GB2027003A

GB2027003A - Detoxification of residual quaternary ammonium salts in waste water

Info

Publication number: GB2027003A
Application number: GB7922358A
Authority: GB
Original assignee: Chemed Corp
Current assignee: Chemed Corp
Priority date: 1978-08-01
Filing date: 1979-06-27
Publication date: 1980-02-13
Also published as: JPS5610390A; CA1116764A; GB2027003B

Abstract

Biocidally active amounts of quaternary ammonium salts present in waste water from industrial plant which inhibit growth of biomass and are therefore undesirable, are detoxified by adding to the waste water an anionic surfactant or soap, especially sodium dioctyl sulphosuccinate.

Description

SPECIFICATION Detoxification of residual quaternary ammonium salts in waste water Several quaternaries (quaternary ammonium salts) are being used at the present time as biocides for the control of microbiological growth in aqueous systems used in industry. The residual quaternaries when discharged into waste streams will interfere in biological treatment processes thereof by inhibiting the growth of biomass. An object of this invention is to detoxify the residual quaternaries present in aqueous solutions before they are discharged into waste streams.

We have discovered that the toxic effect of the residual, biocidally active amounts of a quaternary ammonium salt present in waste water from industrial plant can be removed by adding to the water containing the quaternary ammonium salt an anionic surfactant or a soap. The treated quaternary is found to be non-toxic to bacterial culture; thus it will not interfere in, e.g. activated sludge systems. The anionic surfactant or soap neutralises the activity of the quaternaries by forming stable complexes with active sites of the quaternaries to render them inactive towards aquatic life. Usually at least a stoichiometric proportion of the anionic "detoxicant" will be required for this purpose.

We have obtained particularly good results when using sodium dioctyl sulphosuccinate as a "detoxicant" for an n-alkyl dimethyl benzyl ammonium chloride (Q salt) which is used as a biocide:

wherein R represents a long chain "fatty" hydrocarbyl group. The hydrocarbon group is of the kind derived from a fatty acid. Normally, therefore, R will be a saturated or unsaturated aliphatic hydrocarbyl group having from 12 to 18 carbon atoms. Thus "R" groups include octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, octadecenyl and octadecadienyl. The term "Q salt" covers mixtures of two or more different compounds of the above formula, i.e. compounds having different R groups, usually different alkyl groups within the range C,2H17 to C lBH3,.

The following are examples of other quaternaries whose residues can be detoxified by the me#thod of this invention: N-cetyl-N,N,N-trimethyl ammonium bromide N-cetylpyridinium chloride N,N-dioctyl N,N-dimethyl ammonium chloride N-alkyl N,N-dimethyl N-(dichloro)benzyl ammonium chloride N-alkyl N,N-dimethyl N-ethylbenzyl ammonium chloride N-cetyl N-ethyl morpholiniu m ethosu fate 2-(N-decyl-N,N-dimethylamino)acetate 2-( N-coco-N,N-dimethyla mino)acetate 2-(N-stearyl-N,N-dimethylamino)acetate The following are examples of other anionic compounds, considered for the purposes 6f this invention to be surfactants or soaps, which are useful detoxicants in the method of the invention.

Sodium stearate, sodium laurate, sodium palmitate, sodium oleate, sodium linoleate, sodium dodecyl sulphate, N-dodecylglycine (Ca2H25NCH2COOH) and N-dodecyl N-2-aminoethylglycine

By way of example, 0.3 to 600 ppm of anionic detoxicant can be added to water containing e.g.

0.2 to 500 ppm of quaternary, and a stoichiometric (and usually also a gravimetric) excess of anionic detoxicant over quaternary is preferred.

It has been a practice to add to closed water systems polymeric anionic compounds, such as sodium polyacrylate, but these are not used in the present invention as a detoxicant. The anionic compounds ordinarily understood as surfactants and soaps are monomers.

The following Examples, in which all parts and percentages are by weight, illustrate the invention.

