ELECTRIC STERILIZATION OF WATER
The accompanying illustrations show the details of construction and method of operation and the portability of a new equipment for sterilising water, in order to free it from bacteria and make it palatable for general consumption. The purity of water is of the greatest importance, and many sources of water supply have been found to contain bacteria producing infectious diseases, the same being destroyed only by raising the temperature of the water to about 110° C. The apparatus shown in the accompanying illustration includes a l>oilcr for heating the water properly, with an electrically operated thermometer so arranged that, when the temperature exceeds a given amount, an electrical connection is made in the thermometer ringing a bell, which, by producing an alarm, notifies the attendant that the water coming from the apparatus has exceeded the minimum temperature which is admissible in order to kill the germs. A cooler is also provided to reduce the temperature of the water, so as to be suitable for drinking purposes, and it is aerated and filtered by a special apparatus to remove the vapid after-taste resulting from the heating. The boiler is operated at a pressure of about half an atmosphere; the temperature of the water being raised from 105° C. to uo° C. The construction is such that not a single drop of water can leave the boiler, without being maintained at the proper temperature for a certain definite length of time, as a serpentine is arranged within the water-chamber which causes the steam-pressure above the water-surface to act on the water discharged from the warmest part of the boiler. Loss of heat is prevented, as boiling water surrounds the serpentine, and it takes some time for the water to pass through the same. A thermometer immersed in the discharged water is provided in the serpentine, and it is possible to control perfectly the operation of the apparatus. By a special valve-mechanism steam may be carried through all the conductors from the sterilising boiler, so that all parts of the apparatus, including the piping, are thoroughly sterilised before the apparatus is placed in operation, and a double-seat membrane-valve is pro vided to take the place of the serpentine, in case of intermittent operation. After passing the cooler, the sterilised water enters the filter at a temperature of about 5° C. above the unfiltered and unsterilised water. The cooling water is carried into the sterilising boiler, so that the heat taken up by it is not lost, but is utilised in the sterilising boiler as heated feed-water. In the filter the vegetable matter and earthy matter, as well as the iron precipitates, are removed, the water being then aerated, making it agreeable as drinking water and restoring it so as to have the resit taste and not the vapid taste produced by the boiler, bone-coal, also, being used as a means for destroying this unpleasant taste of boiled water. It is maintained that 640 calories are required for distilling one litre of water at o degree, while only one-sixth as much heat is required for sterilising a litre of water—about 110 calories. By this mechanism, it is also maintained that ninetenths of this heat is recovered by the cooling process from reheating the cooling water as it passes into the sterilising boiler. It is held that for destroying bacteria sterilisation only is necessary and answers the purpose equally as well as distillation for supplying, pure drinking water, while for chemical purposes, of course, distillation is necessary to eliminate soluble salts, killing all germs, of course, at the same time. The accompanying illustrations show both stationary and portable equipments — the portable outfits having been employed to advantage in southwestern Africa during the recent military operations of the German army. The portable steriliser has capacity of 500 litres per hour. The cold water enters through the feed-pump, is sterilised in the boiler for a quarter of an hour at a pressure of half an atmosphere. Tt is then cooled and filtered, the portable plant being constructed on the same principle as the stationary installation. I he stationary sterilisers are constructed with a capacity of 250 litres per hour for use in hospitals, while for use in homes apparatus of 100 litres capacity is sufficient. Small special outfits, weighing 45 kgs., are also employed for military service, sometimes carried by men, sometimes by mules or in sanitary cars. This new type of water-sterilising apparatus was constructed at Berlin bv Messrs. Rietschel & Henncberg, the apparatus being designed by Mr. R. A. Hartmann. also of Berlin, Germany. The others show the apparatus and methods of operations of a new system for the sterilisation of water by means of ozone, electrically produced. Ozone is of practical utility in the sterilisation of water, a large ozone waterworks having been installed at Paderborn, supplying that city with pure water by day and night. For the last three and a half years, this plant has been in successful operation, and, while that city has formerly suffered from annual epidemic of typhoid fever, since this plant was established