for the vessel to be emptied. Benefits of the disclosed wastewater treatment system include reductions in carbon footprint and operating costs, decreased maintenance requirements, minimised or zero emptying requirements, zero odour emissions.

A wastewater treatment method and a wastewater treatment apparatus are disclosed herein. Interior and exterior zone of a chamber of a vessel are defined by a chamber partition disposed within the chamber, and upper and lower regions of the interior zone are in fluid communication with the exterior zone. An inlet directs wastewater to be treated into the interior zone, and an outlet intakes treated wastewater from the exterior zone for discharging outside the vessel. Treatment media is retained within the interior zone, and air is delivered to a lower region of the interior zone by an air delivery arrangement. An underside of a humus crust developed at the liquid surface within the exterior zone is exposed to a continuous flow of oxygenated, circulating received wastewater.

Although illustrative embodiments and examples of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is to be understood that the invention is not limited to the precise embodiment and examples shown and/or described and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims.

Claims

Claims I. A wastewater treatment method, comprising: supplying wastewater and aeration to a wastewater treatment apparatus; the wastewater treatment apparatus comprising: a vessel defining a chamber having a lower end and an upper end, a chamber partition disposed within the chamber to define an interior zone of the chamber, inside the chamber partition, and an exterior zone of the chamber, outside the chamber partition, wherein a lower region and an upper region of the interior zone of the chamber are in fluid communication with the exterior zone of the chamber, treatment media retained within the interior zone of the chamber, an inlet for receiving wastewater to be treated within the chamber, the inlet comprising an exit port arranged to direct liquid into the interior zone of the chamber, an outlet for discharging treated wastewater from the chamber, the outlet comprising an entrance port arranged to intake liquid from the exterior zone of the chamber, and an air delivery arrangement for delivering air to the lower region of the interior zone of the chamber; wherein an underside of a humus crust developed at the liquid surface within the exterior zone is exposed to a continuous flow of oxygenated, circulating received wastewater, and growth of a depth of the humus crust is inhibited by a degradation of the underside of the humus crust being maintained by said continuous flow of oxygenated, circulating received wastewater.
2. A wastewater treatment system, comprising: a wastewater treatment apparatus, the wastewater treatment apparatus comprising: a vessel defining a chamber having a lower end and an upper end, a chamber partition disposed within the chamber to define an interior zone of the chamber, inside the chamber partition, and an exterior zone of the chamber, outside the chamber partition, wherein a lower region and an upper region of the interior zone of the chamber are in fluid communication with the exterior zone of the chamber, treatment media retained within the interior zone of the chamber, an inlet for receiving wastewater to be treated within the chamber, the inlet comprising an exit port arranged to direct liquid into the interior zone of the chamber, an outlet for discharging treated wastewater from the chamber, the outlet comprising an entrance port arranged to intake liquid from the exterior zone of the chamber, and an air delivery arrangement for delivering air to the lower region of the interior zone of the chamber; in which a humus crust is developed at the liquid surface within the exterior zone of the chamber, an underside of the humus crust is exposed to a continuous flow of oxygenated, IC circulating received wastewater, and growth of a depth of the humus crust is inhibited by a degradation of an underside of the humus crust being maintained by said continuous flow of oxygenated, circulating received wastewater.
IS 3. A wastewater treatment method according to claim I, or a wastewater treatment system according to claim 2, wherein a lower portion of the chamber partition defines a lower transfer arrangement comprising a lower aperture arrangement that comprises at least one opening.
4. A wastewater treatment method according to claim 3, or a wastewater treatment system according to claim 3, wherein the lower aperture arrangement comprises a plurality of openings distributed around the circumference of the chamber partition.
5. A wastewater treatment method according to claim I, claim 3 or claim 4, or a wastewater treatment system according to any one of claims 2 to 4, wherein an upper region of the chamber partition is provided with an upper transfer arrangement that incorporates a baffle and an upper aperture arrangement that comprises at least one opening.
6. A wastewater treatment method according to claim I or any one of claims 3 to 5, or a wastewater treatment system according to any one of claims 2 to 5, wherein the interior and exterior zones of the chamber are arranged concentrically about a central axis of the chamber.
7. A wastewater treatment method according to claim I or any one of claims 3 to 6, or a wastewater treatment system according to any one of claims 2to 6, wherein the chamber partition and the chamber each define a cross-sectional shape that is one of: substantially cylindrical, substantially oblong.
8. A wastewater treatment method according to claim 1 or any one of claims 3 to 7, or a wastewater treatment system according to any one of claims 2 to 7, wherein the chamber partition defines a cross-sectional shape that is substantially constant along a depth direction of the chamber.
9. A wastewater treatment method according to claim! or any one of claims 6 to 8, or a wastewater treatment system according to claim 2 or any one of claims 6 to 8, wherein the entrance port of the outlet is closer to the bottom end of the chamber than the exit port of the inlet
10. A wastewater treatment method according to any one of claims 6 to 9, or a 20 wastewater treatment system according to any one of claims 6 to 9, wherein the exit port of the inlet is closer to the central axis of the chamber than the entrance port of the outlet
I I. A wastewater treatment method according to claim 1 or any one of claims 3 to 10, or a wastewater treatment system according to any one of claims 2 to 10, wherein the inlet is provided by an inlet pipe that comprises a straight piece.
12. A wastewater treatment method according to claim 1 or any one of claims 3 to II, or a wastewater treatment system according to any one of claims 2 to I I, wherein the outlet is provided by an outlet pipe that comprises a T-piece.
13. A wastewater treatment method according to claim 1 or any one of claims 3 to 12, or a wastewater treatment system according to any one of claims 2 to 12, wherein the air delivery arrangement comprises an air diffuser arrangement that comprises at least one air diffuser.
14. A wastewater treatment method according to claim 13, or a wastewater treatment system according to claim 13, wherein the air diffuser arrangement is connected to an air blower by air line.
IS. A wastewater treatment method according to claim 1 or any one of claims 3 to 14, or a wastewater treatment system according to any one of claims 2 to 14, wherein the 10 treatment media comprises a plurality of objects that provide a substrate for microbiological colonisation.
16. A wastewater treatment method according to claim 1 or any one of claims 3 to 15, or a wastewater treatment system according to any one of claims 2 to 15, wherein the vessel is fabricated from glass fibre reinforced plastic (GRP).
17. A wastewater treatment method according to claim 1 or any one of claims 3 to 16, or a wastewater treatment system according to any one of claims 2 to 16, wherein the vessel is configured for underground installation.
I 8. A wastewater treatment method according to claim 1 or any one of claims 3 to 17, or a wastewater treatment system according to any one of claims 2 to 17, wherein the vessel defines an access port, providing access into the chamber, the access port positioned to provide access into the chamber from the upper end of the chamber.
19. Use of a wastewater treatment method according to claim 1 or any one of claims 3 to 18, or a wastewater treatment system according to any one of claims 2 to 18, to treat wastewater from one of: a residential property, a commercial property.
20. A package treatment plant installation incorporating a wastewater treatment system according to any one of claims 2 to 18.