Aldershot Camp. 



are merely provisional for working and compara- 

 tive purposes, and need not necessarily be adopted, 

 as they stand, without modification. ... It 

 is not improbable that the strength of the sewage, 

 the length of time the farm has been in operation, 

 the fact that the sludge is ploughed into the land, 

 and the hardy nature of spores as compared with 

 bacilli, may account for the results being seemingly 

 less satisfactory with the B. enteriditis sporogenes 

 test than with the other tests employed in the 

 investigation. It is, perhaps, hardly necessary to 

 add that, considered from the bacteriological point 

 of view, none of the samples of effluent were in a 

 fit state to be turned into a drinking water stream." 

 (Part III., pages 25 and 26.). 



The normal volume of the river is increased con- 

 siderably by heavy rainfall. This small river was 

 not in a satisfactory state at the times when the 

 observations were made, more especially during 

 summer, but this was due to polluting matter en- 

 tering it above the farm. The Aldershot Camp 

 Farm effluent from the old land must have exer- 

 cised an oxidising effect on the organic matter 

 already present in the water. At the same time 

 attention should again be called to the rather con- 

 siderable bulk of fine flocculent weed (from the 

 drain pipes) which is carried into the stream along 

 with the effluent, and also to the high manurial 

 value of the effluent itself. Not only is there a 

 great loss of nitrate and other manurial constitu- 



Effluent and 

 Stream Compared. ' 



The flow of effluent varies 

 considerably according to the 

 ' temperature. In very hot weather 

 the effluent is often only one-half of its normal 

 quantity, the remainder being absorbed or evapo- 

 rated. The normal dry - weather flow is about 

 two - thirds of the ordinary dry - weather flow of 

 sewage, or about 600,000 to 700,000 gallons per 

 twenty-four hours, which shows 1 gallon out of 

 3 gallons as being absorbed or evaporated; the 

 quality of the effluent does not appear to vary 

 much either in summer or winter. The river Black- 

 water, into which the effluent finally passes, is a 

 small, muddy, sluggish stream. The ratio of efflu- 

 ent to river water is about 1 to 6 approximately. 



enta here, but the effluent must tend to choke the 

 stream indirectly by encouraging vegetable growth 

 in it. 



In only six of the seventeen samples was there 

 more than 2 c.c. per litre of dissolved oxygen left 

 when the effluent came to be analysed; in four 

 the oxygen varied from 1 c.c. to 2 c.c. ; and in the 

 remaining seven it was either nil or less than 1 c.c. 

 Being percolation effluents, these were probably 

 not fully aerated when drawn, and, further, the 

 copper chloride oxygen process would give too low 

 readings with such coloured effluents (the first 

 seven were boiled out). But even allowing for 

 this, and for the fact of the rate of absorption of 

 dissolved oxygen being largely a question of tem- 



/ ^' OP THE ^ 



u UNIVERSITY 



15 



