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JOUBNAL OF HOKTICULTUEE AND COTTAGE GAEDENEB. 



[ November 20, 1873. 



information upon the subject than I can do. — P. Grieve, 

 Culj'urd. 



SEWAGE AS A FERTILISER. 



BV CUTHDERT W. JOHNSON, F.R.S. 



The difficulties attending the disposal of sewage commence 

 as soon as cesspools and the consequent fouling of well water 

 are supplanted by sewers. It then becomes necessary to pro- 

 vide for the disposal of the sewage — either by pouring it into 

 a stream or by adopting some plan for its purification. Then 

 commences numerous suggestions to accomplish this very dif- 

 ficult object. These have been, in many cases totally unworthy 

 of notice, in others difficult to be understood. It is needless 

 to examine these in detail, for with one exception these pro- 

 cesses are unable to extract from sewage the salts of ammonia 

 and other soluble matters which render the effluent waters so 

 noxious. That exception is by irrigation, which has been well 

 alluded to by Her Majesty's Commissioners who were ap- 

 pointed to inquire into the pollution of rivers. They remarked 

 (First Report, p. 128), " A most important feature of this plan 

 of treating town sewage is, that although wherever irrigation 

 is carelessly conducted a certain amount of unpleasantness is 

 inevitable, yet no injury to health follows the adoption of the 

 plan. No locality can be named in which typhus fever, enteric 

 fever, dysentery, or any other zymotic disease generally attri- 

 buted to foul emanations has been traceable to irrigation with 

 town sewage. On every ground, therefore, irrigation may be 

 confidently recommended as a safe and trustworthy remedy 

 for the nuisance with which towns have to deal." 



With such evidence before us, and with the knowledge that 

 several hundreds of acres of grass land have long been suc- 

 cessfully sewage-irrigated at Mansfield, and a far larger extent 

 of land at Edinburgh for ages, we might reasonably expect 

 that the question might be carefully and calmly examined, 

 and even condemned with reluctance. But how different has 

 recently been the mode of attack by those who do not even 

 pretend to suggest any other and better mode of purifying 

 town sewage ? It has of late not even been considered neces- 

 sary to ascertain the truth of certain rumours before a violent 

 attack was commenced on sewage irrigation. 



It was asserted that a typhoid fever in Marylebone was attri- 

 butable to the use of the milk from a herd of cows fed on 

 sewage-irrigated grass ; then it was found out that these cows 

 were not fed upon any such irrigated grass. When this charge 

 broke down, then it became necessary to try another tack. 

 It was gravely asserted, by a gentleman who ought to have 

 known better, that typhoid fever was always rife around the 

 sewage-hrigated meads of Beddington, near Croydon, and at 

 Edinburgh. This assertion, however, did not prove more 

 fortunate than the previous one, for it turned out, by the 

 official report of the officer of health for Beddington, that in 

 the surrounding parish of Carshalton and the hamlet of Wal- 

 lington not a single fatal case of typhoid fever occurred in the 

 years 1871 and 1872, two cases only from scirlatiua in 1871, 

 one from diptheria in 1871, and not a single case from either 

 in 1872 ! And then with regard to the meads at Edinburgh 

 we find in the Keport of the Commissioners (No. 1, p. 90) 

 that Dr. Littlejohn, the medical officer of health to the city, 

 " although he looked with prejudice and displeasure on the 

 existence of sewage meadows in its suburbs, he had not been 

 able to connect the ill health of certain localities in Edinburgh 

 with the Craigentiuny meadows as its cause." And Professor 

 Christison, President of the Royal Society of Edinburgh, adds 

 (Ibid, p. 90), "Many years ago my own prejudices were all 

 against the meadows ; I have been compelled to surrender 

 them. I am satisfied neither typhus, nor enteric fever, nor 

 dysentery, nor cholera is to be encountered in or around them, 

 whether in epidemic or non-epidemic seasons, more than in 

 any other agricultural district of the neighbourhood." 



That myth not answering the purpose for which it was con- 

 cocted, another battery was opened. It was gravely asserted 

 that the irrigated land would become supersaturated and in a 

 short time lose its deodorising powers. Those who made this 

 assertion were well aware that the meads of Edinburgh and 

 Mansfield had been sewage-irrigated for generations. Then 

 came _ the report of the Sewage Committee of the British 

 Association at the Bradford meeting in September last, thus 

 reported in the Times of September 2.? :— " The Committee 

 consisted of Mr. Grantham, Professor Corfield, Dr. Gilbert, 

 Mr. W. Hope, and Professor A. W. Williamson, who had 

 attended the meetings ; and Mr. Bailey Denton, Mr. J. T. i 



Harrison, Lieutenant-Colonel Leach, and Dr. Voelcker, who 

 had not attended. The Committee had continued that part 

 of the inquiry for which it was more particularly appointed — 

 namely, the examination of the typical case of sewage-farming 

 at Breton's Farm, near Eomford. An analysis of the soil of 

 the farm showed a considerable increase in the amount of 

 nitrogen and phosphoric acid. The Committee's funds being 

 nearly exhausted, they present a rtsume of the results of their 

 labours, prepared by Professor Corfield. 



