BACKGROUND OF THE INVENTION Many methods and apparatus are known for the anaerobic and also aerobic treatment of waste effluent. An intention of this invention is to provide an apparatus for the essentially aerobic treatment of waste effluent. More particularly the invention relates to an apparatus for treating liquid waste effluent that includes means for separating and breaking down in stages quantities of solid waste in the liquid waste effluent. The permeation from each stage is passed to the next stage. In addition at least the primary stages are arranged such that the separated solids contain organisms, hereinafter collectively referred to as a"biomass", resulting in the break down of the solids.

A further intention of this invention is to provide such an apparatus that includes a first stage that separates out most solids of the waste effluent and retains the resultant biomass in a substantially enclosed but aerated void. In the second stage the permeation from the first stage is diffuse to create a slime to continue the breaking down action.

Yet a further intention is to provide recycle means for the downstream permeation's that they can be charged back onto the first stage separation means. Operated at intervals the recycle means provides a nominal liquid waste effluent input regardless of the actual usage load. At times of low or no usage the recycle means maintains the integrity of the biomass and at times of high usage provides a flushing action to reduce the possibility of clogging.

Also the recycle means is utilised to extend the period over which filtrate is discharged from the apparatus. In times of high usage this reduces the possibility of a disposal means provided for the filtrate being unable to cope. The staged arrangement of the biomasses together with the facilities for recycling the permeation's enables a substantially continuous

essentially aerobic break down of the solid content of liquid waste effluent to create an acceptable filtrate.

A further intention is to provide the public with a useful choice over known liquid waste effluent treatment apparatus. In particular it is envisaged the apparatus will meet environmental standards and waste discharge regulations rendering the apparatus suitable for treating sewage and related foul water from individual and multiunit dwellings. Disposal of the filtrate maybe by various known means such as evaporation and/or irrigation, ground drainage. Such disposal means do not form part of the invention.

DISCLOSURE OF THE INVENTION According to a first aspect of this invention there is provided an apparatus for the biological treatment of liquid waste effluent comprising a substantially enclosed body having a liquid waste effluent inlet and a filtrate outlet, at least one drain plate adapted to have solids entrapment means thereon and disposed in an aerated void within the body adjacently beneath the inlet as will in use trap solids within effluent entering via the inlet as will in use enable, in conjunction with a quantity of organisms, the creation of a biomass to break down trapped solids, and a diffuser to provide a substantial aerated surface area over which permeation from the solids entrapment means flows whereby permeation settling on the surface area forms a slime to continue the breaking down action, the diffuser joining to the filtrate outlet.

According to a second aspect of this invention there is provided an apparatus as described in the preceding paragraph including a reservoir is disposed lower than the diffuser to receive permeation discharging therefrom and controllable means are provided to pump permeation from the reservoir to the filtrate outlet.

According to a third aspect of this invention there is provided an apparatus as described in the preceding paragraph wherein the reservoir is adapted for pressurisation and has an outlet conduit having a controllable intake disposed in an upper section thereof and which terminates at the filtrate outlet, the reservoir also having a recycle conduit with an intake

disposed in a lower section thereof and with an outlet discharging onto the solids entrapment means, and wherein the controllable means comprises an air compressor and permeation flow control means to enable the reservoir to be periodically pressurised to expel a quantity of permeation from the reservoir through the recycle conduit and, if the intake to the outlet conduit is open, also therethrough to discharge from the filtrate outlet.

In further describing the invention reference is made to the accompanying drawings of a preferred embodiment wherein: DESCRIPTION OF DRAWINGS Fig 1 is a perspective view partly fragmented and partly schematic for clarity in depicting the internal layout, and Fig 2 is a perspective view similar to Fig 1 depicting the exterior of the apparatus with covers thereof raised, and Fig 3 is a side view of the apparatus depicting a modification of the apparatus, and Fig 4 is a perspective view of a corner segment of a preferred solids entrapments means of the invention, and Fig 5 is a longitudinal sectional view partly schematic on line A-A on Fig 2, and Fig 6 is a longitudinal sectional view partly schematic on line B-B on Fig 2, and Fig 7 is a cross-sectional view partly schematic on line C-C on Fig 2, and Figs 8 and 9 are cross-sectional view of a float valve as used in the apparatus, Fig 8 depicting the valve closed and Fig 9 depicting the valve open.

DETAILED DESCRIPTION OF THE INVENTION The apparatus has an outer body 1 preferably suitable for burial in the ground. To that end a shoulder or ledge la is preferably formed on the outside to tend to anchor the body 1.

