Effect of Temperature on Fenton oxidation of young landfill leachate: Kinetic Assessment and Sludge Properties

Treatment of young landfill leachate, collected from municipal solid waste site of city of Konya, was
investigated by using the Fenton process. The leachate itself showed the characteristics of pH 7.25,
COD 38.2 g L-1 and BOD5 22 g L-1. Ratio of BOD5 to COD with 0.58 indicates that leachate can be
defined young. Fenton oxidation of landfill leachate was expressed in two-stage process, where a
fast initial reaction (H2O2/Fe2+) was followed by a much slower one (H2O2/Fe3+). Overall kinetics can
be described by a second-order rate equation followed by zero-order one. The kinetic studies were
undertaken at the different temperatures and reaction rates increcesed by increasing temperature.
The apparent kinetic constants at 303 K are k = 3.16 x10-3 L g-1 min-1 and k0 = 0,171 g L-1 min-1,
respectively. Fenton reagents effectively degraded the leachate organics and most of the
degradation was completed within 30 minutes for all temperatures. The performance of Fenton
process was not only presented as a COD removal but also expressed as the amount of generated
sludge and its properties. Sludge properties were revealed with Capillary Suction Time (CST) and
Sludge Volume Index (SVI). The minimum CST value was obtained at the optimum molar ratio of
4.12 mol/mol and increasing temperature resulted in a positive effect on CST values. All SVI values
were significantly low which indicates that sludge itself had good settling properties.