United States
                     Environmental Protection
                     Agency
Industrial Environmental Research
Laboratory
Cincinnati OH 45268
i\\
                     Research and Development
EPA-600/S2-83-060  Oct. 1983
&ERA          Project  Summary
                     Wet Oxidation  and  Ozonation
                     of  Specific Organic  Pollutants
                     C. Robert Baillod and Bonnie M. Faith
                      This study was undertaken to assess
                     the applicability of wet oxidation and
                     ozonation to the treatment of waste-
                     water containing  five specific pollu-
                     tants typical of the 114 organic com-
                     pounds included on the EPA priority
                     pollutant list. The pollutants, phenol; 2-
                     chlorophenol;  4-nitrophenol; 1,2-di-
                     methylphthalate and 1,2-dichloroethane
                     were selected for study on the basis of
                     their occurrence, structure, water
                     solubility, and  volatility. The ability of
                     the wet oxidation and ozonation proc-
                     esses to oxidize these pollutants in
                     aqueous solution was studied using
                     batch laboratory-scale experiments. In
                     the case of wet oxidation, efforts were
                     made to determine the  influence of
                     temperature, pH value, catalyst, and
                     reaction time on the degree of pollutant
                     destruction. In addition, an economic
                     evaluation was made of a wet oxidation
                     process designed to treat a refractory
                     petrochemical waste stream. For ozon-
                     ation, information was  developed on
                     the degree of pollutant destruction as
                     influenced by ozone dosage and contact
                     time. For both processes, the fate of
                     pollutants were studied by measuring
                     products of incomplete oxidation. The
                     ozonation  results showed that  1,2-
                     dichloroethane was  rapidly volatilized
                     and the remaining four pollutants could
                     be removed to less than detectable
                     concentrations, in  5 to 10 minutes, at
                     initial ozone usage rates of 3.9 to 5.9
                     moles of ozone per mole of compound
                     removed. The  wet  oxidation results
                     indicate that all five pollutants could be
                     oxidized under the conditions  of tem-
                     perature (204° C to 260° C) and oxygen
                     pressures studied. The removal rates for
                     each substance depended on tempera-
                     ture,  pH, and  catalyst and were ade-
                     quately described by semi-empirical,
                     first-order kinetics. For both processes.
a significant amount of organic carbon
remained in solution after the specific
pollutants had been  removed. This
carbon was slowly oxidized and con-
sisted primarily of organic acids and
aldehydes. A wet oxidation process was
designed to  treat a  37.8 l/min (10
gal/min) of a high COD (70,000 mg/l)
petrochemical waste which was inhib-
itory to a biological treatment process.
A detailed economic evaluation of this
process indicated that an investor's
interest  rate of 20  percent could be
attained at a treatment charge of $69
per 1000 gallons ($17.81 per cubic
meter) or $0.16 per  pound  of  COD
removed ($.35 per Kg  COD removed).
  This Project Summary was developed
by EPA's Industrial  Environmental
Research Laboratory.  Cincinnati, OH.
to announce key findings of the research
project that is fully documented in a
separate report of the same  title (see
Project Report ordering information at
back).

Experimental Results
  Semi-batch ozonation  experiments
showed that:
  Phenol, 2-chlorophenol,  4-nitrophenol
  and  1,2-dimethylphthalate could be
  removed to less than detectable con-
  centrations (in 5 to  10 minutes)
  through ozonation  at  initial ozone
  utilization ratios of 3.9 to 5.9 moles of
  ozone  per  mole of specific pollutant.
  However,  the removal rates were
  limited by  the rate  of ozone mass
  transfer. During the initial stages of the
  ozonation experiments, reaction in the
  diffusive film enhanced the mass
  transfer rate.
  A significant amount of total organic
  carbon remained in solution  after the
  specific pollutants had been  removed

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   and this carbon was slowly oxidized.
   Increasing the initial pH from 6 to 10: a)
   increased the specific pollutant removal
   rate for phenol and 4-nitrophenol, but
   decreased the rate for 2-chlorophenol,
   and b) decreased  the total organic
   carbon removal rates for phenol and 2-
   chlorophenol.
  Batch wet oxidation experiments showed
  that:
   All five specific pollutants studied could
   be oxidized under  the conditions  of
   temperature  and oxygen pressured
   studied.  The removal rates depended
   on the substances and on temperature
   and were adequately  described  by
   semi-empirical first-order kinetics.
   Alkaline  pH levels markedly increased
   the rate  of  specific pollutant removal
   and only slightly  increased the  rate of
   total organic carbon removal. However,
   over  the one-hour reaction period,
   alkaline pH levels gave markedly lower
   removals for total organic carbon and
   chemical oxygen demand.
   Cupric ion  acted as a catalyst  and
   increased  the  rate and extent  of
   removal of specific pollutants and total
   organic carbon.
   A significant  amount of total organic
   carbon remained in solution after the
   specific pollutants had been  removed
   and this carbon  was slowly oxidized.
   More than three-fourths of this carbon
   was accounted for by low molecular
   weight acids, acetaldehyde and acetone.
   Bioassay tests using Daphnia magna
   indicated that wet oxidation achieved
   90 to 99 percent  detoxification  for
   phenol,  2-chlorophenol and 4-nitro-
   phenol.
   Although acetic acid was a major end
      evident during ozonation. Conversely,
      oxalic acid was a relatively minor product
      during wet oxidation,  but was very
      significant in ozonation.
         C. Robert Baillod and Bonnie M. Faith are with Michigan Technological University,
           Houghton. Ml 49931.
         Ronald J.  Turner is the EPA Project Officer (see below).
         The complete report, entitled "Wet Oxidation and Ozonation of Specific Organic
           Pollutants," (Order No. PB 83-254 060; Cost: $16.00, subject to change) will be
           available only from:
                 National Technical Information Service
                 5285 Port Royal Road
                 Springfield. VA 22161
                 Telephone: 703-487-4650
         The EPA Project Officer can be contacted at:
                 Industrial Environmental Research Laboratory
                 U.S. Environmental Protection Agency
                 Cincinnati. OH 45268
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