xii Contents 



PART III 



Pages 



BACTERIA AND SEWAGE ..... .103-134 



CHAPTER XII 



THE PROBLEM OF SEWAGE-DISPOSAL 103-111 



The cess-pool The new method of the nineteenth century 

 Bacteria in sewage Growth of the problem Inland 

 communities and sewage-disposal The source, com- 

 position and quantity of sewage. 



CHAPTER XIII 



BACTERIAL PURIFICATION OF SEWAGE 112-124 



Sewage-farms Sewage tanks and filter beds Progress 

 in sewage-purification Intermittent sewage-filtration 

 Separation of bacterial activities Temperature and 

 bacterial activities Hydrolysis Treatment of effluent 

 Temperature and filter efficiency Inoculation Kinds 

 of bacteria in filter beds and septic tanks Loss of 

 nitrogen Bacterial efficiency in sewage-purification 

 Factory wastes and bacterial efficiency The working 

 caoacitv of bacterial filters. 



CHAPTER XIV 



SEWAGE-IRRIGATION 125-134 



Economic value of sewage-irrigation Sanitary value 

 of sewage-irrigation Kinds of irrigation Broad irriga- 

 tion Intermittent and mixed irrigation The crops 

 grown on sewage-farms Preliminary treatment of 

 sewage for sewage-farms Objections to sewage-farming 

 Sanitary efficiency of sewage-purification. 



