DOIUIESTIC WASTEWATER TREATMENT SYSTEM

Technical Field of the Invention

The invention relates to the treatment of wastewater, and in particular, to a domestic wastewater treatment system which provides a high buffer capacity membrane filtration process for the separation of solids and treated water to produce a high quality effluent for recycling or reuse.

Whilst the invention may be modified to suit commercial wastewater and wastewater treatment plant applications, for convenience sake, it shall be described herein in terms of a wastewater treatment system for domestic applications.

Background to the Invention

In recent years, (he awareness of water usage and conservation has become of paramount importance as the water levels in Australia, and many other countries across the globe, have become increasingly low. Thus, the need has arisen to develop products which are designed to save and/or recycle used water.

As a result, there has been a number of domestic wastewater treatment systems developed which are designed to use and treat standard activated sludge. The treatment systems currently come in two types which vary depending on whether they utilise a double anaerobic/aerobic process or single aerobic process to digest settled sewage or biomass. The disadvantage of these systems is they rely on the settling of bacteria or biomass in order to achieve and produce a clarified effluent. However, varying conditions within the plant/system can often cause bacteria to grow which will not settle and thus, result in a poor quality or turbid effluent being produced. In addition, the systems of the prior art all require the use of chlorine or UV to provide adequate disinfection for the wastewater which can be eliminated with the membrane filtration process of the invention.

Accordingly, it is an object of the present invention to overcome or substantially ameliorate the disadvantages of the prior art by providing a domestic wastewater treatment system which provides a high buffer capacity membrane filtration process

for the separation of solids and treated water to produce a high quality effluent for recycling or reuse.

Summary of the Invention

The present invention provides a domestic wastewater treatment system including: a body portion in the form of a single tank having at least one chamber and an inlet and an outlet connection; an air/oxygen supply; at least one pump; at least one disinfection means; at least one membrane filtration un ^' rt; at least one level indicator; and a control box whereby the domestic wastewater treatment system provides a high buffer capacity membrane filtration process for the separation of solids and treated water to produce a high quality effluent for recycling or reuse.

It is preferred that a first chamber is preferably adapted to receive the incoming sewage and provide a buffering capacity when there is a high incoming load.

It is further preferred that the first chamber is preferably adapted to have an air supply and a plurality of micro-organisms to enable the aerobic treatment of the wastewater.

It is preferred that a first pump is a transfer pump which is adapted to transfer the partially treated wastewater from a first chamber to a second chamber.

It is preferred that the control box is preferably adapted to be mounted directly above the body portion of the system. The control box preferably has provided an air blower which is adapted to supply air to at least one diffuser of the system.

It is preferred a second chamber is preferably in the form of a membrane biological reactor (MBR) chamber. The second chamber is preferably adapted to provide a second aerobic treatment process for incoming sewage as well as the existing biomass.

It is preferred that the membrane filiration unit preferably has provided at least one membrane.

It is preferred that the membranes are preferably perforated having a plurality of pores to allow for the adequate removal of all faecal coliforms and a suitable proportion of viruses to provide a first means of disinfection for the treatment of wastewater.

It is further preferred that a second pump is a suction pump contained within the control box. The suction pump is preferably a low voltage diaphragm pump which is adapted to draw treated wastewater through the membrane filters and deposit it into the third treated effluent chamber.

It is further preferred that a third chamber is preferably adapted to be a treated effluent chamber which is adapted to hold the treated water until it is ready for use. The third chamber is adapted to provide a second means of disinfection for the wastewater treatment system.

The third chamber preferably has provided an effluent pump which is utilised to supply treated water to the irrigation system.

In order that the invention may be more readily understood we will describe by way of non-limiting example of a specific embodiment thereof.

Brief Description of the Drawing Figures

Figure 1 shows a perεpectfve cross-sectional view of the domestic wastewater treatment system according to an embodiment of the invention.

