INDUSTRIAL A N D ENGINEERING CHEMISTRY
September, 1926
the needs and afford protection. Not only are these studies important, but the economy effected by the industry itself, through consolidation, plays a part. One large company, which today has only six factories, a t one time operated fifty-three; yet with its six plants it produces about three times as much window glass, and of a much better quality. The grouping of factories in various lines, instead of having a great many small plants compete, has succeeded in stabilizing industry. Today there are three very large producers of window glass, four of bottles and containers, and two of plate glass. Table-ware manufacture is still scattered in many small units because automatic and semi-automatic machinery has not been applied so largely in this branch of the glass industry. Figures taken from United States census reports indicate the relative magnitude of the glass industry for 1879 and 1923. Values were not available for 1876 and 1926. 1879 Number of establishments Number of persons engaged Capital Salaries and wages Value of products ” For 1919, as 1923 figures were not
169 24,177 $18 805 000 $ 9’144’000 $21:155:000 available.
899
Science us. Art
Art naturally gives way to science during the early stages of mechanical development, and has done so in the glass industry, as in others. However, art, as a matter of mass production, thrives better in a mechanical age. So, while variety and individuality may be lacking in the products, what art there is can be produced cheaply and reaches a greater number of people. Real art, the “art for art’s sake,” after all appeals to but few producers. To these, American glass manufacture can point with real pride. Science has just begun to investigate the possibilities of glass-making. Her strides are becoming rapid and the prospects promising. Let us hope that her sister, Art, will not fall too far behind, and that Science will not forsake Art in the fascinating journeys into this field of endeavor. Acknowledgment
An article of this length, attempting to cover the progress of an important branch of manufacture during a period of fifty years, is a t best only an outline. Tendencies in the industry as a whole and in its leading branches, have, therefore, had brief treatment. For matter pertaining to business tendencies the writer is obligated to J. ill. Hammer.
1923 333 79,679 $215,680,486“ $105 417 374 b309:353:411
Water Supply and Sewerage during the Past Fifty Years’ By Robert Spurr Weston 14
BEACON
ST., BOSTON,Mass.
Water Supply
IFTY years ago there was a chemist, Pasteur, who had ended the purely mechanical period of water supply by connecting certain bacteria with certain diseases. His discoveries changed the art fundamentally. It was, of course, true that both good and bad waters existed then as they do now, but they were selected largely by appearance and cost, although it was also true, as it was in Galen’s time, that certain waters were rejected because of their corrosive action on lead. By 1876 Prof. William Ripley Nichols, the eminent head of the Chemical Department of the Massachusetts Institute of Technology and an authority on water, made several reports on the subject of plumbism, dealing with the action of water on lead and the protective action of autogenous coatings within lead service pipes. However, many public supplies were drawn from polluted ground and surface sources and, as a general rule, deep ground waters and surface waters from large lakes or upland reservoirs were the only safe sources. Kirkwood, the engineer of the St. Louis Water Works, had recently written about European water filters, and the first two of these in the United States had just been placed in operation at Poughkeepsie and Hudson, N. Y. In Europe, the practice of filtration, begun in London in 1829, had spread through Northern Europe and in 1876 there was no German city supplied with unfiltered river water. The same was largely true in England, although storage rather than filtration was depended upon in many cases. Mechanical filters were unknown. Typhoid fever and cholera were devastating diseases and although vital statistics in the worst localities were not
F
1 Received
June 2, 1926.
