Of TEXOX Process
Are Spent Caustics?
Are Spent Caustics Generated?
Of Spent Caustics
Characteristics Of Spent Caustics
Alternatives For Spent Caustics
Tragedy In The Ivory Coast - What Not To Do
The TEXOXTM Processes
technologies developed by Texas Technology over the past two
decades. The founder of Texas Technology has received several US
Worldwide patents for treating spent caustics and the chemicals used to
oxidize these troublesome waste streams, effectively and economically.
handling and disposal of spent caustics is a paramount problem to the refining,
petrochemical, and LPG industries. Spent caustics produce noxious
odors, toxicity, and high loading effects when attempting disposal in typical
wastewater treatment plants without pretreatment. Spent caustics
contain sulfides, mercaptans, disulfides, phenolics, cresylics, and naphthenic
compounds in endless combinations in sodium or potassium hydroxide "spent
caustic" solutions. All of which are hazardous materials and often
classified as hazardous wastes. All types of spent caustics are amenable
to treatment using the TEXOX
Processes were developed especially for the effective treatment and environmentally
friendly disposal of these troublesome wastewaters. Furthermore,
the family of TEXOX Processes can also transform a wide variety of other toxic and hazardous wastes
into biodegradable products.
Scope Of Process:
The TEXOX Processes
utilize chemical oxidation technologies operating at low pressures and
moderate temperatures extending equipment life for many years.
Compared to "Wet Air Oxidation" (WAO) technologies, extremely high
pressures and temperatures have high O&M costs and short equipment
life expectations. To meet environmentally green practices,
the products of the oxidation must be compatible with the natural
environment in the receiving watershed. To meet this challenge,
it is preferred to use hydrogen peroxide, ozone, oxygen, or potassium
permanganate as the primary oxidant. In some instances, natural
catalysts are used to enhance the performance and economics of the
reactions. However, the TEXOX Processes can easily adapt to
virtually any other oxidizer, if preferred by the customer.
These oxidizers and
catalysts breakdown into water, oxygen, and naturally occurring
compounds found throughout our planet. No adverse effects result
from these environmentally perfect reactants.
Using either of these
oxidizer pathways, with or without catalyst, at controlled pH,
temperature, and pressure ultimately results in an economical and
competitive process compared to any other technology offered
today. Furthermore, the TEXOX family of processes have shown to
be cost competitive with the costs of the least expensive disposal
practices, off-site Deepwell disposal. After all, what could be
cheaper than disposing of spent caustics down a hole in the ground with
Deepwell technology? There, the spent caustics will remain
unabated until poisoning our biosphere and potable water ground water
supplies for millennium.
caustics exhibit similar characteristics, however, each is unique and requires
process development to determine the most cost effective TEXOX program.
Typical concentration ranges of the major substrates are
depicted in the following Figure showing the various categories
including Sulfidic, Disulfide, Mercaptanic, Cresylic, Phenolic, and
lastly Naphthenic spent caustics:
USEPA and local environmental regulations promulgated in the reauthorization
of the Solid Waste Disposal Act of 1984 is a strong driving force to implement
alternative processing and disposal methods. The TEXOX Process
utilizes commercialized chemical oxidation pathways to effectively destroy
noxious odors, toxicity, and reduce the loading impact in downstream processes.
Downstream processes most often benefited include sensitive biological
wastewater treatment plants prone to odor emissions and upsets.
following Figure shows typical results from a TEXOX Process
comparing increasing oxidizer dosage with
standard wastewater treatment parameters used to determine oxidation
performance. The plot
evaluated BOD (Biochemical Oxygen Demand), COD (Chemical Oxygen
Demand), and TOC (Total Organic Carbon) against oxidizer dosage to pre-determine
the impact in a typical downstream wastewater treatment plant for final disposal. Notice the
intermediate increase in BOD where toxic phenolic compounds were
into biological food while the COD and TOC continued to decrease.
The principal goals were to eliminate both the odors and the toxicity
impact in the downstream biological wastewater treatment plant. A secondary goal was also to significantly reduce the
carbon loading to the final treatment plant.
