MANURES AND MANURING 947 



735 - Hygienic, Scientiflc and Economic Disposal of Human Excreta. — gakrigou f., 



iu: I. Comptts Rciuius dcs Seavccs dt VAcadimic dcs Scunci<, Vol. 102. No. 17, pp. 649-651. 

 Paris, April 25, 1916. — II. FcuiUc d' Informations dit Mimsterc dc l\-{s,ri culture, XXIst 

 Year, No. 18, pp. lo-ii. Paris, May 2, 1916. 



Various methods of sewage treatment have been proposed based on 

 distillation of the sewage in the presence of lime, with the object of liberat- 

 ing ammonia, which is afterwards transformed into sulphate. The author 

 has devised a method of sewage treatment dispensing with distillation and 

 almost all the complicated apparatus it involves. The following is a 

 description of it : 



The solid and liquid matter are treated separately. 



A) The operations on the liquid matter are based on the double decompo- 

 sition taking place between sulphate of lime and carbonate of ammonia, and 

 resulting in the formation of carbonate of lime and sulphate of ammonia. 



The urine which has fermented sufficiently for the conversion of the 

 urea into ammonium carbonate is emptied into a vat with water-tight 

 lid. Finely powdered calcium sulphate (gypsum) crude or dehydrated is 

 added, and the mixture is stirred up frequently. The lime is precipitated 

 in the form of insoluble calcium carbonate, while the ammonia passes into 

 the state of soluble ammonium sulphate. The liquid is allowed to settle. 

 The calcium carbonate formed collects at the bottom of the vat, while 

 the ammonium sulphate remains in the liquid which can be racked off. 



This liquid can be concentrated in iron basins until the sulphate crys- 

 taUises. It can also be absorbed by ash, sawdust, or completely dehydr- 

 ated gypsum, and kept in that state until used. It gives off no disagree- 

 able smell. 



The sulphate of ammonia thus produced is very low in cost, being ob- 

 tained from an ammonium carbonate derived from the urea in the urine, 

 with the aid of sulphate of lime or gypsum which is very cheap. 



In addition, the precipitated calcium carbonate, which carries with 

 it mechanically considerable quantities of organic matter from the liqiiid 

 treated, forms a manure of high market value owing to its content of org- 

 anic nitrogen and other fertilising substances. 



In case the whole of the ammonium carbonate in the urine has not been 

 completely converted into sulphLtte by the calcium sulphate, the remainder 

 can, by the addition of acids, be converted into nitrate or other inodorous 

 ammonia salts, which add still more to the value of the liquid containing 

 the sulphate of ammonia. 



This mode of treatment of the liquid sewage can, owing to its sim- 

 plicity, be used not only in large cities but also in small towns or ^^llages 

 and even on farms. 



B) As regards the solid matter, it is separated from the liquid by 

 settling. On reaching the works the sewage is emptied into covered and 

 tightly closed settling basins in which the soHd matter is deposited. The 

 liquid is, after clarification, dehvered into the fermentation basins, where 

 it undergoes the operations described above. 



The solid matter deposited at the bottom of the settling basins in the 



