Note: Descriptions are shown in the official language in which they were submitted.
` ` 447'
` This invention relates to a novel solution and ,~
~- method for reducing air-polluting odors which emanate from
organic waste products, including organic waste products
in storage subject to chemical or microbial degradation.
State of the Art
, . .
Methods have been proposed for eliminating odors
from organic waste products. However, such methods have
- not been wholly successful~ For example, in the treatment
of human wastes, sanitary products, solids or sanitary
0 fluids have been used. Their main objective is to provide
a bacteriostat~c effect. In general, they act as deodor-
izer~. Actually, they provide an odor--masking effect ~y
employing such aromatics as phenolic compounds, camphor,
iso-bornyl acetate, and so foxth, the effect being generally
. .,
~15 temporary.
Different methods have been proposed for reducing
~1, the odor o animal waste products in the field where, for
example, manure is spread. It has been suggested to aerate
animal wastes~on a ~arge scale; however, aeration has not
been satisfactory due to the low threshold values of cer-
tain of the more odorous compounds. The ~hxeshold values
, ox minimum identifiable odor (M.IØ) for mercaptans in `
mg/l in air range between 10 to 3xlO ; for dialkylsul- `
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` ~o6;~47'
fides from about 10 to 2.5xlO ; for hydrogen sulfide
about 10 and for skatole about 1.2xlO mg/l in aix.
Another method which has been proposed utilises
î the deep-level injection of liquia or liquified manure
into the soil. This method diminishes odors in the sur-
. . ~
rounding ~ields but not in the breeding areas. In Sweden,
~' the foregoing was applied to the abatement of odors due to
animal was~es on pig breeding farms. ;~
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The best results, though still not wholly satis-
factory, have been obtained with the use of ammonium
persulfate. While unrealistically high amounts of this
chemical have been used, they still did not eliminate or ,
reduce the odor entirely. Moreover, the chemical does not
.. ~ . ... . .
~ attack sulfur-bearing chemicals. The effect of ammonium ;;
,., ~ .,
persulfate has been studied by others, the observations
~ being that while the odor intensity was reduced, it was still
.. ~ , ., :
~ not satisfactory.
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~ So ~ar, there has been no satisfactory proposals `'~
. ".:j . , .
for abating bad odors from organic industrial wastes, no~ `
~; 20 even from sludge derived from sewage works. For example, ~i
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~j an attempt to~mask the odor of sevage sludge similarly
met with failure.
,.; ' . .
i~ Many organic was~s are produced daily in large
,~ quantities, for example, in large scale animal breeding ~; ;
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62q~47
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` arms, as effluents from the food industry, waste products
, rom slaughterhouses, sewage and sewage sludge, among
.. others~ In ~hese situations, the bad odor is regarded
as a public nuisance and as a health hazard, particularly
in the situation where waote products are stored for a
~- relatively long period of time, for example, manure and
certain soil improving products. ~ .
~ Obiects of the Inventio~
.~ It is thus the object of the invention to pro~
vide an odor removing or odor abating solution using
- chemicals which are not generally harmful to the environ-
. "~
.1' ment and which do not substantially adversely affect
chemical or biological processes usually applied in the
~'1. . further treatment of organic waste products. ~.
15 ~ Another object of the invention is to provide
a method for the ecological recycling of organic waste
products without the attendant disadvantages of bad odors.
.In accordance with these objects, the present
invention is directed to the txeatment of human and animal
waste products arising out of metabolic processes, as
welI as to the treatment of organic industrial wastes and
7:?~l, ef~luents.
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`` 1062~47
Stating it broadly, one aspect of the invention i8 directed
to a method o reducing air polluting odors emanating from a solids-
.~ .,
containing organic waste product selected from the group consistlng of
, organic waste products produced by metabolic processes including animal~'; and human wastes, organic industrial wastes and sewage sludges which com-
prises: contacting said organic waste product with an effective odor-
abating amount of an aqueous acid solution con~aining an oxidizing agent
.i, selected from the group consisting of water-soluble persulfates, nitrates,
chlorates and permanganates of ammonium ion and alkali metals in an
.
