Search

Estimation in Timbers. Jour. Biol. Chemistry , 19:158 (1925). 4. Berk, A. A. & Schroeder, W. C. Determination of Tannin Substances in Boiler Water. Indl. Engrg. Chemistry, 14:456 (1942). 5. Official Methods of Analysis. Assn. of Ofcl. Agricultural Chemists, Washington, D.C. (10th ed., 1965). p. 139. 6. Rosenblatt, M. & Pelnso, J.U. Determination of Tannins by Photocolorimeter. Jour . Assn. Ofcl. Agricultural Chemists . 24:170 M94n.

The value of sunlight in human dwellings as an aid to healthy living has been recognized from involuntary human experience from time immemorial. The actual germicidal effect of light has been a subject of study ever since 1877, when Downes and Blunt,2 in a classic series of experiments, demonstrated that light inhibited bacterial growth, and that the blue end of the solar spectrum was the more efficient for this purpose. A host of investigators studied the phenomenon in the eighties and nineties, some turning to the electric arc as a source of bacterial light, and a group, headed by Finsen, made the first application of the phenomenon in the treatment of certain forms of tuberculosis with the Finsen lamp. It was not until within a few years, however, that the invention of the quartz tube mercury arc lamp, and an awakened interest in water disinfection gave impetus to the study of water disinfection with ultra-violet light.

Chlorine and chlorine derivatives are the most common disinfectants used in water treatment. Water disinfection by chlorination depends on the water's temperature, its chemical composition, and the biological and bacteriological populations present in it. Therefore, chlorine demand varies greatly as a function of time. At present, routine analysis of chlorine demand by direct testing is necessary to operate water-treatment plants. It would be highly desirable to develop automated methods for determining the chlorine demand directly from a knowledge of the characteristics of the water being treated. In order to develop such a method, the relationships between a wide variety of water-quality indices and chlorine demand would have to be understood.

IODINE weight of possesses the four the halogens highest atomic and is weight of the four halogens and is the least soluble in water (and the least hydrolyzed by water) ; it has the lowest oxidation potential, and reacts least readily with organic compounds. Although these somewhat negative characteristics might at first sight appear to be limiting factors with respect to iodine's use for the disinfection of water, just the reverse is the case. Taken collectively, the characteristics mean that low iodine residuals should be more stable and, therefore, persist longer in the presence of organic (or other oxidizable) material than corresponding residuals of any of the other halogens. The high chemical reactivity of chlorine and its ability to react with organic material by oxidation, by substitution, or by addition, constitutes perhaps the greatest drawback to its effectiveness for water disinfection. The ideal water disinfectant would be some material that is chemically weak and unable to participate in such reactions, but, at the same time, possessing bactericidal, cysticidal, and viricidal properties equal or superior to those of chlorine.

Disinfection is necessary where surface water is used. Ground water of dubious bacterial quality, such as is often found in cavernous limestone wells, also needs disinfection. Although chlorination is the most common water disinfection process, it presents the problem of feeding a measured dosage. The need for continual servicing and inspection and the cost of good feeding devices are the principal disadvantages of the process. Because high chlorine residuals make the water unpalatable, there may be temptation to maintain the residual at a low

QF the pathogenic organisms whose transmission by water has been established, the cysts of Entamoeba histolytica are apparently the most resistant to destruction by the dhemical disinfectants that are in general use today. The reaction of these cells to the newer group of synthetic detergents and their possible use in water disinfection are, therefore, of interest. The synthetic detergents are organic compounds of relatively large molecular size. Although they exhibit hydrophobic properties, they are soluble in water. Since the cohesive force between these substances and water is greater than their intermolecular cohesive force, they lower the surface tension of the water and tend to concentrate at liquidliquid, liquid-solid, and liquid-gas interfaces. Hence they are also known as surface-active agents, surface tension depressants, and wetting agents. The synthetic detergents are classified as neutral, cationic, or anionic detergents, depending upon whether they are undissociated, dissociated with cationic

This paper describes fundamental formulas concerning water disinfection by means of a germicidal lamp, and their comparison with experimental data. The formulas show the relation between the average survival ratio of micro-organisms and several varied factors, such as depth of water, absorption coefficient at the wavelength of 253.7mμ, ultraviolet irradiance, lethal energy of the micro-oranisms, exposure time, and the rate of flow of running water.Reference data for design of a water disinfector is described, also.

The chemistry of the formation of various species of titrable iodine in solutions of elemental iodine and iodide are described in a quantitative manner. The relative cysticidal efficiencies of various species of titrable iodine and the effect of temperature on cysticidal efficiency of I 2 are described, and equations are given for computing the cysticidal residual I 2 with a given contact time, and vice versa, at varying temperatures, as well as that for computing the cysticidal residual iodine in I 2 -I-3 systems. The relative viricidal (against Coxsackie B2 virus) efficiencies of various species of titrable iodine and the effect of temperature on viricidal efficiency of I 2 are described, and the employment of the equations used in computing the cysticidal residual iodine for I 2 and I 2 I- 3 combination, with or without modification, are given. Because of the incompleteness of the data other than those on I 2 at 25deg;, values obtained in various computations are presented with reservation but are considered as relatively safe for use in practice. The use of preparations of iodine for water disinfection in practice is discussed.

