Dry Method of Treating Urine
Most of us must have remarked, either in London or some other centre of population, how little annoyance arises from cabstands. One must know of cab ranks where dozens of horses stand for hours daily from year's end to year's end, and where tons of dung and thousands of gallons of urine are spilled upon the same spot and practically without annoyance. I do not mean to say that occasionally one may not get a strongly ammoniacal whiff from such a spot when the weather is hot and muggy, but it is notorious that they are seldom foul, and that on passing them we are never prompted to hold the nose and quicken our pace.
The condition of a cabstand is in strong contrast with the average urinal with an ordinary water supply. Such places are always pervaded with a sickening odour, and the mere addition of practically an unlimited amount of water is insufficient to keep this smell of decomposing urine (than which nothing is more offensive) in abeyance.
It is hardly too much to say that water urinals are always offensive, and that even in clubs and similar smart places the tablet of camphor, which is intended to assert itself over the head of the other smells, is not always successful.
It may, I think, be said that water urinals are never sweet except in those rare instances in which they are constantly wiped perfectly clean by an attendant. The decomposition of urine is due to micro-organisms, and it is well-known that if urine be passed into an impure vessel, its decomposition takes place with great rapidity, especially if the temperature be moderately high. All vessels intended for the reception of urine require a thorough washing and cleansing every day. The form of 'bottle' which is habitually used for bed-ridden patients is most difficult to clean, and is a very undesirable apparatus. If water urinals be provided with 'traps' in which urine, or urine and water, is allowed to stagnate, such traps must be permanently foul and become a source of annoyance if not of danger.
If urine be allowed to filter through absorbent material, the effect produced upon it is as remarkable as it is interesting. I have experimented with a variety of absorbent materials during the last six years, and now propose to shortly set forth the results, some of which have been previously published in 'Essays on Rural Hygiene' (2nd ed.: Longmans, 1894). The vessels used have been of conical form, tapering from one foot in diameter at the upper and wider end to an opening large enough to admit a big quill at the lower end (fig. [20].) The length of these vessels is 30 inches, and they are supported on a metal tripod.
Some of the vessels have been made of metal—galvanised iron—and others have been made of flannel.
Fig. 20.—Urine Filter.
The first experiments were made with ordinary garden earth, and they were conducted for me by Dr. Wells, of Brondesbury. These, and nearly all the subsequent experiments, were made in the same way, viz., by adding day by day what may be called a natural chance quantity of urine, varying in amount from about a quarter of a pint to two pints in the day. In these experiments, when fresh earth was used, the filtrate was always of lower specific gravity than the urine added, notwithstanding the considerable evaporation which must have taken place from the surface of the filter. The total solids of the urine averaged 4·44 per cent., of which 3·45 were organic and 0·99 inorganic, while the total solids of the filtrate were 1·78 per cent., of which 1·07 were organic and 0·71 inorganic. How much of the organic and inorganic matters in the filtrate came from the mould it is not possible to say. The urea was probably all reduced, as the hypobromite method gave a percentage of only 0·15 in the filtrate, a quantity which may be disregarded in the face of the fact that the hypobromite method acts upon nitrogenous bodies other than urea. The filtrate was rather deeply pigmented, but the pigment was submitted to spectroscopic examination by Dr. McMunn, of Wolverhampton, and pronounced by him to be not of urinary origin. Further—and this is most important—the filtrate could be evaporated to dryness without offensive odour, and showed no tendency whatever to putrefy when left for months in an ordinary bottle.
In short, the filtrate, although derived from urine, had none of the qualities of that fluid. The earth in the filter when stirred was distinctly ammoniacal, so that the presence of ammonia could be detected by the nose when held quite close to it, but at no time was there any foulness.
When the same earth, after some months of rest, was used a second time for the filtration of urine, the same results were obtained, with the exception that the filtrate was of higher specific gravity than the urine added, and the mineral residue of the filtrate was double that of the urine. This was caused by the solution of nitrates and other soluble salts which were formed in the earth from the residue of the first instalment of urine, but the filtrate had not the properties of urine. It contained no urea, could be evaporated to dryness without offence, and showed no tendency to putrefy.
In the same way, I have used deal sawdust instead of earth, and the following is the result of an analysis made for me by Dr. Kenwood in the Hygienic Laboratory at University College.
July 25, 1895.
