The present invention relates to a system for treating farmyard waste, a system for irrigating fields utilising farmyard waste, methods for treating farmyard waste and methods for irrigating fields using the treated waste.

Low Rate Irrigation Systems for farms which utilise underground pipework and hydrants to supply mobile or static sprinklers on the area to be irrigated are known. Such systems use dilute wastes such as dirty yard run-off, parlour and dairy washings and thus the sizing of the pump chamber is critical to avoid overflows and pollution from these, eg. in times of unexpected heavy rainfall. The present invention provides an improved irrigation system incorporated within a slurry lagoon in which any overflow from the system is passed into the lagoon, thereby avoiding pollution of the surroundings.

A first aspect of the present invention provides a farmyard waste treatment system comprising an animal waste slurry lagoon, a strainer box adapted to receive liquid waste from the slurry lagoon, settlement chamber means adapted to receive liquid waste from a second waste source, and an overflow means between the settlement chamber and the strainer box.

The slurry lagoon is any lagoon in which animal slurry, eg. raw manure, is stored. The lagoon may suitably be formed as an earthed bank structure or a concrete compound. The second liquid waste source preferably comprises general farm liquid waste eg. parlour or dairy washings and/or yard run off. These include, inter alia, liquids that have been used to clean the equipment and farmyard together with rain water. The system is particularly useful for treating liquid waste of a varying quantity, particularly if that quantity cannot be regulated, eg. for treating waste resulting from rainfall, the volume of which can vary greatly. The settlement chamber means will be understood to

include any chamber adapted to treat liquid waste by settlement. This includes a plurality of settlement chambers that are either independent or interconnected by any suitable means. Preferred embodiments are those which comprise a plurality of settlement chambers, particularly those in which the settlement chambers are interconnected. A particularly preferred embodiment comprises three settlement chambers interconnected by H-pipes.

The strainer box is a slurry separator capable of straining slurry, particularly dairy slurry which is approximately 90?! liquid and 10 solids; the solids mostly consisting of fibres which if undisturbed create a floating crust. The sides of the strainer box which interface with the slurry comprise a strainer means which prevents the fibre entering the box while allowing the liquid portion of the waste to seep in slowly. Thus the strainer box may be used to extract concentrated liquid effluent from compounds holding neat slurry from dairy cows. Because strainer boxes are slurry separators without working parts they are durable and need little maintenance.

One example of a suitable strainer box comprises slats arranged with spaces of 25mm or less between them. The slats may be made from any suitable materials eg. timber or concrete. Preferred embodiments further comprise a mesh capable of excluding small particles from entering the tank, eg. a 3mm plastics mesh, preferably polypropylene.

The overflow means may suitably comprise an overflow weir. The system preferably comprises a dispensing means, eg. a pump means. In one particular embodiment of the invention the dispensing means comprises a chamber from which a pump draws liquid, ie a pump chamber. The dispensing means may suitably feed a field irrigator or may transfer the treated effluent to a storage vessel.

The system preferably further comprises a transfer means adapted to transfer effluent from the strainer box to a chamber from which it may

be dispensed, preferably a pump chamber. An example of a suitable transfer means is a sluice gate, either powered or manually operated. This allows the treated waste from the slurry lagoon to be stored in the strainer box and irrigated onto land when its nutrients will be more beneficial eg, in the spring months. A preferred embodiment of the present invention achieves this by using a nested tank arrangement, incorporating settlement tanks and a pump chamber. The strainer box is incorporated within the nested tank arrangement such that a sluice gate is used to connect the strainer box to the pump chamber, thus allowing concentrated effluent to be transferred to the pump chamber when required and to be isolated when concentrated liquor no longer needs to be applied to the land.

The preferred system provides that any occasional overflow, eg. in heavy rainfall, can be collected in the lagoon via the strainer box which has a greater capacity to store polluting material than the limited capacity of the pump chamber. This results in more effective prevention of pollution.

The system of the invention may be open or it may be enclosed eg. having a concrete covering. The latter provides an improved system for pollution avoidance because the quantity of effluent in the chambers is not directly affected by rainfall. Rainfall will not enter the system directly as it falls, but more slowly as it enters the system as the second waste source. This allows excess rainwater to pass through the strainer box to the lagoon rather than to overflow from the system to the surrounding area.

A second aspect of the present invention provides a farm irrigation system comprising a farmyard waste treatment system as described above together with a means for transferring treated waste to fields for irrigation, eg. a system of pipes or hoses, or it may comprise a means for storing treated waste until it is required, eg. a storage tank.

