In addition, wastewaters usually contain heavy metals such as Hg, Cd, Zn, Ni, Pb,
Cr, Co, and Cu that have long persistence in the environment. The improper disposal
of heavy metals in water bodies can lead to bioaccumulation by aquatic life and thus
affect the entire food chain (human)—cancer and/or pathogens infection (Gochfeld
2003; Hadzi et al. 2018). In this sense, according to Eggers et al. (2018), there is a
synergism among Pb and/or Cd content in blood and methicillin-resistant Staphylococcus aureus infection. Additionally, studies have shown a positive correlation
between virus infectivity (HAdV and HAV) and iron concentration in water
(Fongaro et al. 2019). Poole (2017) compiled more than 15 studies showing that in
the presence of metals such as Cu and Zn, bacteria develop a resistance mechanism
to these metals and simultaneously resistance to antibiotics.
Untreated wastewater can be a source of potentially pathogenic bacteria and
viruses that can lead to diseases as cholera, diarrhea, and dysentery. These diseases
are of strong concern not only due to the mortality and morbidity but also due to the
high cost to treat patients. Most problems are associated with infection, more
specifically Salmonella typhimurium, Vibrio cholerae, Legionella, Escherichia coli
O157:H7, Campylobacter jejuni, and viruses such as adenovirus, astrovirus, hepatitis A and E viruses, rotavirus, norovirus, and enterovirus (Ashbolt 2015; Haramoto
et al. 2018).
Other pollutants that have drawn attention recently are endocrine disruptors such
as antibiotic, antiviral, analgesic, anti-inflammatory, psychiatric drugs, residual
bioactive fractions of medicines, and personal care products (Santos et al. 2010;
Boxall et al. 2012; Tijani et al. 2016). Additionally, many of these compounds have
negative synergistic effects—broad environmental sense (Cizmas et al. 2015; Yu
et al. 2019).
The wastewater treatments of these pollutants, generally, are performed using
physical (sedimentation), chemical (coagulation-flocculation), and biological
methods (activated sludge, nitrification-denitrification) (Kumar and Pal 2015;
Whitton et al. 2015). These steps are sequential commonly: primary, secondary,
and tertiary treatments (Fig. 4.1).
4.3 Wastewater Treatment
Physical-chemical processes, such as coagulation-flocculation, are preliminary treatments that can be applied on sedimentation of suspended solids and organic matters.
After this process, the wastewater still contains considerable organic matter content
(Rao et al. 2012).
The secondary treatment step consists of biological process based on aerobic
and/or anaerobic metabolism of bacteria and/or fungi (biodegradation) (Tran et al.
2013). These processes occur in opened (lagoons) or closed reactors. After this
process, the wastewater passes through disinfection and/or polishing process before
disposal in the environment.
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W. Michelon et al.
Cr, Co, and Cu that have long persistence in the environment. The improper disposal
of heavy metals in water bodies can lead to bioaccumulation by aquatic life and thus
affect the entire food chain (human)—cancer and/or pathogens infection (Gochfeld
2003; Hadzi et al. 2018). In this sense, according to Eggers et al. (2018), there is a
synergism among Pb and/or Cd content in blood and methicillin-resistant Staphylococcus aureus infection. Additionally, studies have shown a positive correlation
between virus infectivity (HAdV and HAV) and iron concentration in water
(Fongaro et al. 2019). Poole (2017) compiled more than 15 studies showing that in
the presence of metals such as Cu and Zn, bacteria develop a resistance mechanism
to these metals and simultaneously resistance to antibiotics.
Untreated wastewater can be a source of potentially pathogenic bacteria and
viruses that can lead to diseases as cholera, diarrhea, and dysentery. These diseases
are of strong concern not only due to the mortality and morbidity but also due to the
high cost to treat patients. Most problems are associated with infection, more
specifically Salmonella typhimurium, Vibrio cholerae, Legionella, Escherichia coli
O157:H7, Campylobacter jejuni, and viruses such as adenovirus, astrovirus, hepatitis A and E viruses, rotavirus, norovirus, and enterovirus (Ashbolt 2015; Haramoto
et al. 2018).
Other pollutants that have drawn attention recently are endocrine disruptors such
as antibiotic, antiviral, analgesic, anti-inflammatory, psychiatric drugs, residual
bioactive fractions of medicines, and personal care products (Santos et al. 2010;
Boxall et al. 2012; Tijani et al. 2016). Additionally, many of these compounds have
negative synergistic effects—broad environmental sense (Cizmas et al. 2015; Yu
et al. 2019).
The wastewater treatments of these pollutants, generally, are performed using
physical (sedimentation), chemical (coagulation-flocculation), and biological
methods (activated sludge, nitrification-denitrification) (Kumar and Pal 2015;
Whitton et al. 2015). These steps are sequential commonly: primary, secondary,
and tertiary treatments (Fig. 4.1).
4.3 Wastewater Treatment
Physical-chemical processes, such as coagulation-flocculation, are preliminary treatments that can be applied on sedimentation of suspended solids and organic matters.
After this process, the wastewater still contains considerable organic matter content
(Rao et al. 2012).
The secondary treatment step consists of biological process based on aerobic
and/or anaerobic metabolism of bacteria and/or fungi (biodegradation) (Tran et al.
2013). These processes occur in opened (lagoons) or closed reactors. After this
process, the wastewater passes through disinfection and/or polishing process before
disposal in the environment.
104
W. Michelon et al.