about four years ago, typhoid fever has been practically eliminated from that community. A glass sterilising column, about 16 ins. high, the ozone apparatus being mounted in a wooden case, is utilised. A water-inlet and exit is provided at the top and bottom of the column, which is filled with small porcelain clay or glass balls and is equiped with differential gauge and a measuring tube having a throttlingvalve. the arrangement determining exactly the amount of ozone passing through the column by noting the data on the standardised table. As shown in the illustration, a ten-piece Siemans glass tube is provided within the case, together with a transformer and a small direct-current motor, operating a small blower utilised for forcing the air through the ozone apparatus. A rotating circuit-breaker is employed, which provides the necessary interrupted direct current for the primary coils of the transformer, and a washbottle is utilised for drying the air by means of calcium chloride or surphuric acid. A vertical switchboard is provided, with the necessary switches and regulating resistances for the motorcircuit, as well as the transformer primary interrupted direct-current circuit. The ozone tubes of the Siemans type consist of concentric glass cylinders, one placed within the other and fused together at the top. The outer one is placed in the cooling water, while the inner one is filled with water, this being utilised as a conductor of the high-tension current to the discharge-poles of the ozone apparatus. The accompanying diagrams show the connection of the filters, transformers, dynamos, pump and ozone apparatus. Motor-generators are provided only where alternating current is available, a small direct-current dynamo supplying the necessary continuous cm rent to the transformer, this dynamo being operated by an alternating current motor of about one-half H,P. in the main supply-circuit. At first the motor-generator set is started, and, when the interruptor is rotating in the proper manner, the circuit is closed to the transformer, and, while starting the ozone apparatus, this method is utilised. The proceeding is reversed in stopping the process, the transformer-circuit being first opened, and then the motor-circuit being opened at the switchboard. It is claimed that about one-halfH.P. is required for operating the laboratory installation which furnished 130 to 260 gals, per hour while six grammes of highly concentrated ozone are measured by introduction into a slightly acid solution of potassium iodide atmospheric oxygen utilised in the form of dr air. It is held that, if pure oxgen is used, instead of air, the output is several times as great. In Munich, as well as St. Petersburg, ozone installations have been established, producing as high as 25,000 gals, per hour. In the former plant the sterilised water is used for drinking purposes in its natural state, while at Munich it is employed in a large brewery, mineral water also being sterilised by ozone at a plant in Astrakhan. Portable sterilisation outfits can easily be furnished. A special wagon is provided, with motors and generator and sterilising apparatus, the power being supplied by gasoline engines, or alcohol motor, directly connected to a generator. A small rotary water pump is provided to draw the feed-water from the source of supply and force it into the sterilising column, and a small blower is used to supply the air for the Ozone apparatus, the air being previously dried while passing it through calcium chloride. There are two spring-supported Siemans ozone cases mounted on another sterilising vehicle, this equipment including eight ozone-tube elements, and a transformer under the ozone apparatus for the production of the high-tension current from the low-tension primary alternating current supplied by the cable from the machine wagon. There are also three parallel, rapid filters provided, consisting of metal cylinders, in which are placed closed filter-bags, through which the feedwater is forced before it is pumped into the column and is, therefore, largely freed from suspended impurities. A cylindrical metal sterilising column about 8 ft. in height is used, filled with pieces of cement-covered pumice stone, about the size of small pebbles. This column is arranged in two parts, each having a perforated space, and placed one upon the other—an arrangement which permits the parts to be easily taken to pieces in sections, as they are joined by bolts. This portable equipment weighs about a ton and produces about 800 gals, of pure water per hour. The engine which drives the small alternating current dynamo is of about 2-H.P. capacity. Such a large amount of ozone is produced that, even if the water is in very bad condition, it is thoroughly sterilised. ‘This is so worked out as a matter of precaution, a very much larger amount of ozone being produced in order to insure pure sterilised water for drinking purposes than is really necessary, for the troops. Each of the military wagons for this portable apparatus is hauled by a single horse and weighs about 900 kgs. Under ordinary conditions this plant supplies from 2 to 3 cu. metres per hour.