EXPERIMENTS ON SEWAGE DISPOSAL IN GERMANY 113 
The quantities used are : 1 kg. lignite to 1 cbm. sewage and then 170 grammes 
ferric sulphate, and finally bleaching powder to the amount of 0.15 n / 00 . 
As examples of the results the following, taken at random, may be quoted : — 
Ammon. N. 
Organic N. 
Oxygen absorbed 
Crude Sewage 
92.4 
33-6 
+°9-5S 
Settled „ 
504 
84 
IOI.86 
Ordinary gelatine 
Kl-gelatine 
Crude Sewage... 
Liquefied 
32 0,000 
Settled „ 
140,000 
Bleaching Powder ,, 
Sterile 
Sterile 
The effluent was not putrescible. Allowing the effluent to go through a 
filter bed usually caused a re-appearance of B. coli ; and since running the chlorine- 
containing effluent straight into the river (Havel) caused no harm to the flora and 
fauna, nor even appreciably affected the amount of chlorides, the filtration seems to 
be superfluous. 
This process is of considerable importance because it demonstrates the 
practicability of obtaining a bacteriologically perfect effluent, and of disposing of the 
sludge. The cost is rather considerable (is. 3d. per head), but it seemed to me that 
the mechanical arrangements might be simplified and made more economical. In 
Potsdam domestic sewage from over 50,000 inhabitants is treated in this way.* 
The problem of 1 sewage disposal ' does not present so many difficulties in 
Germany as in this country. The rivers are mostly of greater size, and there is more 
land available for sewage farms. According to Mr. Lindlev, who has probably the 
greatest experience in the construction of sewage schemes, it would require three of 
the largest English rivers in their non-tidal portion to make a volume equal to that 
of the Main at Frankfurt. It is, consequently, more easy to obtain the minimum 
dilution of 1 in 16 necessary to obviate putrefaction. In many instances the dilution 
reaches 1 in 1,000, or more, so that putrefaction hardly enters into consideration, and 
the deposit of solid matter on the banks only occasionally. Nevertheless, the 
undesirability of allowing untreated sewage to enter even a large river is being 
recognised, and the city of Cologne has been compelled to erect works for treating 
its sewage. 
* Whittaker and Ducat Filters have not, so far as I am aware, been tried anywhere in Germany. 