Parts per 1,000.
| Reaction | S.G. | Solids | Urea | SO3 | P2O5 | Cl |
| [1]Faintly acid | 1·020 | 44·20 | 23·8 | 1·38 | 2·39 | 4·08 |
| [2]Alkaline | 1·034 | 127·9 | Nil (all reduced) | 8·30 | 13·41 | 38·00 |
[1] (1) Fresh urine.
[2] (2) Urine after filtration through sawdust.
'Physical Characters.—(1) Pale yellow, clear, with a slight opaque zone from mucus, normal urine odour.
'(2) Dark mahogany-brown colour—markedly opaque and somewhat turbid. A peculiar woody (resinous) odour, faintly ammoniacal.
'The "two ammonias" cannot be estimated by Wanklyn's process in the fresh urine, where there is so much urea, but in the filtrate they amount to—
| 0·032 | Free and saline | } | per 1,000 |
| 0·0016 | Organic | } |
I have kept two test-tubes half filled with (1) and (2), tightly corked, in the warm cupboard of the laboratory for the past three weeks; the sample of fresh urine has become offensive, but that of the filtered urine is perfectly sweet, and rather pleasant to smell.'
The filtrates from sawdust were a very dark brown colour, like 'stout' or 'porter,' and these have been evaporated to dryness without offence, and have shown no tendency to putrefy.
Experiments conducted in the same way with peat have yielded a filtrate almost identical in appearance to the sawdust filtrate, inoffensive on evaporation and not putrescible. The filtrates from peat and sawdust were always of $1m> than the urine added.
In order to ascertain how much urine could be got rid of by evaporation, I tried the experiment of using a flannel bag filled with sawdust or peat, and I found that with regard to one of these experiments (the bag being hung under a shed in the open between June 15 and July 20, 1895), only 81 ounces of filtrate having the qualities above given were obtained from 729 ounces of urine added to the filter. In this case 648 ounces of urine (over 40 lbs. weight) disappeared. In another experiment carried on in my room at University College I added (between May 9 and July 26) 626 ounces of urine, and obtained only 54 ounces of filtrate, so that in this case 572 ounces (nearly 36 lbs. weight) of urine had disappeared.
As far as my experiments have as yet gone, I have not discovered the limit of sawdust for dealing satisfactorily with urine. Thus in 1894 I filtered during May, June, and July, 39 lbs. weight of urine through 6 lbs. of sawdust in a flannel bag, and neither filtrate nor sawdust was in the least offensive. In the same months in 1895 I passed an additional 41 lbs. weight of urine through the same sawdust in the same bag, and practically with the same result. In 1896 I added over 30 lbs. weight of urine to the same sawdust, but as the flannel bag had become too rotten to hold together, I was obliged to have recourse to the metal filter-vessel. The early filtrate obtained in 1896 had a specific gravity of 1·061, but, like its predecessors, could be evaporated to dryness without offence, and the sawdust was not in the least malodorous, although it was distinctly (as it always has been in these experiments) ammoniacal.
One of the most interesting experiments was that in which the filtering material consisted of crumpled paper in a flannel bag. The paper used was such as is familiar to every one, and was derived from old Bradshaw's Guides, the leaves of which were torn out and crumpled up in the hand before being put into the bag. This paper, like most paper used for printing, is sized and not very absorbent. At the end of a week a considerable quantity of filtrate had been obtained, and both filter and filtrate became excessively foul and malodorous, so that it was unpleasantly obtrusive, even when one stood several yards from it. The foul filtrate was returned to the filter, and no fresh urine was added for a time. This was done on October 15, and on October 21 all had become sweet, and four ounces of a perfectly sweet and faintly acid filtrate were obtained! The filter never became foul after this date. Between October 21 and November 25, 1894, 434 ounces of urine were added, and 54¼ ounces of filtrate were obtained. Between November 25, 1894, and January 6, 1895, the filter rested; then, between January 6 and March 31 urine was added only occasionally, so that the total only amounted to 560 ounces (35 lbs. weight). Three and a half pounds weight of filtrate were obtained. The filtrate was more ammoniacal than that obtained from sawdust, earth, or peat, but it never has shown any tendency to putrefy. The paper became blackish, and was riddled with fungi, and ultimately was scarcely distinguishable from garden mould.
Thus I have shown that these absorbent materials exercise a strangely purifying power upon urine, and its behaviour with these bodies is very different to what is observed when urine is mixed with water.
Now for the practical application. I am not going to advocate that all houses in cities should be fitted with absorbent urinals, but it will occur to many that there are circumstances when such urinals may be very useful.