Preferably body 1 is fabricated from glass fibre to have an upper open topped body section 20 with the interior thereof forming a void 23 with removable covers 25,26 mounted on a lower enclosed body section 28 the interior of which forms reservoirs 3,3a..

Body section 20 preferably includes adjacent one end thereof a transverse wall 21 which separates off a mechanism containing space 22 from the remainder and treatment space or void 23 of the interior of body section 20. A longitudinal wall 24 is preferably provided centrally of void 23. Wall 21 extends the full height of body section 20 whereas wall 24 terminates at a lower point. Removable covers 25 and 26 are attachable to body section 20, cover 25 being removable to provide access to mechanism space 22 independently of cover 26. With wall 24 terminating as aforesaid and with cover 26 in place treatment void 23 is common to both sides of wall 24. Referring in particular to Figs 1 and 2, for convenience hereinafter the portion of the void 23 to one side of wall 24 (in the foreground in the drawings) will be called the primary side and the section of the void 23 to the other side of wall 24 called the secondary side. As described below void 23 is aerated with preferably a small vent pipe 27 being provided to vent both sides thereof. Vent pipe 27 preferably exhausts via a filtrate outlet 15. An intake of vent pipe 27 is preferably adjacent a lower section of void 23 with a lower section thereof being perforated. Lower body section 28 is enclosed as can be pressurised as described below. The interior of body section 28 forms at least one reservoir 3 and preferably an internal bulk-head 20 divides the interior into two separate reservoirs 3 and 3a.

A liquid waste effluent inlet 2 is provided through either cover 26 or adjacent the top of body section 20. Preferably inlet 2 terminates centrally of the primary side of void 23.

Mounted within the primary side of void 23 adjacently below the inlet 2 are solids entrapment means 29. The solids entrapment means 29 are supported on drain plates 4 arranged in an alternating sequence of pairs. A first and upper pair are inclined outwardly and downwardly from a common apex 31 adjacently beneath the inlet 2. A second and next lower pair are inclined inwardly and downwardly adjacently beneath the upper pair and have their outer edges 29a spaced adjacently outward of the associated edges of the upper pair.

The inner edges of the lower pair terminate in a spaced apart relationship to form a gap

below the apex 31 of the upper pair. This sequence is preferably repeated twice to provide four pair sets. of drain plates supporting solids entrapment means 29. Preferably the entrapment means 29 and drain plates 4 are mounted within an open topped bath 32 which in turn is mounted in an upper section of void 23. To assist in directing and controlling drainage, drain plates 4 may incorporate a small weir 5 at their lower ends. Also preferably the upper ends of the inwardly inclined plates 4 abut the adjacent side of the bath 32.

Referring in particular to Fig 4 the preferred entrapment means 29 comprise a series of plastic tiles 33. Each tile 33 has a pair of planar sides 34 spaced adjacently apart by a peripheral edge wall 35. Apertures 36 are formed through the sides 34 and edge wall 35 and a plurality of baffles 37 are formed in the interior of a tile 33. Alternatively, a bed of course aggregate material (not depicted) such as crushed rock or scoria can be supported on the plates 4. In yet a further embodiment (not depicted) the solids entrapment means 29 is integrally formed, such as by moulding, as part of the supporting drain plate 4. Solids within waste effluent discharging from inlet 2 and descending through the solids entrapment means 29 will tend to be trapped thereby. The solids entrapment means 29 are preferably seeded with effluent attacking organisms such as earthworms, insects and beetles to thus create with trapped solids a biomass (not depicted). Permeation from the solids entrapment means 29 is directed to a diffuser 12 and then preferably to a reservoir 3.

Diffuser 12 provides a substantial surface area over which the permeation from the solid entrapment means 29 flows. The permeation contains residual solids and is infiltrated with micro-organisms from the biomass and a quantity thereof settles on this surface area and forms a slime which continues the breaking down action of the residual solids. Preferably the diffuser 12 is formed by a plurality of hollow open-ended plastic components contained within the lower portion of void 23. Preferably bath 32 incorporates a plurality of apertures 13 throughout the bottom thereof which act as a disperser to direct the permeation therefrom over the diffuser 12 elements. A bottom 38 of body section 20 is preferably inclined leading to an outlet 39 joining into reservoir 3. A non-return valve 40 is provided at the outlet 39 to seal offvoid 23 from reservoir 3.

