Note: Descriptions are shown in the official language in which they were submitted.
SUMMARY OF T~IE INVENTION
Waste waters, e.g., "red waters" from iron-ore mining
operations, must eventually be disposed of, and in times past
this was done by discharging the effluent into the nearest stream
or lake, with consequent pollution problems. However, statutes
in most communities now forbid discharge of untreated waste
waters into local streams and lakes. Treatment is generally
with flocculants of various kinds, the purpose being to remove
the red iron oxide particles, which visibly cause discoloration
after discharge into streams. Particularly efficient flocculants
for red water are the polymeric cationic flocculants. However,
such cationics are acutely toxic to fish, and even the rather
small amounts left in the waste water after settling offer
toxicity problems when the treated waters are discharged. Such
toxic after-effects are prevented by the use of this invention,
which provides that an anionic material be admixed into waters,
:.
e.g., waste waters, which have been treated with a polymeric
cationic flocculant and which are otherwise ready for discharge
into local fresh waters. As used herein, the term "anionic
material" means: A~ all anionic polymers; and B) isopropyl salt
of alkyl benzene ~ulfonic acid (alkyl being 10 to 13 carbons);
sodium lignosulfonate; and dioctyl sodium sulfosuccinate; includ-
ing mixtures of any of the foregoing.
In accordance with the present teachings, a method is
provided of rendering cationic-flocculant-treated red water
non-toxic to fish which comprises adding a water-soluble
anionic polymer thereto. The cationic flocculant is selected
from the group consisting of polydiallyldimethylammonium chloride
and a polyquaternaryamine with the cationic flocculant-txeated
red water prior to the addition of anionic polymer being an
effluent containing 0.1 to 1000 ppm of cationic flocculant
residue. The anionic polymer is added to provide an anionic
-2-
~ 33 ~ ~
polymer: flocculant weight ratio of 2.0 to 5:1.
The invention is operable with polymeric cationic
flocculants generally; which is to say, substantially all
waters wh.ich have been treated with polymeric cationic
flocculants of any type and which have residual toxicity
because of such treatment, may ~e further treated with
lQ
~ -2a-
an anionic material in accordance with this invention,
thereby either to remove such toxicity altogether, or to
reduce it to acceptable levels.
Among the polymeric cationic flocculants that leave
toxic residues treatable by the process of this invention
are the following:
Polydiallyldimethylammonium chloride, available
commercially from American Cyanamid Co.
as Magnifloc 589C or from Calgon Co. as M502-
Polyquaternary amines, molecular weight 50,000-
80,000 as made by the processes described in
U. S. 3 738 945. Available commercially
from American Cyanamid Co. as Magniflocs 573C
and 577C. These polyquaternaries have the formula
+ H
N - CH2- C ---CH2 ~ Xn
R OH
where Rl and R2 are methyl or ethyl, X is Cl, Br, or I, and
n is 3 to 10,000, preferably about 5 - 1,000, and can be made
by reacting dimethyl (or diethyl) amine with epichlorohydrin.
In general the invention uses any of the anionic polymers,
e.g.:
Sodium polyacrylate (mol. wt. about 1000 to
250,000, typically about 100,000).
Sodium polymethacrylate (mol. wt. about 1000
to 15,000, typically 4500).
It can also uqe non-polymeric materials, viz.,
Isopropylamine salt of alkyl benzene
sulfonic acid;
Sodium lignosulfonate;
Dioctyl sodium sulfosuccinate.
Effluents containin~ 0.1 to 1000 ppm of cationic
flocculant residue can be treated in accordance with this
invention. The treatment uses about 0.2 to 5 parts of
anionic material per part of residual cationic flocculant,
and more preferably about 0.7 to 2 parts of anionic material
.
per part of flocculant.
The following examples illustrate without limiting the
invention.
Example 1
Red water which had been treated with polydiallyl-
dimethylammonium chloride flocculant gave a clear effluent
which, however, still contained 6 ppm flocculant. The
effluent was found to be toxic to fish. ~he toxicity tests
were carried out using 10 rainbow trout fingerlings in the
effluent. In both runs all 10 fish were killed within 100
hours. Seven ppm of sodium polyacrylate (mol. wt., about
`~ 100,000) was added to the toxic effluent, and this liquid
was tested for toxicity against 10 rainbow trout fingerlings.
All received two replicates of the test (96 hours)- All fis~
were alive at the end of the tests.
This example was like that of Example 1 ~xcept that the
flocculant was a cationic polyamine (prepared in accordance
with U. S. Patent 3 738 945). The effluent contained six ppm
of flocculant and killed all 10 fish in 4 hours. Application
of an anionic detoxicant, sodium polyacrylate, at 27 ppm
~ 3~ 2 ~
eliminated the toxicity of the cationic polyamine. With
regard to the polyamine, 3 ppm were high molecular weight
(abou~ 50,000), and 3 PPM were low molecular weight (about
4,500).
