ANNIVEKSARY ADDRESS. 27 



The general conclusions arrived at by Dr. Clowes are: — that the 

 process offers the readiest and the cheapest method of sewage 

 purification at present known. He says, that "neither on chemical 

 not possibly on bacteriological grounds can any serious objection 

 be raised to the introduction of the effluent from the coke-beds 

 into a portion of the river Thames which is cut off by locks from 

 the intakes of the Water Companies, and the water from which 

 is not employed for drinking purposes, and cannot be used on 

 account of its 'brackish' nature. The effluent certainly will not 

 cause any deposit upon the river-bed, and will even tend to render 

 the turbid water of the lower river more clear and transparent. 

 At the same time, the liquid discharged from the outfall into the 

 river will be sweet and entirely free from smell. Further, it will 

 carry into the river the bacteria necessary for completing its own 

 purification in contact with the aerated river water, and under no 

 conditions can it therefore become foul after it has mingled with 

 the stream. The effluent will in no way interfere with fish-life 

 in the stream." 



As compared with the present process of chemical precipitation 

 and sedimentation, the bacterial process presents the following 

 advantages : — (a) It requires no chemicals ; (b) It produces no 

 offensive sludge, but only a deposit of sand or vegetable tissue 

 which is free from odour ; (c) It removes the whole of the 

 suspended matter, instead of only about eighty per cent, thereof; 

 (d) It effects the removal of 51.30 per cent, of the dissolved 

 oxidisable and putrescible matter, as compared with the removal 

 of seventeen per cent, only, affected by the present chemical 

 treatment ; (e) Further, the resultant liquid is entirely free from 

 objectionable smell, and does not become foul when it is kept ; it 

 further maintains the life of fish. 



" In their report a number of reasons are given, showing that 

 it is unwise in the present state of our knowledge to recklessly 

 condemn an effluent on bacteriological ground alone, without full 

 knowledge of all the requirements of the case. In the attempt to 

 treat sewage on biological lines, it is to be noted that the solution 



