- 1 AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR AN INNOVATION PATENT ORIGINAL Name of Applicant: Toby Gray Actual Inventor: Toby Gray Address for Service is: SHELSTON IP 60 Margaret Street Telephone No: (02) 9777 1111 SYDNEY NSW 2000 Facsimile No. (02) 9241 4666 CCN: 3710000352 Attorney Code: SW Invention Title: WATER TREATMENT SYSTEM The following statement is a full description of this invention, including the best method of performing it known to me: File: 41874AUP00 -la WATER TREATMENT SYSTEM TECHNICAL FIELD The present invention relates to systems and methods of treating water, in particular to treating wastewater. The invention has been developed primarily for 5 treating wastewater and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use. BACKGROUND OF THE INVENTION 10 Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in the field. Previously known systems for communicating water include vertical wall 15 systems consisting of planter boxes. However, previous systems were developed without an intentional wastewater treatment process function. Further, the structures used in designs hitherto have been limiting and bulky. Therefore there has been a need for specifically designed, compact (i.e. small 20 footprint), cost effective and easily maintainable waste water treatment systems, which can provide treated waste water of a quality suitable for use in non-potable water end uses in urban and industrial areas. In a residential context, these end uses can include irrigation, toilet flush toilets, washing machines, outdoor use and the like. There is also a need for an effective substantially non-chemical treatment of water, which returns 25 nutrients from wastewater streams into biomass that can be composted. It is an object of the invention to overcome or substantially ameliorate one or more disadvantages of the prior art, or at least to provide a useful alternative. 30 The present invention therefore provides for a system and method of treating wastewater. The invention also provides for a system of treating wastewater that is compact, allowing for application within, but not limited to, urban areas. The system -2 and method also minimise chemical treatment and utilise natural nutrient absorption and pollutant reduction processes to treat the wastewater. The invention also provides a system that has been designed so that wastewater 5 is substantially contained within the system structure and is not significantly visible which is important in terms of public health. It also minimises water loss by evaporation. DEFINITION OF THE INVENTION 10 In a first aspect, the invention provides a system for treating water including: a plurality of stacked chambers in fluid communication with each other and connected by a filter means; wherein at least part of said filter means includes a vertical trickle filter; and wherein two or more of said chambers include a simulated wetland zone. 15 Preferably, the fluid communication between the chambers is substantially vertical and the water exits each chamber by way of a weir. Preferably, the system for treating water includes: 20 at least three stacked chambers in fluid communication with each other and connected by one or more vertical trickle filters; and wherein each of the chambers includes a simulated wetland zone. Preferably the vertical trickle filter includes porous medium for the water to flow 25 over. Preferably the porous medium is a porous filtration medium. Preferably the simulated wetland zone is a subsurface wetland zone. More preferably the simulated wetland zone is a saturated wetland zone that can be substantially aerobic or aerobic, anoxic and anaerobic. Preferably, the simulated 30 wetland zone includes wetland vegetation like plants, most preferably macrophytes. In some embodiments, the wetland zone includes a porous medium.
- 3 In a preferred embodiment, the at least three stacked chambers are connected by way of a single trickle filter. Preferably, the water is treated by passing the water through the vertical trickle filter, which includes a filtration medium. 5 Preferably the water to be treated is wastewater. In one embodiment the wastewater is grey water. In one preferred embodiment, the vertical trickle filter is followed by the simulated saturated wetland zone. In a preferred embodiment a vertical trickle filter is 10 present in every chamber. In yet another preferred embodiment, the vertical trickle filter has hydraulically connected planted zones. In a preferred embodiment, the system for treating wastewater includes: at least three vertically stacked chambers wherein each of the chambers is 15 configured to be in fluid communication with the next chamber; each of said chambers includes a simulated sub-surface wetland zone; each of said chambers is connected to the next chamber by way of one or more vertical trickle filters; and wherein the one or more vertical trickle filters include a porous filtration 20 medium. In a second aspect, the invention provides a method of treating water including the steps of: contacting the water to be treated with 25 (a) a plurality of stacked chambers that are in fluid communication with each other and connected by one or more filter means, at least part of said filter means including a vertical trickle filter; and (b) a porous filtering medium of said vertical trickle filter; wherein the water flows by gravity feed through said chambers and said filter 30 means at substantially the same rate. In one embodiment, the plurality of stacked chambers include a simulated wetland zone. In one preferred embodiment, the water is contacted alternately with the -4 wetland zone and the porous medium. In another preferred embodiment, the water is contacted simultaneously with the wetland