T H E J O C R N A L O F I N D C S T R I A L A N D ENGIATEERING C H E M I S T R Y
OCt., I914
containing considerable clay, taken at the bottom of the cut. Sample No. 2 , from the middle of t h e next stratum, about 4 feet above the bottom of the cut, was very hard and compact in the bank and contained numerous pebbles. Sample No. 3, from the next stratum above, about 6 feet from the bottom of the cut, was stained yellow and was sandy in texture. Sample No. 4, I O feet from the bottom of t h e cut, was a yellow loam containing considerable fine material and humus and resembled a typical garden soil in texture and appearance. Sample No. 5, the subsoil, was apparently a decomposed glacial till, having the same color and characteristics as No. 2 but not being hard or difficult t o loosen. Sample No. 6 was taken from the surface, formerly a garden, and contained considerable humus. ,411 the samples were air-dried, and passed through a ten-mesh sieve, the residue, comprising 30 t o 40 per cent, being discarded. The analyses of the fine earths thus obtained, together with t h a t of Sample 7 , an ordinary mortar sand, are given in Table I. TABLEI-SIEVE ANALYSISOF FINE EARTHS Percentages passing mesh indicated Sample No. 1 ........ 2........ 3 ........ 4........ 5 6
........ ........
200 77.2 17.0 6.4 10.7 17.2 14.6 0.5
100 98.0 29.7 14.3 18.7 32.5 26.8 5.0
50 99.0 64.4 57.5 52.8 68.7 64.5 71.9
40 All 74.3 69.1 65.0 79.5 76.7 90.0
30
20
85:O 82.7 79.8 87.8 85.5 97.5
90:s 92.2 91.7 93.1 93.1 All
10
95:6 All All All All
........ .. For the preparation of the mortar from the fine earth and the cementing agent, the general procedure was t o mix thoroughly, add 1 2 per cent water, silo in a moist closet for 24 hours, mold into bricks, I in. X 4 in. X 4 in., and press into shape under a hydraulic pressure of 2 0 0 0 pounds per square inch. These bricks, after air-drying for 2 4 hours, were then placed in an autoclave and subjected t o the action of live steam under 8 0 pounds pressure for 8 to 16 hours. The bricks were then broken in an Olsen machine, each brick being laid on the flat surface. Tables I1 and I11 give the results obtained by the use of various mixes of fine earth and cementing agent. 7
TABLE 11-FINE EARTH MIXTURES WITH LIMEA X D WITH PORTLAND CEMENT Percentage r
Fine Sample No. earth 1 . . . . . . . . . . . . 90 80
2....
..
..
80 3. 4 . . .. . . 5 . . .. . . 6 ..
7............
Lime 10 20
..
80 70 85
..
Crushing strength Lbs. per sq. in. 5497 6200
20
3460
10 20 30 10 20 20 30
3290 2740 2650 2540 2440 3680 3820 2980
20 30 15
2520 3410 6200
10
............
-
..
Percentage Crushing strength Fine Portland Lbs.,per earth cement sq. in. 10 20 30 10 20 30
..
... ...
..
80 90
20 10 20
6250 1500 5850
10 20 30 10 20 30
1940 2920 6070 4700 4800 9750
..
80 90
80 70 90
..
..
..
.. 80 .. .. 70 I n using Portland cement, siloing of the mixes was of course impracticable, b u t the other steps were followed as above outlined. Since i t has been shown by Acheson and others t h a t soluble organic matter increases the colloidal content of clay, i t was believed t h a t soils of loamy character might be advantageously
..
797
treated with straw infusion made by boiling oats straw with water and decanting the clear liquid. A quantity of the infusion necessary t o produce the maximum plasticity was then incorporated with the lime and fine earth mixtures and the resulting bricks tested. The earths of sandy texture either disintegrated in the autoclave or gave low strength tests while the loamy earths gave a crushing strength of above 3000 lbs. in mixtures containing less t h a n I O per cent lime. Similar results were obtained with a 2 per cent solution of tannic acid. T o confirm the results given in Table 11, new mixtures were made up with varying quantities of lime, the results of which are given in Table 111.
