IMPROVEMENTS IN THE UTILISATION OF REFUSE

Abstract: A reservoir for use as a heated fish tank, or swimming pool comprises an excavated, or naturally ocurring, cavity covered by an outer containment layer in the form of a synthetic impervious flexible membrane (4), over the containment layer a quantity of biodegradable material (5), and over the biodegradable material a pool (8) lining containing liquid such as water; the liquid being warmed by the biodegradation of the biodegradable material.

Description: Improvements in the Utilisation of Refuse DESCRIPTION This invention is concerned with the utilisation of refuse. The word 'refuse' is broadly used to cover domestic, commercial and industrial (non-hazardous) waste. The refuse should normally contain biodegradable organic material such as paper, food scraps or wood but sewage may be added to enhance biodegradability. The biodegradability of refuse in ordinary land-fill sites owing to the indigenous bacterial population has been recognised. In accordance with the present invention a relatively large volume of liquid is warmed by placing it over refuse undergoing biodegradatioπ with the consequent development of heat. Thus, the invention provides a large volume liquid container comprising an outer containment layer overlying a cavity in the ground, a quantity of a biodegradable material which biodegrades exothermically lying on said containment layer, a liquid impervious layer covering said quantity of biodegradable material and a volume of liquid contained within said liquid impervious layer. The gentle warming achieved makes the invention ideal for a water-filled fish tank or pond. It is known that a mildly elevated water temperature increases the rate of growth of fish and other aquatic life enabling an earlier or better than usual harvest. In a practical realisation of the invention a large excavated cavity is lined, filled with refuse and a tank or pond filled with water placed over the refuse. As biodegradation takes place the water is gently warmed. In this type of construction the refuse is subject to mainly anaerobic degradation in the substantial absence of oxygen and this is advantageous as methane is developed which can, as will subsequently be described be used. Aerobic degradation with the generation of carbon dioxide is not excluded but anaerobic degradation provides not only effective warπiing but also a useful bi-product in the form of methane gas. An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings wherein:- Figure 1 is a longitudinal section through a fish pond in accordance with the invention; Figure 2 is a plan of the pond at ground level; Figure 3 is a typical pond section, whilst Figure 4 is an enlarged view (not to scale) of the excavated and prepared side parts of the pond. Referring now to the drawings approximately 1 to 3 acres of land are excavated down to approximately 2.5. metres. This area with a pond depth of say one metre (Figure 3) develops a sufficient large volume of water in the sense that it is useful as a fish pond and has a thermal inertia sufficiently high to preclude the possibility of water being warmed to a temperature high enough to harm fish or other aquatic life. The spoil from the excavation is placed around the perimeter to form embankments 1 typically 3.8 metres high. These embankments may be grassed and landscaped. Base layers 2 and 3 of, for example, puddled clay and sand are provided so that an impermeable refuse-containing lining of synthetic flexible membrane 4 for example of butyl rubber or polyethylene of low or high density can be laid without the danger of rupturing in use. The lining 4 which may be double skinned is brought up to define a generally rectangular waste containing space 5 as illustrated and the excavation back-filled to support this space. This space 5 is then ready to receive refuse and this is tipped in. It is advantageous that the refuse has added to it pressed or filtered sewage sludge to enhance degradation. On completion of the tipping into the space 5 the impermeable membrane is brought over the final surface of the refuse so as to seal in all of the refuse in an airtight manner. Vent pipes 7 laid into the refuse during deposition are brought through the sides of the liner to a common collection and vent. These pipes 7 serve to collect methane generated by anaerobic degradation together with any other gases developed. The cell is then overlaid for protective purposes with sand or similar at 6 and finally a flexible membrane-lined pond 8 is installed directly over the refuse mass in the space 5. This pond 8 is stocked with fish or other aquatic creatures such as Crustacea. As biodegradation proceeds heat is generated which warms the water in the pond. The whole system may be regarded as a kind of fuel cell. The methane gas may be used as a fuel for further heating the pool for example or as an alternative to drive an electrical generator. When anaerobic degradation is complete the pond can be removed and the system opened up. A soil conditioner remains in the space 5 once residual non-biodegradable materials have been removed. This conditioner is in turn removed for use. The cycle described can then be repeated. The invention has been described with reference to a particular application, i.e. a fish pond. It has however applicability to any large volume liquid container or reservoir which needs to be warmed gently and could, for example, be used for a temporary εwimπiing pool.

Claims: CLAIMS: 1. A large volume liquid container comprising an outer containment layer overlying a cavity in the ground, a quantity of a biodegradable material which biodegrades exothermically lying on said containment layer, a liquid impervious layer covering said quantity of biodegradable material and a volume of liquid contained within said liquid impervious layer. 2. A large volume liquid container according to claim 1, in which said outer containment layer comprises at least one synthetic impermeable flexible membrane. 3. A large volume liquid container according to claim 1 or 2, comprising piping within said biodegradable material for removal of generated methane gas. 4. A large volume liquid container according to claim 2 or 3, in which said piping for the methane is arranged to direct the methane gas to a location for collection. 5. A large volume liquid container according to claim 4 in which collected methane gas is arranged to be used for additional heating of said volume of liquid. 6. A large volume liquid container according to any preceding claim which is in the form of a water filled fish tank. 7. A large volume liquid container according to claim 6, in which said fish pond contains sufficient water to provide thermal inertia to preclude the possibility of water being warmed to a temperature long enough to harm fish or other aquatic life. 8. A large volume liquid container according to any of claims 1 to 5 which is in the form of a temporary swimming pool.

Inventors: MIDGLEY TIMOTHY JAMES, MIDGLEY, TIMOTHY, JAMES
Applicants: BIOMASS RECYCLING LTD
Application year: 1992
Main classification: B09B1
IPC codes: A01K61, B09B1, B09B3, C05F17, C12M1, F24J1