General Conclusions. 



Nottingham (light loamy soil, ' filtration ' efflaents) 

 and the effluents from the sewage farms treating 

 sewage in the main by surface irrigation over heavy 

 land. But it is satisfactory to note that surface irriga- 

 tion effluents from heavy clay soil may, under favour- 

 able conditions of working the land, yield reasonably 

 good effluents. 



(9) The treatment of sewage on land, as com- 

 pared with its treatment by artificial processes, is a 

 matter which is still under investigation, and there- 

 fore no definite pronouncement can here be made. 

 But, speaking solely from the bacteriological point 

 of view, land (if of suitable sort for sewage purifica- 

 tion purposes and properly worked) is, in my opinion, 

 to be preferred to artificial processes as now conducted. 



(10) The intrinsic biological qualities of sewage 

 are not materially modified by land processes of 

 sewage disposal, as judged by the tests employed in 

 this investigation. 



(11) Samples of water derived from the rivers or 

 brooks into which ' land effluents ' are being dis- 

 charged were usually found above the effluent outfalls 

 to be impure (sometimes very impure) on bacterio- 

 logical examination. 



(12) The biological quality of a few samples of 

 the subsoil water in the neighbourhood of sewage 

 farms was determined. The results, as a rule, were 

 satisfactory, but the samples were not examined in 

 the exhaustive manner necessary when the question 

 of potability is involved. 



(13) If the examination of 'storm overflow liquid' 

 be interpreted in the light of the confirmatory results 

 which were subsequently obtained, it would seem 

 that ' storm overflow liquid ' is potentially as dan- 

 gerous as undiluted crude sewage. 



(14) ' Street washings ' liquid (separate system) 

 may be a grossly impure liquid from the bacterio- 

 logical point of view." 



AUTHOR'S SUMMING-UP. 



A comparison of the various farms dealt with in 

 the reports of the Royal Commission on Sewage 

 Disposal is hardly possible — the circumstances 

 differ so widely that it may almost be affirmed that 

 in no two respects do any two farms resemble one 

 another. The chief value of the investigation, in 

 my opinion, lies in the exhaustive manner in which 

 the information with regard to each farm in turn 

 has been presented. I would again draw attention 

 to the light thrown on the work accomplished in or 

 on the land by the discoveries that have been made 

 of late years in the domain of bacteriology. It is 

 no small step forward to have passed from a vague 

 notion of " oxidation " to a realisation of the pro- 

 cesses occurring during the purification of sewage ; 

 to an appreciation (imperfect though it may be) 

 of the activity of the micro-organisms which are 

 so largely concerned in this connection. I trust 

 that the condensation and re -arrangement* of the 

 material to be found in the 787 pages of the four re- 

 ports will be of service to those who, though dealing 

 with the vitally important subject of the disposal 

 of sewage, have not, on account of their manifold 

 duties, leisure sufficient to peruse and digest the 

 blue-books in question. I do not propose to say 

 much by way of final summary, but would direct 

 notice to some few points. 



Sewerage is a matter of engineering, and so is 



• The order of the farms and the particulars detailed are by no 

 means uniformly set out. The value of the reports would hare been 

 enhanced had they been provided with «ro8S-ref erences and been sub- 

 jected to efiBcient " editing." 



sewage disposal to a large extent. The first item 

 to be considered is the destination of the effluent, 

 and when this has been settled (either definitely or 

 provisionally for alternative schemes) the degree of 

 purification needed can be ascertained within rough 

 limits. Such questions as the adoption of the 

 separate, partially separate, or combined system of 

 drainage, the inclusion of manufacturing effluents, 

 the provision of storm overflows, &c., are dependent 

 on local conditions. At the same time the mode of 

 treatment must be borne in mind and all stages pre- 

 liminary thereto — e.g., detritus chambers, screens, 

 pumps (if necessary) and settling tanks. The 

 disposal of screenings and of sludge must be kept 

 in view, especially when a proposed site is not so 

 extensive as might be desired. If the sewerage and 

 adjuncts can be likened to the woof, the disposal of 

 the sewage may be regarded as the warp — the two 

 being essential parts of the whole. 



The treatment of the sewage is a mere matter of 

 money — it can be done in one of a variety of 

 methods. The rival claims of sewage farms and 

 bacterial installations (and possibly, also, of chemical 

 methods) have to be judged by the circumstances of 

 the neighbourhood — the nature, extent and price of 

 the land available, the cost of material suitable for 

 bacteria beds, &c. It is at this stage, more par- 

 ticularly, that an extensive acquaintance with the 

 subject is essential if due economy and efficiency — 

 the maximum of result for the minimum of expendi- 

 ture — are to be obtained. Suffice it to say that the 



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