Activated carbon amendment to remediate contaminated sediments and soils: a review

Activated carbon (AC) amendment for reduction of contaminant exposure in polluted soils and
sediments has recently emerged as a promising remediation technique. Here, we provide a short
overview of the state-of-the-art in activated carbon (AC) amendment to such sites. Most studies not
only in sediments but also in soils were carried out in the laboratory and only a few in the field.
Consequently, practical experience at the field scale is largely lacking, and feasible engineering
approaches for AC amendment still need to be developed, especially for soils. The effectiveness of the
AC treatment was evaluated by comparison of pollutant concentration reduction in the various
endpoints with those in the unamended control matrix. Endpoints in use comprise pollutant
concentrations in benthic organisms, depletive and non-depletive methods to quantify pollutant
exposures, as well as various toxicity endpoints of plants. Half of the studies in soils and 68% of the
studies in sediments showed reduced pollutant availabilities of >50% after AC amendment. Observed
low reductions (<50%) might be due to low exposure time, insufficient equilibrium time for coke
breeze, biochar, and granulated AC, overload of AC material, different uptake pathways of benthic
organisms, and pollutant reductions outside the dynamic range of toxicity endpoints. Further research
is needed to establish ideal AC amendment conditions to sediments and soils, leading to significantly
reduced pollutant bioavailability.