Effluents from X-ray film developing processes feature high contaminant loa
d (COD about 200 g/l). Identification of the main organics present in these
wastewaters was performed by using liquid chromatography-mass spectrometry
in electron impact mode, LC-(EI)MS. Both, unconsumed ingredients and sulph
onate/hydroxylated derivatives and dimers yielded from the developing agent
s hydroquinone and phenidone were found to be the main organics contributin
g to the contaminant load of these effluents. Their potential degradation b
y oxidation with both photo- and thermal-Fenton reactions was investigated
and the optimal degradation conditions were determined. Under these conditi
ons the initial COD was reduced by about 97% within 6 h of treatment. The i
ntermediates detected by LC-(EI)MS in the oxidation of hydroquinone and phe
nidone during the treatment were essentially hydroxylated derivatives and d
imers and the residual organic matter was mainly made up of carboxylic acid
s, Reaction pathways for the oxidation of the developing agents hydroquinon
e and phenidone were proposed. The presence of many organic and inorganic c
omponents in the wastewaters did not affected the favoured oxidation route
of these developers. The results obtained allow to assess the reduction of
costs permitted in the treatment of X-ray effluents with the photo- and the
rmal-Fenton reaction without affecting the degradation degree and quality o
f the discharge. (C) 2001 Elsevier Science Ltd. All rights reserved.