zone and the porous medium. In a preferred embodiment of the second aspect, the residence time is determined 5 by the physical dimensions of a unit in relation to other typical backyard items, i.e. it can be made small to fit. Preferably, the method of treating wastewater includes the steps of: admitting the water to be treated into a first chamber including a simulated 10 wetland zone and contacting said water with a porous medium within the simulated wetland zone; admitting water exiting the first chamber into a second chamber including a simulated wetland zone and contacting said water with a porous medium within the simulated wetland zone; 15 admitting water exiting the second filtering chamber into a third filtering chamber including a simulated wetland zone and contacting said water with a porous medium within the simulated wetland zone; and ensuring that water remains in each chamber for a specific residence time. 20 Preferably, the method includes the step of exposing the water in each of the chambers to both aerobic and anaerobic environments. In one preferred embodiment, the environment is substantially aerobic. Preferably the flow of said water through the plurality of chambers is substantially vertical, cyclical and by gravity feed. Preferably the residence time of the water in the system is at least 12 hours. 25 In a preferred embodiment, the system of the invention will be preceded by a sump with preliminary filter screen to collect the wastewater and complete preliminary filtration. 30 BRIEF DESCRIPTION OF THE FIGURES A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: -5 Fig. I is a system according to the invention including a first, second and third chamber with several vertical trickle filters; Fig. 2 is an alternate embodiment of the system according to the invention 5 including a first, second and third chamber with a single vertical trickle filter; and. Fig. 3 is yet another alternate embodiment of the system according to the invention. DETAILED DESCRIPTION OF THE INVENTION 10 Referring to the drawings, a system for treating wastewater includes a first chamber A, a second chamber B and a third chamber C (Figs. 1, 2 and 3). Chambers A, B and C are configured to be in fluid communication. The flow of said water through the system is substantially vertical and by gravity feed as indicated by Figs. 1, 2 and 3. Chambers A, B and C can be planter boxes. 15 The term "vertical" or "vertically" is meant to indicate that the chambers are aligned in a line or direction towards a zenith. The alignment may be at any angle but in its preferred embodiment the chambers are aligned parallel to a horizontal axis as indicated in Figs. I to 3. 20 Chamber A includes a simulated wetland zone 2 as seen in Fig. 1. The wetland zone 2 is a subsurface wetland zone with overflow that has the potential for denitrification and phosphorus fixation and in Figs. I and 3 is a saturated wetland zone where both aerobic and anaerobic processes can take place. By the term subsurface is 25 meant that the wetland has a water level below the surface of the basic media. In a preferred embodiment, the lower section of chamber A is anaerobic. The transmission of water from aerobic to anaerobic zones allows for the process of denitrification to occur. During nitrification - denitrification nitrogen is removed from the water. The zone includes wetland vegetation like plants 1, 16 and 20. In the embodiments 30 represented by Figs. 1 and 3, the plants are macrophytes. Chamber A is capable of retaining a volume of water, for a predetermined time fixed by the treatment requirements desired. Without being limited by theory, it is believed that this increases -6 the pollutants exposure time to microbial activity and plant roots. Chamber A also includes fixed baffles zone 4 and vertical filtration zone 3 to assist in draining and aerating water leaving the zone 2. Preferably the water level remains at the level of baffle 4 as shown in Fig. 1. 5 Chambers A, B and C can include medium (17 in Fig. 2) which consists of a mixture of synthetic filtration medium, natural aggregates, and soil. The medium includes porous material selected to maximise surface areas for microbiological growth. This medium may also be selected to absorb phosphorous via physiochemical processes 10 of sorption. Chamber A is drained via a vertical filtration zone which may drain from a baffle within the chamber at any point. This vertical filtration zone is to connect chamber A to further treatment chambers hydraulically as indicated in Figs. I and 3. Treatment of 15 water is to occur within this zone via filtration of the waste water in an aerobic environment. The filtration medium within this zone may be either natural sand or gravel or synthetic. Chamber B is to be similar to chamber A in function and components, however 20 may vary in scale. Chamber B is drained in an identical manner to chamber A. Chamber C is also to be similar to chamber A in function and components, however may vary in scale. However, chamber C is drained to a final collection sump from drain 10. 25 The system according to the invention also includes a filter means that is a vertical trickle system which includes vertical trickle zones 3, 6 and 8 which are designed to further aerate the wastewater and expose it to micro-organisms growing on the trickle. These zones are filled with gravel or synthetic filter medium or any other 30 material having good hydraulic conductivity, i.e. allows water to flow through it. In the most preferred embodiments the material is mineral gravel with a honeycomb structure that can trap chemicals. In another preferred embodiment the material is synthetic filter fabric. Nutrient absorption material like blast furnace slag may also be employed.
