Purification of a Waste Brine by Carbon
Adsorption with Emphasis on
Wastewater Reuse
ROBERT D. FOX, Project Supervisor
R. T. KELLER, Group Leader
C. J. PINAMOUNT, Group Leader
J. L. SEVERSON, Group Leader
Environmental Research Laboratory
The Dow Chemical Company
Midland, Michigan
INTRODUCTION
Brine wastes contaminated with organic materials are one of the major disposal
problems in the chemical industry. Brines are a particular concern because the
standard biological treatment plants have no effect on the salt level and usually the
high salt level upsets the bacterial organisms and hinders biological oxidation.
At present, brines are disposed of in three ways. They are discharged into
seawater, if conveneint, or diluted and discharged into fresh water streams, or
injected into disposal wells. Discharge into fresh or seawater is coming into increasing
scrutiny by pollution control organizations, resulting in more stringent requirements
for the brine discharge. Disposal wells are a third way to handle briney wastes
especially for inland plants, but at the same time they are expensive and require
suitable geology. In addition, The Dow Chemical Company feels that subsurface
disposal of organically contaminated brines is not a satisfactory long-term solution to
the waste disposal problems of the chemical industry.
Chlorine and caustic plants all over the United States use salt brine as a raw
material source. Thus, it seems logical and feasible to use waste brines as raw material
sources after suitable removal of contaminants.
As a beginning of an attack on contaminated brine reuse, our Environmental
Research Laboratory working on waste treatment research for the Midland Division
decided to use as an example of an organically contaminated brine, a waste brine
from the phenol plant. The phenol plant is one of Dow's largest producers of waste
brine and this brine is about the same strength as the raw production brine used in
the chlorine-caustic cells. It is thus an obvious candidate for recycle to chlorine-
caustic production.
This brine is 18 per cent sodium chloride, contains 150-200 mg/1 phenol, 2000
mg/1 sodium acetate, has a pH of seven and is at a temperature of 105 C after steam
stripping has removed benzene and acetone. Phenol and other compounds similar to
it, e.g., phenoxy herbicides and chlorophenols, represent organic wastes with serious
disposal problems. Sodium acetate typifies an organic waste which normally presents
few disposal problems, but in a strong brine this highly water-soluble chemical is very
difficult to remove.
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