Water and Wastewater Treatment: Historical Perspective of Activated Carbon Adsorption and its Integration with Biological Processes - Activated Carbon for Water and Wastewater Treatment - page 10

referred to as Adsorbable Organic Xenobiotics (AOX), and represents halogenated
organics that have a high affinity towards activated carbon. This parameter is most
often used to indicate the chlorinated organic compounds (AOCl).
There are also definitions that are specific to water treatment. In this context,
one can list the Disinfection By-Products (DBPs). Specific groups among DBPs are
referred to by terms such as Trihalomethanes (THMs) and Haloacetic Acids
(HAAs). The respective formation potentials of these groups are abbreviated as
THMFP and HAAFP.
In addition to these, in recent decades, a large number of new compounds have
been detected in water and wastewater media. Since in raw and finished waters
these compounds, referred to as micropollutants, are present at m gL 1 or ng L 1
levels, the sum parameters mentioned above prove to be useless in their moni-
toring. Due to this fact, efforts are made to monitor them individually by advanced
analytical techniques. Within this context, one can list various pharmaceuticals
and EDCs that have received a great deal of attention in the last decades.
Various pollutants found in water and wastewater systems are amenable to
either adsorption or biological degradation or transformation. Still, a number of
them can be removed by both adsorptive and biological means. Combination
of activated carbon adsorption and biological processes in the same unit often
offers a synergism, in that a higher removal is achieved than expected from
adsorption or biodegradation alone. For many pollutants that are considered to be
slowly biodegradable or even nonbiodegradable, integration of adsorption with
biological removal may provide the opportunity for biological degradation. This
integrated approach can also enable the effective elimination of micropollutants at
trace levels.
Various organic and inorganic pollutants are encountered in surface waters,
groundwaters, and wastewaters. Table 1.1 provides a brief overview of the relative
reduction achieved in parameters or specific groups by means of adsorption,
biological activity or integration of both. However, the evaluation presented here is
rather general, relative, and qualitative. Comprehensive discussion of the elim-
ination mechanisms, the synergism in integrated adsorption and biological
removal, the laboratory-, pilot- and full-scale studies, and the modeling of inte-
grated adsorption and biological removal in wastewater and water treatment is
presented throughout Chapters 3-11.

References

1 Bansal, R.P. and Goyal, M. (2005)
Activated Carbon Adsorption, CRC Press,
Taylor & Francis Group, 6000 Broken
Sound Parkway NW, Suite 300 Boca
Raton, FL, USA 33487-2742.
2 Inglezakis, V.J. and Poulopoulos, S.G.
(2006) Adsorption, Ion Exchange and

Catalysis: Design of Operations and
Environmental Applications, Elsevier
Science & Technology.
3 Menendez-Diaz, J.A. and Gullon, I.M.
(2006) Types of carbon adsorbents and
their production, in Activated Carbon
Surfaces in Environmental Remediation