-7 The vertical trickle zone can also be a single continuous vertical trickle filter 19 with chambers A, B and C connecting off the vertical section as seen in Fig. 2. In this configuration the transition of water into chambers A, B and C is via a geo-membrane 5 layer 21 from the vertical trickle medium 17. All other functions are the same. This configuration drains via a base drain 22 from the single vertical trickle filter. The wetland zone 2, 7 and 9 can include a porous medium like gravel, sand or synthetic filter medium. 10 Fig. 1 also shows the hydraulic profile of the system. In the first chamber, water to be treated enters via inlet 13 and fills the chamber. It continues to flow upwardly 12 as shown. It passes over and into baffle zone 4 where it moves downwardly via the pipe 5 into vertical trickle zone 6. It passes through vertical trickle zone 6 into the next 15 chamber where the process is repeated, i.e. the moisture rises in the chamber, passes over the top of the weir 14 to enter the baffle zone. Once again it moves down the baffle zone via the pipe into a further vertical trickle zone 8. Again in the third chamber as shown in the drawing a hydraulic flow of water to be treated rises in the chamber, passes over the baffle or weir into baffle zone for ultimate release via outlet 15. 20 A similar profile is shown in Fig. 3 which, as discussed below, uses a pipe for transmission to the vertical trickle zone 6 wall or baffle. The hydraulic profile shown clarifies the cyclic anaerobic/aerobic treatment of 25 the water in the systems of Figs. I and 3. As the water to be treated flows upwardly in the chamber, it passes from an anaerobic treatment (at the lower end/subsurface of the chamber) to an aerobic treatment (toward the surface). As it passes through the trickle zone, aerobic treatment continues. Once again as the water passes from the trickle zone into the second chamber, anaerobic treatment commences again which then transforms 30 to aerobic treatment as the water passes to the upper end of the chamber. This is, of course, continued in the next trickle zone and chamber. Such cycling of anaerobic and aerobic treatment has significant advantages as discussed through the specification.
-8 Since there is a single trickle zone in Fig. 2, the flow is both downwards (24) as well as between the trickle zone and the chambers A, B and C (25) through geo membrane layer 21. The treatment in such a system is substantially aerobic. 5 The wastewater to be treated is grey water or black water. In alternate embodiments, it can be storm water, urine, effluent from septic tanks or composting toilets, raw sewerage and various combinations of all the above types of wastewater. The system is especially suitable for treating greywater or for secondary treatment of 10 black water after it has been through a septic tank or industrial waste water after it has had its solids removed. The treated water obtained from the system according to the invention can optionally be disinfected before being used. 15 As apparent from the figures, the system has been designed so that wastewater will never be visible as it will always be below the growth mediums surface or contained physically within the system structure. This is an important feature in terms of public health. 20 Without being limited by theory, it is believed that the system according to the invention acts as a biological filter that treats the wastewater by both mechanical and biological processes. Biological filtration will occur on the surface of the porous filter mediums and plant roots, the porous filter medium includes that within the chamber and 25 vertical trickle filters. Biological pollutant and nutrient removal will occur via micro organisms and plant bioprocesses. Pollutants and nutrients may also be absorbed via physiochemical reactions between the pollutants and the physical surface of the porous filtration medium. 30 The system provides for nutrient removal and it is expected, again without being bound by theory, that the major mechanism for nitrogen removal from wastewater is through the nitrification - denitrification processes. Nitrification involves the oxidization of nitrogen species by nitrifying bacteria in one or more aerobic zones, -9 including the vertical trickle filter. Then the nitrates are converted to dinitrogen gas by denitrifying bacteria in the anaerobic zone within the chambers A, B or C. The aeration stages of the system will aid in nitrification of the wastewater. A volume of Nitrogen will also be taken up into the plants and retained in their biomass. 5 The removal of phosphorous is expected to take place mainly through absorption, complexation and precipitation reactions with the porous filtration medium and soil medium. Preferably, the porous filtration mediums are selected to have low cation exchange properties in order to facilitate removal of phosphorus. 