Treating Aniline Compounds at a Former Pharmaceutical Plant, Lombardia, Italy


Courtesy of Regenesis

Integrated Remediation Approach with Sodium Persulfate based In Situ Chemical Oxidation (PersulfOx®) and Biosparging on Impacted Soils and Groundwater

  • Geology : Sandy and Clayey Silt
  • Contaminant Of Concern : Aniline and its Derivatives (i.e. N,N-diethylaniline)
  • COC Range : 100 mg/kg in Saturated Soil (source area) up to 1000 µg/L in Groundwater
  • Target Level : 0.05 mg/kg in Soil, 10 µg/L in Groundwater
  • Treatment Area & Thickness : 20,000 m2 4 m to 9 -10 m BGL
  • Former Site Use : Former Pharmaceutical Plant
  • Project Driver : Regulatory Compliance Prior to Site Sale/ Redevelopment
  • Product Design Details : In Situ Treatment (ISCO) & Biosparging

The soil and groundwater under a disused pharmaceutical plant in the North of Italy had become impacted with a mixture of aniline and its derivatives, due to historic spillages and leaks on the site. The contaminated unsaturated soil had been removed previously by excavation and disposal {approx, 1.000-1,500 m;) to a depth of 5 m BGL However, some contamination had infiltrated through the vadose zone and impacted the groundwater, resulting in a 10O*meter long plume. In the source area, residual contamination adsorbed to the saturated soil had been detected at 6-9 m BGL: below the maximum depth of the excavation previously completed. It was observed that during periods of high precipitation, the groundwater level would rise and promote recurrent desorption events from this contaminant mass into the groundwater.

Copernico S.r.l was engaged to delineate the contamination through additional site investigation using Membrane Interface Probe (MIP}. They found that the main contaminant of concern {COCJ was N,N-diethylaniline. which was present at concentrations of approx. 100 mg/kg in saturated soil in the source area, and up to 1,000 ug/L in groundwater across the whole of the site.

Remediation Strategy
A laboratory study previously performed on material and contaminants from this site had shown that aniline was biodegradable under aerobic conditions (especially N.N-diethylaniline). Following this, a biosparge pilot scale study was completed, which proved unsuccessful at dealing with the high concentrations and contaminant loading in the source area. Copernico therefore determined that an integrated remediation approach would be required; initially using ISCO to rapidly address the higher concentrations and then enhanced biological degradation to treat the residual dissolved phase contamination.

It was determined that a persulphate-based ISCO agent was to be applied in two injection campaigns to treat the high levels of adsorbed contamination. After this, the biosparging system would then be operated both in the source and in the plume area. At the downstream boundary of the site, an ongoing pump & treat {P&TJ system was used to provide hydraulic containment of the plume within the property, in line with regulatory requirements.

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