Substitutes for Soda Ash in the Treatment of Boiler Feed Water W. A. TANZOL.4, R. L. REED, AND J. J. MAGLIRE W . H . & L . D. B e t z , Philadelphia 2 4 , P a . T h e current shortage of soda ash is a matter of particular concern in the treatment of boiler feed water where lime-soda softening is used to treat make-up water. Various substitutes for soda ash have been worked out on an ’ indiiidual plant basis. Caustic soda can be used in place of lime and soda ash w-here the carbonate and noncarbonate hardness of the raw water are in the proper proportions. In some cases alteration of the internal chemical treatment of the boiler w’ater permits lime softening without soda ash, and in others recirculation of boiler water to hotprocess lime-soda softeners is effecti\e. Substitution of zeolite mineral in a filter bed can s e n e temporaril) by blending the zeolite effluent with lime-softened w ater. Barium carbonate has been used as a satisfactor! substitute for soda ash although the higher cost with this chemical restricts its use to emergency periods.
T
H E nationwide chemical shortage, particularl? of caustic soda and soda ash, has resulted in production difficulties in many industries. Soda ash is one of the most important chemicals used in the treatment of boiler feed water, and the production of power and steam is dependent on the properly controlled treatment of this feed water. Without properly treated boiler water, unscheduled boiler outages from scale and corrosion cause interruptions in plant operation and shutdowns. One of the most commonly used methods for the external softening of boiler feed water is the lime-soda process, operated both hot and cold. Hydrated lime and soda ash are employed to precipitate the scale-forming calcium and magnesium ions from the raw water; these form insoluble precipitates of calcium carbonate and magnesium hydroxide which are separated from the softened water by sedimentation and filtration. Lime is required for the precipitation of magnesium and the removal of the calcium bicarbonate hardness as follows:
+
+
MgS04 Ca(OH), = CaS04 Mg(0H)z ?\lg(HCO3)2 2Ca(OH)z = 2CaC03 Jlg(OH), 2H2O Ca(HC03), Ca(0H)z = 2CaC03 2H20
+
+
+
+
+
(1) (2) (3)
Soda ash is needed to remove calcium noncarbonate hardness present in the rary water and also to precipitate the calcium chloride, calcium sulfate, etc., produced in the precipitation of magnesium salts by lime:
CaS04
+ S a 2 C 0 3= CaC03 + Ka2SO4
(4)
K h e n soda ash is unavailable for lime-soda softening, the effluent from the treatment process may be quite high in hardness. Use of unsoftened or partially softened make-up water would be disastrous in many cases of boiler operation under high pressure, despite increased application of internal treatment of boiler mater. To maintain boilers on line during temporarv interruptions in soda ash supply or under continuously curtailed supply conditions constitutes a problem often capable of solution by altering chemical balances throughout the system or by substituting treatment chemicals not usually considered feasible from an economic viexpoint. Where the continued operation of
a complete industrial plant is dependent on the power or stc’am generation which, in turn, is directly dependent on the proper softening of the boiler feed water, increased chemical treatment costs of ten, fifty, or a hundred dollars per day are readily justified if continued plant operation can be assured. During the past few years different systems of altered chemical balances and altered chemical treatment have been devised to permit continued and uninterrupted plant operation Vaiious substitution products and methods have been given consideration either to reduce the quantity of soda ash used or to eliminate it entirel) Some of the plants involved xere advised b v their suppliei that they would be allotted only about 70% of previous yearly purchases; other plants \$ere faced with early depletion of their supply of soda ash nithout being able to renew it from legitimate sources. The following examples illustrate methods that have been applied to a number of plants faced n ~ t hthis shoi tagc. CAUSTIC SODA
Khilc most of the sodium salts nere scarce, some plants had available caustic soda nhich was utilized in place of soda ash ( 4 ) . Actually, caustic soda is utilized in place of lime and as a result of this substitution, soda ash is formed; Equations 5 , 6, and 7 illustrate the softening reactions using caustic soda.
