Polymers containing vinylamine/vinylformamide as demulsifiers in oily wastewaters

The invention provides a method of removing emulsified oil from an industrial wastewater stream. According to the method, a vinylamine polymer is added to the oil containing wastewater in a concentration of from about 0.1 to about 100 parts per million based on the total volume of the water being treated. The vinylamine polymer includes from about 1 to about 100 mole percent vinylamine and from about 1 to about 99 mole percent of at least 1 monomer selected from the group consisting of amidine, vinylformamide, vinyl alcohol, vinyl acetate, vinyl pyrrolidinone and the esters, amides, nitriles and salts of acrylic acid and methacrylic acid. The addition of the polymer to the oil containing wastewater causes the emulsified oil to flocculate. The flocculated oil is then removed from the wastewater.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention is directed to compositions and methods for removing oil from 
industrial wastewaters; and more particularly, the invention is directed 
to a method of removing oil from oily waters produced in industry using 
vinylamine containing polymers. 
2. Description of the Prior Art 
In industry, oily wastewaters are produced in various processes located in 
the steel and aluminum industries, chemical processing industry (CPI), 
automotive industry, laundry industry and refinery industry. In these 
industries, highly refined oils, lubricants and greases contact water. 
This results in a highly dispersed or severe oil-in-water emulsion in the 
wastewater streams. 
Wastewater from steel and aluminum mills using hot rolling mills contain 
lubricating and hydraulic pressure hydrocarbons. Wastewater from cold 
rolling mills contain oil that lubricates the sheets and reduce rust. For 
example, in cold rolling mills, oil-in-water emulsions are sprayed on the 
metal during rolling to act as coolants. 
Metalworking plants generate wastewater streams containing lubricating and 
cutting oils, lapping and deburring compounds, grinding and other 
specialty fluids. These oils are generally highly refined hydrocarbons. 
The wastewater streams in animal rendering plants, creameries, bakeries, 
breweries and canneries contain natural fats and oils from animal 
processing and oils from packing and container manufacture. Wastewaters 
from cotton and wool manufacturing plants contain oils and greases from 
the scouring, desizing and finishing operations. Finishing oils are used 
in cotton and wool manufacturing to reduce friction and snagging of fibers 
on spinning machines which use machine lubricating oils, these oils end up 
in the wastewater. Processes in other industries also generate oily 
wastewater such as: paints, surface coatings, and adhesives; oils, fats, 
and waxes; soaps and detergents; dyes and inks; and the leather industry. 
The emulsified oil in the wastewater is typically present in the range of 
several hundred to tens of thousands of ppm. It is critical to remove this 
oil from an environmental standpoint. The United States Environmental 
Protection Agency has placed tight restrictions on total oil and grease 
(TOG) limits for water that is to be discharged into public drinking water 
supplies or into open bodies of water. The removal of this oil is very 
critical to the established discharge limits for total dissolved solids 
(TSS), carbon oxygen demand (COD), biological oxygen demand (BOD) and 
total organic carbon (TOC) into local sewers and rivers. Not only has the 
EPA established severe limits on the oil and grease discharge, these 
industries are affected by local city ordinances as well. 
One of the most effective methods of removing the emulsified oil in 
wastewater is through the use of the chemical aids. Typically these 
dispersions or emulsions require 10 to 100 times the dosage needed for 
other emulsion breaking applications, such as removing crude oil from 
water. 
Historically, dry polymers, solution polymers, inverse emulsion latexes and 
metal ions have been used to treat the produced water. Each material has 
its own advantages and disadvantages. While dry polymers have the benefit 
of being extremely concentrated, thereby reducing shipping costs, the 
equipment to dissolve the polymers is expensive and is not available to 
all end-users on site. 
Latex polymers also suffer from problems but are used quite frequently. 
Latex polymer preparations include 30-35% solids dispersed in oil. The 
latex polymer must be also inverted prior to use. Numerous problems 
associated with this feeding method have caused many customers to avoid 
latex polymers. In addition, the latexes generally have a very narrow 
treating range, often resulting in over-treatment at higher dosages. 