10 The various components of the system are built of a corrosion resistant material suitable to hold untreated water for a long period of time. In the method of treating water according to the invention, turning to Figs. 1 and 15 3, water is admitted to the first chamber A which includes a simulated wetland zone 2. The treated water is then retained in the first chamber for a finite residence time. The contacted water is then conveyed to the second chamber which includes a simulated wetland zone 7. The treated water from the second chamber is collected after a finite residence time in the second chamber. The contacted water is then conveyed to the third 20 chamber C which includes a simulated wetland zone 9. Subsequently, the treated water from the third filtering chamber is released for use as required. Both aerobic and anaerobic processes can take place in the chambers. It will be appreciated that the water also passes through the vertical filtration 25 zones 3, 6 and 8 wherein the water contacts the porous medium of the zone for a finite amount of time. It will also be appreciated that more than three chambers can be present in the system. 30 In a preferred method, the flow of the water through the first, second and third filtering chambers is substantially vertical. In one embodiment, the vertical hydraulic connections between the first, second and third filter chambers includes a vertical trickle - 10 filter 19. The residence time within the entire system is at least twelve hours and more preferably the residence time is at least 24 hours. The method and system according to the invention provides for a reduced surface 5 area and minimises water loss by evaporation. Calculations that follow are based on the data for individual components of the system, where available. All calculations are conservative to allow for unforseen influences on the system and to comply with relevant recycled water standards. 10 In use, the filtered wastewater, for example grey water, is released via the pressurised pipe work system 13 below the surface of the porous medium 2 of chamber A (Figs. I and 3). The wastewater will enter the system via a controlled pumping regime. The water volume entering the system will vary depending on the application. 15 The system can be extended linearly to increase the capacity, in this case the form and function of the system will remain as described here. It is expected that the system can deal with the daily flux by having a storage capacity in the sump that precedes the system, of 300 litres and having a sewerage over flow point in this sump. The sump in some embodiments can have a preliminary filter screen. 20 The loading rate for chambers A, B and C and the vertical trickle filter is important. Too high a loading rate will lead to flooding. Further, whilst in some circumstances the wastewater alone can provide suitable nutrients for the plants I to thrive, a small amount of organic material is usually added to improve growing 25 conditions. However, this can decrease the hydraulic conductivity of the porous medium 2 thereby requiring a reduced loading rate. It is also desirable to have a finer porous medium to increase the surface area for treatment. However, such a medium is prone to clogging and therefore lower loading rate will decrease maintenance requirements. A reduced loading rate is therefore desirable. In general the loading rate for the chambers 30 and the vertical trickle filter is sought to be optimal and will depend upon the material and conditions maintained in the chambers.
- 11 The hydraulic load on the system will depend on the application and treatment requirements. For example, if the system requires water to be treated to a higher degree for reuse in toilet flushing or washing machines, a lower hydraulic load rate is to apply. Conversely if the waste water is to be used only for sub-surface irrigation, a higher 5 hydraulic load rate may be applied. The scale of the system can be adjusted depending on the volume and degree of water treatment required. Data from previous studies has shown that a 48 cm vertical aerated trickle zone can provide up to 70% nitrification, an overall Biological Oxygen Demand (BOD) 10 reduction of up to 78% and a suspended solids (SS) reduction of up to 69%. The effluent used in this study is from septic tanks with much higher pollutant loadings and higher loading rate. The system according to the invention, in one preferred embodiment (Fig. 2) has 15 a vertical trickle zone of approximately at least 80 cm, preferably at least 100 cms and most preferably at least 150 cms. By way of example, the lengths for fig I and 3 are approximately 1 linear metre per bedroom, i.e. 1 metre for 2 persons greywater. The length can be longer if the boxes were skinnier or shorter if they were wider and is also dependent on depth, i.e. depending upon the application the length can be customised. 20 This design allows for better distribution and provides a better performance than the study mentioned above. As such it is expected that the proposed system can achieve an overall similar Biological Oxygen Demand (BOD) reduction. Performance can be further improved by using a finer medium. 25 In order to reduce the remaining BOD and to reduce nitrogen and phosphorus levels in the wastewater, the water is required to be retained in the simulated wetland environment provided by chambers A, B and C. The retention time and subsequent treatment of water is further dictated by the storage volume within the medium's pore spaces and the hydraulic loading rates within the chambers. 