Co-operative Research in Problems of Purification

Co-operative Research in Problems of Purification

Conclusion of Mr. Wolman’s Paper on This Subject Read Before Chemical and Bacteriological Section of A.W.W. A.—Discussion of Subject by Members

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(b)—Filtration.—The internal forces within a sand filter bed are of greater magnitude than is generally realized. Experience in Maryland with a number of peculiar phenomena in filter beds has disclosed a starting variety of forces released in filter beds, which appear to be intimately connected with the character of sand and of applied water. The appearance of internal contraction in a sand bed of such strength that the surface area of the bed may be reduced by more than five per cent, of its original area is of importance in calling attention to the unsolved problems concealed within the bed.

If we consider the whole principle of filtration as founded upon “a sort of instability, both chemical and biological, (and physical—A. W.), in the behavior of matter in solution or in suspension, when spread out in thin films over surfaces, or flowing in fine filaments through interstilial capillaries of constantly varying cross-section” (3) we obtain some idea of the intricacy of the problems. That these problems are of more than academic interest has been clearly demonstrated in the difficulties encountered in the shrinkage of sand beds, in their selective action upon bacteria, in the adsorption of materials in water softening plants, in the sudden discharge of sludge of chlorine taste where chlorine is applied before filtration, and in many other phenomena. The researches of Dunbar (3) and Baldwin-Wiseman (3) on the variations of surface tension within a sand bed and their conclusion that the elimination of a dissolved salt by fdtration is inversely proportional to the degree of concentration of the solution mark only the beginnings of the studies on internal forces. Our own works on the varynig adsorptive capacities of different sands and Hannan’s observations (4) on the effect of surface electrical charges of sands and of bacteria indicate the promising possibilities of more research in filtration.

(c)-Chlorination—Sanitarians have established definitely that waters may be made safe for potable purposes by chlorination. The water works official, however, must go a step further. He must make the water potable in addition to safe. If the water is unpalatable and objectionable because of tastes and odors, then the problem of chlorination may not be considered as solved. It is only a few years since the conception of the mechanism of chlorine treatment has undergone some modification from the simple hypothesis of direct oxidation. But in this comparatively short period, a series of questions have arisen which are still imperfectly answered.

In this field again we must have recourse to highly technical investigations to aid us in clarifying our concepts of chlorination processes and in controlling their operation. Even today it is difficult to answer definitely whether the action of chlorine is physical, physico-chemical, or chemical, whether its action is selective for different types of bacteria and, if so, what the causes for such selection are. The action of other disinfectants is elective and their toxicity is dependent upon their position in definite ionic series and upon the characteristics of the different bacteria, such as their response to Gram stain. The surface character of different classes of bacteria show a marked influence upon their behavior under different conditions.

Where we attempt to treat raw waters of complex organic and inorganic content, our present methods of control are entirely empirical and not infrequently unsuccessful. The causes of tastes with low doses and the absence of tastes, at times, with execessive doses of chlorine are still in the category of the unknown. It is not a solution of the difficulty to state that tastes and odors may be prevented by proper regulation of applied chemical, for the terms “proper regulation” are indeed broad in interpretation. Proper chlorination control, on the contrary, would seem to be possible of attainment only after a complete understanding of the details of the complex disinfection processes has been reached. May we not call upon this Association to take the lead in the initiation of these studies?

(3)—Baldwln-Wlseman, W. R., Statistical and Experimental Data

on Filtration, Proc. Institution of Civil Engineers, Vol. CLXXXI., 1909-10.

(4)—Personal Communication.

DISCUSSION

MR. POWELL-I have had the privilege of reading this paper before its presentation at this meting and I was very greatly surprised by Mr. Wolman’s efforts. I think the time is ripe not only for this association or this section, but for all scientific bodies in America to take the same advanced step along the line of cooperative research. The problems which Mr. Wolrnan had mentioned I feel (and I am sure that all who are talking water purification realize) are real problems and not imaginary ones. For the past fifteen years these problems have been presented to me and I think that if we could get together in this section, in a discussion and follow out the lines that Mr. Wolrnan has spoken of this morning, we would go far along the lines of co-operative research in America.