EXAMPLE 1 Experiments were conducted in an 18 litre glass tank containing a synthetic cooling water having 135 ppm CaCI2, 341 ppm NaCI, 185 ppm NaHCO3, 519 ppm MgSO47H2O and 444 ppm CaSO4 . 2H20.

The Q salt to be tested was weighed and added to the tank so that it could be mixed thoroughly as the solution was brought up to the final temperature. Mixing and heating were accomplished with a combination circulating pump and high quality thermostat which maintained the bath at a constant temperature of 1000F (380C).

Results were monitored by the use of a colorimetric method in which the quaternary was complexed with Bromophenol Blue and extracted with ethylene chloride and the absorption at 610 mlu read using a Beckman DK-2 Spectrophotometer.

After approximately 30 minutes, the first sample from the tank was extracted, and "SDS", i.e.

sodium dioctyl sulphosuccinate, was added as detoxicant. The time noted for extraction began with t=o, the time of addition of the "detoxicant". Extractions were made hourly. The results are given in Tables 1 and 2. Table 1 indicates that the detoxicant SDS is very effective for removing the Q salt in an aqueous system within an hour. Table 2 shows the stability of Q salt over a period of time in aqueous solution.

To check the non-toxic behaviour of the treated water, a few experiments were conducted with Q salt and a combination of Q salt and SDS against a mixed bacterial culture. The mixed bacterial culture consisted of A. Aerogenes, B. Mycoides, E. Coli a nd Pseudomonas aeruginosa. Results are given in Table 3. Results after an incubation period of 24 hours showed Q salt inhibited the growth of bacteria at 25 ppm at pH 7 and 8.5. In the presence of SDS, the anti-bacterial effect of the Q salt was destroyed.

TABLE 1 Inactivation of Q salt with Sodium dioctyl sulphosuccinate (SDS) Conditions: 25 ppm Active Q Salt are used for each-test The temperature is maintained at 100 F (38 C).

% % Removal of Q Salt Time in Hours from adding SDS Conc. of SDS, ppm pH 1 2 -# 3 4 5 15 6.7 60 60 60 60 60 30 6.7 100 100 100 100 60 6.7 100 100 100 -- TABLE 2 Stability of Q Salt in Aqueous Solution at 100 F (38 C) Conditions: The initial sample in each test contained 25 ppm of active Q salt in water at pH 6.7.

Concentration of Q Salt found (ppm) Time in Hours 1 | 4 8 24 30 25 25 1 25 25 25 TABLE 3 Evaluation of SDS and Q-salt against mixed bacterial culture Compound - pH - Concentration in ppm Growth o Salt 7.5 3 6 - 13 19 - 25 - QSalt - 8.5 3-25 SDS 7.5 2-40 + SDS 8.5 2-40 + OSaIt & DS 7.5 3+4 + 6 + 8.5 + 13 + 17.0 + 19 + 27.0 + 25 + 34.5 + O Scant Growth - No Growth + Growth

Claims

1. A method of treating waste water from industrial plant, the water containing residual, biocidally active amounts of a quaternary ammonium salt, which method comprises adding to the water before it is discharged from the industrial plant a detoxifying amount of an anionic surfactant or soap.

2. A method according to claim 1 wherein the anionic surfactant or soap is added in at least a stoichiometric proportion relative to the quaternary ammonium salt.

3. A method according to claim 1 or 2 in which 0.2 to 500 ppm by weight of the quaternary ammonium salt is present in the waste water.

4. A method according to any preceding claim in which sufficient anionic surfactant or soap is added to provide 0.3 to 600 ppm by weight thereof in the waste water.

5. A method according to any preceding claim in which the waste water contains a quaternary ammonium salt of the formula

wherein R represents a long chain fatty hydrocarbyl group or a mixture of such quaternary ammonium salts.

6. A method according to claim 5 in which in the formula of the quaternary ammonium salt(s) R represents an n-alkyl group having from 12 to 1 8 carbon atoms.

7. A method according to any preceding claim in which the anionic surfactant or soap is sodium dioctyl sulphosuccinate.