CHAPTER V WATER (Part 2)

earth. The objections to all of these are their liability to become infected, to pass impure water and to clog. Fragility and limited output are further deterrents to their use in the field. Filtration by sand has been practised by placing a box or barrel inside another, the inner receptacle being open at both top and bot- tom. Sand filled both inner and outer receptacles to about one- fourth their height. Water was usually poured into the inner re- ceptacle whence it passed through the layer of sand and rose to its proper level in the outer barrel, from which it was drawn off by a faucet. This apparatus clarified water, but did not remove all bacteria. Also it was liable to become infected, unless fresh sand was used frequently, so that the output was worse than the intake. The efficiency of filtration by sand depends upon the formation of a gelatinous layer, due either to natural agents which produce zoo- glea, or to aluminum hydroxid which is formed when alum is thrown into water. The defects in the filtration plant which used two barrels or boxes may be overcome by using sand which has been purified in sterile water, and by precipitating a layer of aluminum hydroxid upon the surface of the sand in the inner receptacle. In the opera- tion of such a purification plant it is essential that the gelatinous filtering layer be not disturbed and that this sand be cleansed at least every other day. Water must be introduced into the inner receptacle gently, preferably through a syphon whose discharge end is turned upward, otherwise the value of the apparatus b destroyed. Filtration through sand and a layer of aluminum hydroxid may also be practised by digging a trench near a stream, lining Ihe trench f with puddled clay and two revetments, one between the trench and the stream, and the other on the further side of the trench. The trench is partly filled with successive layers of small stone, grave and sand, and on these a layer of Socculent gelatinous aluminum hydroxid. The water from the stream is led into the trench by a syphon, whose discharge end is upturned ia order that the filtering surface may not be disturbed by the flow of water. The filtered water is drawn from the trench ihrough a pipe which passes through ^ 1 i Fit;, III. — Filtering apparatus nf D^irr.all liltfr ylI<ivi:'.L) he outer revetment and into the layer of small stones. Thj tiethod can be followed to advantage only where the geographica ituation is unusual, i.e., when one bank of the stream is highe han the land near it, as the lower side ol an irrigation ditch. A much simpler and quite satisfactory procedure is to dig a pi ear the side of a stream, and dip from it the water that seep hiough. Such water has been strained by the natural nooglca i[ he stream bed aa well as by the intervening soil. In seml-perma A 134 FIELD HYGIENE AND SANITATION nenl camps this pit may be lined with wattle work, or a barrel, keg'l or box, from which both ends have been removed. Several other more elaborate devices utilize the straining effect I of aiuminum hydroxid. The best of these is the Damail filter, j which consists of a syphon witb a cylindrical metal framework sur- J rounding its ascending arm; a doth which surrounds this framework I and is the essential part of the filter; a syphon primer, two water J cans, a galvanized iron tank and a crate. The precipitant consistfl J of alum hydroxid and sodium carbonate in proportions which satisfy I each other chemically. Five grains of alum to the gallon are suffi-J cient lo clear the most grossly polluted water. When the precipi- tant is added to water a flocculent precipitate is formed which en^ i tangles parasites and arrests them on the surface and in the body o£ I the filtering clolh. This becomes clogged eventually and must be I removed and brushed, but aa the output continues to diminish, the | cloth is removed, washed, boiled and dried. Meanwhile it placed by another. This apparatus removes 98 per cent, of thel bacteria in water; clarifies it and will deliver 50 gallons of water a hour. It weighs 51 pounds, and is quite the best apparatus j devised for filtering water in the field. The Japanese field filter (the Ishiji filter) consists of a conici canvas bag having a capacity of 24 gallons and with two spouts O branches just above the apex. These spouts contain sponge d WATER 135 which effect filtration. The apex of the cone receives the sedi- ment. This filter employs two powders, the first conusting of potassium alum, potassium pennanganate, aluminum silicate, the second chiefly of aluminum silicate and small amounts of tannic and hydrochloric acids. After the filter has been filled a suitable quan- SELF CLEANING FILTER ■Sand and alum filter. {After Leitan.) tity of the first powder (enough to plainly discolor the water) is added and stirred up. After a few minutes about one-half as much of the second powder is added and stirred until the discoloration caused by the first has been removed. After the precipitate sub- sides, in IS or 30 minutes, the leather spouts are untied and the 136 FIELD HYGIENE AND SANITATION water allowed to pass. The hydrochloric acid assists the decompo- sition of the permanganate while the tanmc acid removes the color. The result is satisfactory with clear water but much less so with tur- bid water. A modification of this process is to place in the radial spouts perforated boxes containing alum, silicon, potassium per- manganate and charcoal. As the water passes through it forms aluminum hydroxid which is arrested by the sponges and helps their filtering action. A gand and alum filter which may be extemporized in camp con- sists of two concentric inverted cones or pyramids, separated by a narrow interval. The outer