Methods and devices for bacterial treatment of sewage

Preface

All of this work except the Introduction and Chapter II is devoted to Bacterial Sewage Purification regarded from the view¬ point of the Civil Engineer. The second chapter is given to reference works containing information upon sewage purification and kindred subjects, including bacterial and chemical analyses of polluted waters.

Chapters III to VIII, inclusive, discuss sewage purification in its various aspects, the several methods of treatment being considered in historical order but kept distinct in the presenta¬ tion. The extensive use made of drawings of United States patents, both old and recent, will be found a valuable aid to the engineer and to the student.

Chapter IX consists of a summary of the known engineering principles involved in the subject under treatment, and a state¬ ment of the problems still unsolved. In considering the effect of capillary attraction in filter beds, the author has introduced certain laws which it is believed have not hitherto 3en suffi¬ ciently appreciated. The last two chapters su . .esigned to illustrate the importance of the principles sef rth, — Chap¬ ter X by reference to troubles in actual worksj .md Chapter XI by suggestive designs for small installations.

in

I

LIST OF ILLUSTRATIONS

Page

Precipitation Tanks of G. W. Wigner, 1870 . . 37

Precipitation Tanks of F. Hille, 1873 . ...... 39

Precipitation Tanks of A. S. Glover, 1882 . . 41

Sewage Strainer of B. F. Woods, 1883 . 42

Air-cleaned Strainer of George E. Waring, 1895 . 43

Intermittent Strainer of A. S. Glover, 1896 . 45

Cameron Septic Tank, 1899 . . 59

Septic Tank and Filter Beds of O. W. Pfouts, 1900 . . 60

Septic Tank of A. J. Provost, Jr., 1902 . 61

Septic Tank of John W. Alvord, 1904 . 63

Septic Tank of Reid and Hanley, 1904 65

Anaerobic and Aerobic Filters of Scott-Moncrieff, 1899 . 75

Contact Beds as arranged by W. J. and C. J. Lomax, 1896 . 80

Method of Aerating Filter, J. A. Maignen, 1899 82

Elongated Contact Bed of W. L. Church, 1900 . 83

Method of Aerating Filter, G. D. Mitchell, 1903 . . _ 84

Automatic Valve of G. L. A. Meyssonnier, 1901 . 100

Timing Siphon of S. J. Miller . . . 102

Dosing Siphons of S. J. Miller, 1902 . 103

Rocking Valve of Williams and Whitman, 1904 . 104

Dosing Siphon of M. J. Adams, 1904. . . 106

Sewer Flushing Siphon of Vibbard and Chandler, 1882 . 107

Siphon, by G. E. Waring, 1886 . 109

Siphon, by A. Rosewater, 1886 . 110

Blow-off Siphon, by J. W. Berry, 1900 . Ill

Rhodes-Miller Blow-off Siphon . 112

Rhodes- Williams Blow-off Siphon ... 113

Discharging Siphon of W. M. Venable, 1906 . 114

Miller’s “Automatic” Siphon . 115

Lowcock’s Aerated Filter, 1894 . 119

W. M. Ducat’s Percolating Filter, 1898 . 123

Venable’s “Breathing” Percolating Filter, 1905 . 126

v vi LIST OF ILLUSTRATIONS

Page

Venable’s Artificial Draught Percolating Filter, 1905 . 127

Stoddart Distributor, 1899 . 129

Radial Distributor of G. E. Ridgeway, 1901 . 130

Radial Distributor of Scott-Moncrieff, 1902 . 130

Plan of Septic Tanks at Fort Des Moines, Iowa . 165

Plan of Filter Beds at Fort Des Moines, Iowa, as first constructed .... 166

Section through Sediment Chamber and Septic Tank, Fort Des Moines,

Iowa . 167

Rearrangement of Contact Beds at Fort Des Moines, Iowa . 175

Suggested rearrangement of Sand Filter at Fort Des Moines . 179

Enclosed Works of Sewage Purification Sub-system at Fort Leaven¬ worth, Kansas . 210, 211

Design of Contact Bed System for 2000 Persons .... 217, 218, 219, 222 A Simple Combination for a Small Institution . 225

LIST OF PLATES

Antecedents of the Septic Tank . . opposite page 52

View of Contact Beds at Fort Des Moines, Iowa, during reconstruction

opposite page 177

View of Contact Beds at Fort Leavenworth, Kansas, overgrown with Weeds . . opposite page 207

Contents

Chapter. Page.