+ 2SaOH = CaC03 + SanCOs + 2H10 + PSaOH = llIg(OH)? + Na2S04 lIg(IICOa)i + 4SaOH = ;\lg(OH)z + 2Sa2C03 + 2 H 2 0 Ca(HC03)r
3\IgS04
(5) (6)
(7)
Equations 5 arid 7 show that soda ash is produced when caustic soda reacts with calcium or magnesium bicarbonate hardness. The soda ash thus becomes available for softening calcium sulfate hardness (Equation 41. Depending on the characteriatics of the raw water, complete softening may be brought about by caustic soda alone or by a combination of lime and caustic soda. However, on waters that consist predominantly of noncarbonate hardness caustic soda can accoindish only partial softening. I n general, caustic soda alone can be utilized for softening waters that possess a methyl orange alkalinity that evceeds half of the calcium content by 15 to 30 p.p.m. (Table I). Where methyl orange alkalinity exceeds half the calcium content of the Jyater by more than 30 p.p.m., a combination of lime and caustic soda should bc utilized to avoid an excessive alkalinity of the softened TTater. Waters that possess a methyl orange alkalinity leqs than half the calcium content can be only partially softened by caustic soda alone. BOILER WATER RECIRCULATIOh
I n many cases soda ash requirements have been partially reduced by recirculating boiler water blowdown to thc softener, and thus making use of the caustic soda and soda ash content of the boiler water t o replace a portion of the lime and soda ash normally used in the softening operation (1, 2, 3, 7 , 9, 10, f2). Softening reactions follon. Equations 4, 5, 6, and 7. Since the major portion of the boiler water alkalinity exists as caustic soda, the additional soda ash produced in Equations 5 and 7 is of bcne-
1440
INDUSTRIAL AND ENGINEERING CHEMISTRY
Kovember 1947
TABLE I. ;IPPI.I(-ABILITT OF Cat-STICSODA Raw R-ater CharacteristicaU
Treatiiieni
SI < '.'&a 11 = '/&a (13-30 p p.111.j \ I > 1, nCa I30 p p.m.
Caustic soda Caustic soda Caustic soda a n d lime
+
9
Degree of Softening Partial Complete Complete
31 (methyl orange n1k:iliiiiry) a n d C s a s CaCOa.
TxBI.~; 11. A S A L T ~ E SWITH
ASU WITHOUT
BOILER\TATER
In some of the plants employing batch cold-process lime-soda softeners with gravity filters, consideration was given to converting &ne of the gravity filters t o a gravity zeolite softener and blending the effluents of both softening processes to produce a water as illustrated in Table IV. The quantity of soda ash saved by this procedure \vas in proportion to the amount of water softened by the zeolite unit. Since only 75c7, of the make-up water was softened by the lime-soda process, a direct saving of 25% in soda azh was achieved.
RECIRCGLATIOS
Hardness a s CaCOa, p.p,m, L'a as CaC08, p . p . m , AIg as CaCOd, p.p.111. Ukalinitv a%C'aCOa, p.p.iri. Phenolphthalein RIethyl orange Julfaie as SO4 Chloride a s C1 Phosphate as PO4 pH
n ' i t h o u t Recirculationa Lime-soda R a w softened Boiler 180 120 ti0
20 16 4
0 120 35 10
32 60 35 10
...
..
0
.., ,
..
630 ?00 a38 154 60 11.7
BARIUM CARBOXATE K i t h Recirculationb Lime-soda R a w softened Boiler
180 120 60
0
120 35 10
...
20 16 4 32 60 65.5 19
..
0 ..,
...
