Land Treatment of Sewage. 



cent of trade refuse . . . The result is an effluent of 

 altogether exceptional quality, clear and sparkling, 

 and approaching in the best samples within measur- 

 able distance, from a chemical point of view, of a 

 drinking water . . . There is only one other point 

 to which attention may be drawn before closing — 

 viz., the rapidity with which the soil of the Notting- 

 ham farm recovers itself after being over-sewaged 

 ... I trust that in this report the great purity of 

 the Nottingham farm effluents, from a chemical 

 point of view, has not been dwelt upon too much ; 

 but one feels that too great stress can hardly be laid 

 upon this, because it shows what admirable results 

 can be obtained from good land under good manage- 

 ment." (Part II., pages 201 and 202.) 



The Bacteriological figures may be summarised as 

 follows : — 



for potable purposes. None of the other sewage farms 

 under investigation yielded effluents which ap- 

 proached the degree of biological purification effected 

 by the land treatment in the case of Nottingham 

 sewage farm." (Part III., page 131.) 



Effluent and 

 Stream Compared, 



The ratio of farm effluent to 

 river water is normally about 

 1 to 160, but the variations of 

 volume are great — the minimum ratio is 1 to 60. 

 It may be mentioned that the Trent receives the 

 sewage from most of the populous villages on the 

 banks except Arnold, Carlton and Beeston ; the 

 sewage from Radcliffe flows untreated into the 

 Trent a short distance above the Nottingham sewage 

 farm, the ditch conveying the sewage to the river 

 being (July, 1900) in a filthy condition. The river 



BACTERIOLOGICAL ANALYSES (TOTAL NUMBER OP BACTERIA PER CO.). 



Sewage. 

 (2-3 samples.) 



Effluent.* 

 (8-16 samples.) 



Stream. 

 (1 sample.) 



(1) Gelatine at 20 deg. C 



(2) Agar at 37 deg. C 



(3) B. coll or closely allied forms (say at") 



least) 3 



(4) B. enterlditis sporogenes (spores — sayl 



at least) j 



23,350,000 

 5,146,666 



550,000 

 400 



304 770 [ ®^ ^' ^^^ reduc- \ 



101 157 [ ^^ P®' "^^^ reduc- ) 



' l tion i 



^ Varied from absent ") 



QC-, 5 from 100 c.c. to at ( 



°°^ } least 10,000 but less C 



^ than 100,000 J 



C Varied from none in ") 



1 5 100 c.c. to at least [ 



(.10 but less than 100.) 



3,300 

 100 not 1,000 



f At least 1 but 

 I less than 10 



• Satisfactory (1) 7 out of 8, (2) 11 out of 15, (3) 11 out of 12 (absent from 7), and (4) 14 out of 16 effluents (absent from 13). 



" The results as a whole were unquestionably 

 very good, and some of the effluents might, on super- 

 ficial observation and without a knowledge of their 

 source, have been classed as pure drinking water. 

 But, as has already been pointed out, evidence was 

 not lacking that the intrinsic biological qualities of 

 the sewage were not materially altered by the land 

 treatment but only ' masked ' to a remarkable 

 extent. If this supposition be correct . . . immunity 

 from danger to health arising from the discharge 

 of such effluents into drinking-water streams would 

 be relative, not absolute. But whether or no ques- 

 tion arises as to the propriety of discharging effluents 

 possessed of the biological qualities observed in the 

 case of the Nottingham effluents into a drinking- 

 water stream, there can be no doubt as to the fitness 

 of these effluents to discharge into a river not used 



below the effluent outfalls at the time of visiting the 

 farm was apparently in good condition, and no sewage 

 weed was seen. In the months of July and August, 

 1900, the water of the Trent was not at all of high 

 quality, though there was nothing ofiensive about 

 it ; it contained for a river water a large proportion 

 of oxidisable matter, and usually a considerable 

 quantity of solids in suspension. The volume of 

 effluent as compared with that of the river is very 

 small, but, so far as it goes, the effluent must exercise 

 an oxidising effect on the water of the river. 



The first two series of effluents (drawn in Decem- 

 ber, 1899, and in July and August, 1900) were very 

 well aerated for percolation effluents (probably 

 aerated in the drains), containing as they did, when 

 analysed, an average of about 5 c.c. dissolved oxygen 

 per litre for thirteen samples ; and of the two 



46 



