Environmental Engineering Reference
In-Depth Information
subsidiary benefits such as workplace efficiency improvement (see Sect.
8.10
),
horticultural systems become competitive. Biological air cleaners may also be
more effective at removing the most volatile VOCs, such as formaldehyde than
physiochemical processes that do not use activated carbon adsorption (Chen et al.
2005
). More recent work (e.g. Torpy et al.
2013a
,
b
) has shown that there is a large
and mostly unexplored potential for horticultural biotechnology to improve the
efficacy of biological systems.
Thus physiochemical methods of IAQ amelioration, whilst effective in the short
term, have a number of crucial disadvantages. Most are incapable of removing all
of the key gaseous pollutants simultaneously, some are unsafe due to the emission
of ozone, and all require expensive regular maintenance and are costly to install
(Soreanu et al.
2013
). Research into biotechnological alternatives thus may offer a
realistic alternative to engineering solutions for the maintenance of acceptable
IAQ.
8.6 Hybrid Physiochemical-Biological Systems
As noted previously, physiochemical air quality improvement systems require
regular replacement of the filtration medium to remain effective, and to prevent the
re-emission of absorbed gases. To address this problem, Wang and Zhang (
2011
)
used activated carbon as a support for a microbial biofilter, postulating that in such
a system the microbial community may constantly degrade accumulating VOCs,
alleviating the need for constant replacement. Their system, installed in a new
96.8 m
2
office, was highly effective: 5 % outdoor air plus biofiltration using plants
lead to similar indoor formaldehyde and toluene concentration level as 25 %
outdoor air without biofiltration.
Aydogan and Montoya (
2011
) compared the performance of three hydroponic
supports: growstone, expanded clay and activated carbon, with and without plants,
to remove formaldehyde. Activated carbon was the most effective, remov-
ing *98 % of the formaldehyde in 10 h, a rate somewhat more efficient than that
achieved by four hydroponic indoor plant species, although the authors unfortu-
nately did not describe the hydroponic support used for this assessment.
Such hybrid physiochemical-biological systems may have major potential for
development as the most effective means of non-ventilation-mediated removal of
VOCs from indoor air.
8.7 Phytoremediation and Horticultural Biotechnology
Phytoremediation, the process whereby plants are used to ameliorate a pollution
source, is a well-developed and economical technology for remediation of soil and
water contaminated with heavy metals, fertilisers or hydrocarbons (Pilon-Smits
Search WWH ::
Custom Search