336 374 538 154 60 11.5
Barium carbonate was considered an emergency substitute For soda ash. Lime-barium softening for reducing the sulfate concentration is a process of historical interest but is in usc, to the authors' knoxledge, at onl3- one plant in this country ( 5 , 5, 8, 11). Barium carbonate vias applied during t,he soda ash ehortagc, not Jvith the primary intention of reducing he sulfate content of the treated Jvater, but rather to obiain the advantage of the sod urn carbonate produced as a by-product of sulfate removal:
+ BaC03 = BaSOl + Sa2COa + BaC03 = BaS04 + CaCOJ l I g S 0 4 + BaCOJ = BaS04 + CaS04 SIgC03 + = CaC03 + lIg(OH;s
10.1 i.3 10.1 0 Lime requirement, 147 p , p . m . on r a w water; soda ash. 106 p . p . m . o n raw water. 6 . j c A boiler a a t e r blowdown (69,500 pounds per million pounds ateam). t Lime requirement, 132 p p . m . on r a x water; soda ash, 84 p.p.m. on :aw water. 6,5y0 Fystern blowdoan (139,000 pounds per million pounds s t e a m , of \+hich 69,500 pounds are returned to softener). i.3
tit in the removal of noncwbonate hardness as illustrated by Equation 4. Table I1 s1iow.s the normal balances nmiutained o n a hot process joftener and the resulting boiler water characteriutics, as well as the balances utilizing boiler water recirculation to the softener to briny about a reduction in d a ash requirements. .Isa result of recirculation, the reduction in linie requirements as approximately 105; and in soda ash requirements, 2 1 5 . d normal balance was maintained on thc .;oftener, and all factors of the boiler water balance remained the saine with the esception of boiler tvater alkalinity. The reduction of boiler water alkaliiiity is a direct result of consuming it i n the softening process. I n niany cases reduction in boiler xater alkalinity is a desirable feature to mininiize carry-over that may result from escessive boiler lvater alkalinity; boiler water is often recirculated solely for this purpose. In general, the application ~f boiler lyatcr recirculation to viaters that, consist predominantly of carbonate hardness brings about 3 greater percentage saving in soda ash than is covered by the case cited. Noiicarbonate hardness waters involve only a minor percentage savings in the soda ash requirements. ZEOLITE SOFTEYISG
C'n(HC03i2 S a 2 Z = CaZ + 2SaHC'O ]\Ipsol S:iJ = LIgZ + sa,so*
Say304
(10) (11) (12)
CaSOl
(13)
-1s reaction 10 s h o w , sodium carbonate is formed by the reaction between barium carbonate and sodium sulfate present in the raw ivater. The sodium carbonate is then available for use in accordance with reaction 4. I n addition, as reactions 11, 12, and 13 show, calcium sulfate and magnesium sulfate can be renioved without the w e of soda ash.
T ~ B L 111. E BLESDIXGOF ZEOLITE SOFTEKED W ~ T E RPRIOR TO
LIW3-SOD.i
Hardness as CaCOa Ca a s CaCOa
3 I g as CsCOi .Ilkalinity a3 CaCOE Phenolphthalein l l e t h s l orange Sulfate as SO1 Chloride as C1
SOFTESISG (IU P l R T S PER l I I L I , I O N )
Raw$ 160 110 50
0
130
30
12
ZeoliteSoftened 4 ,..
... 0
130 30 12
Blendedt 121 84 37
Lime-soda Softened 20 16 4
0 130 30 12
32 60 30 12
Chemical requirements: lime, 149 p . p . m . : soda ash, 68 p.p.m. ijc, r z w water, 25% zeolite-softened Chemical requirements: lime. 137 p.p.m.; soda ash, 27 p . p . m . ; salt, 140 p.p.m. a b
TABLEIv. BLESDIXGO F
ZEOLITE SOFTEXED \\-ITER
\VITH
LIME-SODA EFFLCEST(IS PARTSPER ~ I I L L I O S ) Raw
A ferr of the plants faced with tlie nwd for reducing soda ash requirements had enough filters and filtering capacity to permit conversion of one of the filters to a zeolite softening unit, operated o n tlie sodium cycle. In the zeolite softening process calciuni and magnesium hardness is rcnioired in cscliange reactions with sodium iniis substituted for the calcium and magnesium:
+ +
1441
T.ime-Soda Softened
Zeolite Softened
Hardness as CaCOj 220 35 4 Ca as CaCOa 160 23 , . . Alg a3 CaCOs 00 10 Alkalinity ns C u X h 0 4.5 0 Phenolphthalein 100 80 100 3Iethyl orange 80 Sulfate as YO, 80 80 30 30 30 Chloride as Cl 'I i5Gc cold liliie-wda softened, 2 j i , zeolite-softened.
