Conversion of the refractory ammonia and acetic acid in catalytic wet airoxidation of animal byproducts
Virginie Fontanier , Sofiane Zalouk , St′ephane Barbati
DOI:
Received April 13, 2010,Revised September 15, 2010, Accepted , Available online
Volume 23,2011,Pages 520-528
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Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) of slaughtered animal byproducts (ABPs) were investigated. Two
step experiment was carried out consisting of a non-catalysedWAO run followed by a CWAO run at 170–275°C , 20 MPa, and reaction
time 180 min. TheWAO (1st step) of sample (5 g/L total organic carbon (TOC)) yielded (82.0 4)% TOC removal and (78.4 13.2)%
conversion of the initial organic-N into NH4
+-N. Four metal catalysts (Pd, Pt, Rh, Ru) supported over alumina have been tested in
catalytic WAO (2nd step) at elevated pH to enhance ammonia conversion and organic matter removal, particularly acetic acid. It was
found that the catalysts Ru, Pt, and Rh had significant e ects on the TOC removal (95.1%, 99.5% and 96.7%, respectively) and on
the abatement of ammonia (93.4%, 96.7% and 96.3%, respectively) with high nitrogen selectivity. The catalyst Pd was found to have
the less activity while Pt had the best performance. The X-Ray di raction analysis showed that the support of catalyst was not stable
under the experimental conditions since it reacted with phosphate present in solution. Nitrite and nitrate ions were monitored during
the oxidation reaction and it was concluded that CWAO of ammonia in real waste treatment framework was in good agreement with
the results obtained from the literature for ideal solutions of ammonia.
