http://twri.tamu.edu/projects/00-04/researchProjects/Morse-Short.html
Date: 2/11/2003 6:23:17 PM Central Standard Time
The challenges of reusing wastewater are renewed each day. Historically, the concern of
recycling wastewater as a potable water supply was the presence of disease causing
pathogens. However, in many areas of the country and even in Texas, discharges from POTWs
at certain times of the year may constitute most of the stream flow and the stream maybe used
downstream as a drinking water source. So in actuality, we are currently recycling our
wastewater. Recently, the newest concern of recycling wastewater is the presence of chemicals
such antibiotics, endocrine disrupters compounds, and personal health care products.
Endocrine disrupters, which interfere with the body's natural ability to produce, release,
transport, metabolize, bind and eliminate hormones in the body, have been observed in
wastewater discharges therefore in water bodies all over the world. For example, the steroid
17b-estadiol is an important hormone in fish experiments conducted has indicated possible
reproduction consequences (Schoenfuss et al., 2001).
Several studies have observed antibiotic agents in the aquatic environment, including
groundwater, surface water, and wastewater treatment plant (WWTP) effluent (Ternes et al,
1998; Heberer et al., 1998; Hirsch et al, 2000; Qitting and Xiheng, 1988). Sources of antibiotic
agents to the environment include effluent from WWTPs, leachate from landfills, discharge from
septic tanks, runoff from veterinary medicine and growth promoters in livestock, and the
application of manure and sludge containing antibiotics. Despite knowing the sources and
pathways of pharmaceuticals into the environment, actual concentrations and availability are
unknown.
Another concern of pharmaceuticals in the environment is the development of antibiotic
resistance of bacteria due to the presence of antibiotics in wastewater. In fact, several studies
have identified antibiotic resistance in bacteria at WWTPs and in WWTP effluents (Stelzer et al.,
1985; Grabow et al., 1976; Bell, 1979; Misra et al., 1979; Radtke and Gist, 1989; and Malik and
Ahmad, 1994). Antibiotic resistances can be identified in bacteria by a traditional agar dilution
method or by surveying for beta-lactamase activity using acidometric tests or chromogenic
cephalosporing tests (Handal and Olsen, 2000). The acidometric test is less expensive than the
chromogenic cephalosporin tests, but the latter test is more sensitive. Materials to perform both
tests are commercially available. Susceptibility tests may be used to detect the presence of
beta-lactamases using the double-disk diffusion test, isoelectric focusing and the E-test.
Antibiotic resistance is of great concern in that pathogens may develop resistances to
antibiotics when exposed at the WWTP. Antibiotic resistant bacteria would then be released to
the environment where a host may be infected. To over come the resistance developed by the
bacteria, new antibiotics may need to be developed or doses may have to increase, resulting in
a vicious cycle.
Pharmaceuticals have been identified in the environment for several decades (Kummerer,
2001); however, the fates of pharmaceutical agents are in many cases of unknown. In order to
understand the potential impacts of antibiotic agents in the aquatic environment at trace
concentrations, the fate of the pharmaceuticals needs to be investigated. Specifically,
information needs to be collected regarding the emission, occurrence, fate and effects of
pharmaceuticals in the environment. The objective of this research is to a) investigate the fate
of amoxicillin in a full-scale wastewater treatment plant and to b) determine the antibiotic
resistance of bacteria utilized in activated sludge process and sludge treatment.
The Lubbock Wastewater Treatment Plant