kept until later, death rates were horrible to contemplate In fact, the contagiousness of typhoid fever, following the work of William Budd (1873) and others, had only just been accepted, but not generally, and the typhoid bacillus had not been discovered. Thousands died of cholera yearly, and the protection afforded by filters against the cholera spirillum, not yet discovered by Koch, was not proved until the Hamburg epidemic in 1892. Water softening by the lime or soda-lime method was practiced quite extensively, but the methods were empirical and crude. The past art of water supply reflects the work of bacteriologists and analysts, but now is reflecting to an increasing degree the work of biological and physical chemists. Water purification methods now rest upon the excellent experimental foundations laid by the Massachusetts State Board of Health a t its Lawrence Station, and by such workers as Drown, Sedgwick, Mills, Hazen, Fuller, and Clark in this country, and Lindley, Houston, Thresh, Piefke, Kemma, and Halbertsma in Europe. The English filter as refined and standardized by Hazen and others is still employed, but the more economical and adaptable rapid filter standardized by Fuller and others, and using coagulants, is rapidly outstripping it in practice. I n 1876 only thirty-five thousand people in the United States were supplied with water purified by filtration. At present, in the United States alone more than as many million people are so supplied and from works having an output capacity of over five billion gallons daily. Many of these plants combine softening with purification. Fifty years ago the theory of filter action was simple. Professor Nichols mentions three effects--straining, “a kind of sedimentation,” and absorption. In this day one
thinks of surfaces, lilnis, orieutatioii of niolecules, gels, diffusion, part.ia1 pressures, equilibrium, nitrification of organic matter, and biolysis. No longer are filters considered as static but as dynamic entities. Waters are now coagulated by using various alkalies and metallic hydrates, notably sulfate of alumina, thus permitting higher rates of filtration. The work of Clark and Lubs, and others, in popularizing the hydrogen-ion conceutration method, has refined chemical treatment, xhile improved mixing has bettered flocculation. The same improved methods have becn applied to water softening and deferrization processes with excellent effects, and the use of zeolites, artificial and natural, now permits the complete softening of wat,er, whereas in 1876 it was difficult to reduce the hardness belorP 60 p. p. m. by trez :rnc11t with lime and soda alone. The "hot-softening" process has come into use, and industrial waior purification umcy increasing importance. Corrosion, which characterizes soft, pure waters, is now prevented by proper adjustment of reaction, by deactivation by contact with iron, or by the addition of silicate of soda to form a protective fdm on metals which come in contact with the water. The work of Whipple in the field of limnology is now available, and Kellerman's method of killing odor-producing organisms by treatment with copper sulfate is widely employed. Infectious waters are now made safe by disiufect,ion either with chlorine, ozone, or the ultraviolet rays. Tlirough the work of Houston in London and others elsewhere, waters may now be treated and used with entire safety and satisfaction which in 1876 would either have been rejected or, if used, would have been bearers of disease. The work of water supply has been greatly facilitated by that of the water analyst. In 1876 the analyst usually reported total solids, organic matter, nitric oxide, chlorine, and hardness, and the ammonia method of Wnnklyn, C h a p man, and Smit,h was three years in the future. At present,
thauks to tlie conimittees of the AMEnlcAx CHEMICAL SOCIETY, American Public Health Association, and t h k l ) Association of Official Agricultural Chemists, and the information derived from foreign sources, there are standard chemical and biological methods which show not only the present charact,er of a water, hut its history. The consuming public is continually raising the standard of water supply and calling for more refined methods of treatment. To meet the demand a water must not only he safe and suitable for domestic purposes, but must satisfy the esthetic sense as well. Sewerage The changes in methods of sewerage and sewage treatment liave been more revolutionary than those of water supply. While it is true that fifty years ago the water carriage of sewage was practiced in a few cities, largely through the transforming of storm-water drains into sewers, methods of disposal included those described in the twenty-third chapter of Deuteronomy as well as the cesspool, that unscientific precursor of the modern scptic tank. Many of the so-called sewcrs of the seventies excluded fecal matter, and earth closets and open privies were common even in large cities. Bath tubs and sanitary plumbing were rare objects. The writer remembers the slow-filling, slowemptying copper tub and the complicated hopper watercloset of his boyhood home, also the "odorless" excavator which made the rounds of the cesspools and pumped their contents into a tank wagon for conveyance to & suitable disposal area. It is hard to believe the authentic story that when President-emeritus Eliot, now ninety-two years of age, was a teacher at IIarvard there was hut one bath tub in the whole college. This was the property of a wealthy student from New York, and even this was diverted from ita intendd purpose and used as a store for wines. Sewerage systems followed water works as eesspoolv proved inadequate. Fift.y years ago there were no water
September, 1926
I-YDrSTRIA L 9 S D EiiGINEERING CHEMISTRY
