Phytotechnology and Photosynthesis - Environmental Biotechnology: Theory and Application - page 168

ongoing viability of the system, with the intention of linking it into a compost-
ing operation to achieve the long-term carbon lock-up desired. The ACSACS
though performing well at both bench and small pilot scale, never attained indus-
trial adoption though remaining an interesting possible adjunct to the increasing
demand for methane flaring or utilisation at landfills.
A similar idea emerged again about 10 years later, with a system being devel-
oped by Ohio University, which, in a perfect example of selecting an organism
from an extreme environment to match the demands of a particular man-made
situation, utilised thermophilic algae from hot springs in Yellowstone National
Park. In this process, which received a $1 million grant from the US Department
of Energy, smoke from power stations was to be diverted through water to permit
some of the CO 2 to be absorbed and the hot, carbonated water produced then
flowed through an algal filter formed on vertical nylon screens.
This design, which was essentially similar to the earlier ACSACS, enables
the largest possible algal population per unit volume to be packed into the filter
unit, though like the previously described HRAP, light is a limiting factor, since
direct sunlight will only penetrate through a few feet of such an arrangement.
However, it was claimed that these carbon bio-filters could remove up to 20% of
the carbon dioxide, which would, of course, otherwise be released to atmosphere.
This made solving the problem something of a priority. One solution which was
put forward involved the use of a centralised light collector, connected to a series
of fibre-optic cables linked to diffusers within the vessels to provide adequate
illumination within the filters. An alternative approach was also suggested to use
large artificial lakes, but this would have required a much larger land bank to
produce the same effect, since they would have had to have been very shallow
by comparison. It was also suggested that cooling the carbonated water first, a
feature of both the BioCoil and ACSACS, would have allowed normal mesophilic
algaetobeused,whichtakeupCO 2 more efficiently. In the end this technique
seems to have been little more successful in gaining industrial or commercial
acceptance than either of the earlier British systems. However, with both carbon-
consciousness and fears over energy security growing, the vast potential that
algae have for locking up carbon and providing a non-contentious alternative
form of biofuel (see Case Study 7.1) it seems unlikely that new ideas will not
continue to emerge.
Pollution Detection
One final application of phytotechnology to the environmental context to
consider involves the possible use of plants in a variety of industrial sectors
as pollution detectors. The aim is principally to provide valuable information
about the toxicological components of contamination from a wide variety
of sources, including the automotive, chemical and textile industries. Unlike