CA1116324A

CA1116324A - Detoxification of cationic flocculants

Info

Publication number: CA1116324A
Application number: CA000313928A
Authority: CA
Inventors: Stewart N. Paul; John E. Waller; James E. Cairns
Original assignee: Individual
Current assignee: Veolia WTS USA Inc
Priority date: 1978-10-23
Filing date: 1978-10-23
Publication date: 1982-01-12
Also published as: GB2032905A; JPS55104691A; ES8100226A1; IT1125552B; FR2439748A1; GB2032905B; ES485286A0; DE2942111A1; FR2439748B1; SE7908732L; IT7926697A0

Abstract

Reference 5322 DETOXIFICATION OF CATIONIC FLOCCULANTS
Abstract of the Disclosure Waters, e.g., waste waters which have been treated with polymeric cationic flocculants for settling and clarification generally contain residual amounts of such flocculants which are toxic, e.g., to fish. This toxicity can be removed by treatment with anionic materials, e.g., polymers.

Description

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.

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 _ ~ _ 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 Nanograms 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 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 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.

Claims

WE CLAIM:

l. The method of rendering cationic-flocculant-treated red water non-toxic to fish that comprises adding a water-soluble anionic polymer thereto, said cationic flocculant being selected from the group consisting of polydiallyldimethyl-ammonium chloride and a polyquaternaryamine; said cationic-flocculant-treated red water prior to addition of anionic polymer being an effluent containing 0.1 to 1000 ppm of cationic flocculant residue; the anionic polymer being added to provide an anionic polymer; flocculant weight ratio of 0.2 to 5:1.
2. Method according to Claim 1 in which the anionic polymer flocculant weight ratio is about 0.7 to 2:1.
3. Method according to Claim 1 in which the anionic polymer is a member of the group consisting of sodium polyacrylate, molecular weight about 1000-250,0000, and sodium polymethacrylate, molecular weight about 1000-15,000.
4. Method according to Claim 3 in which the flocculant is polydiallyldimethylammonium chloride and the anionic polymer is sodium polymethacrylate.
5. Method according to Claim 3 in which the flocculant is a polyquaternaryamine and the anionic polymer is sodium polymethacrylate.