THERE water disinfection are many occasions must be when pracater disinfecti n must e prac ticed on a small scale and under adverse conditions. The need for a ready-to-use disinfectant is greatest during military operations or at times of natural disasters when small groups of people or even individuals have to depend upon sources of water which might be contaminated. Even during peace time, campers, sportsmen and adventurers have need for a packaged, instant-disinfectant such as a tablet. This need was first recognized more than 50 years ago.1 However, only a few preparations, usually containing either iodine or chlorine, were in use at the beginning of the Second World War. At that time a team of scientists and engineers conducted an extensive investigation at Harvard University under a contract with the Committee on Medical Research of the Office of Scientific Research and Development. The Harvard researchers 2 listed the following desirable properties of chemical disinfecting agents which are intended for use under field conditions

purpose of this paper is to present the history of taste and odor control as it unfolded before the efforts of the men who devoted their interests to water research. Developments are viewed, wherever possible, from the standpoint of a person living during the particular period or epoch discussed, so that the difficulties encountered, as well as their solutions, will be more fully appreciated. Methods of treatment, which today seem elementary, may thus be seen as the result of the efforts and frequent mistakes of numerous workers. It is believed that the true significance of taste and odor control to water purification can best be realized by this approach. The human race consumes more water than any other single article of diet. Considering this fact, it is surprising that little serious attention was devoted to the subject of water purification until little more than a hundred years ago, when, in 1829, a slow sand filter was installed in the Chelsea Water Works Co. of London and, in 1832, the first filters in this country were put into service at Richmond, Va. (cited in ref. 1). Early purification efforts were directed principally toward producing clear colorless water, then believed to be safe. Water works operators also realized the desirability of supplying a palatable water, but progress in this direction lagged far behind developments in water disinfection. This was probably due, in large part, to the provincial mode of living before the advent of modern transportation. The population was not acquainted with the palatability of other water supplies and did not develop a "taste-and-odor consciousness. " The dream of a hundred years ago that someday consumers could turn on the tap and obtain a glass of taste-palatable water is today a reality. Early in 1940, Baylis (2) said: "In the very near future there will be little, or almost no unpalatable water served the public."

The steadily increasing use of ultra violet light for the disinfection of water supplies, large and small, seems to indicate that the art is sufficiently well advanced to warrant a discussion of the theory upon which it is based. This theory, recruiting its hypotheses and proofs from the basic sciences of physics, chemistry, and biology, deals with the nature and general physical properties of ultra violet light and with the photoabiotic effects which it is able to produce, so far as any of these are related to the application of ultra violet light to water disinfection. It is hoped that an elementary discussion of this nature will be of interest to water works engineers, and that it will be instrumental in dispelling the clouds of mystery which enshroud to so many this most natural of all methods of water disinfection. The advance in our knowledge of the theory of ultra violet light is due especially to Schumann, Lyman, and other physicists who investigated the spectroscopy of the ultra violet, and to Bovie and his coworkers, who reported upon its biological activities, while the list of names of those who have been connected with its scientific application to water disinfection includes those of many scores of French, German, and American workers. Radiation. The word "light" is familiarly associated with the sensation of vision alone. If, however, the electromagnetic waves which produce the sensation of light when they fall upon the eye and therefore become post facto " light or luminous radiations' ' be allowed to fall upon an opaque body, the same may be warmed and the radiations become " radiant heat." If, on the other hand, they fall upon a living green leaf or a photographic plate, they may produce chemical changes and thus become " actinic" or " chemical" rays. All three names luminous, heat, or actinic radiations may therefore be given to the same wave train, depending upon the

The Bubbly Creek filtration plant at the Chicago Union Stock Yards requires no introduction. It has stood in a class by itself purifying probably the most polluted supply of any water purification system in the country. It was at this plant that hypochlorite of lime was first used on a practical scale for water disinfection, in the summer of 1908. Numerous articles have appeared about this plant, its operation and the wonderful results obtained. The results have been uniformly good. To many people, the results have been almost unbelievable. The Bubbly Creek water softening plant is in its infancy and needs an introduction. At the present time the record of the filtration plant is much better than is that of the softening plant, as will be explained later. The plants are one and the same. An agreement was entered into with the city of Chicago several years ago about the use of the filtered water from the Bubbly Creek plant. Since that time, the filtered water has not been used for watering live stock but its use has been confined to mechanical purposes. At no time, however, has the purification been discontinued, as much care is being used now to obtain a satisfactory degree of purity at all times as was used formerly. The conditions and problems to be met with in order to soften the water with this plant were somewhat novel and peculiar to local conditions. The power house of the Union Stock Yard and Transit Company, the same company that owns the filtration plant, is nearby.The boilers there require about 125,000 gallons of water per day. Previously they have been supplied with the returns from the heating system, some 50,000 or 60,000 gallons per day, and the balance of the water was taken from the Permutit system softening city water. The Chicago Junction Railway has some 50 or 55 locomotives operating in the Stock Yards. They have been supplied with filtered water that was not softened. The amount

The current review of canteen water disinfection proceeded along three general lines. A summary has been prepared of the information available from the literature on canteen water disinfection. The current opinions of two outstanding investigators in the field of disinfection have been solicited in personal interviews and summarized. The 'Harvard Report,' possibly the most detailed research study of canteen water disinfection ever conducted, has hitherto been published only in fragments. A summary of the most salient features of this work has been completed.