Bioassay Methods
The bioassays consisted of simple pass-fail procedures
in which rainbow trout fingerlings were exposed to full-strength
te~t solutions for 96 hours. The test indicates whether
acute toxicity is present or absent in the sample. Controlled
test parameters and monitoring procedures for bioassays were
ba~ed on the Federal Government Guidelines for Measurement
of Acute Toxicity in the Mining Industry and methods described
by A.S.T.M. 1971. In brief, certified "disease-free"
rainbow trout fingerlin~s were used. Tests were conducted
in duplicate, where possible, and fish tank stocking ratios
averaged 2.2 liters per gram of fish. Dissolved oxygen
levels were maintained above 8 mg/l and pH values ranged
between 6.6 and 8.7. Mortality in the test tanks was recorded
after 1/4, 1/2, 1, 2, 4, 8, 24, 48, 72 and 96 hours of
exposure. Similarly pH, dissolved oxygen and temperature
were monitored at 0, 4, 8, 24, 48, 72 and 96 hours.
Example 3
A series of experiments were made to determine the
; effect of the invention on certain commonly encountered
bacteria.
A culture isolated from a sludge sample from a cooling
water system was used as a test medium. Cultures were
prepared by spreading an lnnoculum of the organism over an
agar plate, followed by incubation overnight at 37 C. This
yielded a lawn of bacteria which was washed from the plate
into 20 ml. of sterilized deionized water.
-- 5 --
Test Procedures
100 ml. of 50 ppm of polyquaternary amine
(Magnifloc 573C, above) was added to a sterile plastic
bag, and to this was added a known concentration of material
to be tested as detoxicant. To this mixture was added 1 ml.
of stock bacterial solution and the bag was shaken and incubated
for one hour at room temperature. Then the living biomass was
measured by performing an ATP (adenosine triphosphat~J assay.
It had been shown in previous experiments that the viable
bacterial population was significantly reduced after this
treatment with 50 ppm of polyquaternary amine alone, and this
was confirmed in the first experiment of this series. Several
experiments were carried out in this work and a neutralization
index (NI~ ~as calculated according to:
ATP in treated sample
NI = X 100
ATP in control
Thus a neutralization index of 100 means compl~te removal of
the toxic effect of the polyquaternary amine. The experimental
results are given in Tables 1 - 5. (There was a slight variation
in procedure for generating the results in Table 3, in that
the sample was stored at 4~C. for three days before the ATP
assay was performed--this had been shown by earlier work to be
a valid procedure).
In the Tables the following code is used.
I = Polyquaternary amine (e.g., Magnifloc 573C.)
II = Sodium polymethacrylate~ M.W. 4500
III = Isopropylamine salt of alkylbenzene sulfonic acid
IV = Dioctyl sodium sulfosuccinate
V = Sodium lignosulfonate
_ ~ _
TABLE 1
ATP ng~ ml
Tr~atment (after 1 hr.) NI
50 ppm I + 300 ppm II 66 93
50 ppm I + 75 ppm III 26 37
50 ppm I + 75 ppm IV 4.1 5.8
50 ppm I + 170 ppm V 3.5 4.9
50 ppm I 0.23 0.3
No Treatment (Control) 71
1/
Nanograms
TABLE 2
Treatment ATP ng/ml NI
(after 1 hr.)
50 ppm I + 100 ppm II 46 90
50 ppm I + 200 ppm II S0 98
50 ppm I + 300 ppm II 48 94
50 ppm I + 400 ppm II 46 90
50 ppm I + 500 ppm II 46 90
50 ppm I + 200 ppm III 43 84
No Treatment (Control) 51
TABLE 3
r
Treatment ~ NI
(after 1 hr.)
50 ppm I + 10 ppm II 0.59 1O8
50 ppm I + 50 ppm II 0.29 0.9
50 ppm I + 75 ppm II 23 72
50 ppm I + 300 ppm III 37 116
50 ppm I + 250 ppm V 20 63
No Treatment (Control) 32
3~
~? ~3~24
TABLE 4
ATP ng/ml NI
Treatment (after 1 hr.)
50 ppm I -~ 250 ppm IV 36 71
50 ppm I ~ 500 ppm V 72 141
No Treatment (Control) 51
TABI.E_5
~ NI
Treatment (after 1 hr.)
(i) 100 ppm I -~ 50 ppm II 0.52 1.0
(ii) 100 ppm I ~ 100 ppm II 0.68 1.3
10(iii) 100 ppm I + 200 ppm II 37 74
(iv) 100 ppm I -~ 300 ppm II 45 90
(v) 100 ppm I + 400 ppm II 36 72
(vi) 200 ppm I -~ 100 ppm II ~0.2 ~0.4
(vii) 200 ppm I + 200 ppm II C0.2 C0.4
(viii) 200 ppm I + 300 ppm II 6.6 13
(ix) 200 ppm I + 400 ppm II 52 100
(x) 200 ppm I + 500 ppm II 57 110
(xi) No Treatment (Control) 50
These results show that 50 ppm of I can be effectively
detoxified using 100 ppm or more of II, 200 - 300 ppm of
III, and S00 ppm of V. Table 6 shows tha~ an increased
level of I requires a proportionately higher dose of II.