MR. Weston—1 would like to say a word of praise for Mr. Wolman’s paper. I think most of us, especially these who are approaching the age of Dr. Bartow and myself, who have graduated from college before the date of modern physical chemistry, do not realize the vast field of physical chemistry and its importance to our water works. Only the other day I was talking to Professor Cook, whom you know, and he said “we have gone just about as far as we can in analytical chemistry in the field of water works operation and water purification. We have now got to turn to physical chemistry to help.” 1 think that is true. All these problems which Mr. Wolrnan mentioned this morning are very pertinent, and I think, are problems, for the solution of which we must look to physical chemistry more and more, and it is for these younger men who have had a chance to secure training in physical chemistry, which I had not time to aquire after graduating but which I know Dr. Bartow has acquired, to whom we must look to for health.

THE Chairman—I am afraid Mr. Weston flatters me when he says I acquired a knowledge of physical chemistry.

MR. Goodell—From the point of view of the Publication Committee, we ought to get some good information out of Mr. Wolman’s paper, and we thought that paper was admirable proof of the conclusion that we had reached, namely, that some kind of a council should be appointed which in the next year might get together and suggest how to do these things that Mr. Wolrnan suggested should be done. That is all that could be done in a year. Now, gentlemen, have you any suggestions that you can make that can be passed on to the council.

MR. Orchard—Speaking a word of commendation of the very scholarly paper that Mr. Wolrnan has presented, it is a pity that it was heard by so few in comparison with I he numbers in attendance at the convention. It is quite easy to get together a few statistical facts and get up a talk about them, but when a gentleman gives the thought and study to a paper, as Mr. Wolrnan has done, surely a large number should hear it. We must not let these highly technical matters scare the water works man, and if they would listen to a paper like Mr. Wohnan’s they would appreciate more what the technical man is doing. Mr. Wolrnan made certain specific recommendations and there was passed, at the convention yesterday, a motion, authorizing the appointment of a council of research, and I make the motion, if in order:

“That it may be the sense of this section that Mr. Wolman’s paper be referred to the council with the endorsement of this section, to do whatever they can to investigate the possibility of co-operative research before the next convention.” (Carried.)

THE Chairman—I have not attended one of these meetings for three years and apparently we should have some action taken. Without the organization we can elect a secretary and chairman of the section unless some other provision has been made.

MR. Rosenthal—I believe that this is really a splendid opportunity at the present time. There are quite a few at present to perpetuate the organization. I take pleasure in nominating Dr. Edward Bartow as chairman of this section.

DR. Bartow—I have already been chairman and the honor should be passed around. I was the first chairman, and I think someone else should be appointed. I think we could have a nominating committee appointed, or else we can offer to this convention, nominees for the secretaryship, and the membership of the committee. I think we ought to have a nominating committee appointed. Will you nominate officers from the floor or will you nominate and elect a nominating committee?

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MR. WESTON-I move that the chairman appoint a nominating committee to retire and nominate candidates for such offices.

THE Chairman—The city of Dallas has requested a member to present a paper on the operation of the water filters they have, and Mr. Rosenthal was sent here by the city of Dallas to give that paper before you gentlemen who are specialists in this matter. It is impracticable to read the papers anywhere else. This city has taken this matter up and we have requested you gentlemen to hear this matter and discuss it because, as I say, the city of Dallas desires an opportunity of presenting this matter to the gentlemen of this organization in this manner. Gentlemen, we have five more papers. We cannot finish this before twelve or twelve-thirty, so it seems to be desirable to have an afternoon session. There is a motion here that the chair appoint a nominating committee to report on officers for the coming year, also to report to the session this afternoon at two o’clock. (Carried).

(To be continued)

Co-operative Research in Problems of Purification

Co-operative Research in Problems of Purification

Mr. Wolman Considers Important Water Supply Topic at Montreal Session of the Chemical and Bacteriological Section, A. W. W. A.—Discussion of Mr. Hinman’s Paper

ABEL WOLMAN

Division Engineer

State Board of Health, Baltimore, Md.