A third aspect of the present invention provides a method of treating farmyard waste comprising slurry and liquid farm waste comprising:

a) inputting the slurry to a slurry lagoon interfacing with a strainer box so as to allow concentrated liquid effluent to pass into the strainer box

b) inputting the liquid farm waste to a settlement chamber means associated with the strainer box

c) selectively transferring effluent from step (a) into the settlement chamber means

d) providing an overflow means between the settlement chamber means and the strainer box

e) dispensing treated effluent from the settlement chamber means.

The terms slurry lagoon, strainer box, settlement chamber means, and overflow means will be understood to have the same meaning as described in the first aspect of the invention.

Effluent from step (a) may be transferred into the settlement chamber means using any suitable transfer means eg. those described in the first aspect of the invention. A preferred embodiment comprises the use of sluice gate to allow effluent to pass from the strainer box to the settlement chamber means when required.

Treated effluent may be dispensed from the settlement chamber means using any suitable dispensing means eg. those provided in the first aspect of the invention. A preferred embodiment comprises the use of a pump means, preferably a pump chamber associated with the settlement chamber means.

The methods described above are particularly suitable for treating dairy farm waste. The liquid farm waste comprises eg. parlour washings, dairy washings, dirty run off or any combination thereof. A preferred embodiment comprises the use of the system described in the first aspect of the invention. More preferred methods are those in which excess effluent is directed to the slurry lagoon, avoiding pollution of the surrounding environment.

A fourth aspect of the present invention provides a method of farm irrigation wherein farmyard waste is treated in the system described in the first aspect of the invention and/or by the method described in the third aspect of the invention and treated waste is transferred to an irrigator. This may be performed by any suitable means, eg. pipes may be fitted to a dispensing means incorporated within the system or the effluent may be transferred to a storage tank and used when required. In a preferred embodiment of this aspect the effluent is transferred directly from the system to fields to be irrigated.

The apparatus and methods of the invention will now be illustrated by example only with reference to the following non-limiting Examples and Figures. Further embodiments will occur to those skilled in the art in the light of these.

FIGURES

Figure 1 shows a plan view of the dairy farm waste treatment system as described in Example 1.

Figure 2 shows the location of the system described in Example 1 in a dairy farm slurry lagoon.

Figure 3 shows a cross section through line A-A' of the system described in Example 1.

Figure 4 shows a cross section through line B-B' of the system described in Example 1.

Figure 5 shows an isometric sketch of the complete system as described in Example 1.

EXAMPLE 1: POLLUTION CONTROL SYSTEM FOR THE TREATMENT OF DAIRY FARM _____!

A dairy farm waste treatment system is provided comprising a strainer box (1), a primary settlement chamber (2), a secondary settlement chamber (3) and a pump chamber (4) arranged as shown in Figure 1. Figure 2 shows the location of the system (5) in a dairy farm slurry lagoon (6). formed within an earthed bank (7) opposite an unloading ramp (8) . Two sides of the strainer box comprise vertically orientated slats (9) spaced 25 apart which support a 3mm polypropylene mesh (10), and interface with the slurry lagoon. H-pipes (11) and (12) connect the secondary settlement chamber to the primary settlement chamber and the pump chamber respectively. The primary settlement chamber comprises an inlet (17) through which parlour and dairy washings and dirty yard run off may be fed. The pump chamber comprises a pump house (13) connected to an outlet (14) leading to a field irrigator. The strainer box and pump chamber are connected by a manually operated sluice gate (15) and overflow weir (18). A concrete cover (16) encloses the strainer box, settlement chambers and pump chamber.

Figure 3 shows a cross section of the system through line A-A' in Figure 1, showing H-pipe (12) in more detail. A suction pipe (19) is shown which feeds the pump house. Figure 4, a cross section through line B-B' in Figure 1, shows the location of the sluice gate (15) and the overflow weir (18) in more detail. Figures 3 and 4 show safety rails ( 20 ) which ensure the safety of operating or inspecting personnel. The complete system is shown in isometric view in Figure 5»

In operation the slurry lagoon is filled with dairy slurry, whereby concentrated effluent seeps into the strainer box while larger solids, eg. fibrous materials, are excluded by the slats and mesh. Parlour and dairy washings and dirty yard run off are fed into the inlet (17) as they are produced. This dilute effluent passes from the primary settlement chamber to the secondary settlement chamber via the H-pipe (11) and then into the pump chamber via H-pipe (12). Treated effluent in the pump chamber is pumped as required, via the outlet (14), to a field irrigator. When desirable, eg. in early spring, the sluice gate (15) is opened to allow concentrated effluent to pass from the strainer box into the pump chamber from which it is pumped to a field irrigator. In times of overcapacity effluent in the settlement chambers overflows into the strainer box by means of the overflow weir between the strainer box and pump settlement chamber. In this way excess effluent can be passed passively into the lagoon rather than overflow and pollute the immediate surroundings of the settlement chambers.