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These compartments would be either (a) shallow, open comparts. under cover to hold a bed of material between 5 ft. and 6 ft. deep and provided with perforated floors over a space for drainage and acration, or (b) docp, enclosed compartments provided at the bottom with a forced supply of air under gentle pressure. The compost would remain in those initial compartments long enough to develop active fermentation and to generate the maximum temperature and sustain it for a day or two as a means of destroying pathogenic organisms.
Equipment would be provided for distributing mature compost in a layer over the surface of fresh compost in open compartments, as a precaution against flybreeding and nuisance.
Transfer of the compost to maturing heaps from the shallow compartments would be effected with mobile mechanical loading equipment and dumpers. The deep compartments would have mechanical discharge gear at the bottom, dolivoring either directly into durpors or on to a conveyor belt system.
A second transfer might not be necessary but it would be done with mobile equipment in both types of installation.
Pipelines would be installed for supplying liquid to the heaps to maintain their moisture content in dry weather.
A total retention period of 70 days should be ample for producing
a virtually mature compost by this method.
(ii) The continuous flow method would use a digester of Earp- Thomas type, or similar, to the top of which pulverised garbage and nightsoil would be delivered.
I believe that the continuous stirring of the compost, which occurs in this type of digester, would encourage a much more rapid decomposition than is achieved in the batch method, with the result that, allowing for a subsequent maturing stage, a product of similar maturity to that achieved in 60 to 70 days by the batch method, might be obtained in 20 to 25 days.
The shorter retention period moans that a smaller site area would be required.
It must be borne in mind here that, in the event of a complete lack of both nightsoil and sewage material, which might be a result of development of the water carriage sanitation system, some advantage might occur in the treatment of garbage by itself from the use, as inoculents, of the special secret bacterial cultures which are made by the Earp-Thomas laboratories and which would, presumably, bo supplied only for use in the special digester. This is a matter which I propose to discuss with qualified biochemists and bacteriologists in London who have made a special study of composting.
It is known to me that an engineering organisation in Great Britain is in negotiation with the proprietors of the Earp-Thomas prccess with the intention of arranging to manufacture the digester and curing unit in England. This type of plant may, therefore, shortly be available for sterling.
Site area required. The maximum area would be required for the batch method with shallow compartments. On the assumptions that 350 tons of garbage would be made into compost every day with 200 tons of nightsoil and other liquids and that the material would be retained on the site for a total of 70 days in the initial compartments and maturing heaps, I estimate that a not area of about 12 acres would
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