receptacle is extended upward as a cylinder or rectangular box to form a tank. A pipe drains the drink- ing water from the bottom of the inner receptacle, and another pipe drains the waste water from the apex of the outer one. The inner receptacle is filled with a heaped-up quantity of sand, and this is covered by a layer of alum hydroxid. Water is poured gently into the tank. Gross impurities roll down the sides of the heaped-up filtering mass and escape in the waste water, which may be poured in again after sedimentation. If no filtering apparatus is at hand, but alum and sodium bi- carbonate are available, the addition of five grains of the former and one and one-half grains of the latter to a gallon of water will clarify the muddiest water in one or two hours and carry down 95 per cent, of the contained bacteria. Chemical Sterilization. — The most generally satisfactory means of purifying water in the field is the use of chlorinated lime — the so-called chloride of lime. This is a lumpy powder, made by satu- rating slaked lime with chlorine. It should contain 35 per cent, of this gas available for use. By available chlorine is meant the amount that is liberated readily from its combination in the powder. The chlorine content diminishes rapidly on exposure to air. A per- cent ual calcium chloride carrying 7 5 per cent, of chlorine is advocated but is not now obtainable in America. Its advantages are greater stability, and the smaller amount of the chemical necessary for a given result. The germicidal value of calcium chloride is due to the action of carbon dioxid in water upon the calcium hypochlorite in the powder, producing hypochlorous acid which in turn liberates oxygen, and develops chloramines. WATER 137 U is tbe nascent oxygen and more especially the chloramines which destroy bacteria and not the chlorine content of the calcium chloride, as such. The amount o£ chlorinated lime which must be used to purify water depends upon the strength of the former and the composition of the latter, particularly in reference to the amount of organic mat- ter the latter contains. In water containing little organic matter bacteria will be reduced 99 per cent, by i part per million, but for a similar reduction in sewage r part per 25.000 is necessary. When impute water containing organic matter is attacked by hypo- chlorites, it develops unpleasant fUivors; therefore it should undergo filtration through several layers of cloth before the powder is added to it. Five parts of powder per million parts of water are usuaUy considered adequate, but if there is grave danger of pollution, more should be added. Havard recommends for general field service from 5 to 15 parts per million. Lyster controls deterioration of the powder by preserving it in brown glass capsules which are broken just before use. In order to effect a percentual certainty one tube is provided for each bag of water containing 40 gallons. Each tube 138 FIELD HYGIENE AND SANITATION contams 15 grains, giving two parts of available chlorine for a mil* b'on parts of water. The Lyster water bags are made of rubber lined canvas, with a hemispherical bottom to receive sediment and 6 spring faucets are placed around the bottom of the bag just above this hemispherical portion. These bags have given excellent serv- ice in Mexico and along the border. Improvements recommended in the bag are that it be made of heavy canvas and provided with a cover preferably of a filtering material that can be tied over the top, used as a strainer, removed and boiled. Another modification suggested is that the bag be made in half sizes so that platoons operating independently may be equipped. The manner in which the powder is added is important. It should not merely be thrown into the water but should be first made into a paste, all lumps being carefully broken up, then thinned to a dilute suspension, and then stirred into the water to be purified. The contents of one of the Lyster tubes should be thinned by the gradual addition of at least a pint of water before it is stirred into the water in the bag. Parties not supplied with measured quantities of the powder use the following method recommended by Havard: A teaspoonful is leveled off by rolling a pencil over it, rubbed up with a cup of water, and diluted with three more cupsful. A teaspoonful of this dilu- tion is thoroughly mixed in a 2-gallon pailful of water. This water should not be drunk for at least an hour after the chloride has been added. Disadvantages of the hypochlorite method are that it increases the hardness of water and may give it an unpleasant odor and taste. The formor objection is more theoretical than practical. The latter may be overcome by agitating the water. The advantages of this method are cheapness, quickness, con- venience and general reb'ability. A portable plant weighing 222 pounds for the h3rpochlorite treat- ment of piped water supplies has been devised by H. A. Whittaker. It will treat satisfactorily 1,000,000 gallons a day which can be increased to 4,000,000 with added effort on the part of the operators. Its use in the military service is restricted to fixed camps or billets with piped water supply of doubtful purity. Sodium hypochlorite is slightly more efficient than the calcium salt and forms less precipitate but it is more expensive. WATER 139 Sodium bisulphate is an excellent agent for sterilizing water iii canteens. For that reason it is of peculiar value in the cavalry serv- ice whose equipment must be as scant as possible and where small detachments operate without apparatus for piuif 3nuig water. Thirty grains should be added to each quart. Firth recommends that it be made up in tablets with saccharine and oil of lemon. The water should not be