SYNERGETIC REMEDIATION OF HCH-POLLUTED SEDIMENTS BY THE ALKALINE AND ULTRASONIC ACTIVATION OF PERSULFATE: PERFORMANCE AND RESIDUAL TOXICITY

Lindane (γ-hexachlorocyclohexane, γ -HCH) has been commonly used as an insecticide in the last decades. This isomer was the only HCH with insecticidal properties, whereas the other HCH isomers (80-90% of the production) were uncontrolled disposed in unmanaged landfills [1]. An example of this large-scale HCH waste hot spot is the Bailín landfill (Sabiñánigo, Spain). Due to the global dimension of HCHs contamination, enormous research effort has been made to remediate this site. Several chemical oxidation technologies, such as Fenton process (H2O2 + Fe) and different persulfate (PS) activation methods (thermal, alkaline, and simultaneous application of temperature and alkali) have been tested for the remediation of these sediments, polluted with α-HCH and β-HCH [2]. Among them, the last one (PS/NaOH/T(40ºC)) has resulted in promising results, achieving a pollutants conversion of 95% in 14 days of treatment. To reduce the reaction time, the process can be intensified by the application of other energy sources such as ultrasound (US) energy.