Furthermore, latex polymers add even more oil to the stream to be treated. 
Of course, adding more oil is something most customers would not want to 
do when treating their wastewater streams. 
Although solution polymers require no prior make up, the percent solids and 
molecular weight are severely limited due to the nature of the material. 
These materials are often used to break oil-in-water emulsions, but they 
are unable to flocculate the dispersed oil, thus requiring another 
chemical to accomplish this. 
Metal ions, such as, Fe.sup.3+, Zn.sup.2+, Al.sup.3+, etc., have long been 
used to break oil-in-water emulsions, but recent government regulations 
have restricted their levels in discharged streams. Although effective at 
breaking oil-in-water emulsions, they, too, require another chemical to 
flocculate the oil. 
The vinylamine polymers of the invention offer many solutions to these 
problems and represent a new method to industrial wastewaters. 
SUMMARY OF THE INVENTION 
A method of removing emulsified oil from industrial waste water stream, the 
method comprising the step of adding to oil containing water from about 
0.1 to about 100 parts per million of the polymer based on the total 
volume of the water being treated, the polymer including from about 1 to 
about 100 mole percent vinylamine and from about 1 to about 99 mole 
percent of at least 1 monomer selected from the group consisting of 
amidine, vinylformamide, vinyl acetate, vinyl alcohol, vinyl acetate, and 
vinyl pyrrolidinone, wherein the addition of the polymer to the oil 
containing water causes the emulsified oil to flocculate; and removing the 
flocculated oil from the oil containing water. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The invention provides a superior method for removing emulsified oil from 
industrial wastewater. Vinylamine containing polymers have been discovered 
to be more effective in removing emulsified oil from industrial 
wastewaters than currently available chemical treatments. As will be 
discussed in more detail below, polymers of the invention offer numerous 
advantages which have previously been unavailable to operators of 
industrial processes. The polymers are water-soluble and, unlike latex 
polymers, there is no oil solvent. This is important since: the polymers 
do not present a fire hazard; oil is not added to the water which is to be 
treated (more environmentally friendly); dissolution of the polymer 
requires only the addition of water--no special activators are needed; the 
ability for these materials to dissolve/invert is superior to that of oil 
dispersion latexes; and the polymers may be diluted to virtually any 
concentration by using water. This physical property enables any standard 
chemical pump to deliver the material at the injection site. 
The invention provides a vinylamine polymer demulsifying composition and a 
method of using the same. The invention provides improved oil removal from 
industrial water containing emulsified oil. The invention uses a 
vinylamine copolymer or homopolymer to accomplish this goal. According to 
the invention, the polymer is a homopolymer, copolymer or terpolymer which 
contains from about 1 to about 100 mole percent vinylamine monomer and/or 
a monomer hydrolyzable to vinylamine, and/or from 1-99 mole percent of 
amidine, vinylformamide, vinyl alcohol, vinyl acetate, vinyl pyrrolidinone 
or the esters, amides, nitriles and salts of acrylic acid and methacrylic 
acid. 
For purposes of this invention, vinylamine monomers includes vinylamine and 
those monomers which are hydrolyzable to the following formula: 
##STR1## 
wherein: R and R' are, preferably, one substituent group selected from the 
group consisting of hydrogen and an alkyl group having from 1-10 carbon 
atoms. More preferably, R is hydrogen or is an alkyl group having 1-4 
carbons. 
The vinylformamide monomer of the invention is non-hydrolyzed and has the 
following structure: 
##STR2## 
wherein: R and R' are, preferably, one substituent group selected from the 
group consisting of hydrogen and an alkyl group having from 1-10 carbon 
atoms. More preferably, R is hydrogen or is an alkyl group having 1-4 
carbons. 
