3.2 The Source, Release, and Fate of Antibiotics
After the discovery of ampicillin in 1928 by Alexander Fleming (English Bacteriologist), from a soil fungus Pencillium notatum, it was widely used in human clinical
treatment in 1940 (Schlegel 2003; Russell 2004; Etebul and Arikekpar 2016). The
continuous uses of ampicillin in human health care system have propagated to
develop and transform the management for bacterial infections disease treatment
(Aminov 2010), as well as, for promoting faster growth of livestock (White and Cox
2013). The additional use of antibiotics in intensive fish farming and infected plants
leads to the discharge of these compounds either to sewage treatment plants or
directly into water and soil. The concentration of drugs used in agriculture is low
compared to that used in human, veterinary care, and animal production (Cabello
2006; Dolliver and Gupta 2008).
According to the basic structure, antibiotics are either natural, which are produced
by bacteria and fungi, to kill or inhibit other competitive microorganisms with
bacteriostatic or bactericidal effect, such as penicillin that is easily degraded, or
semisynthetic/synthetic compounds that are chemically modified to increase the
efficiency by insertion of additives to their active site (Piorel et al 2005). Thus
would be more stable, less degradable, and accumulate to higher concentrations,
such as fluoroquinolones and tetracyclines (Kümmerer 2009). After administration
and release of these compounds into different environmental compartments, they are
not fully metabolized and a large quantity (30-90 %) are exerted as active compounds through urine and feces (McManus et al. 2002; Jjemba 2006; Lienert et al.
2007); therefore, antibiotics from human use can enter to the wastewater treatment
plants (WWTPs) (Kemper 2008). The WWTPs are considered to be one of the major
pathways for occurrence and existence of antibiotics in different aquacultures,
because all WWTPs are not fully designed to remove antibiotic residues, resulting
in a direct release to the receiving environment (Louvet et al. 2010). In megacities
with well-developed sewage infrastructure, antibiotics enter the aqueous environment via sewage.
Antibiotics are released to the water stream as a natural product with their
metabolites in their partially metabolized forms, and thus the concentration becomes
lower. However, within treatment plants, microbial communities may expose to
higher concentration of selected antibiotics. Around 50–80% of total natural compounds are released to the sludge via urine and partially through feces as a complex
of metabolite-binding compounds, if not completely eliminated and accumulate in
the sludge and reach the farmlands and receiving surface water (McManus et al.
2002; Jjemba 2006; Singer et al. 2008). In some cases, antibiotic contamination can
be delivered in non-routine pathway like breakage in sewer or industrial effluent
pipe, or mixing of storm water with un-treated effluent (Zuccato et al. 2010).
Antibiotics can also reach the groundwater, surface drainage systems, and soils by
application of municipal biosolids on land. The pharmaceutical industries and
hospitals allow the direct discharge of discarded or unused or expired antibiotics
into sludge or waste bins and later into wastewater treatment plants and landfills
3 Existence of Antibiotics in Wastewater as a Pollution Indicator
45
After the discovery of ampicillin in 1928 by Alexander Fleming (English Bacteriologist), from a soil fungus Pencillium notatum, it was widely used in human clinical
treatment in 1940 (Schlegel 2003; Russell 2004; Etebul and Arikekpar 2016). The
continuous uses of ampicillin in human health care system have propagated to
develop and transform the management for bacterial infections disease treatment
(Aminov 2010), as well as, for promoting faster growth of livestock (White and Cox
2013). The additional use of antibiotics in intensive fish farming and infected plants
leads to the discharge of these compounds either to sewage treatment plants or
directly into water and soil. The concentration of drugs used in agriculture is low
compared to that used in human, veterinary care, and animal production (Cabello
2006; Dolliver and Gupta 2008).
According to the basic structure, antibiotics are either natural, which are produced
by bacteria and fungi, to kill or inhibit other competitive microorganisms with
bacteriostatic or bactericidal effect, such as penicillin that is easily degraded, or
semisynthetic/synthetic compounds that are chemically modified to increase the
efficiency by insertion of additives to their active site (Piorel et al 2005). Thus
would be more stable, less degradable, and accumulate to higher concentrations,
such as fluoroquinolones and tetracyclines (Kümmerer 2009). After administration
and release of these compounds into different environmental compartments, they are
not fully metabolized and a large quantity (30-90 %) are exerted as active compounds through urine and feces (McManus et al. 2002; Jjemba 2006; Lienert et al.
2007); therefore, antibiotics from human use can enter to the wastewater treatment
plants (WWTPs) (Kemper 2008). The WWTPs are considered to be one of the major
pathways for occurrence and existence of antibiotics in different aquacultures,
because all WWTPs are not fully designed to remove antibiotic residues, resulting
in a direct release to the receiving environment (Louvet et al. 2010). In megacities
with well-developed sewage infrastructure, antibiotics enter the aqueous environment via sewage.
Antibiotics are released to the water stream as a natural product with their
metabolites in their partially metabolized forms, and thus the concentration becomes
lower. However, within treatment plants, microbial communities may expose to
higher concentration of selected antibiotics. Around 50–80% of total natural compounds are released to the sludge via urine and partially through feces as a complex
of metabolite-binding compounds, if not completely eliminated and accumulate in
the sludge and reach the farmlands and receiving surface water (McManus et al.
2002; Jjemba 2006; Singer et al. 2008). In some cases, antibiotic contamination can
be delivered in non-routine pathway like breakage in sewer or industrial effluent
pipe, or mixing of storm water with un-treated effluent (Zuccato et al. 2010).
Antibiotics can also reach the groundwater, surface drainage systems, and soils by
application of municipal biosolids on land. The pharmaceutical industries and
hospitals allow the direct discharge of discarded or unused or expired antibiotics
into sludge or waste bins and later into wastewater treatment plants and landfills
3 Existence of Antibiotics in Wastewater as a Pollution Indicator
45