710 REPORT— 1900. 



— spoken of as Phosalite — was uael as a precipitating- agent for sewage, and as a 

 pressing agent for sewage sludge. 



Experiments at Chiswicic Sewage AVorks, where Phosalite was used as a 

 precipitating agent, yielded in tlie dried sludge cake : — 



Nitrogen = Ammonia , , 1'44: Pliospliate of Lime . . 6-21 



Wlien used as a pressing agent in conjunction with half the usual amount of 

 lime, the dried sludge cake yielded: — 



Nitrogen = Ammonia . . 1-94 Phosphate of Lime . . 12-06 



Experiments at Glasgow Sewage "Works with Phosalite as a pressing agent 

 gave the following results : — 



a. Sludge pressed with J per cent, of lime and 1 per cent, of Phosalite : — 

 Nitrogen = Ammonia . . 1"74 Phosphate of Lime . . 5'72 • 



b. Sludge pressed with ^ per cent, of lime and 2 per cent, of Phosalite : — 

 Nitrogen = Ammonia . . 2'04 Phosphate of Lime . . 9*49 



By the use of Phosalite as a pressing agent for sludge there was obtained — 



(a) an economy of lime necessary for pressing ; (b) a much-improved press liquor ; 

 (c) a greatly enhanced manurial value for the sludge. 



These specially enriched sludges, whan dried and ground, formed excellent 

 manures, giving results equal to those produced by many high-priced artificial 

 manures. The experiments show that for the effective utilisation of sewage sludge 

 as a manure there are two requisites : — 



1. The use of some such phosphatic material as Phosalite when pressing the 

 sludge. 



2. Tlie resultant sludge-cake must then be dried and ground, so that it may 

 easily mix with the soil. 