30 This treatment should provide a further reduction in BOD of around 55 % from the effluent that entered chambers A, B and C. Making the assumption that the effluent's BOD was reduced by 60% by passing through chamber B, the water leaving - 12 the chamber B should have a BOD of less than 14.9mg/L. This is within the limit for recycled greywater standards required to reuse greywater for toilet flushing, washing machines and above ground irrigation in countries like Australia. 5 The level of Nitrogen removal is harder to estimate. The water entering the chamber B will be highly aerated and therefore only small anoxic zones will be present to aid in de-Nitrification. However a medium structure will be used to aid in the development of such zones. There will be a small uptake of nitrogen into the plants biomass. Likewise the effectiveness of the medium to remove phosphorous cannot be 10 determined empirically. However, it can be reasonably estimated that nitrogen and phosphorus are removed by the system and method of the invention by denitrification and absorption, complexation and precipitation reactions. The vertical trickle zones 19 are expected to further assist in the reduction in 15 BOD and SS. Table 1 shows the expected reductions in pollutants between each stage. These are conservative figures, they do not take into account the effect of the vertical trickle zones and assume conservative levels for the individual chambers, i.e. A, B and C, level 20 of performance. For example it is expected that Stage 3 will not provide the same level of treatment as stage 1, due to less defined drying periods therefore the level of treatment by this stage has been assumed to be much lower. Table 1: BOD (mg/L) SS (mg/L) Greywater Pollutant 45 163 Loadings Stage 1: Chamber A 27 65 Stage 2: Chamber B 14.9 32 Stage 3: Chamber C 7 12 25 The level of thermo tolerant coliform expected at each stage has not been calculated empirically. These bacteria do not survive long out side the warm conditions -13 within the body, and will therefore be deplete with time and be destroyed physically within the system according to the invention. Test results confirm the before mentioned theory, with the following test results 5 achieved through prototype units. Parameter Value Units BOD5 <5 mg/L Total suspended solids @ 1003-105 0 C < 5 mg/L Faecal Coliforms < 1 CFU/OOmL The testing regime covered 3 years over I1 test runs. Testing was completed by SGS Australia. These results relate to two systems according to the invention 10 (GreenwallI
TM
), designed to service 3 and 4 bedroom homes respectively. A typical width would be about 1 meter per bedroom. It will be appreciated that the present system provides for wastewater treatment by predominantly physicochemical and biological mechanisms and reduces chemical 15 treatment. In preferred embodiments, the system allows water to flow via gravity, therefore decreasing the energy requirements of the system. The water trickles down through different engineered environments, which are designed to reduce the pollutant loading and produce a high quality effluent. The system can also be installed on the sides of building and walls, uses minimal space and is aesthetically pleasant. The 20 system increases the effectiveness of treatment, by distributing the wastewater evenly over the medium. The saturated chamber, namely chamber B, mimics and matches the natural wetland environment where water purification processes occur. This is also good at removing nutrients from the wastewater and also retaining the wastewater for longer and is thereby expected to decrease the BOD and numbers of pathogens. Vertical 25 trickle zones in the system further carry out water purification via physical and biological means. Therefore this system provides a high level of treatment and can be adapted for a variety of uses. The most preferred use is for the treatment and subsequent recycling of greywater. However other wastewater streams such as stormwater, urine, - 14 effluent from septic tanks and from composting toilets, raw sewerage and various combinations of all the waste streams can also be treated. Alternate embodiments of the system include components described previously 5 connected in different configurations. Fig. 3 shows an alternate embodiment of the invention, which includes a vertical trickle zone 28 connected to a saturated subsurface wetland zone 30, which is drained via a weir 34. It will be appreciated that more than one vertical system according to the 10 invention can be employed in varying configurations to effectively treat wastewater. The system according to the invention can be in an off the shelf, ready to use format or may be provided as a kit that can be assembled in accordance with instructions. 15 It will be appreciated that the illustrated system and method of treating wastewater provides for reduced environmental impact and can be employed in medium and high-density urban areas and in high-rise developments. 20 Although the invention has been described with reference to a specific example, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.