’
TABLE111-LIME-FINE EARTHMIXTURES Percentage I Crushing strength Lbs. per sq. in. Lime Sample No. Fine earth * 5550 10 3 . . . . . . . . . . . . . . . 90 15 4630 4 . . . . . . . . . . . . . . . . 85 3300 2.5 97.5 5820 7.5 6200 5 . . . . . . . . . . . . . . . . 92.5 95 5.0
CONCLUSIONS
As the result of this work, i t is shown t h a t under t h e influence of heat and pressure, various fine earth plastics may be hardened t o an extent approaching that of concrete. The presence of soluble organic matter does not prevent the hardening of loamy mixtures of fine earth and lime. Furthermore, as small quantities of lime as z1/2 per cent develop considerable strength in the hardened brick. LABORATORY OF IIQUSTRIAL CHEMISTRY OF WASHINGTON UNIVERSITY SEATTLE
WATER PURIFICATION BY OZONE-WITH THE ANN ARBOR PLANT
t
REPORT OF
B y R. Ti. FRYER Received June 13, 1914
The problem of obtaining a safe water supply is one of the greatest questions of the day for many cities. The difficulty of obtaining a pure water in sufficiently large quantities has proved too great for most cities of any considerable size, and compelled them t o use a less desirable supply a n d , t o purify t h e same. A method of purification t h a t has met with some success in several European cities is t h a t of ozonization. Some cities t h a t have all, or part of their water supply purified in this way, are Paris, Lille and Nice in France, Ginnekin in Holland, and St. Petersburg in Russia. I n this country there are only a few of these plants, none of them of any great size, and none of them attracting any particular notice as examples of cheap efficient water purification. In the summer of 1912 a large force of men were a t work just above the intake of the Ann Arbor Water Co. plant, building a dam for the Eastern Michigan Edison Co. The situation was very similar t o t h a t a t Ithaca, New York, a t the time of the epidemic of typhoid fever in 1903; with this disastrous experience in mind, these two companies united to avoid, if possible, an epidemic in Ann Arbor. The major part of the work was done during this
798
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
Vol. 6 , No. I O
time, while t h e writer was in t h e service of these t w o corporations as sanitary inspector. T h e usual precautions, such as locating t h e camps below t h e intake, having all closets t h a t were above t h e intake watertight, a n d having t h e contents burned below, were taken. T h e water was plated daily a n d as soon as t h e course of t h e river was turned, hypochlorite of lime was used in large amounts. It is indeed gratifying t o report t h a t not a single case of typhoid fever, t h a t could be in a n y way laid t o t h e water, developed during this time. WATER SUPPLY
T h e water t h a t is treated a t t h e Ann Arbor plant is t a k e n from t h e Huron River a b o u t t w o miles above t h e city. T h e source of t h e river is in a chain of lakes t w e n t y t o thirty miles, b y river, from this place. T h e river is comparatively free from contamination b y man, b u t as t h e valley of t h e river a n d its tributaries are much used for grazing purposes, chances for contamination from animals are exceedingly good. Indeed t h e writer has pictures showing thirty-five head of cattle wading in t h e river less t h a n one mile above t h e intake. T h e water is p u m p e d from t h e river t o a roughing filter located on a hillside back of, a n d above, t h e pumping station. This filter is 30 ft. square a n d consists of a b o u t 5 f t . of sea sand. Head of water on filt e r is from 4 t o 5 f t . T h e filter is washed frequently b y reversing t h e flow of the water. F r o m t h e filter t h e water flows b y gravity t o t h e bott o m of t h e fore bay, a single compartment just in front of t h e rear bays. F r o m this fore b a y t h e water flows through regulating valves into t h e rear bays, which are three separate compartments located in front of t h e first well of each unit. Concrete construction is used throughout.