Blended' 28 ..
.-,
:j
8i
50 30
s (9
Heaction 8 shows that the bicarbonate hardness ib converted t o sodium bicarbonate. \Then the zeolite softened water is blended n-ith the r a Jvater, ~ the resulting characteristics are such that :hr h:rrtlnc-~ beconirls tritally carbonate. Table 111 s h o w the makc-up of the blentltd n-ater arid the resulting softened water, which tirought about a saving of 8cc in lime and SO';, in soda ash. .\t thti same time the external chemical treatment cost was slightly lower rvitli this treatment than was obtained by the normal procedure. By softening increased pcrcentages of the raT1- water by the zeolite process, t,he use of soda ash could be totallj- (,liminated.
n.hi.re the natural sodiuni sulfate content of the raw watrr was iiisuffirient t o produce the desired sodium carbonate excess required in the softener effluent, it was necessary to feed sodium sulfare to tlw witener and thereby produce soda ash directly in ac.corclarice ivith reaction 10. Theoretical efficiency in the uscl of barium carbonate to produce soda ash has not been obtained in either laboratory test or full scale plant operation. Barium carbonate can be used in bot11 hot and cold softening, hut its action is more efficient in the hot !Table S'). Table V illustratrs hot process tests in Tvhich normal softeuing fwtion is ohtained with theoretical quantities of lime and soda
INDUSTRIAL AND ENGINEERING CHEMISTRY
1442
Vol. 39, No. 11
The reason for this condition has not been closely investigated but was possibly due t o C O L D PROCEasb an insoluble barium sulfate Treated waters coating on the barium carbonate particles. I n addition, 100 100 100 100 100 100 slightly larger lime charges . . 100 icio iio zoo iio '3'00 were required, of the order 100 1.50 150 200 230 300 of approximately 10%. ID 172 172 172 172 172 172 general, reasonably good agree. . ... 370 370 5 5 5 iiO Qii iiio ment is observed betviecn labo223 334 334 466 3.58 670 ratory and field tests on the 112 118 $$ 66 GO 56 hot process use of barium car10- 101 42 33 31 I li 19 24 27 25 bonate. 26 2G 26 36 48 54 The use of barium carbonate 38 38 52 74 92 40 in place of soda ash docs not 112 176 I S 2 192 248 296 164 164 164 164 164 164 require alteration of normal softener control procedures, so no disadvantage has been encountered in this phase of operation. Lime control can be establislicd on the basis of maintaining certain residual hydrate alkalinity values, and barium carbonate.can be regulated t o develop optimum excess carbonate alkalinity concentrations. Determinations for excess sodium sulfate ~voultlnot be imperative since experience proved that the feed of this material, if required, could be adjusted in direct ratio to the barium carbonate charges. Some state health authorities consider the barium-containing Judge to be a health hazard and will not permit it to be dumped i n waterways. Potential users of barium carbonate process who must discharge sludge to streams and rivers should seek informittion concerning the attitude of their state health authorities heforc installing the process.
TABLE V. RESULTS OF LABORATORY TESTSox HOT ASD COLDPROCESSES WITH 7 -
Raw water
Treated waters
% of theoretical requirements Lime Soda ash Barium carbonate Sodium sulfate Amounts used, p.p.m, Lime Soda ash Barium carbonate Sodium sulfate Analvsis, p.p,xn. Hardness a s CaCOt Ca as CaCOa hlg as CaCOs, p . p . i n . Alkalinity as CaCO: Phenolphthalein Methylorange Sulfate as SOa Chloride a s C1 5
t
Conditions of t e s t : Conditions of t e s t :
...
