Economic aspects of phytoremediation

The replacement of a traditional crop in favor of a phytoremediating culture is not a neutraloperation, The social acceptability of introducing a phytoremediating crop depends on thecondition that the net present value of the gross labor income (the total revenue diminished bythe non-labor variable costs) earned on the area to be cleaned up and calculated over asufficient long period, is at least not decreased. The case study considered applies to a largearea cross bordering the eastern part of Flanders and the Netherlands characterized withdiffuse heavy metal pollution. The reclamation activity aims at removing 2,5 kg to 5,4 kgcadmium/ha, As a social acceptable, but weak phytoremediation scenario, the yearlycultivation scheme for a 'modal' farn1er starts with 14 ha of rape (in 4 year rotation); 4 ha ofwillow (with harvest every 4th year) and 18 ha of roughage. The resulting median net presentvalue (NPV) over a period of 40 years of the gross labor income is nearly the same as theNPV of continuing the current land occupation (the benchmark), that is 36 ha only forroughage. However, taking into account the uncertainty of the assumed values for importantparameters, the probability of obtaining a lower value for the NPV than currently is, is 62%.We also note that after 40 years only 22 % of the surface is satisfying the remediation target.Increasing the ratio of willow versus rape to 14 ha/4 ha results in the sanitation of the total 36ha after 32 years (willow has a higher uptake performance than rape). On top of this, themedian value for the NPV is now 5 % larger than the benchmark due to the expected largerlabor income on the 'cleaned' hectares. In this scenario the probability of obtaining a lowervalue for the NPY than currently is only 15%.