Figure 2 shows a schematic view of the domestic wastewater treatment system according to an embodiment of the invention.

Description of a Preferred Embodiment of the Invention

Figures 1 to 2 show a domestic wastewater treatment system according to an embodiment of the invention.

The present invention provides a domestic wastewater treatment system which provides a high buffer capacity membrane filtration process for the separation of solids and treated water to produce a high quality effluent for recycling or reuse. The term wastewater should be understood to be any wastewater coming from a domestic household such as black and grey water or grey water only. Accordingly, the system 1 with additional disinfection can be used to treat water for reuse back into other applications such as reuse back into toilets, car washing, laundry or any other suitable application. The system 1 is designed to treat wastewater safely and in a manner which will produce a standard suitable for use for surface irrigation. The system 1 is adapted to be installed in the garden below the ground surface so as not to detract from the aesthetic appeal of the domestic property. However, it is envisaged that the system could also be installed above ground or be free-standing. The system 1 preferably utilises membrane filtration far the separation of solids and treated water, rather than relying on settling processes, to produce higher solid levels within the biomass of the system to result in a smaller overall footprint. The system 1 has provided a body portion 2 which is adapted to house all the necessary components of the system for the treatment of domestic wastewater. The body portion 2 is preferably made of a high-density polyethylene material. However, it is envisaged that any other suitable material may also be used provided that it is strong, durable, water and weather-resistant and meets the requirements of the invention and regulatory safety and hygiene standards. It is envisaged that the shape, style and dimensions of the system 1 and its components may be varied as desired to suit different requirements and/or applications.

The body portion 2 of the system 1 is in the form of a single tank divided into at least one chamber which is designed for the treatment of wastewater 4. In a preferred embodiment of the invention, the body portion 2 is preferably divided into three chambers 10, 20, 30 which are adapted to treat the wastewater 4 therein. The chambers 10, 20, 30 are adapted to be integrally formed with the body portion of the system, such that the outer perimeter of the chamber is formed by the walls of the body portion, and be located adjacent to each other and separated by at least one common/dividing wall.

A first chamber 10 is preferably a main tank for treating the wastewater 4. The first chamber 10 is adapted to receive the incoming untreated sewage and provide a buffering capacity when there is a high incoming load. The first chamber 10 is adapted to have an oxygen supply 12 to enable the aerobic treatment of the

wastewater 4 and function as a primary aeration chamber. A plurality of microorganisms 11 are placed within the first chamber 10 which are adapted to breakdown and digest the impurities within Ihe wastewater 4 or sewage to provide an initial means of treating the wastewater.

The first chamber 10 has provided an input connection 13 which is adapted to receive the incoming wastewater 4 diverted from the household sewage line. The sewage connection 13 provides connection for a single household to use the system and can preferably be retrofitted to a household's existing sewage system. The system 1 of the invention has provided a control box 14 which is adapted to house the components necessary for controlling and regulating the supply of air/oxygen to the system 1 and movement and treatment of the water through the system 1. The control box 14 is adapted to be mounted directly above the body portion 2 of the system 1. The control box 4 has provided an air blower 12 which is adapted to supply air for the system 1. However, it is envisaged that any other suitable means for supplying oxygen may also be employed. At least one diffuser is provided for recefving the air/oxygen and distributing the oxygen into the relevant chambers of the system 1. A first diffuser is preferably a fine bubble air drffuser 15 which is adapted to provide aeration to the first chamber 10. The aeration allows the micro-organisms contained within the first chamber 10 to mix with the wastewater 4 and breakdown and digest the organic material contained within the wastewater 4 through biological activity. The control box 14 and/or air blower 12 is preferably adapted to have provided a pressure switch (not shown) which is adapted to monitor the operation of the air blower 12 and activate an alarm (nofshown) of the control box 14 in the event that the air output drops below the required level for optimal aeration within the chamber 10. In a preferred embodiment, the incoming sewage/wastewater 4 is aerated on a cyclic basis (ie. it is aerated for a prescribed period followed by a prescribed period where there is no additional air/oxygen added).

