Page 462 - Air Pollution Control Engineering

11_chap_wang.qxd 05/05/2004 5:19 pm Page 434
434 Gregory T. Kleinheinz and Phillip C Wright

Table 6
Summary of VOC Abatement Technologies
Technique Advantage Disadvantage
Reformation of the • Mostly removes the need to treat • Nearly always impossible to
process the VOC remove ALL of the offending
VOC
Absorption • Low capital cost • High operating cost
(scrubbing) • Reasonably high efficiency • Poor performance at unsteady
•Method is economic at high state and relatively low
airflow rates pollutant concentrations
• Good also for trapping
particulates.
Adsorption • Relatively high efficiency, • High capital cost, especially if
especially for hydrocarbon-based the unit is regenerable
systems • Often large units required
• Compounds are recoverable • Cost versus efficiency works
best for narrow operating
ranges
• Prior removal of dusts and
mists
Incineration • Reliable • Very high capital cost
(noncatalytic) • Good for varying concentrations • Unwanted byproducts (often
and types of VOCs toxic themselves)
Incineration • Lower temperatures and higher • Very high capital cost
(catalytic) efficiency than conventional • Unwanted byproducts (often
incineration process toxic themselves)
Masking agents • Low capital and operating costs • Do not remove VOC, simply
“hide” it
•Very specific
• Unreliable (no adsorption)
Dilution and • Inexpensive • Nonpositive control
dispersion • Not a removal technique.
Biological methods • Proven technology • Variation in efficiency
(e.g., biofiltration • Low operating cost depending on pollutant
and bioscrubbing) • Good performance at low • Not flexible to changes in gas
concentration of pollutant stream concentration and
loading
• Poor performance at high
loadings or with complex
organic materials
Source: ref. 6.

inhibition term becomes more pronounced as the concentration of pollutant rises (see
also Fig. 1).
Depending on the results of the study, it may be important to multistage the treatment
process. This can be because, during the biodegradation process, some of the primary
compounds or their degradation products may be recalcitrant. In this way, it may be