Bacterium coli no longer a true criterion of sewage pollution.
It may be convenient to point out in this place that bacterium coli can no longer be looked upon as a typical inhabitant of the human intestines after the very elaborate investigations carried out by Dr. Weissenfels, who arrived at the following conclusions:
Dr. Weissenfels’ conclusions.
1. The so-called bacterium coli can be cultivated from almost every kind of water, and its presence can be
demonstrated in nearly every case, provided a sufficient volume of water is utilised.
2. It is not possible by the result of the experiments upon animals to decide whether the bacterium coli was cultivated from a pure or infected water, and the discovery of a virulent bacterium coli in any sample of water cannot, therefore, be regarded as a criterion that such water has been polluted with fæcal bacteria.
After these remarks, it would seem quite possible that the bacterium coli discovered in eighteen cases by Dr. Korn in the Freiburg effluents was not derived from sewage at all but from the ordinary subsoil water of the land.
The possibility of further mischief by pathogenic micro-organisms on sewage farms is exceedingly remote, if it exists at all.
Bearing these observations in mind, it is quite clear, therefore, that neither theoretical investigations, as available up to now, nor practical results, support the theory that pathogenic micro-organisms may do mischief on sewage farms, and one is forced to conclude that this possibility—if it exists at all—after systematic treatment on land is an exceedingly remote one.
Sewage farms reduce the quantity of final effluent.