Recharge systems for protecting and enhancing groundwate

TOPIC 4
Pharmaceutical active compounds and endocrine disrupting compounds / Health aspects 531
recharge sites without or only little significant retardation (Heberer and Mechlinski, 2003; Heberer and Adam,
2004; Heberer et al., 2004).
Steroid hormones such as 17β-estradiol (E2) and 17α-ethinyl estradiol (EE2) have received considerable attention
because of their potential in causing feminization in freshwater fish. These compounds are difficult to study because
they only appear at very low but still environmentally important concentrations of between 0.1 and 10 ng/L in
wastewater effluent (Ternes et al., 1999; Baronti et al., 2000; Huang and Sedlak, 2001). On the basis of their hydrophobicity
(log Kow~4) and taking into account their potential for biotransformation, these hormones would not be
expected to persist in the subsurface. However, Kuch and Ballschmiter (2001) and Adler et al. (2001) reported
several detections of estrogens including EE2 in ground and drinking water in Germany. However, other investigations
of steroid hormones in sewage, surface, and bank-filtered water do not indicate the presence of such compounds
for ground or drinking water (Zühlke et al., 2005). Thus, even short distances between the river or lake
banks and monitoring wells can lead to dramatic decreases of estrone concentrations illustrating the potential of
groundwater recharge systems for the retention of estrogenic steroids (Zühlke et al., 2005).
REMOVAL BY OTHER TECHNIQUES
Besides other purification techniques such as ozonation (Andreozzi et al. 2002, Ternes et al. 2002, 2003, Huber et
al. 2003) or filtration applying granular activated carbon (Ternes et al. 2002), membrane filtration using nanofiltration
(NF) or reverse osmosis (RO) membranes is one of the most promising techniques for the removal of pharmaceutical
residues from contaminated raw water sources (Heberer and Feldmann, 2004).
Kimura et al. (2003) investigated the rejection of disinfection by-products, endocrine disrupting compounds and
pharmaceuticals by polyamide NF/RO membranes. According to the results of their investigations, negatively
charged compounds such as the analgesic drug diclofenac can be rejected to a great extent (i.e., >90%) regardless
of other physical/chemical properties of the tested compounds due to electrostatic repulsion whereas rejection of
non-charged compounds was influenced mainly by the size of the compounds. Adams et al. (2002) evaluated
conventional drinking water treatment processes including RO under typical water treatment plant conditions
demonstrating that RO was very efficient in removing all studied antibiotics. Heberer et al. (2002b) and Heberer
and Feldmann (2004) successfully tested the performance of membrane-based mobile drinking water purification
units for the removal of pharmaceuticals from highly contaminated raw-water sources in two extended field-trials.
In investigations of large-scale operations in the U.S., Drewes et al. (2002) have shown that NF and RO might also
be able to remove pharmaceutical residues from municipal sewage effluents.
CONCLUSIONS
Persistent residues of pharmaceuticals used in human medical care are discharged by municipal sewage treatment
plants into the receiving surface waters. Under recharge conditions, especially some of the polar compounds are
able to leach into groundwater aquifers and a few of them have also the potential for turning up into water-supply
wells. Natural processes such as bank filtration or other groundwater recharge techniques are able to remove pharmaceutical
residues or at least to decrease the concentrations of such compounds from contaminated raw waters. A
prerequisite for obtaining maximum attenuation of such contaminants are both background knowledge of the
potential contaminants and their fate during groundwater recharge at different hydrogeological conditions and a
proper construction and operation of the recharge facilities. Nevertheless, even this will not guarantee a complete
removal of all pharmaceutical residues occurring in raw waters that are under the influence of sewage effluents
(Heberer and Verstraeten, 2002). Additionally, reliable methods such as membrane filtration are available and might
be used for the removal of remaining traces of pharmaceutical residues in terms of a multi-barrier approach
10 – 16 June 2005, Berlin ■ 5th International Symposium ■ AQUIFER RECHARGE ■ ISMAR 2005