SEWAGE AND THE BACTERIAL 

 PURIFICATION OF SEWAGE 



CHAPTER I 



INTRODUCTION 



All organisms are injuriously affected by the continued 

 presence of their own excreta, so that if they are kept in a 

 confined space they gradually die off. In the case of higher 

 animals the earliest remedy for such self-poisoning has been 

 migration, but with the increase of numbers the opportunity for 

 this has become more and more limited, and ''murrains" and 

 other pests have set in as a consequence of overcrowding. 

 With man there has been the additional burden of the refuse 

 of his industrial occupations. 



It was an injunction of Moses that unclean matters were to 

 be carried outside the camp and burnt, and the necessity of this 

 will be recognised by anyone who has seen m Eastern towns, 

 and even in British villages, decomposing heaps of garbage. 

 But the cremation of such products requires fuel and produces 

 intolerable odours ; hence the resort to a primitive and effective 

 method which is still in use in dealing with the dead — namely, 

 a committal to earth. Deut. xxiii. 12, 13, enjoins that all 

 excreta shall be covered with earth, following the natural 

 instinct of many animals. This instinctive effort to cover the 

 dejecta is most prominent in the carnivora, in which the 

 matters are nitrogenous, and therefore more highly offensive, 

 whereas in the herbivora no such natural propensity is observed. 



Pastoral populations depending on springs and wells found 

 water too scarce and valuable to be purposely polluted. Those 

 residing on the banks of rivers also refrained to a great extent 

 from casting their refuse into the streams used for their bathing 



I 



