| 摘要 |
<p>Compost is obtained by placing waste organic material together with a minor proportion of compost from a previous fermentation in an open-topped vat of which the side walls are formed to allow abundant natural aeration of the material, spraying with an aqueous solution of a nitrogenous compound to bring the water content of the mixture to 50 to 60% and the carbon to nitrogen ratio to 25 to 35:1. The vat preferably has a volume of less than 100 cubic metres and less than 85 cubic metres of household waste is placed in it. In a preferred plant refuse is unloaded by gravity from vehicles on a platform 4 into a vat 1 and about 20% of its weight of compost from previous fermentations added and also up to 30% of sewage sludge. In a room 6 a solution of 30 kgs. of urea in 1000 litres of water is prepared and passed through a main 7 to a spray through which it is applied to the waste. If the pH is below 6.2 then calcium carbonate may be <PICT:0955338/C1/1> added. After 6 days the mass is moved by a mechanical shovel to a sieve 8 and a conveyer belt 9 and a magnetic drum 10 which removes ferrous impurities and then to a rotary drum separator 12 and a crusher 13 and finally by a conveyer belt 15 to storage.</p> |
