0\ THE TREATMENT AXD UTILIZATIOX OF SEWAGE. 



139 



operations, and especially as to the constniction, size, and action of the 

 tanks. They had analyses made of the sewage and effluent water, and com- 

 pared the quantity of the sewage with the capacity of the filtering media, 

 and in all respects fully investigated the matter ; and they came to the con- 

 clusion, which the analj'ses proved, that the process did not fulfil the condi- 

 tions of purifying sewage, so as to render it fit to bo discharged into running 

 streams. They particularly remarked upon the amount of filtering media 

 not being of sufficient bulk for the purpose. 



The following are the results of the analyses as contained in the Report of 

 the llivers Pollution Commissioners : — 



Treatment of Ealing sewage by upward filtration. 



EeauUs of analyses espressccl in parts per 100,000, and including both suspended and 



dissolved matteris. 



Since this inquiry a series of experiments has been conducted by Gener a 

 iScott with the sewage of the same place, which the Committee has consi- 

 dered of sufficient promise to justify an inquiry into the results as far as they 

 have hitherto gone. 



The pi-inciple of General Scott's process is to arrest the flow of the sewage 

 by tanks, the suspended matters being preciiutated bj'^ means of lime and 

 clay, which are added to the sewage in the sewer previous to its ari'ival at 

 the tanks, the proportion of lime so added being about 10 cwt., and of clay 

 5 cwt. to 400,000 gallons of sewage. After the sludge has sufficiently accu- 

 mulated in the tanks it is drawn ofi^, placed in a Idln and burnt by intense 

 heat, and then ground into cement. 



The effluent water passes off very much clarified, and without any ofl'en- 

 sive smell at the time of discharge. 



The burning of the deposited matter, with the mixture of the lime and clay, 

 renders the cement perfectly inodorous, and is one of the means by which 

 the difficult question of the disposal of the precipitated sludge from sewage 

 may be solved ; and the method is one which may be adopted in cases where 

 sewage cannot be used for irrigation in its crude state. 



The chief points which are insisted upon in this case are : — 



" 1st. The more intimate mixture which can be brought out in the 

 " sewage--s\'ater, owing to the impali)ible nature of the precipitate of 

 " carbonate of lime which takes place on the addition of the lime. 

 " 2ud. The more rapid settlement of the sewage-precipitate than the 



" mixture of ch;',lk and clay. 

 " 3rd. The amount of organic matters which is carried down from the 

 " sewage with the carbonate of lime and clay, and which serves fcr 

 " the fuel to burn the mixture into lime or cement." 

 The amount of fuel which sludge will yield is stated to be so large that, in 



