Pre-treatment of industrial landfill leachate by Fenton’s oxidation

Biological treatment (aerobic and anaerobic) of industrial landfill leachate is limited by the
presence of toxic contaminants (e.g., heavy metals) and recalcitrant (biopersistent) organics
(e.g., polyphenols, pharmaceuticals, cosmetics, etc.,), hindering viable conditions for biomass
proliferation in biological reactors, with difficulties in meeting concentration limits imposed by
applied regulations.
Fenton’s oxidation by the use of Fe2+-H2O2-H+ mixture may be used as a pre-treatment of
industrial landfill leachate for preliminary abatement of the organic load and to improve
biodegradability (BOD/COD>0.4) to favour biological oxidation in conventional wastewater
treatment plants.
Leachate from Grottaglie (S.E. Italy) non-hazardous landfill (pH 8.6; COD=11.000 mg l-1;
BOD5=2.400 mg l-1; NH4-N=2.900 mg l-1; conductivity=60.000 μS cm-1) was laboratory tested in
different operative conditions, i.e., initial pH, Fe2+/H2O2 ratio, concentrations and reaction time.
The oxidation reaction was monitored by equilibrium pH and residual COD and BOD5
concentrations.
Best operative conditions were obtained at pH 3, Fe2+=700 mg l-1, H2O2=9,900 mg l-1
(H2O2/Fe2+ratio~13w/w), reaction time=2h. Following the oxidation reaction, solution pH was
neutralized by the addition of Ca(OH)2 or NaOH (120 meq l-1) for further abatement of target
parameters by precipitation/sorption.
Preliminary technical/economical evaluation of possible process schemes is also given in the
paper.