THE SEWAGE DISPOSAL PROBLEM 195 



statement that the Hampton doctrine is entirely opposed to the 

 generally accepted conception of sewage purification — viz. that 

 the operation is essentially one of bacterial liquefaction and 

 oxidation. 



It has long been noticed that filter beds begin to show signs 

 of loss of capacity after they have been in use for a time. This 

 period may be a few months to a few years, depending upon 

 various factors — e.g. the disintegration of the filtering material, 

 the consolidation of the filtering material, the deposition of 

 colloidal matter, the growth of organisms, the amount of sus- 

 pended matter in the liquid passed on to the bed, etc. Leaving 

 out of account several of the above factors, it is sufficient for 

 our purpose to say that from the " Hampton " point of view 

 the amount of suspended matter in the liquid passing on to the 

 filter bed and the deposited colloidal matter form the most 

 important factors, and the essential principles associated with 

 the Travis system of tanks are (1) the necessity for eliminating 

 the more readily removable suspended solids and colloidal 

 matters from 'the sewage, in order to exclude the main pro- 

 portion of the liquid from a prolonged tank operation, and so 

 prevent it becoming impregnated with the gaseous and other 

 products of putrefaction ; (2) the desirability of more perfectly 

 removing these impurities by the interposition of self-cleansing 

 surfaces which will attract the fine suspended solids, and upon 

 which a proportion of the colloidal matters will be deposited, 

 and to effect this separation in a self-cleansing- sedimentation 

 chamber ; (3) the importance of providing adequate means for 

 the removal of sludge and scum, in order to minimise the 

 carrying forward of deposited matters, and so as to maintain 

 continuously the working capacities of the tank. 



The plant consists of sedimentation chambers, reduction 

 chambers, and hydrolysing chambers. For a full description 

 of this system it is necessary to consult the more technical 

 books and journals (e.g. Journal of the Royal Sanitary Institute, 

 August 1909). It is claimed that by this system the sewage, 

 after leaving the tanks, is in a much better condition for 

 application to land or artificial filters, and certainly the results 

 so far obtained seem to support Dr. Travis's contentions. But 

 it is scarcely necessary to add that as yet, at all events, many 

 of our best-known experts do not appear to be disposed to 

 accept the Hampton doctrine. 