I. Introduction . 1

II. Sources of Information about Sewage Purification . 10

Chapter I

When any science has advanced to such a stage that practical applications of its principles may be made on a commercial scale, there arise engineering problems that are quite distinct in aspect from the problems of abstract science which precede them. The relation of the science of bacteriology to the con¬ struction of plants for sewage purification strikingly illustrates the difference between investigation which merely extends the range of our conceptions and that which applies these concep¬ tions to practical affairs. That certain changes are wrought in sewage by the activity of minute organisms called bacteria and by the enzymes that such organisms produce, is a fact well established by the laboratory work of scientific investigators equipped mentally as well as with delicate mechanical appli¬ ances for observing the very minute. How these changes are brought about, and what is the nature of bacteria, are matters with which pure science has to deal; but how to apply the result of such study to the actual purification of the sewage of any municipality, is a problem for the engineer, and in its solu¬ tion the services of a bacteriologist or of a chemist are required only to determine the character of the sewage to be treated, or of the effluent produced.

The biologist, in studying a group of micro-organisms, must

l endeavor to isolate individuals or colonies and then determine the conditions of life and the vital functions of these individuals by careful microscopic study and chemical tests, which interest the engineer professionally only when they have resulted in the discovery of laws applicable to the growth of millions of millions of millions of bacteria each hour. The engineer is concerned with the sanitary effect of the lives of these diminutive beings in mass, considered with reference to engineering works, designed to produce certain results with the least expenditure and under the conditions imposed by a given locality. The engineer, there¬ fore, needs know, not what is the particular history of the gen¬ eration of each colony of bacteria, but what conditions are necessary in order that the bacteria may act upon the sewage most effectively. If these conditions can be determined, and if they can be stated precisely as the laws of mechanics or hydrau¬ lics can be stated, the engineer may utilize them to design sewage purification works without any further reference to the bacteria themselves.

To draw a clear distinction between the engineering problem and the biological problem is not to undervalue the work of the biologist and the chemist. Unless their work had been done, the engineering applications of it could not be made, or, if they were made, they would be entirely empirical, and in con¬ sequence uneconomical. But it should not be thought that the engineer can afford to be altogether ignorant of the sciences of biology and chemistry. It is essential for him to understand something of both of these sciences in order that he may be intelligent in applying the principles derived from them.

There are, however, many problems in the practical art of sewage purification which the engineer alone must solve, and with which the biologist and the chemist are very little concerned. The hydraulics of filter beds in which bacterial action is taking place should be thoroughly understood by the engineer. The hydraulics of filter beds presents very many difficult and complicated problems, even if bacterial action be left out of consideration. The sewage purification engineer must also understand the hydraulics of flow in open and in closed channels, pumps, and siphons, in order that he may make all these parts of proper size and may utilize the hydraulic fall available in the design of the purification works, as will appear in discussions that follow. There are also engineering problems in precipita¬ tion, problems in pneumatics, and problems in mechanics, all of which are different from the ordinary problems in these branches of engineering, because of the changes which are taking place owing to the action of the bacteria in the sewage under¬ going treatment.

Since, then, the engineering of sewage purification works may be considered as a combination of other branches of engineering, modified by a consideration of certain mechanical and chemical changes brought about in the sewage by bacterial action, it is necessary in a study of the principles of Sewage Purification to establish ideas as to how the character of sewage and the action of bacteria and other organisms make the passage of sewage through engineering works different from the passage of pure water.

Sewage is defined by the American Public Health Association as “ water-conveyed excreta.” This definition is somewhat too limited to apply strictly to the material carried in most sewers, which is made up of all of the domestic wastes from houses, including discharges from kitchen sinks and laundry tubs. Such mixed sewage is usually called “ domestic sewage” to distinguish it from sewage which also contains waste prod¬ ucts from manufacturing plants, dye houses, steam laundries, stables, etc. The introduction of these wastes into domestic sewage often modifies its character and renders its treatment by ordinary methods impracticable. Sewage may contain a great deal of foreign matter or a comparatively small amount of foreign matter per unit of water. The water consumed per capita in cities and towns of the United States varies from twenty-five gallons per day to two hundred and fifty or more gallons per day; therefore it appears that the amount of impuri¬ ties per gallon of sewage varies tenfold in different localities. The writer has visited two army posts; at one of which the water consumption has exceeded 400 gallons per capita, while at the other, which is located where the water supply is failing, the consumption has been about twenty-five gallons per capita. The conditions for purifying the sewage at these posts were so different as to make the character of the two works required quite unlike.