drunk for about 20 minutes. This agent can be used only in aluminum canteens as it forms toxic sulphates with other metals. Calcium permanganate has been used recently in the German army to purify the water in canteens in the proportion of about i grain to the quart. A tablet containing the salt is dissolved in a canteen full of water agitated and allowed to stand for 10 minutes, when a tablet of manganous sulphate is added. A precipitate forms which must be filtered off by a filter paper cap over the mouth of the canteen. The disadvantages of this method are the fragility of the filter paper cap, the possibility of confusing the tablets and the time interval which thirsty soldiers would be prone to abbreviate. Potassium permanganate has been used to purify water in the proportion of a grain to the quart. As a workable nile, enough is added to give the water a pinkish tint. Its effects are due to the nascent oxygen liberated but its action is weak, very slow, somewhat uncertain in the strength used, and it imparts an unpleasant taste and color to the water. Its use is restricted usually to purifjdng waters supposed to have been infected with the B. cholerae which is peculiarly susceptible to its action. Wells are disinfected by adding potassium permanganate in the proportion of 60 grains to the gallon. After 24 hours the water is pumped until it is colorless. Dead aquatic flora and fauna should be removed. Copper sulphate destroys algae in water in the proportion of one part per million, but it will not destroy pathogenic organisms except in such strength (one part to 50,000) that it would be toxic to per- sons drinking it. Iodine liberated from a mixture of iodide and iodate and after an interval removed by sodium hyposulphite has been used for steril- izing water in canteens in the French army. The agents were put up in red, white and blue tablets in order to make them easily dis- tinguishable. Because of the fact that the first two must be crushed I40 FIELD HYGIENE AND SANITATION together before they were added to the water and because of the time interval — ^ten minutes — that had to be allowed before the third was added their use has been discontinued. Dakin and Dunham report that the most suitable substance for sterilizing drinking water in the field is one which they have devised, viz., p-sulphon dichloramino benzoic acid. As the synthetic name is cumbersome, the term halazone^ has been proposed for the tablets containing it (Cl2N.O2S.C6H4.COOH). These are easily prepared from cheap, readily available materials and are reasonably stable. One part of the agent per 300,000 wDl sterilize an ordinarily heavily contaminated drinking water in about thirty minutes destroying b. typhosus and b. cholerae, etc. In this concentration a very slight taste is perceptible, especially in warm water containing little organic matter, but the water is perfectly palatable. The active chlorine is utilized less rapidly than that in bleaching powder, for which reason the disinfection process continues for a longer period. By the use of this agent fifty gallons of water can be sterilized for one cent. Its action on aluminum is negligible. Ultra-violet Light. — Ultra-violet light has been used to purify water in the French and Austrian services but its development requires the use of bulky apparatus, parts of which are very delicate. Also its value is much diminished in turbid waters or those contain- ing colloid material. Its use in the field has not proven practicable. Several methods have been employed for carrying water to troops at points where this is not readily accessible. The Hennenberg sterilizer is provided with a water cart. A cart which both purifies and retains the water is used in the English service. In the Austrian service a small native wagon in the service of each company carries barrels. The French employ a water train and also have steel water wagons, each weighing 1200 kg., and carrying 3000 kg. of * The starting point, in the production of this agent is the development of p-toluene sulphonamide by the action of ammonia on p-toluene sul- phonic chloride. This last mentioned is a very cheap waste product in the manufacture of saccharine and is obtainable in relatively large quantities. A description of the technique followed to produce halazonc is believed to be out of place here. It can be found in the article by Dakin and Dunham on page 682 of the British Medical Journal for May 26, 1Q17. WATEK water. Each wagon has a purifying capacity of 3000 litres per hour and can supply 25,000 lo jo.ooo litres per day. Fifty tcct of woven wire hose arc supplied. The wagon is divided equal compartments. Chloride of lime is used for the purification of the coQtents. Lyster has recommended for use in our service a canvas tank which would fit ihe hody of hii I'scorl wagon. Il would be provided 141 ■ s per ■ i feet ■ tank. I vided ■ Fic. 115.— Field with spring faucets similar to those used on the water bag he devised. It has also been recommended that a flat water tatjc be fastened to the bottom of the company wagon. This should be provided with spring faucets at the rear of the vehicle, from which men may re- plenish their canteens. The necessity for some such apparatus was often keenly felt by the troops in Mexico, where the heat and aridity conspired to increase thirst. The difficulty was overcome in part by carrying kegs of water on wagons, in some organizations, but this primitive arrangement did not fully meet requirements. Troops in the 142 FIELD HYGIENE AND SANITATION ^ -» — i •< ^ " ■ - 1 -•1 ;■« •mM i^ ^•'^•1 H^^^^^^l WATER ^ 1 ji^ r H B^X2^^^.. 1 ^^■H . ' fitixE^fisS. B -ir'^jBM H BBg^»£,aJlKiBsy'S^aaB H pi^^s^^ ' 1 -s 1 BLj!^^ r " id 1 .jaBgam^-HW' ^ 1 K iWl-lZ_ Ps. ■