~' 10 amount sufficient to provide between about 8 and 68 mg 02/g of solution,
. a precipitating agent selected from the group consisting of water-soluble
ferrous and ferric compounds in an amount sufficient to provide between
about 28 and 70 mg Fe/g of solution, and about 3 to 25~ by weight of
sulfuric acid; and maintaining said contact until said odor has been
substantially removed.
The use of the foregoing solution results in simultaneous
~I reactions involving the acidification and oxidation of the waste and
~;i/ also in the precipitation of odorless and lnsoluble sulfides. The
~Y~
chemicals selected are those which have sufficient solubility in cold
water and which are substantially harmless to the surrounding
environment.
The reactants employed include substantially all acids, the
inorganic acids being the most efficient, e.g. sulfuric acid, Acid salts
may be employed, such as peroxidisulfates ~persulfates~, hydrogen sulfates,
ferric chlor-lde, and the like. The amount of acid material employed
; should be such
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- 106Z44t7
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,; as to assure a pH of less than 5, and preferably less
~; than 4, in the waste product treated. If the pH rises
during treatment, more acid may be added. Examples of
efficient odor-removing oxidizing agents include soluble
persulfates, soluble chlorates, soluble nitrates, soluble
. :
pexmanganates and ferric chloride.
In order to transform such odor-producing chemicals
as hydrogen sulfide and organic sul~ur compounds into preci-
pitates, water soluble ixon salts are used, with ferrous
.;,
~ 10 sulfate and ferric chloride being the most efficient.
,
Each rPactant must be present to achieve the
~ xesults of the invention. For example, neither acidifica-
;,l tion alone, nor oxidation alone, nor sulfide precipitation
'~ alone will adequately remove odors. Successul results are
ii 15 obtained when all three reactants are employed together.
!;,.',i,l Complete analysis of odorous compounds derived
from organic wastes are not available in the literature.
~!` The type, as well as the amount of odor-forming compounds,
~`, . i8 dependent on the origin of the organic wastes and the
20 ~ conditions and time~of storage. The foregoing consider-
ably influence the formation of odorous degradation pro-
ducts.
Empirically, I have observed some chemical pro-
perties to be typical of certain types of organic wastes.
For example, proteinic wastes, containing relatively more
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~-`` 1062447
sulfur and nitrogen, develop more odorous compounds and
more amm~nia. This is particularly true of organic ~astes
produced by metabolic processes. These wastes contain
urea which soon becomes degraded by enzymes to form am-
monia, among other by-products~
The chemical demand for certain wastes for the
removal of odors is summarized, by way of example, as
follows.
... '
Human wastesare treated with about 50 to 100 mg -~
- ;~' . '-
oxygen~kg of waste (850-950 ml); and animal wastes with ~ -
about 190 to 205 mg oxygen/liter of waste. As regards
organic industrial wastes, average figures are not avail-
able as such wastes tend to vary in composition~ The
chemlcal demand for sewage normally ranges from about 8
to 10 mg oxygen/l, while sewage sludge (e.g. excess sludge)
I requires about 17 to 21 mg of oxygen/l (liter). ;
!~ With regard to the use of iron salts as preci- ~
,' ~ . ;?
pitation agents, for human wastes, about 112 to 180 mg
Fe/Xg (850-950 ml) of waste is normally required; for
animal wastes, about 150 to 200 mg Fe/l; for sewage, about
30 to~ 35 mg Fe~l; and ~or æewage sludges, about 12 to 30
.
I m~ Fe!1.
~1
~¦ The acid ùemand expressed in terms of sulfuric
acid comprises the following: human wastes, about 3.35 to
3.37 grams/Kg (850-950 ml) of waste; for animal wastes,
I~ about 7.9 to 13 grams/l; for sewage, about 0.23 to 0.30
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gram/l; and for sewage sludges, about 0.13 to
0O17 gram/l............ ',.