FORE
BAY
U N / TN O 2
UNIT N O 3
U N I T NO P
UN/T N O 5
--
STERILIZING WELLS
These wells are from 8 t o g f t . from water level t o t h e bottom, a n d are arranged in step-like formation, t h e b o t t o m of each being a b o u t 5 f t . lower t h a n t h a t of t h e one before. There are three of these wells i n each unit a n d three units in all. T h e water flows from t h e rear bays, through pipes, t o t h e bottom of t h e first well, rises through, flows over a n d through pipes t o t h e b o t t o m of t h e second well a n d similarly from t h e second t o t h e third. T h e openings from t h e third well lead directly into t h e pumping basin. T h e ozonized air under from 5 t o 8 lbs. pressure is forced u p through each well, which is divided into two sections b y baffling plates consisting of a metallic screen covered with small pebbles t o a d e p t h of about 6 in. TYPE O F OZONIZER USED
T h e ozonizer in use is very similar t o t h e Siemens-De Frise type, some of t h e differences being the use of a n outer aluminum pole, substitution of mica tubes for a glass dielectric a n d t h e absence of a water jacket for cooling purposes. T h e outer aluminum pole is fastened in a n iron casing a n d is grounded, while t h e inner aluminum pole is insulated away from t h e casing a n d is connected
I
I
I
JSL
9-i
I It
-8’
J
1 S
L 7
-K
PLATE I-ARRANGEMENT OF OZONIZINO WELLS
t h e mica dielectrics, where it is ozonized, a n d from there t o the b o t t o m of t h e sterilizing wells. O Z O N E C O N T E N T O F A I R A N D V O L U M E R A T I O O F OZONIZED AIR TO WATER
T h e average of several determinations of ozone in t h e ozonized air shows t h a t t h e a m o u n t of actual ozone averages about 0.5 gram per cubic meter, the lowest amount found being 0 . 3 8 4 gram, a n d t h e highest amount being 0 .7 0 5 gram. It should be said, however, t h a t when the amount of ozone was found t o be 0.705, the voltage on the circuit from t h e generator was 1 2 5 , indicating a voltage of 1 2 , 5 0 0 in t h e ozonizers. This is higher t h a n is usually carried a n d indeed higher t h a n can be carried without constant danger of breakage. T h e amount of water passing through t h e ozonizing wells per hour is calculated t o be 50,000 gallons, or 189.4 cubic meters. The-amount of OZO-
T H E J O C R N A L O F I N D C ' S T R I A L A N D EAVGINEERING C H E M I S T R Y
OCt., I914
nized air varies somewhat, b u t the maximum a m o u n t observed b y t h e writer was 8j.4 cubic meters per hour. This makes t h e ratio of ozonized air t o water I : 2 . 2 a n d t h e amount of actual ozone averages 0 . 2 2 7 gram per cubic meter of water, or is 0 .2 2 7 part per million. T h e comparison of the ozone content a n d the volume ratio of ozonized air t o water a t this plant, with the figures from some other plants, presents a n interesting contrast. Ozone content G r a m s per cubic meter of air Plant a t Saint M a u r . . . . . . . . . . . . . . . 2 . 0 Nice.. 2.591 St. Petersburn.. . - . . . . . . . . 2 . 5 Ann Arbor. . . . . . . . . . . . . . . 0 . 5
...................
R a t i o of ozonized air t o water 3 : 4 1 : 4 4 : 1 1 : 2.2
COST O F O P E R A T I O P ;
T h e exact cost of operating this plant is rather difficult t o obtain, owing t o its close connection with t h e PC9'
0 ,
n
YO/.< n
stPm
-+
-~~ ~~
PLATE
11-CROSS
-
SECTION OF
I
OZONIZING
WELLS
rest of t h e system, a n d these figures must be regarded as a n estimation only. This Cstimate does not include t h e cost of pumping from t h e river, as i t is assumed t h a t this would be done whether the ozone plant were operated or not. For t h e production of t h e electrical energy a b o u t I 2 H. P. are required, while t h e air compressor is estimated t o require 7 H. P. On t h e assumption t h a t I H. P. per hour requires 4 lbs. of coal, this would make t h e operating cost for coal alone, approximately $ I . 90 per million gallons. Oil packing repairs, etc., total t o a b o u t $1.44 per million gallons. T o this must be added $ 6 . 56 t o cover interest o n investment, calculated a t 5 per cent, taxes a n d insurance, calculated a t prevailing rates, a n d depreciation calculated a t 4
799
per cent per year. This makes a total operating cost of approximately $9.90 per million gallons. AS ordinarily operated, one million gallons pass through in 20 hours. Estimates of the operating costs per million gallons for several other ozone plants are as follows: St. N a u r , $15.60;Ginnekin, $ 2 0 . 0 0 ; Howard-Bridge System, S16.80 (estimate for IO,OOO,OOO gallon plant, $7. 2 0 ) ; Estimate for 20,000,000 gallon plant for Paris, $ 8 . 0 0 . BACTERICIDAL ACTION