Connected between the first chamber 10 and second chamber 20 is a transfer pump 16 for transferring the wastewater 4 for the next stage of treatment. The transfer pump 16 is preferably a PVC air venture pump which is adapted to transfer the treated wastewater 4 from the first chamber 10 to the second chamber 20 for further treatment and/or disinfection. The transfer pump 16 is adapted to periodically pump the partially treated sewage to allow for adequate treatment of the wastewater 4 in the first chamber 10 prior to its transfer into the second chamber 20. However, if there is a high level of wastewater 4 within the first chamber 10, it is envisaged a high

level alarm will be activated to activate the transfer pump 16 to pump the wastewater 4 though to the second chamber 20 to maintain a suitable capacity level for the first chamber 10.

A second chamber 20 is a membrane biological reactor (MBR) chamber. The second chamber 20 is designed to provide a second aerobic treatment process for incoming sewage as well as the existing biomass. The second MBR chamber 20 preferably has provided a second air diffuser 21 which is adapted to provide aeration for the second MBR chamber 20. The air diffuser 21 is preferably a fine bubble air diffuser which is adapted to be attached tα the bottom of the second MBR chamber 20. The air/αxygen for the air diffuser 21 is supplied via the air blower 12 of the control box 14 mounted on top of the body portion 2 of the system 1. The aeration allows the microorganisms contained within the second chamber 20 to mix with the wastewater 4 and further breakdown and digest the organic material contained within the wastewater 4. The control box 14 and/or air blower 12 is adapted to have provided a pressure switch which is adapted to monitor the operation of the air blower and activate an alarm of the control box 14 if the air output drops below the required level and stop the suction pump 24.

The second MBR chamber 20 has provided a membrane filtration unit 22 for the separation of solids and treated water. The membrane filtration unit 22 preferably has provided at least one submerged membrane 23. The membranes 23 are preferably adapted to be self-cleaning, utilising the shearing action of the diffused air/oxygen and mixed liquor as it rises, to scour the external face of the membranes 23 and break any trapped solid particles, or build up of bio-mass. The membranes 23 are preferably flat plate membranes which are perforated having a plurality of pores. In a preferred embodiment, the pore size is 0.2 microns or smaller to provide a suitable physical barrier in order to guarantee the effluent quality which is not available from systems using settling processes only. However, it is envisaged that the pore size may be variable to allow for the adequate removal of all faecal coliforms and a suitable proportion of viruses to provide a first means of disinfection for the treatment of the wastewater 4. The membranes 23 are designed to provide "membrane disinfection" to thermo-tolerant coliforms via the physical blocking of such bacteria due to the membrane pore size. This physical disinfection without the use of chlorination, UV radiation or oiher chemical means is quite unique for these systems.

Movement and/or transfer of the treated wastewater 4 within the second chamber 20 preferably occurs via a suction pump 24 contained within the control box 14. The suction pump 24 is preferably a low voltage diaphragm pump which is adapted to draw the treated/disinfected wastewater 4 through the membrane filters 23 and deposit it into the third treated effluent chamber 30 /or further treatment of the wastewater 4. The second MBR chamber 20 is adapted to have provided a working level float (not shown) which is adapted to control the transfer of treated effluent through the membranes 23 into the third chamber 30. The float is preferably set to operate at a differential of 200mm. In a preferred embodiment, a high level of treated wastewater 4 will cause the activation of the suction pump 24 and de-activation of the transfer pump 16, and a low level of treated wastewater will cause de-activation of the suction pump 24 and activation of the transfer pump 16 to regulate the wastewater 4 capacity through the system 1,

