Transforming sludge into a recyclable and valuable carbon source by wet air oxidation

The wet air oxidation (WAO) process generates residual solids that can be landfilled without additional treatment. This practical advantage stems from the intrinsic leaching-resistant behaviour of the solids, which is linked to the treatment conditions in water at high temperature and to the composition of the solids. X-ray analysis confirmed that the fine powder (diameter 2-6 mu m) mainly comprises aluminium phosphates, kaolin, quartz, calcite and an amorphous fraction which immobilises heavy metals in the form of hydroxides, carbonates and insoluble phosphates. The residual solids contain a low amount of organic matter (1-2 wt.\% TOC, depending on the process parameters). They are easily settled and dewatered with dry solids (DS) content between 50 and 60\%. The re-use of WAO sludge supernatant as a carbon source in biological denitrification have been investigated. The initial results are deemed very satisfactory. The most significant results obtained during process development are reported in this paper

Performances of soluble metallic salts in the catalytic wet air oxidation of sewage sludge

SSCI-VIDE+CARE:CDFA+CDS:MBEInternational audienceNon

Catalytic wet air oxidation of sewage sludge: performances of soluble metallic salts

SSCI-VIDE+CARE:CDFA+CDS:MBEInternational audienceNon

Catalytic wet air oxidation of sewage sludge: Performances of soluble metallic salts

internationa

Performances of soluble metallic salts in the catalytic wet air oxidation of sewage sludge

Bernardi, Marco Cretenot, Didier Deleris, Stephane Descorme, Claude Chauzy, Julien Besson, Michele 6th World Congress on Oxidation Catalysis (6WCOC) JUL 05-10, 2009 Lille, FRANCEInternational audienceVarious soluble transition metal salts were compared in the wet air oxidation of industrial and municipal sewage sludges (2 5-25 g L-1 total organic carbon) at 200-250 degrees C under 4-15 bar O-2 partial pressure The evolution of the TOC content in both the liquid and solid phases and the overall TOC conversion were monitored While copper sulphate prevented the dissolution of the suspended organic matter due to strong bounding of copper to a fraction of the organic matter in sludge and showed high activity in the mineralization of the solubilized organic compounds (liquid phase) the implementation of iron sulphate resulted in a higher transfer of the organic matter to the liquid phase but in a moderate activity in the oxidation of solubilized molecules When used in combination a synergetic effect between these two salts was evidenced (C) 2010 Elsevier BV All rights reserve