| 摘要 |
<p>Nitrogen losses in urine, especially during storage thereof, are prevented by passing a gas containing carbon dioxide into the urine, in the absence of oxidizing agents, so that the pH is adjusted to below 7. A suitable source of carbon dioxide is flue gas, and the effect is increased if the urine is additionally mixed with a salt having cations forming insoluble carbonates such as water-soluble calcium salts, suitably calcium chloride, nitrate, and primary or secondary phosphate. The maximum amount of salt added should be about equivalent to the sum of the amount of ammonia formed on decomposition plus the amount of bicarbonate already present. If phosphates are employed they should preferably be added in such amounts as to give the urine a content of 1 to 2 mols. of ammonia per mol. of phosphoric acid. Other salts capable of improving the fertilizing properties of the urine such as potassium salts, may be added. It is preferred to separate the liquid from the precipitate formed when calcium salts are added, to avoid the danger of a reversed reaction. The urine so treated has a low ammonia pressure and may be stored or spread as fertilizer without danger of nitrogen losses. To improve storage in tanks the treated urine may be covered by a thin oil film. U.S.A. Specification 2,072,154 is referred to.ALSO:Nitrogen losses in urine, especially during storage, are prevented by passing carbon dioxide into the urine, in the absence of oxidizing agents, so that the pH is adjusted to below 7. A suitable source of carbon dioxide is flue gas, and the effect is increased if the liquid is additionally mixed with salts having cations forming insoluble carbonates, such as water-soluble calcium salts, suitably calcium chloride, nitrate, and primary or secondary phosphate. The maximum amount of salt added should be equivalent to the sum of ammonia formed on decomposition plus the amount of bicarbonate already present. If phosphates are employed they should preferably be added in such amounts as to give the urine a content of 1 to 2 mols of ammonia per mol of phosphoric acid. Other salts capable of improving the fertilizing properties of the urine, such as potassium salts, may be added. It is preferred to separate the liquid from the precipitate formed when calcium salts are added. The urine so treated has a low ammonia pressure and so may be stored or spread as fertilizer with reduced nitrogen loss. In storage tanks, the treated urine may be covered by a thin film of oil. U.S.A. Specification 2,072,154 is referred to.</p> |
