i6o SEWAGE AND ITS PURIFICATION 



alumi no-ferric and lime, in proportions adjusted to the volume 

 and to some extent to the strength, and averaging about 5 grains 

 of each per gallon. During this period^ the average results in 

 parts per 100,000 are given as : Oxygen consumed — sewage, 

 4*92 ; effluent, 1*58. Albuminoid ammonia — sewage, 0*469 ; 

 effluent, o'lii. But beyond its organic impurity, the effluent 

 was made too alkaline by the lime, and complaints arose as to 

 its action on fish in the river; therefore during 1897 alumino- 

 ferric alone was used, and the average results are recorded as 

 follows : Oxygen absorbed — sewage, 7*95 ; effluent, 2*36. 

 Albuminoid — sewage, i*2i ; effluent, 0*266. As the results were 

 so unsatisfactory, biological treatment was commenced in 1899. 

 It is reported that during fifty- six days of the first working of 

 an open septic tank and continuous filter the sludge was only 

 one-ninth of that produced by the former chemical precipita- 

 tion, and the effluent was of good quality. 



At Kingston-on-Thames the "ABC" process has been for 

 some time in operation. This method is of early date ; the 

 letters originally signified alum, blood, and clay as precipitants, 

 but it is now stated that the three principal ones are sulphate 

 of alumina, clay, and carbon, and that 50 grains " of materials 

 including sulphate of alumina " are used per gallon of sewage, 

 with a purification measured by albuminoid ammonia of 83 per 

 cent. An essential feature is the production by sludge-pressing 

 and drying of a manure called " Native Guano," offered at 

 £^ los. per ton. Sir Alexander Binnie reported to the Corpora- 

 tion of Kingston in 1903 that the process was very expensive 

 and not protected by patent, nor, probably, patentable. The 

 effluent, under proper working, was clear and bright, but 

 appeared in the conduits and near the river outfall to cause the 

 growth of considerable quantities of sewage fungus. The 

 sludge . produced was comparatively free from odour, and 

 amounted, at 90 per cent, moisture, to 27 tons per million 

 gallons of sewage. Pressed, dried, and ground, it gave about 

 2,000 tons per annum of manure. 



Metallophilic organisms — a convenient term I would suggest 

 for vegetable and animal species whose growth is encouraged 

 by the presence of small quantities of metals in solution, 

 especially iron, aluminium, and manganese, which they secrete 

 in their tissues or as an incrustation (see Chapter IV., p. 79)— 



^ "Sewage Disposal, York," A. Creer, City Engineer and Surveyor, Public 

 Health Engineer^ May 21, 1904. 