, The foregoing requirements are met by odor~
removing aqueous compositions containing the following
am~unts of reactants based on mg/gram of solution as '-
~ . ,
applied to certain wastes~
~. .
~: . - SOLUTION COMPOSIOIO~
Acid ~umber ,~ .
: Type of Waste mgO2/g mg KOH/g* mg Fe/g
. _ ~,.,~
Human Wastes 8.6-14 097 2-194.5 28-56 ,'
: ~- . ., I i~ .
~nlmal Wastes 56.0-68.0 57.0-69.0 50-60
Sewaqe 40 0-41.0: ~-45 0-46 0 60 :'';
~ ~___ . ~ '` ' .
~:~ Sewaqe Sludqes 28.0-35.0 45.0-237.0 50-70 ¦'~
~:~ * -- The acid is determined by the amount of
'15 KOH required to neutralize the acid in . ~'
' soIution, .
..
In certain cases, further acid may be added to ,'
:the~waste~product following treatment with ,the odor-
removinglcompositions. ~ ':
20~ ' Organic waste products containing phosphates, such
as in excess sludge from post-pxècipltation sewage treat- ,~ '
i .
ment systems, may be treated with solutions containing ~",,
' . sufficièntly~hi~h ferrous'or ferric compounds to effect ',~
removal of the phosphorous by precipitation as well as ~' ',.
~:25 removal of the odor.
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06Z~47
The ollowing are examples of waste-treating
solution compositions pxovided by the invention:
Example A
Water 568 1
H2SO4 120 kg
. . :~- .
Crystallized 250 kg (corresponds to 50.35 g
Ferrous Sulfate Fe/Kg or 68.9 g Fe/l
(Heptahydrate) solution)
Sodium Chlorate 62 kg
L0 The sulfuric acid~is added to water followed by the other ~
ingredients.~ The final solution has a density at 20C ~d20) ~ ;
- oi 1.370. The total weight of the solution i9 about 1000 kg,
the solution containing 12.0% H2SO4, 25.0% ferrous sulfate,
6~2~/o sodium chlorate and the balance about 56.8% water.
5~ Example B
; Water 345 1
400 Kg solu. 400 kg (corresponds to
containing 280 Kg 58.26 g Fe/Kg or
Ferric Chloride 77.68 g Fe/l
0~ Hexahydrate ~ solution)
i ; ;
Ammonium ~itrate 85 kg
H2S04 170 kg
The sul~uric acid is added last to the solution, the solu~ ~;
'~ tion having a density (d20) of 1.333. The total weight
. o the solution is about 1000 Kg and contains 28% ferric ~ -
chloride hexahydrate, 8.5% ammonium nitrate, 17% sulfuric
acid and the balançe essentially 46.5% water.
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_ mple C ,~s,
Water 570 1 .,
H2S04 40 kg '~;'
Crystalliæed 300 kg (60.A2 g Fe/kg or .
. Ferrous Sulfate 77.4 g Fe/l ,
(heptahydrate~ solution) ~,
;.. .
' Sodium Chlorate 90 kg '- ,
, .
The-sulfuric acid is added ~io the water followed succes- '
?.
sively by ferrous sulfate and sodium chlorate to produce
~,
a ~olution having a d~nsity (d20) of 1.282. ~The weight
i ~ of the solution is about 1000 Xg and contains 4% H2SO4, ' .
i;,; -
30~/O ferrous sulfate, 9~/O sodium chlorate and the balance '.~,,
~ about 57% water. ; `,
¦~ ' ' Example D
1~ 15 Water 498 1 .',
3' ~ . . ' ,;~:.
3; , H2So4 ~ 40 Xg
Crystallized 357 kg '.. , ~ ':
Ferrous~Sulfate . ',:;','
~ . (hepta,hydrate)
3~ 2~ Ammonium~c'hlorate 105 kg . '~
5 :~ ` ~ : . i i` . .