100
100
. . . . . . 100 . . . . . . . . . . . . . . . . . 172 l i 2
...... , ,
.
,
.
200 ,
.,
. . . . . . . . . 248 168
80 0
100 30 164
-
BARIUMCARBOXATE
HOT PROCESS^-
...
100
100
100 io6 100 150
iio
172
172
172
..
172
370 223
3% 334
;Si
.
..
334 38 23
100
...
...
176 174 2
16 14 2
G! 13
52 30 22
6 16 30 164
1G 40 30 164
G 2-1 80 164
12 38 128 184
JO
150
15
100
100
.. , . 100 . . . . . . . . .
.........
172
. . . . 200 ,
.
,
,
. . . . . . 248 188 80
12
0
44
100 30 164
QG 164
-
R31~ water _.
176 172 4
24 21 3
20 46 3-1 64 30 30 164 164
1-hour retention, 200' I-., 1.0-liter samples 4-hour retention, 8 0 3 F . , 1.0-liter samples.
ash. Lime alone is effective in precipitation of magnesium, but obviously additional softening poi? er is required to reduce the calcium content. Using theoretical quantities of barium carbonate and sodium sulfate as substitutes for soda ash jields reasonably satisfactory results, with reduction in calcium to 55 p.p.m. as calcium carbonate. Further improvement in lowering the hardness of the treated TTater is obtained with additional barium carbonate and sodium sulfate. Table V also shows the results of cold process teats with the same rarv water. Application of theoretical quantities of barium carbonate and sodium sulfate does not achieve the same degree of hardness removal as secured a t higher temperatures. Increased quantities of barium carbonate and sodium sulfate show steadily decreased calcium contents of the softened n-ater, but these data indicate that this process iS considerably less efficient a t lower temperatures, possibly as a result of lower barium carbonate solubility a t lower temperatures. The insoluble barium sulfate precipitate formed in these reactions is removed along with the calcium carbonate and magnesium hydroxide through sedimentation and filtration as in normal lime-soda softener operation. Inasmuch as barium salts are toxic, qualitative barium determinations were conducted on the softener effluent, and the efficiency of filtratiov n-as also checked closely to make certain. of the removal of the finely divided barium sulfate precipitate. Only small traces of barium were observed. During initial application of barium carbonate to plant operation, the raw make-up water to the softener was depended upon to supply the amount of sulfate required for barium precipitation. Sulfate removal taking place during this process decreases the dissolved solids of the softener effluent, which is beneficial in numerous applications. Further analyses revealed that 100% of the natural sulfate content of the ralv water did not react with the barium carbonate, but rather a sulfate residual of 20-40 p.p.m. as SO, remained in the softener effluent. Consequently, not enough carbonate was produced to yield as complete noncarbonate hardness removal as desired. Barium carbonate fed Considerably in excess of theoretical requirements failed to produce further sulfate or hardness reduction. Excess barium carbonate feed without the sulfate available for precipitation was simply wasted, since this material remained in a n insoluble, inert form. Table VI illustrates the results obtained in field tests with barium carbonate in conjunction with a hot process lime-soda softener, having a capacity of 10,000 gallons per hour and operating a t 218" F. Somewhat greater than theoretical quantities of barium carbonate were required, varying from 2 6 4 0 % .
8 ,
TABLE VI. RESULTSOF FIELDTESTSKITH (IN PARTS PER RIILLIos) Raw 'Kater Hardness as CaCOa Ca as CaCOt l l g as CaCOa Alkalinity as CaCOi Phenolphthalein 3Iethyl orange Sulfate as SO, Chloride as C1 a b c d
188 122 66
0
48 152 8
--
THE
HOTPROCESS
40 10
Softener Effluents S o . 3C S o . 4d 22 16 28 .. 14 10 .. 2
26 40 24
16 34 32
No. l G S o . 2b 50 38
8
8
26 40 28
8
30
50 24
8
No. 5 d 14 12 2
30
52 36
8
Theoretical lime a n d barium carbonate: no sodium s u l f a t e . Theoretical lime: 50% excess barium carbonate: no sodium sulfate. 10% excess lime; 2 5 7 , excess barjum carbonate a n d s o d i u m sulfate. 10% excess lime: 40% excess barium carbonate a n d s o d l u m sulfate.