The organic material that pollutes the water of domestic sewage is already undergoing a process of decomposition when it reaches the sewer. This process is largely the result of the action by micro-organisms known as bacteria, which multiply with great rapidity, changing the character of the organic material in which they are found. There are many different kinds of bacteria, and the different kinds are capable of being nourished by different forms of organic matter; and in the processes of growth they produce different by-products. Some bacteria in acting upon organic material decompose it so as to produce gases which escape into the atmosphere. The gases produced by different substances when undergoing putrefaction are different, some of them being very offensive. The foul odors usually resulting from decomposition are not the bacteria themselves, but the by-products of their vital processes, and are caused by a chemical action of a kind similar to that which causes gas to be evolved in wine or in cider, or in bread under the action of yeast.

The bacteria are exceedingly small, there usually being mil¬ lions per cubic centimeter in ordinary sewage which might not appear to the eye to be anything but water. They multiply with great rapidity wherever there is sufficient food in the liquid to sustain them provided there is not poison in the liquid to kill them or to prevent their activity. Poisons which may kill bacteria are of two kinds: first, substances introduced into the sewage from some other source than the materials which cause the pollution upon which the bacteria feed. Such a substance is sulphate of copper, which has been employed exten¬ sively to kill algse in reservoirs for public water supply. Almost all waste liquids from manufacturing establishments contain poisons that act in this manner to prevent the bacterial action, but the quantity of each poison per gallon required to inhibit bacterial life has a wide range of variation. The other group of poisons consists of those that are products of the bacteria themselves, and these act in a manner that may be likened to that in which poisonous gases in the atmosphere act upon a human being if he be shut in a room to which no fresh air can find access. Therefore, if we are to utilize bacteria syste¬ matically to cause the decomposition and the consequent purifi¬ cation of sewage, we must prevent the sewage from being contaminated by any material that would lessen the bacterial action, and we must also remove from it those products caused by the life of the bacteria which tend to bring that life to a close.

The conditions of life for various kinds of bacteria are quite different, and all organisms that are popularly termed bacteria do not belong to the same class of creatures. It is difficult to classify these beings as either animal or vegetable, for, in the microscopic world, the highly complex organizations which enable us to classify the higher animals and plants into dif¬ ferent kingdoms, either do not exist or cannot be detected by means at our disposal. Moreover, these two kingdoms may not cover all the world of life. However, the living things that are found in sewage that are so small as to require microscopic study to determine their anatomy, are popularly grouped under the general name bacteria, although the biologist is ready to provide more precise terminology for each group. The following classification of microscopic organisms found in water is given by Mr. George Chandler Whipple on page 171 in his book entitled “The Microscopy of Drinking Water.”

CLASSIFICATION OF THE MICROSCOPIC ORGANISMS

Plants

Diatomaces0 Algae (in the narrower sense).

Chlorophycece.

Schizophyceae.

Schizomycetes. Fungi.

Cyanophycece. Various Higher Plants.

Animals

Protozoa. Crustacea.

Rhizopoda. Entomostraca.

Infusoria (in the narrower sense). Spongidae.

Rotifera. Various Higher Animals.

Professor Whipple gives a discussion of the microscopic char¬ acteristics of these various groups, in chapters which will be found of interest to those desiring further information regard¬ ing this matter. The lower forms are more abundant in sewage, the fungi usually growing on the surface of the liquid, or attached to solid particles of floating matter or to the vessel in which the liquid is contained. The algae flourish only in the presence of air and light, as they are capable of converting carbonic acid into the higher forms of organic matter. The various higher plants are only found in the effluent from sewage works, or feeding upon the product of sewage that has progressed to an advanced stage of decomposition. Of the animals, protozoa are the most important in sewage. While they do not perform such an active function in bringing about decomposition as many of the forms classified as plants, they are extremely important, because many of them are known to be the cause of some of the worst diseases to which mankind is exposed.

