3 Effluent Characterization
The treated effluent was obtained from an NSAID-manufacturing plant in Lerma
(State of Mexico) and was sampled according to the official Mexican norm for
wastewater sampling (NMX-AA-003-1980). Sampling point was in the production
area that connects directly to the municipal sewer. The following physicochemical
characteristics of the effluent were determined: total organic carbon (TOC) with a
Shimadzu TOC analyzer, TOC-L CPN with integrated autosampler Shimadzu
ASI-L, chemical oxygen demand (COD) according to the NMX-AA-030-SCFI2001 using a HACH DR/5000 and a digestive solution HACH, total suspended
solids (TSS) and temperature according to NMX-AA-034-SCFI-2001 and
NMX-AA-007-SCFI-2013 norms, and turbidity and dye with the NMX-AA-0038SCFI-2001 and NMX-AA-45-SCFI-2001 methods in a HACH DR/4000. The quantification of paracetamol (PAR) in water was determined by the method reported by
San Juan [33] using liquid chromatography tandem-mass spectrometry (LC-MS/MS)
and employing an Agilent 1290 Infinity HPLC unit (Santa Clara CA) and an RRHD
Plus C 18 (2.1 Â 50 mm, 1.8 μm) chromatography column.
The official Mexican norm responsible for regulating the discharge of wastewater
to sewage systems (NOM-002-SEMARNAT-1996) establishes limits only for COD,
TSS, and temperature, these being 500 mg/L for COD and 220 mg/L for TSS and
temperature of 40
C. The lack of inclusion of more physicochemical characteristics
has led to increase water pollution and therefore damage to aquatic systems. Turbidity, TOC, and COD are key to the efficiency of the effluent treatment with photoFenton, being turbidity a limitation in the use of light [34]. The photo-Fenton process
is used with low values of TOC and COD. Therefore, it is important to mention that
the effluent COD and TOC are very high in comparison with effluents studied by
Klamerth and Michael [2, 35]. Actually, it is worth clarifying that the TOC values of
the industrial effluent were so high that mineralization was not observed at all and
therefore it was decided to test different dilution degrees. It was found that the
minimum dilution degree to observe mineralization was 1:100. The characterization
of such diluted effluent is shown in Table 2.
4 Effluent Treatment
The results presented here were obtained in a reaction system consisting of a Pyrex
glass batch reactor with a volume of 100 mL (2.5 cm in diameter and 20 cm of
height), equipped with a UVP Pen-Ray Lamp of mercury of 5.5 W UV light (UVP)
placed inside at the center of reactor. This lamp emits primary energy at 254 nm with
a typical intensity of 4,400 μW/cm
2 and uses a UVP Pen-Ray power supply of
115 V/60 Hz. Also, there was inside the reactor an electrode Boeco Germany BA
17 connected to a pH meter accumet XL15, Fisher Scientific. Stirring was conducted
using a magnetic stirrer and temperature was kept constant with a water bath. The
Photo-Fenton Treatment of a Pharmaceutical Industrial Effluent Under Safe pH. . .
247
The treated effluent was obtained from an NSAID-manufacturing plant in Lerma
(State of Mexico) and was sampled according to the official Mexican norm for
wastewater sampling (NMX-AA-003-1980). Sampling point was in the production
area that connects directly to the municipal sewer. The following physicochemical
characteristics of the effluent were determined: total organic carbon (TOC) with a
Shimadzu TOC analyzer, TOC-L CPN with integrated autosampler Shimadzu
ASI-L, chemical oxygen demand (COD) according to the NMX-AA-030-SCFI2001 using a HACH DR/5000 and a digestive solution HACH, total suspended
solids (TSS) and temperature according to NMX-AA-034-SCFI-2001 and
NMX-AA-007-SCFI-2013 norms, and turbidity and dye with the NMX-AA-0038SCFI-2001 and NMX-AA-45-SCFI-2001 methods in a HACH DR/4000. The quantification of paracetamol (PAR) in water was determined by the method reported by
San Juan [33] using liquid chromatography tandem-mass spectrometry (LC-MS/MS)
and employing an Agilent 1290 Infinity HPLC unit (Santa Clara CA) and an RRHD
Plus C 18 (2.1 Â 50 mm, 1.8 μm) chromatography column.
The official Mexican norm responsible for regulating the discharge of wastewater
to sewage systems (NOM-002-SEMARNAT-1996) establishes limits only for COD,
TSS, and temperature, these being 500 mg/L for COD and 220 mg/L for TSS and
temperature of 40
C. The lack of inclusion of more physicochemical characteristics
has led to increase water pollution and therefore damage to aquatic systems. Turbidity, TOC, and COD are key to the efficiency of the effluent treatment with photoFenton, being turbidity a limitation in the use of light [34]. The photo-Fenton process
is used with low values of TOC and COD. Therefore, it is important to mention that
the effluent COD and TOC are very high in comparison with effluents studied by
Klamerth and Michael [2, 35]. Actually, it is worth clarifying that the TOC values of
the industrial effluent were so high that mineralization was not observed at all and
therefore it was decided to test different dilution degrees. It was found that the
minimum dilution degree to observe mineralization was 1:100. The characterization
of such diluted effluent is shown in Table 2.
4 Effluent Treatment
The results presented here were obtained in a reaction system consisting of a Pyrex
glass batch reactor with a volume of 100 mL (2.5 cm in diameter and 20 cm of
height), equipped with a UVP Pen-Ray Lamp of mercury of 5.5 W UV light (UVP)
placed inside at the center of reactor. This lamp emits primary energy at 254 nm with
a typical intensity of 4,400 μW/cm
2 and uses a UVP Pen-Ray power supply of
115 V/60 Hz. Also, there was inside the reactor an electrode Boeco Germany BA
17 connected to a pH meter accumet XL15, Fisher Scientific. Stirring was conducted
using a magnetic stirrer and temperature was kept constant with a water bath. The
Photo-Fenton Treatment of a Pharmaceutical Industrial Effluent Under Safe pH. . .
247