Assuming reaction 10 to proceed a t loo% theoretical efficiency, the cost of the soda ash thus produced is 6.2 cents per pound. This cost is based on 3.25 cents per pound for barium carbonate of 98% purity and sufficient natural sulfate content of the raw water to complete the reaction. Where sodium sulfate must be supplied for the reaction, based on a cost of 2.1 cents per pound for this chemical, the cost of thus producing soda ash is 9.0 cents per pound. Where higher than theoretical quantities of barium carbonate and sodium sulfate are necessary, the cost of producing soda ash is correspondingly increased. All applications proved that barium carbonate gave as great a hardness reduction as possible with the conventional use of soda ash. Obviously, operating chemical costs increased as a result of the cost of barium carbonate in comparison with soda ash and also the necessity of employing sodium sulfate in a large number of cases. Hovcver, the use of barium carbonate enables normal softening operatlons to be maintained during emergencl periods when the soda ash supply may be inadequate, and thereby permits continuous operation without fear of interrupted production.
November 1947
INDUSTRIAL AND ENGINEERING CHEMISTRY ACKSOWLEDGMENT
The authors wish to thank J. K.Polsky, n-ho conducted the majority of the laboratory tests, and also express appreciation to W. H. &- L. D. Betz for permission to present these data. LITERATURE CITED
(1) Baker, Combustion, 12, 31-4 (1940). (2) Betz, Handbook of Industrial Water Conditioning, Chap. 1E. p . 547 (1945). (3) Flickinger. P o m r , 85, 118-20 (1941).
1443
(4) Heiskell, I bid., 90, 747-9 (1946). ( 5 ) Hundesshagen, 2. ofeentl. Chem., 24, 159-67, 175-86 (191s) (6) Leick, T'om F u s s e r , 7 , 197-205 (1933). (7) Naguire and Tomlinson, Combustion, 11, 26-39 (1939). (8) Mehring, Cliem. &. -Vet. Eng., 21, 629-32 (1919). (9) Paris. Chaleur &. industrie, 5, 277-9 (1924). (10, Paris, Chimie 6 industrie, 4, 722-30 (1920). (11) Itodman, Chem. 6 X e t . E ~ Q 35, . , 221-3 (1928). (12) Ypcrry. Combustion, 10, 27-33 (1939). RECEIVED September 6, lQ47. Presented beiore t h e Division of Water, Sexyage, and Sanitation Cherni>try a t the 112th Meeting of the .\VEP.ICAN C R E M I C ASOCIETY, L S e x S o r k , S . I'.
Butanol-Acetone Fermentation of Wood Sugar REID H. LEONARD AND W. H. PETERSOY
GEORGE J. RITTER
Cniversity of FVisconsin, .Madison, W i s .
Cnited States Forest Products Laboratory, Madison, Wis.
Wood h3droljzates were fermented with Clostridium b u t y l i c u m No. 39 to butanol and acetone. The wood species and method of h?droljsis affect the fermentabilitj of the liquors. I er) mild or i e r ) \igorous conditions of hjdrol?sis do not produce an e a s i l ~fermentable solution. Complete utilization of sugar could be obtained up to 3Yo concentratioiis. Solient jields ranged from 21 to 38Y' of the sugar fermented.
by the JIadison wood sugar process as described by Harris and Beglinger (4:. These samples xere neutralized to pH 4.2 with lime at 138" C. (4, 7 ) . The oak sample represented the first 2 5 5 of the hydrolyzate ~eceivedfrom the digester, and the Douglas fir liquor was from a normal run.