Process Destroys Many Hazardous Compounds:
order of destruction of selected substrates is depicted in the following
Figure with respect to increasing oxidizer dosages. For example,
inorganic sulfides (i.e. hydrogen sulfide) are the easiest and fastest
reacting compounds compared to un-substituted phenol (carbolic acid), however,
substituted phenols (i.e. cresols) react easier. The concentrations
were determined during treatability studies using typical spent caustics
and further supported during field applications.
destruction of toxic and inhibitory compounds commonly found in spent caustics
is imperative to the health and overall performance during final treatment
in the receiving wastewater treatment plant (WWTP). Toxicity effects
are quantified using biological respirometry to measure the rate of oxygen
uptake in the mixed liquor. The oxygen uptake rate of the mixed liquor
is proportional to the rate at which the chemical compounds are digested
and also determine the retention time necessary for complete destruction.
easily digested (e.g. carboxylic acids) stimulate the microorganisms and
consume oxygen at a high rate; whereas, toxic compounds (e.g. phenolics)
inhibit or kill the microorganisms resulting in a low rate. When
the oxygen uptake rate is decreased, the time for effective biological
assimilation may exceed the hydraulic retention time in the WWTP and result
in a poor discharge quality and breakthrough. If the uptake rate
falls to zero, the microorganisms are dead and a reseeding program is necessary
to rebuild the population.
demonstrate the effectiveness of the TEXOX Process for toxicity abatement, samples of both the raw spent caustic and
the TEXOX Process effluent were placed into separate biological respirometers
(e.g. Warburg Apparatus) containing the same biological mixed liquor seed.
To determine the specific toxicity effects, the sample volumes were adjusted
to reflect the same TOC loading used in the operation of the WWTP.
The results are shown in the Figure below where the oxygen uptake rates
clearly show that the TEXOX Process eliminated the toxicity effects compared
to the raw untreated spent caustic.
in the above Figure that a typical WWTP retention time of 24 to 48 hours
resulted in complete assimilation of the pre-treated spent caustic.
This result is evidenced by the oxygen uptake rate reaching endogenous
respiration within 24 hours. The raw un-treated spent caustic resulted
in a toxicity upset and inhibited the microbes respiration well beyond the maximum
48 hour period.
TEXOX Process was also applied at a chemical plant in Freeport, Texas,
during a remedial response action to treat over a million gallons
collected in an interim containment pond. The remedial action was
to eliminate both the foul odor emanating from the pond and blowing
downwind into a nearby residential neighborhood and to eliminate the
toxicity effects when initially attempted to dispose of in the plant's
wastewater treatment plant.
The foul odor
recognition was determined by a team of plant personnel walking around
the containment pond and downwind from the pond and plant. Once
the foul odor was eliminated, being transformed to an "earthy" or
"dirt" like odor, then the task was to dispose of the pond water in the
plant's WWTP without toxic effects.
Samples of the
pond water were tested in a biological respirometer (referenced above)
and found not to exhibit toxic properties. The pond water then
began pumping into the WWTP, cautiously at first at a low flow rate to
allow acclimation with the microbes. After a few hours the
pumping rate reached its capacity and samples of the mixed liquor were
tested in the respirometer. In the figure below, the oxygen
uptake rates showed that the new influent matrix was easily assimilated
by the microbes with no inhibitory or toxic effects. Actually,
the effects with the new influent demonstrated a higher oxygen uptake
over the Control suggesting that the once toxic pond water had been
transformed into a biological food (conversion of indigestible COD into
Process solves spent caustic handling and disposal concerns.
TEXOX destroys all odor and toxicity precursors thus allowing final disposal
in conventional wastewater treatment plants without the otherwise adverse
effects without TEXOX. The treated spent caustics are highly amenable
to biological assimilation, improve the wastewater treatment plant's primary and secondary clarification,
and produce less biological sludge than without TEXOX. While using
the TEXOX Process, environmental discharge quality and permit requirements
are easily met.
For Further Information On The TEXOXTM
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