The writer has tested this plant frequently during t h e last two years, a n d a t no time has found a n y considerable reduction in the bacterial count between t h e ozonized a n d t h e filtered water; indeed, usually more bacteria were found in t h e ozonized t h a n in the filtered water. Possible reasons for this will be considered later. T h e results as shown in the tables below were obtained with the ozonizing wells as described in t h e first part of this article. Several changes have been made in t h e arrangement a n d operation of these wells, a n d they were tested out thoroughly with no noticeable improvement as regards bactericidal action. The first change made was t o t u r n all t h e ozone through wells No. I a n d No.2 of each unit. The second t o cut out one unit entirely a n d t u r n all the ozone through wells No. I a n d No. 2 of units No. I a n d KO.2 . No apparent benefit resulted from these changes, however, a n d the tables give one a fair idea of the action of the filter alone a n d of the filter a n d ozone combined. These tables show t h e total number of organisms found per cc. on standard nutrient agar after 48 hours a t 37' C. hTo.O F BACTERIA IN WATER Aug. 15, 1912 Raw Filtered 9 A.M . . . . . . . . . . . . . . . 650 560 11 A.M . . . . . . . . . . . . . . . 440 300 1 P . M . . . . . . . . . . . . . . . 370 190 Filter washed at 2.30 P.M. 3 P.M . . . . . . . . . . . . . . . 700 480 170 5 P.M . . . . . . . . . . . . . . . 460 120 7 P . M . . . . . . . . . . . . . . . 350 270 9 P.M . . . . . . . . . . . . . . . 580 rlug. 27, 1912 9 A.M.. . . . . . . . . . . . . . . 450 70 10 A.M . . . . . . . . . . . . . . . 480 180 11 A.M . . . . . . . . . . . . . . . 420 90 12 M . , . . . . . . . . . . . . . . 280 200 1 P.M . . . . . . . . . . . . . . . 520 150 2 P.M.. . . . . . . . . . . . . . 460 140 140 3 P.M . . . . . . . . . . . . . . . 340 4P.M . . . . . . . . . . . . . . . . 610 180 5 P.M . . . . . . . . . . . . . . . 200 130 120 6 P.M.. . . . . . . . . . . . . . 320 7 P.M . . . . . . . . . . . . . . . 410 220 8 P.M.. . . . . . . . . . . . . . 460 130 Filter was washed at 8 . 3 0 A . M . Nov. 23. 1912 1 0 . 3 0 A . M . . . . . . . . . . . . 240 200 1 2 . 3 0. ~ . . .~. . . . . . . . 160 110 3 . 4 5 P.M.. . . . . . . . . . . 140 60 20 5 . 4 5 P.M . . . . . . . . . . . . 160 8 . 3 0 P.M.. . . . . . . . . . . 70 40 9 . 3 0 p . .~. . . . . . . . . . . 300 120 Average of 25 samples 382 175+.
+
Ozonized 620 220 160 710 210 140 310 220 120 120 140 160 130 130 170 210 150 180 120 120 60 30 30 160 90 188+
Particular attention was paid during this time to presumptive tests for t h e colon germ. During the summer this organism was only occasionally found in the river water a n d very rarely found past the filter. However, on Kov. 23, 1912,a n d many times since, many acid-producing colonies were found on t h e writer's plates of the water made with ConradiDrigalski media, a n d these seemed t o be practically as numerous in the ozonized as in t h e filtered water. M a n y of these acid-producing colonies have been
8 00
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
tested out in pure culture, a n d the fact t h a t B . coli can go through t h e ozonizing wells has been proven beyond a doubt. As a n explanation of t h e negative efficiency of the ozone considered alone, I might state t h a t the bottom of t h e third well of each unit is lower t h a n t h e height of water in t h e pumping when full. Consequently, these third wells are flooded with basin water, a n d as this is open a n d located near a railroad, it is liable t o receive more or less contamination. This is the explanation advanced b y some; b u t each day, during t h e entire time t h a t the writer was taking samples, t h e water in the basin was low, a n d consequently no basin water could get back into these wells. It would seem t h a t they would gradually sterilize themselves if t h e ozone were present in large enough quantities t o have a n y beneficial action on t h e water in them, b u t samples taken after ten hours' continual operation, during which time no basin water could get into these wells, showed no improvement in the ozonized water. Another explanation of this negative efficiency, advanced b y Dr. F. G. Novy, professor of bacteriology in t h e University of Michigan, is as follows: a microscopical particle of organic matter may contain several bacteria a n d still appear as one colony a n d be counted as a n individual. Now this ozonized air tears through t h e water under several pounds pressure, a n d it is probable t h a t some of these particles of organic matter, containing germs, are broken into several sections a n d give several colonies, whereas they all showed