~ . The sulfuric acid is added to the water followed succes~
j sivel~ by ferr~5 sulfate and ammonium chlorate to produce ,~ '
a solution having a density (d20) of 1.351. The weight of ,,;'.,','
; , the solutiQn is ,about 1000 kg and contains ~% sulfuric ~',;~'; ' ';
~ 25 aci*, 35.7% crystallized ferrous sulfate, 10.5% ammonium ,, '`' ':
'I chlorate and the balance about 49.~/O water. ' .
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Exam
Water 335 1 ~
H2 S4 170 kg .;
400 kg solution .
containing 280 kg .. :of ferric
chloride
.hexahydrate400 Xg ;~ .
;
~ Sodium nitrate95 kg .;
- ! ,
10: The suluric:acid is added last to the solution which .~:
has a density (d20) of 1.335. The total weight of solu-
~- tion is about 1000 kg and contains 28% ferric chloride ~.
hexahydrate, 9.5% sodium nitrate, 17.0% H2S04 and the ~ ~ ;
balance about 45.5% water~ ` :
It is understood that re~erence to crystallized ,,?~ '
~ ferrous sulfate means the heptahydrate, while referencè ;~.
:~ . to ferric chloride means the hexahydrate.
As illustrative of the use of solutions of the
~ foregoing~type in removing odors from organic wastes, the ;.
.~20~ ~ ~ following examples are given: . .
. ~ Example 1 ~,.
1, . . . .
In the txeatment of pig wastes, 3 kg of an odor~
l~ remo~ing solution are added per cubic meter o~ waste, said
I ~ ~ solution having dissolved therein 25% by weight of crystal- :.~ -
~ lized ferrous su~fate, 15% sodium chlor~ate, 6% sulfuric .
acid and the balance essentially 54% water. To assure a
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1~;24g~'7
satisfactory pH in the final mix, a urther addition of
3 kg o~ sulfuric acid is made to the pig wastes The
odor from the pig wastes was immediately abated and, after
one day, was substantially eliminated~
The soluble reaction products comprised 246 mg
of sodium chloride and 4.5 kg of ammonium sulfate per cubic
meter.
.
Example 2
Pig wastes are treated with 3.5 kg of an odor-
10 removing solution per cubic meter of waste, the solution
containing by weight 30~/O crystallized ferrous sulfate,
12.3% sodium chlorate, 5.5% sulfuric acid, and the balance
. . ~, .....
essentially 52.2% water. The pH of the wastes is urther
,. j .
adjusted by the addition o~ 2.8 kg of sulfuric acid. The
results obtained are the same as for Example 1.
~he soluble reaction products included about x
239 mg/l o~ sodium chloride and about 3.9 kg of ammonium
- '. :'.. ::
sulfate per cubic meter.
:, . ~. .
Example 3
To 1000 kg of human wastes is added 2 kg of an
,~!
odor-removin~ solution according to Example B containing
28% ferric chloride hexahydrate, 8.5% ammonium nitrate,
17% sulfuric acid and the balance essential`ly 46.5% water.
The odor was immediately abated and was long lasting. A ;
faint odor of garden compost remained.
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1062~7 ` ~ ~
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Th~ soluble products ormed included about
138 mg N02/Kg (850-9S0 ml), about 458 mg/kg ammonium
sulfate, and about 856 mg/kg of ammonium chloride.
ExamPle 4
In the treatment of human wastes in a non-
l~ ~ flushed caravan toilet, about 10 grams of solution is
i ~ .
, proportioned per individual per day, the solution con-
taining by weight 14% ferric chloride, 4 3% ammonium
nitrate, 8.5% sulfuric acid andi the balance essentialIy ~'
73.2% water.
The soluble reaction products comprised
about 244 mg N02/Kg, about 800 mg ammonium sulfate/Kg
j~ ~ and about 1.5 gram ammonium chloride/Kg.
Example 5 '
lS Excess sludge from a pre-precipitation sewage ;
treatment is treated by adding 0.75~kg of solution per
cubic meter thereof according to the compcsition of
Example A containing about Z6.7/ of crystallized ferrous
~.
