US EPA

1346887 

Journal Article 

A combined removal of oil, toxic metals and arsenic from contaminated soils 

Groudeva, VI; Groudev, SN; Ivanova, IA 

1999 

7-11 

WOS:000082416400002 

In the Tulenovo oil deposit, Northeastern Bulgaria, soils
have been heavily contaminated with oh, toxic heavy metals (mainly lead and cadmium) and arsenic.
A pilot scale operation for a combined removal of these pollutants from the soils was carried out
using the heap technique. The soil remediation was based on the activity of both indigenous and
laboratory-bred microorganisms which formed a stable community. The oil was degraded to non-toxic
products, while the heavy metals and arsenic were solubilized mainly as complexes with secreted
microbial metabolites and were removed from the heap by drainage waters percolating through the
soil mass. The regular ploughing up of the soil, the injection of air, the addition of nutrients
(ammonium and phosphate), the maintenance of water content in the range of about 30-35 % and
temperature of the soil were the most essential factors for enhancing the microbial growth and
activity. The oil content in the heap was decreased from the initial 20-25 to less than 2 g/kg
dry soil within 8 months of treatment (from the middle of March 1997 to the middle of November
1997). Simultaneously, the contents of lead, cadmium and arsenic were decreased below the
relevant permissible levels.