The classifying of micro-organisms in sewage, according to their position in the animal and vegetable kingdoms, is not of as much practical interest to the engineer as the classification into aerobic and anaerobic groups, for it is by giving these groups in turn favorable conditions for growth that the sewage purification engineer proceeds, as the farmer proceeds by pro¬ ducing favorable conditions for the plants and animals he raises. The term “ aerobic ” is used to indicate that the organisms thrive in the presence of air, and cannot live or be active in liquid from which fresh air has been excluded, or after all the air originally present has been consumed. The term “ anaerobic ” designates the reverse of this. It is applied to those bacteria which do not require the presence of fresh air, or which may be even injured by the presence of fresh air.

There are many forms that, while they do not require air for their own vital activities, thrive best in the presence of other forms which do require air. Thus it is impossible to make these classifications of bacteria into aerobic and anaerobic forms strictly scientific with regard to each particular organism.

A third classification or intermediate group, to be known as “ facultative bacteria,” has been suggested to apply to those organisms which are most active when sewage is undergoing an anaerobic process and commences to enter upon an aerobic process.

The sewage purification engineer is practically concerned principally with two processes, — the one, anaerobic treatment of sewage, and the second, aerobic treatment. These two pro¬ cesses require entirely different methods. The first is con¬ ducted so as to avoid the introduction of air into the liquid, and *

the second is chiefly concerned with the introduction of air into the liquid, and provision for its absorption by the liquid. The organisms which assist in these processes are of peculiar interest to him, although he never has occasion as an engineer to inves¬ tigate the properties of individuals or of families. He is also interested in the life history of those organisms which produce disease, in order that he may know whether his engineering works are adapted to destroy these or to greatly reduce them in number. He is also interested in the fungi and the algae, for they afford an index of the degree of purification that the sewage has undergone. He is also interested in those higher forms of animal and vegetable life that abound in the sewage effluent when the process has been carried to a certain definite point, as their presence indicates without any further test approxi¬ mately the degree to which the purification has been carried. In subsequent chapters reference will be made to works that deal more fully with the subjects of bacteriology and micro¬ scopy and to the methods of conducting bacterial and chemical tests.

The sewage purification engineer, however, seldom has any occasion to identify particular microscopic organisms. Where such studies are necessary, they usually fall to the expert biol¬ ogist. If the engineer makes any bacterial tests at all, they are usually limited to making a count of the number of bacteria per cubic centimeter in the effluent from the works. In most cases where a test of the effluent and of the process in its various stages is required, chemical tests only are applied.

As has been previously stated, sewage consists of water polluted by organic matter, chiefly excreta, and it varies as to the amount of the pollution. The process of bacterial purifi¬ cation consists of three stages:

First. The absorption by organic matter through the agency of bacteria of all of the free oxygen dissolved in the water, and the production of a corresponding quantity of carbonic acid, water and salts containing nitrogen.

Second. The fermentation of the organic material in the water without the agency of air, resulting in the production of nitrogen, ammonia, hydrogen, and marsh-gas, and in reducing to solution some of the organic material in suspension.

Third. The oxidation of the organic matter in solution and in suspension by the proper introduction of air through the agency of bacteria, resulting in the production of carbonic acid gas and of nitrates and nitrites in solution, and of a peaty precipitate in suspension.

It is readily seen that certain materials present in sewage are not seriously affected by these processes. Among these is chlorine, which occurs chiefly in common salt. A sewage effluent, therefore, should be expected to contain about the same amount of chlorine as the crude sewage. It should contain a very small amount of material capable of being oxidized, and should also contain nitrates in proportion to its original pollution, although the actual amount of nitrates depends partly upon the extent to which the anaerobic process has been carried as well as upon the efficiency of the subsequent treatment. The routine work of testing a sewage effluent of a plant in operation is reduced to making oxygen absorption tests with sufficient frequency to enable the attendant to ascertain whether the works are behaving normally. The process of oxidation may be carried to any desired extent, resulting in the production of water of exceedingly great purity; but practically the object of sewage purification is not to produce drinking-water, but to produce water that will not have an injurious effect when discharged into natural watercourses. Sewage purification is not intended to take the place of the purification of water for municipal purposes, although it adds enormously to the ease with which water from natural streams may be purified for municipal use.

