In the Netherlands the FORTEC process (fast organic removal technology) for treating contaminated sediments combines several separation technologies with bioreac-tor treatment (ten Brummelen et al., 1997). The first step in the process is the use of hydrocyclones to remove the sand fractions. The efficiency of the separation step is optimized by a multistage hydrocyclone configuration, and separation down to a particle size of 20 pm is achieved. After the sand separation, the contaminated fine fraction is fed to the bioreactor section. Based on initial experiments with aerated stirred-tank bioreactors, a full scale bioreactor section with a total volume of 300 m3 (several reactors) was constructed (RIZA, 1997).
A heavily contaminated harbor sediment (port of Amsterdam) was treated with the FORTEC process. After sand removal, the fine fraction (<20 pm) was treated batchwise in full scale bioreactors. On this scale 85% of the PAH and 78% of the mineral oil were removed after 15 d of batch processing (ten Brummelen et al., 1997).
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