Land Treatment of Sewagre. 



tanks except in damp foggy ■weather. The chief 

 difficulty experienced in the working of the farm is 

 the disposal of the sludge, on acconnt of the long 

 time it takes to dry sufficiently to admit of removal, 

 and a large area of land has to remain uncropped in 

 consequence of the necessity for reserving a place 

 for the deposit of some of this sludge. (See also 

 last sentences under " Treatment") 



sewage of Belgrave would bring the population per 

 acre up to 154. As the result of numerous 

 experiments, having for their object the clarification 

 of the sewage before its application to land, process 

 No. 7 was recommended. This consisted of a closed 

 detritus tank, clarifying bacteria beds (three fillings 

 a day), and old pasture (one application). The 

 results averaged : — 



" The sewage (three-quarter 

 Conclusions. domestic, one-quarter trade refuse) 

 is only of moderate nitrogenous 

 strength, but contains a considerable amount of 

 oxidizable matter. For a combined surface irrigation 

 and filtration farm Leicester was treating a fairly 

 large volume of sewage per acre of the ' working ' 

 daily irrigable area, but not a large volume per acre 

 of the total irrigable area. As regards the organic 

 matter, it was treating about one-half that of 

 Nottingham. The soil and subsoil (stiff clayey soil 

 overlying dense clay) are certainly not well suited 

 for purifying a large volume of sewage. The 

 sewerage system is partially separate. The farm 

 does not deal with very much storm water. We 

 think that 21,500 gallons per acre per twenty-four 

 hours (5,370 gallons per acre of the total irrigable 

 area per twenty-four hours) is rather too large a 

 volume of a mixed sewage of moderate strength to 

 be treated by screening, settling, and surface irriga- 

 tion (with some fitration) on soil of the above 

 nature." (Part I., p. 89.) 



LATER WORK. 



The population at the commencement of work, 

 September, 1890, on the Beaumont Leys farm 

 was 114 persons to the acre, though, it should be 

 noted, many houses were not provided with water- 

 closets. In 1900 Mr. Mawbey presented to the 

 Corporation of Leicester a report from which the 

 following information is largely derived. The 

 sewage from no less than 145 persons per acre 

 together with the dense trade water of the borough 

 is now being treated. The proposed addition of the 



The suspended matters in the crude sewage during 

 the thirty-three weeks of the experiment averaged 

 43'7 grains per gallon, the albuminoid ammonia 

 1-182 grains per gallon, and the oxygen absorbed 

 7-442 grains per gallon. [62-43, 1-7 and 10-63 parts 

 per 100,000.] Alternative schemes for the treat- 

 ment of the sewage by this process were prepared, 

 and the one recommended was commenced in January, 

 1905. The works comprise (a) seven detritus tanks 

 of a total capacity of 1,400,000 gallons, or rather 

 more than one-sixth of the present dry- weather flow, 

 (6) eighteen clarifying bacteria beds, each 350 ft. 

 by 83 ft. (total about twelve acres), and with filtering 

 material of an average depth of 4 ft. 4 in. ; the 

 water capacity, calculated at fifty gallons per cubic 

 yard, being about 4,194,600 gallons ; and fitted with 

 automatic inlet feeds and timed discharges ; (c) an 

 effluent pumping station where the clarified sewage 

 will be sent through two 34-in. rising mains into the 

 existing main carrier, and (d) a sludge rising main 

 which -will discharge on to the land at various 

 points. Some of the general conclusions of the 

 report before referred to are : — 



" Having regard to the facilities afforded and 

 success achieved by the peculiar and perhaps almost 

 unique manner in which our heavy clay land has 

 been prepared, drained, and managed, it does not 

 appear from the experiments that any improvement 

 in final purification can be obtained by an entire 

 system of bacteria treatment, as opposed to a system 

 of clarification by detritus tanks and bacterial 

 filters followed by final purification on old pasture 

 or rye grass. The experiments do, however, show 

 that our sewage could be purified without treatment 



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