T
HE fermentation of vvood hj-drol>-zates by butanol-acetone
bacteria is difficult. Sjolander, Langlykke, and Peterson (10) conducted butanol-acetone fermentations on hydrolyzates prepared by a method similar to the Scholler process arid obtained a fermentable medium aftcr precipitation of metals a t pH 10, neutralization, and clarification with Sorite decolorizing carbon. I n the present paper other types of hydrolyzates have been studied, and attempts have been made to simplify the pretreatments for fermentation. Two cultures had previously been selected for wood sugar fermentations: Cl. felsineum Carbone S o . 41 by Sjolander et al. (IO) for hydrolyzates and Cl. butylicum (Fitz strain) No. 39 by Wiley et al. (11) for sulfite waste liquor fermentation. These two cultures, as well as Cl. butylicum S o . 37, Cl. beijerinckii No. 67, and C1. butylicun KO.69, were compared on wood hydrolyzate, and No. 39 was selected as the most suitable organism. Fermentations were conducted with cultures transferred three to five times from the spore stock. Iiutrients were supplied by 1%malt sprouts and 0.1% (NH4):HPOd. A trace of reduced iron was added to the media before autoclaving. From 0.1 to 0.3% calcium carbonate was added to the media after inoculation. Inoculum was produced on glucose-malt sprouts medium and used after 12 t o 20 hours a t 870 of the fermentation volume. Determination of reducing sugars was made by the method of Shaffer and Somogyi (9); furfural by a colorimetric method ( 1 ) ; ethanol and butanol by Johnson's procedure (6); and acetone by Goodwin's method (3). Volatile acids were determined by titration of 11 volumes of distillate from 1volume of sample. Hydrolyzates of maple and spruce were prepared in a rotary digester similar to that described by Plow et al. (8). RIaple sawdust was hydrolyzed by 3% sulfuric acid with an acid-wood ratio of 1 : l a t 181' C. for 30 minutes. A milder hydrolysis of maple and of spruce was made with 1.8% acid, ratio 1:l at 173" C. for 5 minutes. Oak and Douglas fir were hydrolyzed
FACTORS AFFECTIKG FERMESTATIOX
It was first desirable to repeat the results of Sjolander et al. In their work the amount of decolorizing carbon was not stated, arid it was found that n-ith maple hydrolyzate, folloving their procedure, 10 to 20 grams of Sorite decolorizing carbon per 100 nil. n-cre required to duplicate their fermentation results. Fermentation of high temperature maple hydrolyzate prepared horved that 92% of the sugar in a -1.04 grams per 100 nil. solution was fermented in 5 days. The quantity of decolorizing carbon was found to be important; the use of 1 gram per 100 nil. resulted in the fermentation of 2 5 5 of the sugar, 5 grams gave 6-15, 10 grams gave 72y0,.and 20 grams gave 937,. .iftcr the furfural vas removed from the sample, the quantity of carbon required was decreased to less than 5 grams per 100 ml. The pH was found to be important, since 1 gram of carbon a t pH 2.0 gave 17% fermentation, while 1 gram at p H 6.8 gave 51 7,. The difficulty found with maple wood hydrolyzates was also found with spruce, Douglas fir, and oak. The fermentations were characterized by a long induction period and a slow sugar utilization. I n some samples much of the inhibition could be accounted for by the presence of furfural-for example, the maple hydrolyzate made a t 181" C. contained from 0.5 to 0.8 gram of furfural per 100 ml. On synthetic medium 0.1% furfural decreased the fermentation by 15%. Hydrolyzates containing more than 0.1% furfural stopped the development of the bacteria completely. Furfural was removed easily by distillation or by passing the liquor through a steam stripping column. When furfural was added back to the stripped liquor, t,he fermentations were not inhibited to the same extent as initially. This indicated that substances other than furfural were removed by the distillations. When the concentration of the inhibitory substances was decreased b)- dilution of the liquor, the extent of fermentation was improved. Complete fermentation of sugars in wood hydrolyzates v a s usually obtained a t about 3% concentration. With glucose-malt sprouts medium 5% concentration was about, the maximum quantity which could be completely fermented with