While permeation from diffuser 12 can be discharged directly from outlet 15 preferably permeation from diffuser 12 is collected in reservoir 3. Preferably means are provided to transfer permeation in reservoir 3 to outlet 15 via secondary filters 9 described in more detail below. To that end, preferably a suitable air compressor pump 16 is mounted in the mechanism space 22 and an outlet conduit 7 therefrom mounted along the bottom of the reservoir 3. Controls for air pump 16 are preferably mounted outside of the body 1 such as on an adjacent console (not depicted). The controls enable the pump 16 to be operated in a variety of manners in particularly automatically at intervals such as set by a timer mechanism provided on the console. The terminating section of the outlet conduit 7 preferably incorporates a plurality of apertures 17 therealong. The intake to outlet conduit 19 is controlled by a valve 18 which is biased closed. Thus with valves 40 and 18 closed reservoir 3 can be pressurised as described below. The intake to outlet conduit 19 is positioned in an upper section of reservoir 3 and preferably valve 18 is a float operated valve. Referring to Figs 8 and 9, preferably the intake incorporates a valve seat 41 and a float member 42 incorporating a seal 43 seats thereover. Float member 42 preferably comprises a tubular body 44 which telescopically mounts over the intake end of outlet conduit 19. When the quantity of permeation in reservoir 3 reaches the level of the float 42 valve 18 will open.

Valve 18 will close when the quantity of permeation in the reservoir 3 reduces below valve 18.

When the pump 16 is activated air is pumped into reservoir 3 and the increased pressure therein expels a quantity of permeation from the reservoir 3 through recycle conduit 8 to discharge over the solid entrapment means 29. This also serves to aerate void 23 and it will be appreciated that aeration can take place in the absence of any permeation being recycled.

If the quantity of permeation in reservoir 3 is such that outlet valve 18 is opened a quantity of permeation will also be expelled therethrough.

Referring in particular to Fig 3 in a modification of the invention an auxiliary reservoir 45 is provided. Auxiliary reservoir 45 is connected to reservoir 3 via connecting conduits 46.

The connecting conduits 46 are controlled by valves 53 that close when reservoir 3 is pressurised. Auxiliary reservoir 45 may be included when it is expected that the apparatus

will be required to treat the occasional extra heavy or shock loading. Auxiliary reservoir 45 provides extra storage capacity and isolates the extra permeation from that in reservoir 3.

Thus the normal cycle of the apparatus can be maintained during the extra loading period.

With the load reducing permeation in the auxiliary reservoir 45 will drain through to reservoir 3 and be treated.

As aforesaid outlet 19 from reservoir 3 is preferably directed to secondary filters 9 before being discharged. Preferably two secondary filters 9a and 9b are provided they being mounted in the secondary side of void 23. Preferably the first and upper secondary filter 9a includes an open topped bath 47 that contains a quantity of crushed rock or scoria or similar detritus aggregate 49. Preferably the bottom of the bath 47 incorporates perforations 50 to drain into the second and lower secondary filter 9b. Preferably secondary filter 9b comprises a quantity of fine filtering material such as sand 51 contained in the lower portion of the secondary side of void 23. The associated bottom 48 of body section 20 is preferably inclined to an outlet 39a controlled by valve 40a in similar manner to the bottom 38 of the primary side of void 23. Dispersing means 11 in the nature of a block of open cellular plastics foam material may be provided on top of the sand 51 to act as a disperser means.

The secondary filters 9 may also be seeded with organisms or may merely rely on infiltration from the through-put as aforesaid to create a further biomass for the further breaking down of any remaining solids prior to the permeation being discharged from the filtrate outlet 15.

Preferably a secondary pressurised reservoir 3a is also provided between secondary filters 9 and the filtrate outlet 15. In similar manner to reservoir 3 conduits 8a, 39a and associated air pumping means 16a, and valves 18a provide for re-cycling of permeation in reservoir 3a.

The secondary recycling is discharged over secondary filter 9a and if valve 18a is open the discharging of permeation to the filtrate outlet 15.

Referring in particular to Figs 1 and 2 a secondary inlet 52 may be provided in cover 26.

Inlet 52 includes a removable cover 53 and in situ projects clear of ground level. Inlet 52 is intended to take degradable solids waste such as kitchen scraps that can be deposited therein from time to time. Preferably inlet 52 is disposed directly above the outlet of recycle conduit 8 as to be caught by and on the solids entrapment means 29. Thus recycling permeation will regularly flush thereover.