(Conclusion of Discussion on the paper by Jack J. Hinman, Jr., upon Standards of Water Quality by the Chemical and Bacteriological Section, A. W. W. A. at Montreal).

MR. MESSIER—I think that Mr. Hinman has presented a very valuable paper, one that will lead to some future work and lead to the strengthening of this section. This I believe is very much needed. I was particularly interested in the point that he brought out as to the importance of the sanitary survey, and I believe in the past there has been too much of a tendency for the bacteriologist and the chemist to interpret the results without the knowledge of the sanitary survey. I believe that the present tendency is one among State Boards at least to have these results interpreted as far as possible by the division that is familiar with the local condition. In other words, the laboratories act as an auxiliary of the engineering division, so that with all the information at hand you can interpret the results to better advantage. Of course it is admitted that there will be some difficulty, so it will be some little time perhaps before we can get at the standards which I believe in the long run will be adopted. The opinion of the many different investigators in different States as to what is actually standard could be threshed out and studied so that perhaps we can reach some point where we can get what we think are reasonable standards. We have two classes of supplies. The largest supplies are under expert supervision of daily laboratory analysis, and then we have a number of small plants that have only infrequent examination and the usual water samples that are sent to the laboratories in these smaller places, it is practically impossible or impracticable anywhere to conform to the Treasury standards. I do not think that there are more than three or four States at present that have license supplies. That means that you cannot keep your standard as far as the laboratory results are concerned below 100, but as time goes on, and we are able to come in closer contact with the bacteriologist, and arrange to have more frequent examinations, we can arrive at that point, so that we can tell when the water is safe or reasonably safe.

DR. BARTOW—The bacterial standards are all right. That is, we can have bacterial standards. On the other side we had occasion to compare the U. S. A. or the Treasury Standards, which we adopted for the American .E. F. with French standards. The French standards were apparently much stricter than ours. They demanded absence of B. Coli in one liter of water, but when we came to anayze their methods, we found that our Treasury standards were not the same. Using their methods we found B. Coli in one liter of water to correspond to 1 B. Coli to 50 c. c. because of their use of Phenol broth which inhibits B. Coli.

At three different times that I remember we made actual comparative test with the French standards, and we found that our standards compared quite closely with theirs. About chemical standards. We all admit that it is difficult to have a general standard. I was a member of the standards committee of the Treasury Department and I have just learned that the committee found a general chemical standard impracticable. I never knew why it was dropped. Wilto Hanford made a number of investigations of water supplies to be used by common carriers. I felt that a chemical standard would be valuable in determining which of two or more sources of water should be used in putting in a new water supply or in extending all water supplies. We have found them of great value in a case where one of our towns had to extend its water supply. It has the possibility of putting down deep wells. When they go down deep they may find water with a residue of from 1,000 to 3,000 parts per million. If they use a shallow well from 150 to 200 feet deep they would get water with a residue of about eight parts per million. If they use steam water they will get water with a residue of 250 to 300 suitable for manufacturing purposes, which must be considered, as it is one of the most important things in connection with the supply of a city. The water with the best chemical contents is the water which should be used if it is possible to get it. We have cities that are using water with a residue of over three thousand parts per million. The manufacturers don’t come in there. They cannot. That city is, of course, handicapped, but when that is the only water they can get, it has to be used and it is an exception to the chemical standard which we use for the water supplies of Illinois.

MR. HINMAN—You understand in the first place that what I read was simply an extract from the paper itself, and one in doing so is liable to be misinterpreted to a certain extent. When you handle the thing in that manner, you have always to expect that. But in regard to these chemical standards, I base my statement on a letter received from Dr. Frost in which he said that they, after having gone through these matters, have dropped the matter of the chemical water standards for the time being as being chemically impracticable. If we are going to have satisfactory water standards, of course it would be necessary that they embody data which is absolutely correct and also that they reject anything which is not satisfactory without, at the same time, working any hardship on water supplies in other places. It seems to me, however, that our greatest prospects with regard to the standardization of water supplies lie more particularly in the standardization of the construction and operation of our water supply plants rather than in the adoption of standards as applied to waters generally, irrespective of their source, whether ground water or stored or whatever water it may be.

