24 Refuse Disposal and Sewage Purification. 



In the system originated by Mr. Adeney the polluted liquid 

 sewage, after separation of solid matter, is reduced to simple 

 substances by micro-organisms, the process being facilitated by 

 the introduction of materials into a series of tanks for main- 

 taining a healthy condition of the microbes, the operations 

 being continued until the fluid is sufficiently purified to enable 

 it to be safely discharged into any ordinary outfall. 



The septic system is of a different character, and is differenti- 

 ated from the previous process by encouraging putrefaction of 

 the solid elements in sewage. It is an accepted dictum that 

 "the tendency of nature is to return to the status quo^'" and the 

 modern science of bacteriology teaches that if seriously pol- 

 luted water is given sufficient time and oxygen, it will be 

 changed back to a wholesome fluid. Mr. H. E, P. Cottrell 

 states that water bacteria consume all substances that are 

 eatable, including putrefying matter, the germs and spores of 

 other bacteria, and even each other, A lack of food produces a 

 curious phenomenon : the dead bodies of myriads of deceased 

 generations which preceded them exert a toxic effect, by 

 which the living are quickly exterminated, and the water 

 becomes sterilized. 



Mr. Cameron proves that the disappearance of solids in 

 sewage is due to micro-organisms feeding on the organic matter 

 which they exude in a simpler and liquid form ; this action 

 taking place in a closed tank. The fluid is then subjected to 

 filtration and a clear effluent obtained. 



Sewage farming offers three great advantages : — i. The 

 effluent is thoroughly purified. 2. A profitable agricultural 

 return is ensured. 3. Under proper management the public 

 health is not endangered. These essentials are not easily 

 realised owing to the difficulty of obtaining suitable land near 

 large cities, but farming may be used as an adjunct to any 

 sewage scheme for utilizing the resultant sludge. Chemical 

 precipitation has now been in constant operation for over thirty 

 years, and is a ready process for effecting a clear affluent. It 

 involves the use of collecting tanks, which, however, can be 



