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Patented Jan. 28,1947
2,414,930
STATES 1 PA
2,414,930
WASTE LIQUOR DISPOSAL
Benjamin W. Collins, Swarthmore, and Edmond
T. Roetman, Ridley Park, Pa, assignors to
American Viscose Corporation, Wn,
Del., a corporation of Delaware
No Drawing. Application February 19,1943,
1
Serial No.
4 Claims.
This invention relates ‘to improvements in
2
.
?rst treated with an acid such as waste sulfuric
methods of preparing waste liquors for disposal.v
More particularly, the invention relates to im-'
provements in methods of preparing for disposal
waste liquors which result from the manufacture
acid to reduce the pI-I of the waste liquor to ap
proximately within the range of 8 to 10, prefer
ably approximately 8.‘ The waste liquor is then
this process containing the polysuliides presents
in contact with the waste liquor and atmospheric
collected in a storage tank and is withdrawn from
of viscose rayon and which contain sul?des.
the tank and sprayed’ or otherwise deposited onto
In the manufacture of rayon by the viscose
'
a
?lter bed. The ?lter bed contains aerobic and/
process, a cellulose xanthate solution is extruded
or anaerobic micro organisms which cause the
into an acid bath wherein the cellulose inthe so
lution is regenerated and free sulfur and sulfur 10 sul?de in the waste liquor to be oxidized to stable
sulfur compounds, chiefly sulfates. The filter
compounds are formed. The cellulose product
bed
is made of crushed rock having sufficient
containing free sulfur is then treated with an
spaces or interstices to permit the waste liquor
alkaline sul?de such as ammonium sul?de or an
to slowly trickle or percolate through the bed
alkali metal sul?de preferably sodium sul?de
and
at the same time to present extended sur
which forms with the sulfur readily removable
polysul?de compounds. The waste liquors from 1153 faces on which the micro organisms may grow
oxygen. Sludge such ‘as activated or digested
a dimcult disposal problem. The polysulfldes as
sludge from a domestic. sewage disposal system
such have a biochemical oxygen demand (B. O.
D.) and if discharged directly into a river or 20 is deposited on the ?lter bed and serves to supply
the micro organisms used in carrying out the
stream will deplete the supply of dissolved oxygen
process. A portion of the e?luent that has
' in the water, thereby endangering the biological
trickled through the ?lter bed may be introduced ‘
life (?sh, crustacea, etc.) in the stream. Also it
into the waste liquor collected in the storage tank
. will lower the capacity of the river or stream to
to seed the waste liquor with micro organisms to
dispose of other polluting substances.
25 act on the sul?des and assist the action of the
A principal object of the present invention is
micro organisms in the ?lter bed. Also, the micro
to provide a method or" preparing for disposal
organisms
added to the waste liquor in the storage
waste liquors containing sulfides wherein the sul
tank serve to replenish the micro organisms in
?des are converted into more highly oxidized
compounds which may be discharged into a river 30 the filter bed ‘which, in effect, increases its op
erating capacity as well as the length of time
or stream without endangering the biological life
that the ?lter bed can be continued in operation.
therein or decreasing the capacity of the river or
In the operation of the process the Waste liquor
stream to dispose of other forms of oxidizable
containing the sul?de is maintained in contact
matter.
.
A further object of the invention is to provide 35 with the micro organisms until substantially all
of the sul?des are oxidized to sulfates, which are
a method of preparing for disposal waste liquor
‘ containing sul?des wherein the sul?des are sub
jected to the action of micro organisms and are
final oxidation products and are therefore stable,
and the pH of the waste liquor is reduced to with
the range of approximately 5 to 7, preferably
converted into more, highly oxidized compounds. . in
Other objects and advantages of the invention 40 approximately 7. By applying this procedure
the treated waste liquor may be discharged into a
will be apparent from the following description '
riverv or stream without affecting its biochemical
and appended claims.
oxygen demand, endangering the animal life
in the manufacture of rayon by the viscose ‘ therein,
or lowering its capacity to dispose of
process, the rayon containing sulfur is treated
with an alkali metal sul?de such as sodium sul 45 other forms of domestic or industrial pollution.
While a preferred procedure has been de
?de, portions of which react'with the sulfur in
scribed, it is to be understood that changes and
the rayon to form-sodium polysul?des of varying
variations may be made without departing from
chemical composition such as NazSz, NazSs, Na2S4,
the spirit and scope of the invention as de?ned
or Nazss. The rayon is drained and washed and
the appended claims.
the preparation of the waste liquor from this 50 in We
claim:
stage of the process forms the subject matter of_
1.
A
method of treating of waste liquor from
the present invention. In accordance with the
the manufacture of viscose rayon containing sul
present invention the hydrogen ion concentration
?des and polysul?des comprising adding acid to
(pH) of the waste liquor is carefully controlled.
the waste liquor to reduce the pH of the waste
The waste liquor, being substantially alkaline, is 55 -liquor
to approximately within the range of 8 to
aeiaoeo
I
10, and then subjecting the waste liquor to the
action of micro organisms which occur in sludge
thereby oxidizing by their action the sul?des and
polysul?des to stable-sulfurofcompounds.
waste liquor from
2. A method of treating
-
d
mately within the'range oi.’ 8 to 10, passing the
waste liquor through a ?lter bed containing
micro-organisms which occur in sludge thereby
oxidizing the sul?des to stable‘ sulfur compounds
hy the action of the micro-organisms.
4. A method of treating waste liquor from the
manufacture of viscose rayon and containing sul
tides, comprising adding sulfuric acid to the waste
liquor to reduce the pH of the liquor to approxi
uor to reduce the pH of the waste liquor to ap- proximately within the range of 8 to 10. and then
mately within’ the range of 8 to 10, passing the
10
passing the waste liquor through a ?lter bed con
waste liquor through a ?lter bed containing
talnlng micro organisms which occur in sludge
micro-organisms which occur in sludge thereby
thereby oxidizing by their action the sul?des to
oxidizing the sul?des to stable sulfur compounds
stable sulfur compounds and adding a portion - by the action of the micro-organisms, and adding
of the effluent from the ?lter bed to the raw waste
a portion of the e?iuent from the ?lter bed to
liquor before the waste liquor is passed through 15 the raw waste liquor before the waste liquor is
of viscose rayon containing sul
the
manufacture
?des comprising adding an acid to the waste liq
the ?lter bed.
i
3. A method of treating waste liquor from the
manufacture of viscose rayon and containing sul
tides, comprising adding sulfuric acid to the waste
_ liquor to reduce the oil of? the liquor to apprcxi= 20
passed through the ?lter bed.
BENJAMIN ‘W. COLLINS.
EDMOND T. ROETMAN.
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