~ sulfate, abouit 6.6% sodium chlorate, about 12.7% H2S04
..
. .
~i 20 and the balance essentially 54/0 water. The repulsive odor
wàs immediately abated to a faint odor of mould. This `~
odor lasted to at least the dewatering and concentration
.. ~
steps. The Iatter steps were facilitated due to a marked
~ 12-
3'~
1~62~7
decrease ln sedimentation time and increase in the final
solids content. The foregoing operation was carried out
continuously for 6 weeks at a flow rate of 35 to 45 liters
of excess sludge per second. ~;
S The soluble reaction products included about
25 mg/l of sodium chloride and about 120 mg/l of ammonium
sulfate (87 mg/l 504). ~ ;
Example 6 ~
About 0.5 Kg of an odor-removing solution corres- L
ponding to Example C is added per cubic meter of excess ~-;
sludge from a pre-precipitation sewage treatment system, ;`
t~e iolution containing 30~fO dissolved crystallized ferrous ;
sulfate, 9% sodium chloriate, 4% sulfuric acid and essen-
~ tially 57% water. The results obtained are similar to ~ i
Example 5. In addition to the solution, the pH was adjus- ;```
ted to below S by adding 80 grams of sulfuric acid per
~5 . ::
cubic~meter of waste~.
The soluble reaction products include about
2~5 mg/1 of sodium chloride and about 126 mg/l o ammonium
sulfate (92 mg/l S04).
~ Example 7
Excess sludge from a post-precipitation sewage
treatment system is treated by~adding 0.5 Kg of odor-
I, removing solution per cubic meter of waste, the solution
- -13 ;"~
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comprising 35% of dissolved crystallized ferrous sul~ate,
7~6% sodium chlorate, 4% sulfuric acid and the balance
essentially 53.4% water. Following the addition of the
solution, the pH was further aajusted by the addition of
90 grams of sulfuric acid per cubic meter of waste~ The
results obtained corresponded to those obtained in `
Examples 5 and 6. ;
The soluble reaction products included about
21 mg/l of sodium chloride, and about 138 mg/l of ammonium
sulfate (101 mg/l SO4).
Example 8
Sewage previously treated mechanically to remove
coarse solids is subjected to the method of the invention
by adding 0.4 Kg of odor-removing solution per cubic meter
of said sewage. The solution contained by weight 30% dis-
.
solved crystallized ferrous sulfate, 9% sodium chlorate,
( . .. .
I~ 4% sulfuric acid and essentially 57% water. Following addi~
,;~, . .~ tion of the solution, the pH of the mixture was adjusted by
i a further addition of 195 grams per cubic meter of sulfuric
acid. The odor was immediately eliminated and spontaneous
flocculation and sedimentation occurred. About 90~/O of the
original phosphorus was removed.
The soluble reaction products included about
19.6 mg/l of sodium chloride and about 267 mg/l of ammonium
sulfate (194 mg/l SO4).
:' `,'
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~;Z447 ~ ~
As will be evident from the foregoing examples,
the composition of the odor-removing solution may vary
,,, . :.:
over a relatively broad range. Thus, the solution may .:. :- :
Ji . .
comprise by weight about 3% to 25% sulfuric acid, about
: . '
3~/O to 20~/o of an oxidizing agent from the group consisting ;.
of sodium chlorate and ammonium nitrate, about 10% to 40% ..
.-~
of an iron salt from the group including hydrates of fer- . :
rous sulfate and ferric chloride, and the balance at least , ~.
about 40% water. ~!,
~'' ': .
' ' :''.'.:.
~lthough the present invention has been des- ;
cribed in conjunction with pre~erred embodiments, it is
to be understood that modifications and variations may be ;:
resorted to without departing from the spirit and scope /: : .
of the invention as those skilled in the art will readily
understand~ Such modifications and variations are consi-
dered to be wlthin the purview and scope of the invention
~: and the appended claims. ,~ .
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