Chapter II Sources Of Information About Sewage Purification

In all branches of engineering, the knowledge of one genera¬ tion is communicated to the next through published records in magazines, official public documents and books, the books usually being to a great extent the compilations of knowledge from a large number of sources, often not recorded, for reference. To trace the successive steps in the advancement of each branch of engineering, and to give credit by name to each discoverer or inventor, great or obscure, is an interesting work, but, like the study of genealogy, it is of small interest to the man who seeks primarily information as to how to build. Therefore, in giving these references to available sources of information regarding sewage purification, the writer has not attempted to cover the subject completely from a historical point of view.

Data regarding sewage disposal in Great Britain are to be found in the Report of the Royal Commission on Sewage Dis¬ posal, in July 1901, and in subsequent reports by that body, as well as previous government reports dealing chiefly with sewage farming. The data contained in that report have been drawn upon frequently by writers upon sewage disposal, some of whom were, in fact, the media of presenting it to the Com¬ mission. These reports are available in a number of libraries in the United States.

In America the most extensive data have been collected by the Massachusetts State Board of Health, which has conducted experiments at Lawrence, Mass., for a score of years, and has likewise made systematic observations upon the results of sewage pollution throughout the State, as well as upon the results of purification works established by various cities. The work of the Massachusetts Board has been conducted by dis¬ tinguished engineers, chemists, and bacteriologists, and the reports have been liberally distributed in the United States, so that access to them is not difficult. First published in 1890, these reports on sewage purification have been continued year by year, and the later ones are now even more valuable than the earlier ones in the data they contain, though they are not so generally known, or at least referred to, except by specialists in this line of work.

The principal books dealing with this subject that are now available for ready reference are as follows:

Sewage Disposal in the United States, by George W. Rafter, Mem. Am. Soc. C. E., and M. N. Baker, Ph.B. (Associate Editor Engineering News), published by D. Van Nostrand Company (New York) and Sampson Low, Marston & Co., Ltd. (London), 1894. This large work consists of a compilation of data from various American sources, with comments and discussions, forming Part 1, by Mr. Rafter, and a collection of illustrated articles describing various sewage works in operation by Mr. Baker, originally published in the Engineering News, forming Part 2. The information contained does not, of course, extend beyond the knowledge available at the date of publication, and little attention is therefore given to contact filters, percolating filters, and other devices that are now receiving considerable attention.

British Sewage Works , by M. N. Baker, Ph.B., C. E., pub¬ lished by The Engineering News Publishing Co., 1904. This book contains descriptions of a number of sewage works in Great Britain, from the personal observations of the writer during a tour of inspection ending in June, 1904. It has the great advantage of being written by a party in no way inter¬ ested in either magnifying the success obtained by any plant, or belittling any attainment. It is especially valuable for the light that it throws upon the actual condition of various plants several years after they were built. It contains much data regarding capacity of beds, quantities of filtering materials, and methods of operation, but it contains very little data showing chemical or bacterial purifications secured, and it is without drawings or illustrations of any description. It is certainly one of the books that should be read by one wTho would be familiar with the state of this art.

The Purification of Sewage (1899), and Bacterial Purification of Sewage (1901), by Sidney Barwise, M.D., of London, pub¬ lished by Crosby, Lockwood & Son, London, and D. Van Nostrand Company, New York, the first containing 150 pages 12mo., the second 48 pages 8vo., give able presentations of the subject in concise form. They are adapted to the requirements of city officials rather than engineers, containing little quanti¬ tative information of value to the designer or operator of a purification plant.

Sewage and the Bacterial Purification of Sewage, by Samuel Rideal, D.Sc., published by the Sanitary Publishing Company, Ltd., London, and John Wiley & Sons, New York, 1900, second edition 1901, deals with the subject at considerable length. It contains discussions of the bacterial and chemical changes involved in sewage purification works, as well as descriptions of a number of engineering works. The spirit in which the book is written is expressed in the following sentence, taken from the preface of the work:

“ The theoretical basis of the bacterial changes so far as they have been at present studied, must underlie all the practical schemes which may in the future be put forward, and it has been my endeavor in the following pages to deal with the subject from this point of view.”

The book contains much information of value to the engineer, though not arranged especially for his reference. Dr. Rideal is recognized as an eminent authority.