They are admirably suited for use on race-courses, cricket and football grounds, and other places where people congregate occasionally. On my advice they have been placed on two cricket grounds near London, and have given great satisfaction; they have been used also in the engineers' yard attached to the Twickenham Station of the London and South-Western Railway, which is visited by a large number of men (averaging perhaps 150) every day, and the South-Western Railway have fitted them up at one of their country stations.
Again, in country houses a urinal for gentlemen placed in some accessible but secluded spot, and formed of a basket or barrel of convenient height, filled with peat or sawdust, will be found both economical and inoffensive. In the garden of a little cottage I have such a urinal, consisting of a small barrel filled with peat, which has been in use for nearly eighteen months, and which has never been changed, and is yet perfectly free from offensive odour. It is only when the top layers are removed that the nose perceives an ammoniacal odour, and then only when placed almost in contact with the peat.
I am accustomed to advise that such urinals for public use should be in the form of troughs made of basket-work or hurdling, or of wood panelled with perforated zinc, the trough to be triangular in section, with apex downwards, 3 feet 6 inches wide at the upper part, and 2 feet 4 inches in depth.
The shape of the trough and the material of which it is made facilitate evaporation. Such a trough should be under cover to prevent the access of rain, and it is obvious that with a width of 3 feet 6 inches it might be used from either side, provided a match-board screen were placed vertically along the centre (see fig. [21]).
Allowing 2 feet of length for every 'place,' it follows, there being a 'place' on either side, that each foot of length would afford one place.
It might be necessary to allow the wicker-work trough to have an open gutter beneath it, but it is only exceptionally that any effluent would be afforded.
If such a trough is in constant use the sawdust must be turned over and stirred occasionally, and if this be done it will never be foul, and the sawdust can be used for surprisingly long periods of time without emptying.
If sufficient sawdust, or peat, or dry earth be provided for a double charge, so that one charge may be drying in a shed while the other is in use, my belief is that this might be used for indefinite periods.
A final question, and one of very great importance, is the ultimate destination of the absorbent material.
Sawdust has a very bad reputation with agriculturists, who assert that when used in large quantities it grows fungi and poisons the land. If fresh sawdust be used, and if it be employed in relatively large quantities, and especially if it be buried too deeply, I can well understand that it would prove prejudicial to crops.
Fig. 21.—Dry Urinal.
I can positively assert, however, that deal sawdust or peat, after being soaked with urine, shows no disposition whatever to become mouldy. I have never seen mould upon deal sawdust, but I have seen it upon oak sawdust.
My experiments further show that when sawdust or peat has been used as a top-dressing good crops have followed, whether on grass or garden ground. The cricket clubs which have, in accordance with my advice, put up dry catch closets and dry urinals have used the products as a top-dressing at the end of the season, and with the result that their wicket pitches have been the envy of their neighbours.
Chemists tell us that urine is of high manurial value because of the large amount of nitrogen which it contains. This is doubtless true, but we all know that the immediate effect of pure urine is fatal to herbage. Whether this be due to the heat of the fresh urine or the salts, I do not know, but I fancy the latter. In the same way we know that a sprinkling of salt, or salt and water, kills weeds; but we are told that salt is a bad weed killer, because it ultimately acts as a manure, and causes increased growth. Now urine does the same thing.
The farmer who uses the urine and dung of his animals mixed with absorbent material (generally straw), and ultimately places it on the land as a top-dressing, gets nothing but good from it.
The practices I advocate are exactly analogous to those which have been used by agriculturists in every age, and with the best results. I am merely advocating a return to customs which have been tried again and again and have never been found wanting.
In the 'Journal of the Royal Agricultural Society' (vol. vii., part iv., December 1896) I find a statement (p. 631), that in the delta of the Nile a compost of earth and cattle urine is generally used as a manure.
'Owing to the lack of wood, the people are compelled, as in India, to use the solid droppings of their cattle as fuel, but they conserve the urine on a very ingenious system. Loose earth, shifted and renewed from time to time, is used as a covering for the stable floor, and earth is so much in demand for this purpose that the irrigation officers can hardly prevent the people from carrying away the canal banks.' Analyses show from 1·25 to 2·5 per cent. in equivalent of nitrate of soda. It is obvious, however, that a chemical analysis gives but a poor idea of the value of the compost. It is applied at the rate of eight tons to the acre for growing sugar and maize.