A third chamber 30 is a treated effluent chamber which is adapted to hold the tre.ated water until it is ready for use. The third chamber 30 is adapted to provide a second means of disinfection for the wastewater treatment system. In a preferred embodiment of the invention, the disinfectant means is a chlorinator 31, preferably in a tablet form, which is adapted fo provide a secondary disinfection rf required. The chlorinator 31 is located between the second chamber 20 and third chamber 30 so that the wastewater can be pumped through the membrane filters 23 and into the third chamber 30 flowing over the chlorinator 31. However, in an alternale embodiment it is envisaged that any other suitable disinfection means such as UV or chemical treatment could also be adopted. Ideally, the system 1 of the invention is adapted to treat domestic wastewater 4 without the use of any chlorine, UV or other chemicals. The third chamber 30 preferably has provided an effluent pump 32 which is utilised to supply treated water to an irrigation system. The third chamber 30 preferably has provided an irrigation pump float switch (not shown) which is adapted to activate the effluent pump 32 and pump the treated water through to the irrigation system when there is an adequate volume of treated water within the third chamber 30. Thus, the frequency of discharge of the treated effluent is determined by the level of effluent within the third chamber 30. In the event that the treated effluent within the third chamber 30 reaches a level which is determined to be too high, a high level float switch (not shown) will be activated and the suction pump 24 will be stopped to prevent overflow of the system 1.

The system 1 of the invention has provided a control box 14 which is adapted to house the components necessary for the supply of air/oxygen to the system 1 and control the movement and treatment of the wastewater 4 through the system 1. The system 1 has provided an aeration timer (not shown) which is adapted to control the operation of the aeration/oxygen supply via a solenoid valve {not shown) which opens and closes to allow the air from the blower 12 to periodically feed into the first 10 and/or second 20 chambers of the body portion 2. The air blower 12 is preferably situated so that it operates to continuously supply air to the MBR chamber. The control box 14 has provided a suction pump 24, in the form of a low voltage diaphragm pump, which is adapted to draw treated wastewater through the membrane filters 23 and deposit it into the treated effluent chamber 30, The control box 14 has provided a control panel (not shown) which ensures the system is operating efficiently is adapted to generate an alarm in the event that an abnormal condition occurs. The control b.ox 14 is preferably mounted directly above the primary chamber and is connected to a power source, which may be a direct and/or alternate current source, for the operation of its components.

In practice, the sewage from the domestic property is diverted into the body portion 2 of the system 1 via an incoming sewage line and connection <not shown) connected to the first chamber 10 of the body portion 2. In the first chamber 1 O ₁ the incoming wastewater 4 is partially treated by aeration and digestion of organic and biomass material via micro-organisms and/or microbes contained within the first chamber 10. Following the initial treatment, the partially treated sewage/wastewater 4 is periodically pumped into the second MBR chamber 20 for further aeration and filtration/disinfection of the wastewater 4. The frequency of operation of the transfer pump 16 is preferably determined by the hydraulic loading applied to the treatment system 1. The wastewater 4 is further treated in the second chamber 20 and is pulled through the membrane plates 23 of the membrane filtration unit 22 via the suction pump 24 to undergo a first means of disinfection in the form of filtration through a physical barrier. The treated wastewater 4 is then passed from the second chamber 20 into the third chamber 30 where it is held until ready to be pumped into an irrigation system and/or undergo a further disinfection process.

The system of the invention ensures that there is almost no build up of excess sludge as all or most of the organic matter and excess biomass contained within the wastewater 4 should be oxidised to keep the sludge build up within the aeration chambers 10, 20 to a minimum. As a precaution, sludge levels should be monitored

aπd recorded at prescribed service intervals to ensure that the treatment process is working correctly. Fn the event that the microbes are subjected to large amounts of toxic substances, the contents of the system 1 may need to be removed and "re- sεeded".

While we have described herein a particular embodiment of a domestic wastewater treatment system 1, it is further envisaged that other embodiments of the invention could exhibit any number and combination of any one of the features previously described. However, it is to be understood that any variations and modifications can be made without departing from the spirit and scope thereof.