For purposes of the invention, acrylic acid monomer includes acrylic acid 
and those monomers hydrolyzable to the following formula: 
##STR3## 
The amidine moiety, derived from the amine hydrolysis of polyvinyl 
formamide has the following structure: 
##STR4## 
One preferred method of producing the vinylamine/vinyl alcohol containing 
polymers of the invention is to polymerize vinylformamide and vinyl 
acetate. Thereafter, the copolymer is hydrolyzed to a vinylamine/vinyl 
alcohol copolymer. 
According to one embodiment of the invention, the demulsifying composition 
of the invention includes a vinylamine/vinyl alcohol copolymer. 
Preferably, the copolymer will include from about 1 to about 99 mole % 
vinylamine and about 1 to about 99 mole % vinyl alcohol. More preferably, 
the copolymer will include from about 2 to about 50 mole % vinyl alcohol 
and from about 98 to about 50 mole % vinylamine. Most preferably, the 
vinyl alcohol is included in the copolymer in an amount of from about 10 
to about 20 mole % and the vinylamine is included in an amount of from 
about 90 to about 80 mole %. 
According to a further embodiment of the invention, the demulsifying 
composition includes a vinylamine/vinylformamide copolymer. Preferably, 
the copolymer includes from about 1 to about 97 mole % vinylamine and from 
about 1 to about 97 mole % vinylformamide. More preferably, the copolymer 
includes from about 10 to about 50 mole % vinylamine and from about 10 to 
about 50 mole % vinylformamide. Most preferably, the copolymer includes 
from about 10 to about 20 mole % vinylamine and from about 10 to about 20 
mole % vinylformamide. 
According to a further embodiment of the invention the demulsifying 
composition includes a vinylamine/vinylformamide/amidine terpolymer 
(A/B/C) in monomer ranges of: A 15-90%; B 5-60%; and C 5-60%. Most 
preferably the monomer range is about 65/5/30, respectfully. 
The demulsifying compositions of the present invention are applied to the 
oily wastewaters as a dilute aqueous solution. Preferably, the aqueous 
solution is applied to the oily wastewaters in a dosage of from about. 
0.100 to about 100.0 parts per million (ppm) of the polymers of the 
invention based on the total volume of the water. More preferably, the 
polymers of the invention are added to the oily wastewater in a dosage of 
from about 1.0 to about 50 parts per million. Most preferably, the 
polymers of the invention are added to the wastewater in a dosage of from 
about 2.0 to about 20.0 parts per million. It should be noted, however, 
that there does not appear to be a maximum dosage at which the polymers 
adversely affect the system. It does appear that at some higher doses the 
beneficial affect plateaus, and on a cost basis such higher doses, 
probably above about 100 ppm, are not cost effective. 
Processes for making the polymers of the invention are well known in the 
art. U.S. Pat. Nos. 5,126,395, 5,037,927, 4,952,656, 4,921,621, 4,880,497 
and 4,441,602 all describe methods for preparing the polymers of the 
invention. Solution polymerization produces the desired molecular weight 
dosage. The resulting vinylformamide homopolymers are susceptible to 
alkaline or acid hydrolysis which converts some or all of the amide groups 
to amine groups. These U.S. patents all describe methods for preparing the 
polymers of the invention. Hydrolysis of the amide groups to yield the 
amine can be achieved by using acid or base. By controlling the 
stoichiometry of the hydrolyzing agent it is possible to produce 
vinylamine/vinylformamide copolymers of varying composition. If 
vinylformamide is polymerized with other ethylenically unsaturated 
monomers, then hydrolyzed, it is conceivable that the polymer produced 
will contain at least three and possibly more functional groups. Cyclic 
amidine is produced by the amine hydrolysis of polyvinylformamide. 
Once the polymers of the invention are added to the wastewater stream, the 
treated water is naturally agitated as it moves through the process system 
of an industrial plant. The polymers of the invention will cause the 
emulsified oil to separate from the water and float to the surface of the 
water as a floc. The floc is subsequently removed from the surface of the 
water and handled further. The treated water can now be discharged either 
into a river, lake or recycled into an industrial process.