Page 205 - Materials Chemistry, Second Edition

186 Life Cycle Assessment of Wastewater Treatment

amino or carboxylic acid groups in the molecule, and chemical properties, including
K , pK , and K ) and the sludge (organic compound fraction, cation exchange capac-
ow
d
a
ity, suspended solid size) and operating conditions (pH and sludge retention time)
(Verlicchi and Zambello, 2015). For instance, Martínez-Alcalá et al. (2017) reported
that the mechanism of elimination of carbamazepine, naproxen, and diclofenac from
wastewater is due to sorption onto sludge, whereas the elimination of ibuprofen and
ketoprofen is due to biodegradation (54.3% and 99.7%, respectively), and to a lower
extent to sorption onto sludge (45.7% and 0.3%, respectively).
In this section, we describe the application of the analytical determination of
pharmaceuticals in sewage sludge to obtain information about their evolution in the
sludge treatment line and their occurrence and fate in sewage sludge from different
treatment technologies, and assess the ecotoxicological risk of sewage sludge applica-
tion to agricultural soils. Sixteen pharmaceutical compounds from seven therapeutic
groups (five anti-inflammatories, two antibiotics, an antiepileptic drug, a β-blocker, a
nervous stimulant, four hormones, and two lipid regulators) were selected based on
their high consumption and environmental relevance. The physicochemical proper-
ties of the monitored pharmaceuticals are shown in Table 9.2. The analytical method
applied was the one described in Martín et al. (2010).

9.3.1 evoluTion of concenTraTions of pHarMaceuTicals
in sluDge TreaTMenT line
To obtain information about the concentrations of pharmaceutical compounds in the
sludge treatment line, sewage sludge from different treatment stages was sampled
from four urban WWTPs based on activated sludge technology and from a com-
posting plant. Wastewater treatments involved pretreatment and primary (settling)
and secondary (activated sludge) treatments. Primary sludge is produced by settling
pretreated wastewater in primary clarifiers. Secondary sludge is produced after acti-
vated sludge processes in a biological reactor and settling in secondary clarifiers.
Digested sludge is produced by the anaerobic digestion of primary and secondary
sludge mixtures. Compost sludge is obtained in a composting plant where anaerobi-
cally digested and dehydrated sludge from the above-mentioned WWTPs is treated
in dynamic batteries thermally controlled with aeration facilitated by turning. Nine
samples of each type of sludge were sampled from each WWTP and from the com-
posting plant in a 1-year monitoring campaign. The characteristics of each type of
sludge are shown in Table 9.3.
In Figures 9.1 and 9.2, the concentrations of the most concentrated pharmaceuti-
cals (Martín et al., 2012b) are shown as box-and-whisker plots. Lines in each box show
the lower (≤25%), median (≤50%), and upper quartile (≤75%). Lines from each box
show the highest and lowest concentrations. The concentrations of some compounds
(salicylic acid, ibuprofen, and caffeine) decreased from primary to secondary sludge,
but the concentrations of others (naproxen, 17β-estradiol, and estrone) remained
constant or even increased (carbamazepine, propranolol, and 17α-ethinylestradiol)
from primary to secondary sludge. This fact can be explained not only by the dif-
ferent physicochemical properties of the pharmaceutical compounds (log K and
ow