COOPERATIVE RESEARCH IN PROBLEMS OF WATER PURIFICATION

By Abel Wolman

To the practical water works man, “research” frequently connotes investigative effort directed into abstract fields to develop scientific axioms. The publication of such material is hailed with delight by bespectacled and ethereal scientists and with suspicion and perplexity by those upon whom rests the duty of converting unpalatable mud into the clear and sparkling elixir of life. To present a paper, therefore, upon a subject which combines in it the scientific and the practical, it is necessary to demonstrate that research of highly specialized and scientific character is necessary in problems of water purification and that co-operative rather than individualistic investigative effort should be the desideratum. The first of these hypotheses should concern more particularly the man in the works upon whom rests the responsibility of adopting the scientific methods and of absorbing the new truths which the investigator discloses. To the experimenter the second problem is of interest. In it the distinction between isolated and concerted attack upon the unsolved problems of science is made clear. It is my purpose to outline in brief these two phases of cooperative research in problems of water purification. For purposes of clarity, however, the second phase will be discussed before the first.

1—Co-operative Versus Individualistic Reseach

Scientific investigation in the field of water purification has progressed for a number of decades, but it may be stated with safety that during this entire period the study of problems has been, for the most part, intermittent, sporadic and disconnected. The development of data has been the result of local efforts in the laboratories of individual colleges, states, municipalities, or private corporations. What co-operation has existed has been localized and not national. Dr. Burton E. Livingston of the Johns Hopkins University describes this situation in excellent terms when he states: “There appear to be a large number of good experimenters who do not have well-selected problems in mind, who work on that which lies close to them rather than on that which seems to be most fundamental, most far-reaching or most imperatively needed for the growing structure of knowledge.” (1)

The history of individualistic research effort in water purification. as in a number of allied fields, has been that of “a kind of guerrilla warfare upon the unknown” (1). While such warfare may result in temporary victories over isolated problems, in intermittent eliminations of difficulties in one place, it never produces a complete surrender of natural opposing forces to the control of man. The solution of the problem of chlorinatting the St. Lawrence River water, for instance, while of immediate value, is of but little aid in solving the general problem of chlorination of waters, unless the methods, conclusions and conditions of the first problem are subjected to the composite scrutiny and checking of cooperative workers elsewhere. It is true, no doubt, that under present conditions the individual scientists find it difficult practically to choose arbitrarily that line of study which seems to promise more remote, but more valuable results, while the materials at hand has the attractiveness of immediate practical application, if only to the restricted field with which he is familiar. Every problem will be solved, however, more satisfactorily and more permanently if the attack is made from many viewpoints, under different conditions, and by various investigators. The personal stressing of unimportant aspects, the individual errors, the apparent but unreal significance of local characteristics, and the restricted mental conception of a problem are all likely to be eliminated or reduced by cooperative research, with the ultimate production of a sounder and a more accurate series of scientific observations and conclusions.

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Co-operative Research in Water Purification

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It seems hardly necessary to emphasize the abstract desirability of solving the problems of water purification by a more constructive system of cooperative effort than now exists. It is of value, however, to direct the attention of our members to the fact that this organization may serve as an excellent medium through which to inaugurate a comprehensive system of cooperation. In this manner, we may do much to advance scientific knowledge and its practical application. It has been pointed out that cooperation in research involves “the union of a number of minds in planning the attack on a problem, in working out the different parts, and in bringing the several components results together into a well-considered presentation that might really mark a tangible advance in scientific knowledge.” (1) These various functions in the American Water works Association can and should perform. It should not be a difficult matter to supply that “union of minds” to plan the attack on a series of problems by the proper organization of a research committee. To subcommittees in turn may be delegated the further task of “working out the different parts and bringing together the several component results.” It is these functions of cooperation and initiation in cooperative research which I should like to suggest to this body. As far as I am aware, no other organization is at present so well suited to undertake its development and no other has yet deemed it desirable to assume this responsibility. My intention is to indicate the desirability of this Society fostering the principle of cooperative research.