meters, and consequently much waste of water and dilute sewage. Where tidal lake and river waters were available the disposal was easy, but the inland cities had difficult problems. In 1876 some progress had been made in disposal by irrigation or sewage farming. There were a score of these farms in England and those a t Paris and Berlin had just been begun. This method is still in use, particularly in arid districts. One is liable to forget the work of such pioneers as Frankland, so well set forth in the report of the Rivers Pollution Committee of Great Britain (1870) and the staff of the Massachusetts State Board of Health under the leadership of Dr. Walcott (1887--). These and others established intermittent sand filtration as a method for disposing of organic matter by nitrification, a process of oxidation. This is still one .of the best methods where sand is found in situ, and had its real beginning about fifty years ago in the works of Pasteur, Schloessing, and Muentz, who showed that iiitrifieation was a biological process. The efficiency and economy of this process have been increased greatly by the use of dosing tanks and preliminary treatment. However, sand for filters was not always available, and the half-century has witnessed the development of numerous devices designed to bring the organic matter of sewage into contact with atmospheric action and bacteria. To describe all existing methods is beyond the scope of this writing, but the processes that are now prominent are the sand bed, the contact bed, the trickling filter, and the activated sludge process. It was just fifty years ago that Colonel George E. Waring, Jr., described a closed tank for sewage treatment which he had built a t Newport, R. I., and in which “the solid deposit of organic matter decomposes in the form of ammonia, which helps dissolve the grease and make it soluble so that both the deposit and scum are constantly wasted.” This tank had its prototypes in France and elsewhere. Its modern representative is the septic or biolytic tank, improved in this day by separating digestion from subsidence, using twostoried tanks like the Imhoff tank, or separate digesting tanks as recommended by Clark and used successfully a t Baltimore. The digestion of sewage solids by hydrolysis is due to various groups of anaerobic bacteria, which were not known fifty years ago and were not studied carefully until this century. At the present time these useful deoxidizing organisms, and the conditions under which they will best function, are better understood, even though much work remains to be done. The contact bed is practically a tank containing a coarse contact medium (broken stone) and filled with sewage, emptied, and rested in cyclic order. It combines oxidizing and deoxidizing functions; that is, it both liquefies and nitrifies organic matter. Furthermore, because of the large surface in contact with the sewage, it furthers clarification. It is less used than formerly, although it produces better effluents than are produced by plain subsidence or screening. I t is now used chiefly either where a high degree of purification is not required or preliminary to intermittent filtration through sand. The trickling filter of coarse material over which sewage is sprayed or otherwise distributed mechanically is a development of thirty years. It is the result of trying to expose sewage in thin layers to a large contact surface, alive with aerobic bacteria and well aerated. Usually this device produces a nonputrescible effluent, turbid with humuslike matter, which latter is usually removed by the secondary subsidence before the final discharge of the effluent, ,4 recent development a t Fitchburg, Mass., and elsewhere is the return of this humus-like sludge to the Inihoff tank, which precedes the filter.
BOI
The activated sludge process was developed by Clark a t Lawrence, Mass., and by Fowler and his associates (Arden and Lockett) , a t Manchester, England, and was improved in principle by Bartow, Mohlman, Pearse, Hatton, Copeland, and others. It consists, in brief, in agitating sewage in contact with air and an accumulation of its own sludge. It is the acme of treatment by oxidation. The sludge particles, bearing nitrifying and other bacteria, circulate through the liquid, causing both flocculation and oxidation. Separation of sludge in the effluent is effected in tanks or clarifiers, the latter device being an adapted ore-dressing machine. The effluent from this process is excellent. Mention must be made of the development in the way of preliminary treatment by screens, grit chambers, or subsiding basins, without which the operation of filters and activated tanks would be difficult. Practically all of these devices, with the exception of plain subsiding basins, have come into use within iifty years. By adding lime and other chemicals the precipitation of organic matter may be accelerated. This process has come and largely gone during fifty years. Last year saw its abandonment a t Worcester, Mass. Precipitation by sulfur dioxide has been suggested by Miles. It produces a partially disinfected sludge of low water content and high in recoverable fats and potential fertilizer value. The practicability of recovering the fats and fertilizer from this awaits research. Any treatment of sewage produces sludge, which like “the poor, we have with us alway.” This sludge may be a coarse deposit from grit chambers, a finer and more putrescible matter from basins, humus-like sludge from deposit chambers or the trickling filter, or the watery sludge from the activated sludge process. To utilize these sludges has been the dream of scientists since the days of Herbert Spencer.
Sewage Farm a t Ach‘eres, France
Digested sludges are now sold, and it is quite probable that the rich experiences at Chicago and, more especially, Milwaukee will result in a profitable recovery of grease and fertilizer base from activated sludge, and so reduce the cost of that process that it can displace other processes which are now more economical but which produce inferior effluents. Conclusion
I n brief, the half-century has seen both the beginning of sanitary science as founded upon biochemistry, and also marked development therefrom. Much as this development has been, the sanitary arts have but begun, and there is no doubt but that a t the end of another fifty years the sanitary writer will look back upon many of today’s prized achievements as the crude beginnings of a finer art.