as one colony in t h e raw or filtered water. I n t h e summer of 1912 a large d a m was built just above t h e former intake of t h e water company. As t h e manager of this company wished t o be absolutely sure of t h e quality of the water supplied t o t h e city, t h e use of hypochlorite of lime was begun. Plate counts of t h e t a p water in t h e city are made every d a y a n d t h e a m o u n t of lime is varied t o suit t h e requirements. At t h e present time t h e intake is above this d a m , a n d as t h e water is backed up for nearly two miles, a very good settling basin is formed. This water contains considerable organic m a t t e r a n d t h e a m o u n t of hypochlorite used is rather high, from I O t o 16 Ibs. per million gallons. T h e percentage of available chlorine in this averages about 331/3 per cent, t h u s making the available chlorine used come t o a n average of a b o u t 0 . j part per million. Even with this comparatively high amount of hypochlorite, t h e germ count in t h e service water will average more t h a n j o per cc. However, t h e colon bacillus is rarely found. Now chlorine is much more soluble in water t h a n is ozone, a n d gram for gram is as strong, if not a stronger, disinfecting agent. Consequently, t h e fallacy of t r y ing t o purify a water with 0 . 2 2 7 part per million of ozone, when the water is comparatively rich in organic matter, a n d when 0 . j part per million of available chlorine does not give ideal results, must be plain t o all. T h e writer wishes t o t h a n k Dr. A. K. Hale, of t h e Ann Arbor Water Co., for his many favors. The
Vol. 6, No.
IO
writer desires also t o t h a n k Dr. V. C. Vaughan a n d Dr. F. G. Novy, of the University of Michigan, a n d Mr. Gardner S. Williams for their many helpful suggestions. DEPARTMENT O F MEDICINE AND SURGERY UNIVERSITY OF MICHIGAN ANN ARBOR
STUDIES ON THE ABSORPTION OF WATER BY BUILDING BRICK By H E R M A N N W. M A H R Received July 2, 1914
T h e absorption of water b y building brick has probably been given more attention t h a n all the other properties of this important construction material. We are, however, still in doubt as t o t h e best method of conducting the test for absorptive power. Attempts t o explain the significance of the amount of water taken up a n d the relation of this value t o t h e strength of t h e material have been unavailing. Howard' has presented papers pointing out t h e indefiniteness of t h e term absorption as applied t o brick. I n spite of this confusion, t h e absorption requirement is regarded as of importance in judging quality, apparently because of a well-grounded belief t h a t future investigations would open up this dark continent. Some experimenters have a t t e m p t e d t o evolve absorption test methods which give total porosity, a n d t h e standard method of T h e American Society for Testing Materials, proposed in 1913, has this object in view. It has been pointed out by several authorities, among t h e m J . C . Jones,2 t h a t no constant relation exists between the absorptive power a n d porosity of bricks. We are, therefore, forced t o conclude t h a t t h e two are distinct properties having some small dependence on one another. Investigations of absorption of water have been mainly from t h e exterior of t h e brick, a n d these have failed t o answer many queries. Necessarily the structure of t h e brick holds these secrets. T o investigate the structure of bricks as revealed b y t h e absorption test a n d t h e significance of the latter, a s t u d y of these materials was undertaken. T h e bricks employed were of different degrees of 'burning a n d were submitted b y Hudson River a n d New Jersey manufacturers. Previous t o immersion t h e y were dried for 2 4 hours a t 110' C. They were then subjected t o absorption tests, either t h e 48 hours' total immersion or t h e boiling test proposed b y a committee of T h e American Society for Testing Materials in 1 9 1 3 . ~The immersion liquid was a 2 per cent solution of potassium ferrocyanide. At t h e close of t h e test superficial moisture was removed a n d weights determined. The bricks were t h e n split across (or lengthwise), into sections, b y means of a brick chisel. T h e surfaces t h u s obtained were treated with a j per cent solution of ferric chloride. When the section was dried t h e zones a n d channels of penetration by t h e liquid were colored blue. T h e two surfaces from t h e same fracture showed markings in practically all instances 1 National Brick Manufacturers' Association, Buffalo Meeting, February 5 , 1909. 1 Trans. Amer. Cer. Sac., 9. a Proc. Amer. SOL.f o r Testing Materials. 13 (1913), 287.