Granting the abstract desirability of developing such cooperation, what are some of the problems which today remain to be solved? Although considerable advance in the practical methods of water purification has taken place in the United States, may we state definitely that the fundamental laws of Coagulation, filtration and chlorination are accurately known? If so, are these laws applied in every-day operation? Some of us, perhaps, are not so sanguine about our complete understanding of the processes involved in the above mechanisms of purification. An opportunity to engage in a cooperative attack upon such problems will be welcomed. In order to make clear some of these unsolved difficulties, the second portion of this paper is devoted to a brief survey of a few of the possible fruitful sources of investigative work. These possibilities doubtless are already known to most of you, but summarizing them in this connection may make more apparent the necessity for the plan which this discussion has set forth.

2—Some Unsolved Problems in Water Purification

(a) Coagulation and Sedimentation. The factors determining effective coagulation and sedimentation of waters differ in degree with different waters, but their characteristics in general are the same, regardless of the nature of the water. The effects of time, temperature, agitation, and hydrogen-ion concentration upon coagulation have been studied only superficially. The material for such study has been accumulated in a number of different fields in allied sciences, but has not yet been adapted to water purification problems. It is stated often, for example, that the formation of satisfactory floc is retarded by low temperature and by inadequate agitation, yet how many plants observe and record the nature of the floc produced each day, so as to provide the material for correlated study of its variations with other characteristics of the water during an entire year? Isolated observations of inadequate floc formations which are roughly and often fallaciously connected with temperatures aid little in pointing out fundamental principles. An adequate measure or series of measures of the characteristics of floc offers an excellent research problem the solution of which would aid considerably in the studies of water work’s control.

The measurement of floc formation in its various aspects, however, should be preceded by a study of the raw waters with a view to determining a more accurate and satisfactory method of apportioning coagulant to raw water to obtain satisfactory coagulation. The usual method of turbidity reading with adjustments for rising, falling, constant, fine, medium, and coarse turbidities leaves much to be desired, particularly when frequently the actual procedure results in abandoning all methods other than adding chemical until the coagulation becomes satisfactory. These methods are necesasrily wasteful, since for each water there exists a critical concentration of coagulate which is most effective and economical. Can we not devise a satisfactory index to the “coagulant demand” of a water by a simple test? When it is borne in mind that the flocculation of waters is dependent upon the nature and amount of fine particles present, it would appear that the search for such a measure should be in the field of colloid chemistry. It is suggested that perhaps the use of a nephelometer, an instrument measuring the cloudiness of a water, may be developed to study the character of a water after a very brief period of settling when the coarse material of low “coagulant demand” has been removed. It would be interesting to learn what such “post-settling” turbidity readings would disclose as to proper chemical dosage. An experimental quantitative study of the “coagulant demand” of the various sizes of particles in the same water should prove interesting and valuable.

Another phase of the coagulation problem which has taken on an importance in recent years is the effect of the varying hydrogen-ion concentration upon flocculation. There appears to be an optimum range of PH within which the coagulation proceeds most satisfactorily. Water works operators and investigators should begin to accumulate complete data regarding the PH values of different waters in the country under all conditions. In the State of Maryland we have been making, for several months, determinations of hydrogen-ion concentration on all waters and have instituted these tests as a daily procedure in several large filtration plans. It is too early to predict the results of these studies but, at any rate, material should be collected to determine the importance of this characteristic.

The study of sedimentation problems in the light of recent developments in physical chemistry may require some modifications in our older concepts. The effect of electrolytes, or competing and protective colloids, of surface tension and osmotic pressure are of more than purely scientific interest. Recent work has demonstrated, for instance, that the Brownian movement is observed with practically every type of clay suspended in water, varying from the rapid motion of the finest particles to the more sluggish one of the larger particles or aggregates or when hampered by the presence of electrolytes (2). An extended journey into the field of physical chemistry promises an excellent return to the water supply investigator.

  1. Livingston, Burton B., Constructive Scientific Research by Co-operation, Science, March 19, 1920.
  2. Alexander, Jerome, Quoted in “Ceramic Processes Associated with Colloid Phenomena,” by A. V. Bleininger, Journal of Industrial and Engineering Chemistry, Vol. 12, No. 5, May, 1920.

(To be continued)