Economic aspects of phytoremediation

Abstract

The replacement of a traditional crop in favor of a phytoremediating culture is not a neutral
operation, The social acceptability of introducing a phytoremediating crop depends on the
condition that the net present value of the gross labor income (the total revenue diminished by
the non-labor variable costs) earned on the area to be cleaned up and calculated over a
sufficient long period, is at least not decreased. The case study considered applies to a large
area cross bordering the eastern part of Flanders and the Netherlands characterized with
diffuse heavy metal pollution. The reclamation activity aims at removing 2,5 kg to 5,4 kg
cadmium/ha, As a social acceptable, but weak phytoremediation scenario, the yearly
cultivation scheme for a 'modal' farn1er starts with 14 ha of rape (in 4 year rotation); 4 ha of
willow (with harvest every 4th year) and 18 ha of roughage. The resulting median net present
value (NPV) over a period of 40 years of the gross labor income is nearly the same as the
NPV of continuing the current land occupation (the benchmark), that is 36 ha only for
roughage. However, taking into account the uncertainty of the assumed values for important
parameters, 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 36
ha after 32 years (willow has a higher uptake performance than rape). On top of this, the
median value for the NPV is now 5 % larger than the benchmark due to the expected larger
labor income on the 'cleaned' hectares. In this scenario the probability of obtaining a lower
value for the NPY than currently is only 15%.