" Mr. Hope presented the Report on Breton's farm. Bom- 

 ford, and stated that the systematic observations hitherto 

 carried on had been continued. The point of chief import- 

 ance was that the effluent water was slightly purer, thus 

 exploding the idea that land becomes " sick " of sewage. An 

 analysis of samples of the soil taken in April, 1853, at the 

 same part of the farm as the samples were taken for analysis 

 in 1870, prior to the application of any sewage, showed very 

 appreciable quantities of phosphoric acid, ammonia, and nitric 

 acid, which valuable manures were almost, indeed practically, 

 absent in the same soil in 1853. The Committee also found 

 that the population of Eomford had been largely overstated 

 by the Local Board, and that, instead of between 7000 and 

 8000 persons feeding the sewers, there were only about 4CO0 

 persons in all. This, of course, gave a very different com- 

 plexion to the agricultural results, and among other things 

 gave the important and new fact that in the case of this town 

 the sewage of the population, including, of course, kitchen and 

 washhouse slops, and that due to horses and to live stock on 

 market days, contained 13 lbs. to 14 lbs. of nitrogen per head 

 per annum. Professor Corfield recapitulated the contents of 

 all the Eeports ^which had been presented by the Committee,, 

 and said they had come to conclusions which were substan- 

 tially as follows :— First, All conservancy plans, including 

 heap and cesspool systems, dry-ash and dry-earth closets, 

 pail closets, &c., are quite incompetent as solutions of tho 

 general question of the removal of the refuse matters of a 

 population ; they only deal with a small part of the liquid 

 manure. Towns which resort to one of them require to ba 

 sewered, and the sewage requires to be purified. The manure 

 produced is in all cases (excepting that of simple pails or tubs, 

 where no extraneous materials are added) poor, and will only 

 bear the cost of carriage to a short distance ; that produced by 

 the dry-earth system being, even after the earth has been used 

 three times over, merely a good garden mould. Moreover, 

 these plans all violate one of the most important of the Sanitary 

 Laws, which is that all refuse matters which are liable to be- 

 come injurious to health should be removed instantly, and 

 then be dealt with afterwards. With all these plans it is au 

 obvious advantage, on the score of economy, to keep the 

 refuse about the premises as long as possible ; and the use of 

 deodorants of various sorts, or even of disinfectants, proves 

 that this is the case, and that these systems all depend upon 

 a fallacious principle. They should therefore be discouraged 

 as much as possible, and only resorted to as temporary expe- 

 dients or with small populations in very exceptional instances. 

 Second, The water-carriage system, on the other hand, is based 

 upon the sound principle of removing all the refuse matters at 

 once and in the cheapest possible manner by gravitation, and 

 ought to be resorted to in all but the most exceptional cases. 

 The opinion of the Committee that all sewers should be made 

 of impervious materials, and that separate drains to dry tho 

 subsoils should be constructed where necessary, has already 

 been most emphatically expressed. The freest possible ven • 

 tilation of sowers, house drains, and soil pipes, in order to pre- 

 vent accumulations of foul air, is also essential. With regard 

 to utilisation of sewage, the Committee has come to the con- 

 clusion that the precipitation processes which it has examined 

 are all incompetent, and necessarily so, to effect more than a 

 separation of small parts of the valuable ingredients of sewage, 

 and that only a partial purification is effected by them. Some 

 of them may, however, be useful as methods of effecting a 

 more rapid and complete separation of the sewage sludgC; 

 The upward-filtration process only effects a clarification of the 

 sewage, and is therefore no solution of the question. Weare's 

 charcoal filtration process, as carried on at Stoke-upon-TreuS 

 Workhouse, did not give satisfactory results, the eflluent water 

 being in effect (weak sewage; an opportunity wiU, however, 

 soon be given for an examination of this process in a modified 

 form on a much larger scale at Bradford, and under more fa- 

 vourable conditions. Intermittent downward filtration through 

 soil has been shown at Mertbyr Tydvil to afford a means of 

 purifying the sewage under favourable conditions, but it can- 



