Page 159 - Materials Chemistry, Second Edition

140 Life Cycle Assessment of Wastewater Treatment

8.1 INTRODUCTION: BACKGROUND AND DRIVING FORCES
The presence of pharmacologically active organic micropollutants (PhACs),
including pharmaceuticals and personal care products (PPCPs) as well as endo-
crine-disrupting chemicals (EDCs), is an emerging issue and an increasing con-
cern both in the effluent of wastewater treatment plants (WWTPs) and in natural
water courses (Lienert et al., 2007; Marco-Urrea et al., 2009; Jones et al., 2005).
These active substances are often highly persistent compounds and come from
various sources, including human and veterinary medicine (Richardson et al.,
2005), chemicals used as fragrances in perfumes (Simonich et al., 2002), indus-
trial wastewater, and other household products (Kosjek et al., 2007). In fact, most
of these compounds are designed to affect physiological functions in humans and
animals; therefore, the permanent presence of these pharmaceuticals, even at low
concentration, is of great importance (Rodarte-Morales et al., 2012). Increased
aquatic toxicity (Santos et al., 2010) and endocrine disruption (Kim et al., 2007)
have been previously reported due to the presence of pharmaceuticals in water
resources and in sewage-impacted water bodies.
The severity of the potential risk from PhACs to the ecosystems, the biotic com-
munity, and human health is dependent on several factors, including the concentra-
tions, adsorption efficiencies, time of exposure, bioaccumulation, and nature of the
PhACs and the vulnerability of the contaminated ecosystem (Rodarte-Morales et al.,
2012; Daughton and Ternes, 1999; Kümmerer, 2008). The environmental impact of
PhACs is not restricted to the aquatic ecosystem. PhACs are also a great potential
risk to soil matrices. The soil can become contaminated by diffusion of the PhACs
through the soil from landfill leachates or by contaminated sewage sludge biosolids (a
byproduct generated during wastewater treatment, which is used as a soil improver)
(Rodríguez-Rodríguez et al., 2011; Drillia et al., 2005). On the one hand, PhACs are
resistant products by nature, which are not easily degraded or removed at WWTPs
(Carballa et al., 2004), and on the other hand, the current WWTPs are not designed
to remove these components, and in most cases, they fail to remove PhACs effec-
tively. The extensive contamination potential of PhACs, along with their contribu-
tion to severe ecotoxicity and human health problems, necessitates the development
of cost-effective and efficient methods for the elimination of PhACs from wastewater
or contaminated soil (Prieto et al., 2011; Asgher et al., 2008; Yang et al., 2013).
Conventional WWTPs are based on activated sludge technologies and are not
designed for or capable of the removal of PhACs, which are present at low concentra-
tions (nanograms per liter to milligrams per liter). Consequently, PhACs often pass
through, untouched or partially transformed, and reach environmental compartments
(air, water, and soil) (Verlicchi et al., 2012b; Cruz-Morató et al., 2013). Currently, three
potential treatment technologies have been suggested for the efficient degradation and
removal of PhACs in wastewater streams: conventional treatments (physical–chemical
methods: photodegradation [Liu et al., 2009], activated sludge [Nakada et al., 2006],
nitrification–denitrification [Suarez et al., 2010]); advanced treatments (UV, ozone,
hydrodynamic cavitation [Zupanc et al., 2013], anammox reactors [Tang et al., 2011],
activated carbon [Snyder et al., 2007], photo-Fenton systems [Shemer et al., 2006],
and membrane bioreactors [MBRs] [Clara et al., 2005]); and bioremediation methods