The Purification of Sewage and Water, by W. J. Dibdin, F.S.C., F.C.S., published by the Sanitary Publishing Company, Ltd., London, and D. Van Nostrand Company, New York, third edition, 1903, contains 357 pages. About two thirds of the work is devoted to sewage and its purification. Mr. Dibdin is an authority on sewage purification in Great Britain, identi¬ fied with the development of the art.

Sewage Works Analysis, by Gilbert J. Fowler, M.Sc. (Viet.), F.I.C., Superintendent and Chemist, Manchester Corpora¬ tion Sewage Works, published by P. S. King & Son, London, and John Wiley & Sons, New York, 1902, is perhaps the most valuable small book dealing with this subject. The work is confined to giving directions regarding the methods to be pursued in making chemical and mechanical tests of sewage and sewage effluents. No engineer of purification works can afford to be without this book. A similar work, dealing with the bacteriology of the subject, is much to be desired.

The Microscopy of Drinking Water, by George Chandler Whipple, Consulting Professor of Water Analysis, Brooklyn Polytechnic Institute, etc., published by Chapman & Hall, Ltd., London, and John Wiley & Sons, New York, 1899, second edition 1905, is a valuable work for those who desire to acquire knowledge of the organisms active in water and sewage, though it is not written with special reference to sewage bacteria. The nineteen plates are exceedingly interesting.

Elements of Water Bacteriology , with special reference to sanitary water analysis, by Samuel Cate Prescott and Charles Edward Amory Winslow, both of the Massachusetts Institute of Technology, published by John Wiley & Sons, New York, and Chapman & Hall, Ltd., London, 1904, and

Examination of Water (Chemical and Bacteriological), by William P. Mason, Professor of Chemistry, Rensselaer Poly¬ technic Institute, published by John Wiley & Sons, New York, and Chapman & Hall, Ltd., London, 1905, are small, handy volumes for those interested in the analysis of water for drink¬ ing purposes, as well as of more polluted waters.

Transactions of the American Society of Civil Engineers , con¬ tain valuable contributions to the literature of sewage purifi¬ cation, of which the following are of especial interest:

The Antecedents of the Septic Tank, by Leonard Metcalf (Vol. LXVI, Paper No. 909, presented September 25, 1901). This is invaluable in tracing the history of this subject. It is well illustrated. The discussion accompanying it is also valuable.

Sewage Disposal in America, by George W. Fuller, and Sewage Disposal in France, by M. Bechmann, with an extensive dis¬ cussion participated in by seventeen engineers especially interested in this line, the whole forming a valuable resume of the condition of this branch of engineering. Before the Inter¬ national Engineering Congress, 1905 (Vol. LIV, Part E, pages 148 to 262).

The writer has largely drawn upon the records of the Patent Office, the periodical press and trade publications, for informa¬ tion upon various branches of sewage works engineering, and he has endeavored to embody some of this information in available form in the present work.

LIST OF ARTICLES ON SEWAGE PURIFICATION PUBLISHED BETWEEN JUNE, 1905,

AND OCTOBER, 1907

Note. Compiled from “ List of Recent Engineering Articles of Interest ” in Monthly Proceedings, Am. Soc. C. E.

In the Engineering Record.

Concerning Sewage Disposal, from the Standpoint of Pollution of Oysters and Other Shellfish, and Especially with Reference to their Transmission of Typhoid Fever. George W. Fuller. Abstract. August 12, 1905.

The Significance of Analyses of Effluents from Sewage Works. August 5,

Sewage Disposal in Ohio, Wisconsin and Illinois. September 2, 1905.

Sewage Purification at the Eastern Indiana Hospital for the Insane. October 28, 1905.

The Tankage of Sewage. F. Wallis Stoddart. (Paper read before the Royal Institute of Public Health.) Nov. 18, 1905.

Sewage Disposal at Berlin, Ontario. December 23, 1905.

The Sewage Purification Works at Columbus, Ohio. Julian Griggs. December 30, 1905.

Present Practice in Sewage Disposal. January 27, 1906.

Sewage Disposal at Downer’s Grove, Ill. W. S. Shields. (Paper read before the Illinois Society of Engineers and Surveyors.) February 3,

Some British Sewage-Disposal Apparatus. February 10, 1906.

Sewage Purification and Refuse Incineration Plant, Marion, Ohio. George H. Pierson. March 17, 1906.