2.1 Factors Affecting Pharmaceutical Concentrations
in Wastewater Effluent and Irrigation Water
Kasprzyk-Hordern et al. [21] explained that the probability of soil and groundwater
contaminations by PhACs as a result of the discharge of wastewater treatment
effluents depends on factors such as the physicochemical properties of these pollutants, the type of wastewater treatment used, and climatic conditions (e.g., temperature, rainfall, and irradiation).
Irrigation wastewater quality must be compliant with FAO guidelines [22]. The
characteristics of the wastewater used for irrigation can help in elucidating the
potential transfer of these contaminants from water to soil. We can find an example
in the following parameters: the concentrations of Biochemical Oxygen Demand
(BOD 5 ) and Chemical Oxygen Demand (COD). COD is the amount of oxygen
required to chemically oxidize organic matter in wastewater into inorganic matter,
whereas BOD is the amount of oxygen required to biologically oxidize the organics,
usually after 5 days or 21 days of incubation time, depending on the bioassay
followed. The ratio of BOD/COD of wastewater is a good indicator of the concentrations of the total organic load (or oxygen demand) that is bioavailable for
degradation. This organic load affects the bioavailability of weakly acid pharmaceuticals. Polar interactions between acidic pharmaceuticals and dissolved organic
matter (DOM) create water-soluble complexes that are not available for uptake or
sorption to the solid phases, which also reduces their concentrations in soil. Another
important parameter is the water pH, because it determines the dissociation of ionic
organic compounds. For instance, in slightly alkaline water, contaminants such as
diclofenac and sulfamethoxazole are present mainly as ions, whereas trimethoprim is
in its neutral form.
Wastewater treatment plants were not designed to remove PhACs. In fact,
removal efficiencies drop to <10% for compounds such as carbamazepine, atenolol,
mefenamic acid, and atenolol. The PhAC concentrations discharged into the environment vary according to time, space, season, and socioeconomic aspects, as they
depend on usage patterns, location, input of manufacturing facilities, and the presence of hospitals. For example, antihypertensive, antibiotic, and nonsteroidal antiinflammatory drug use increases during winter while sunscreens and antihistamines
during summer. The concentrations found in effluents used for irrigation are in the
range up to μg L
À1 [23, 24], and it depends on the season due to the dilution effect
brought by the higher flow in January respect in spring/summer season. Biel-Maeso
et al. [25] established the connection between presence, quantity, and seasonal
distribution of several PhACs in wastewater and sewage-impacted receiving soils.
Compounds in urban wastewater were detected at concentration from 73 to
372 μg L
À1 in the influent and from 3 to 41 μg L
À1 in the effluent. Removal
efficiencies were <50% and only traces (ng g
À1 ) of PhACs such as diclofenac,
acetaminophen, and caffeine were detected in soil irrigated with TWW.
146
M. Brienza et al.
in Wastewater Effluent and Irrigation Water
Kasprzyk-Hordern et al. [21] explained that the probability of soil and groundwater
contaminations by PhACs as a result of the discharge of wastewater treatment
effluents depends on factors such as the physicochemical properties of these pollutants, the type of wastewater treatment used, and climatic conditions (e.g., temperature, rainfall, and irradiation).
Irrigation wastewater quality must be compliant with FAO guidelines [22]. The
characteristics of the wastewater used for irrigation can help in elucidating the
potential transfer of these contaminants from water to soil. We can find an example
in the following parameters: the concentrations of Biochemical Oxygen Demand
(BOD 5 ) and Chemical Oxygen Demand (COD). COD is the amount of oxygen
required to chemically oxidize organic matter in wastewater into inorganic matter,
whereas BOD is the amount of oxygen required to biologically oxidize the organics,
usually after 5 days or 21 days of incubation time, depending on the bioassay
followed. The ratio of BOD/COD of wastewater is a good indicator of the concentrations of the total organic load (or oxygen demand) that is bioavailable for
degradation. This organic load affects the bioavailability of weakly acid pharmaceuticals. Polar interactions between acidic pharmaceuticals and dissolved organic
matter (DOM) create water-soluble complexes that are not available for uptake or
sorption to the solid phases, which also reduces their concentrations in soil. Another
important parameter is the water pH, because it determines the dissociation of ionic
organic compounds. For instance, in slightly alkaline water, contaminants such as
diclofenac and sulfamethoxazole are present mainly as ions, whereas trimethoprim is
in its neutral form.
Wastewater treatment plants were not designed to remove PhACs. In fact,
removal efficiencies drop to <10% for compounds such as carbamazepine, atenolol,
mefenamic acid, and atenolol. The PhAC concentrations discharged into the environment vary according to time, space, season, and socioeconomic aspects, as they
depend on usage patterns, location, input of manufacturing facilities, and the presence of hospitals. For example, antihypertensive, antibiotic, and nonsteroidal antiinflammatory drug use increases during winter while sunscreens and antihistamines
during summer. The concentrations found in effluents used for irrigation are in the
range up to μg L
À1 [23, 24], and it depends on the season due to the dilution effect
brought by the higher flow in January respect in spring/summer season. Biel-Maeso
et al. [25] established the connection between presence, quantity, and seasonal
distribution of several PhACs in wastewater and sewage-impacted receiving soils.
Compounds in urban wastewater were detected at concentration from 73 to
372 μg L
À1 in the influent and from 3 to 41 μg L
À1 in the effluent. Removal
efficiencies were <50% and only traces (ng g
À1 ) of PhACs such as diclofenac,
acetaminophen, and caffeine were detected in soil irrigated with TWW.
146
M. Brienza et al.