**3. Techniques for treatment of pharmaceutical wastewater**

#### **3.1 Adsorption technique**

The efficiency of adsorption process is studied by numerous workers for treatment of wastewater containing varieties of drugs. Especially the porosity and surface area of adsorbent shows the extent of adsorption [19]. Dutta et al. [21] reported that both adsorption and desorption efficiency of 6-aminopenicillanic acid (6-APA) in aqueous effluent using activated carbon as an adsorbent was found to be 93% and the process is highly reversible in nature. About greater than 90% of oestrogens is removed from both powdered activated carbon (PAC) (5 mg/L) and granular activated carbon (GAC) can remove [22]. However, dissolved organic compounds (DOC), surfactants and humic acids participate with binding sites to block the pores within activated carbon structures [22]. A filtration step is important to increase removal efficiency before treating micro pollutants using PAC [23, 24].

High molecular weight compounds reduce the blocking of micropores that leads to decrease in carbon demand. Thus, PAC will be suitable for the treatment of pretreated effluent with a low organic loading [23]. Separation of fine carbon particles is the general difficulty with PAC treatment. An additional step of separation is usually needed such as sedimentation, which necessitates the use of precipitants, or via (membrane) filtration.

#### **3.2 Membranes processes**

Membrane-based separation methods like MBR (membrane bioreactor), MBR/RO (MBR followed by reverse osmosis) and UF/RO (ultra-filtration followed by RO) are used for the removal of PhACs from wastewater [22]. Maeng et al. [25] suggested that PhACs like ibuprofen, naproxen, caffeine and acetaminophen and can be expressively removed using MBR and the degradation efficiency can be as high as 82%. However, the adaptation of microorganisms to less degradable compounds can occur due to its enhanced sludge retention time (SRT) in MBRs. MBR treatment has a better performance (removal >80%) than the conventional processes for diclofenac, ketoprofen, ranitidine, gemfibrozil, bezafibrate, pravastatin and ofloxacin. Chang et al. [17] obtained about 95% COD and 99% BOD reduction from a 10 m3 per day capacity MBR operated at a pharmaceutical facility. Nano filtration (NF) and RO membranes are more efficient in eliminating PhACs having different physico-chemical properties. The removal using NF is mostly over 85%, except for gemfibrozil (50.2%), bezafibrate (71.8%), atenolol (66.6%), mefenamic acid (30.2%) and acetaminophen (43%) [26]. Short circuiting of membrane or failure of membrane support is responsible for the reduction of permeate quality. However, the retentate must be treated further to degrade the more concentrated form of PhACs.

**359**

*Fate and Occurrences of Pharmaceuticals and Their Remediation from Aquatic Environment*

These processes use to remove contaminants by assimilating them and it has long been a support of wastewater treatment in chemical industries using bacteria and other microorganisms. In any biological system, the main factor is the supply of an adequate oxygen as cells need not only organic materials as food but also oxygen to breathe. A wide range of natural and xenobiotic chemicals in pharmaceutical wastewater are recalcitrant and non-biodegradable in nature. Anaerobic processes are not always effective in removing such substances [23]. Conventional activated sludge treatment (AST) with a long hydraulic retention time (HRT) generally is the choice for pharmaceutical industry wastewater [27]. It needs a lower capital cost than advanced treatment methods and a limited operational requirement. However, it suffers from the production of large amounts of sludge [22]. Removal efficiencies are decreased due to development of more resistant microorganisms towards many PhACs [28]. Ibuprofen, naproxen, bezafibrate and estrogens (estrone, estradiol and ethinylestradiol) showed a high degree of removal while sulfamethoxazole, carbamezapine and diclofenac displayed limited removal efficiency [29]. A few studies are carried out using sequence batch reactors (SBRs) and MBRs to improve the efficiency of AST [29]. Ileri et al. [30] achieved removal efficiency of 82% biochemical oxygen demand (BOD), 88% chemical oxygen demand (COD), 96% NH3 and 98% suspended solids (SS) from domestic and pharmaceutical wastewater in a SBR operated for 4 h aeration followed by 60 min sedimentation. In another study, slightly lower COD removal efficiencies between 63 and 69% are reported [31]. MBRs are known to be effective for the removal of bulk organics and can replace traditional methods when operated in combination with a conventional AST [32]. The main advantage of MBRs over AST is that they require less space and can also treat variable wastewater compositions [17]. Biologically active filters are also used

for pharmaceutical wastewater treatment and can remove PhACs [33].

that species react with dissolved oxygen to form peroxyl (ROO•

Advanced Oxidation Processes (AOPs) those are generating the very reactive

organic compounds. The pollutants and by-products are degraded through a series

through electron transfer leading to formation of organic intermediates and after

undergo rapid decomposition. The overall process leads to partial or total mineral-

Fenton's reagent, a mixture of Fe2+ (catalyst) and hydrogen peroxide (H2O2)

mechanism of FP is studied by several workers [17, 35]. The main reactions occur-

2 3• Fe H O Fe OH HO 2 2

<sup>+</sup> + − + →+ + (1)

2 •3 Fe HO Fe OH <sup>+</sup> + − +→+ (2)

• • HO RH H O R +→ + <sup>2</sup> (3)

radical, a strong oxidizing agent (E0

ring in Fenton oxidation of organics are appended bellow (Eqs. 1–4):

) which are able to react with most of the

radicals react with organic compounds

) radicals which

= 2.8 vs. NHS). The

**3.4 Advanced oxidation processes (AOPs)**

radicals, such as hydroxyl radicals (HO•

ization of pollutants [34].

*3.4.1 Fenton processes (FP)*

which produces HO•

of complex reactions. In the first step, HO•

*DOI: http://dx.doi.org/10.5772/intechopen.94984*

**3.3 Biological treatment**

*Fate and Occurrences of Pharmaceuticals and Their Remediation from Aquatic Environment DOI: http://dx.doi.org/10.5772/intechopen.94984*

### **3.3 Biological treatment**

*Environmental Issues and Sustainable Development*

industry wastewater are shown in **Table 2**.

**3.1 Adsorption technique**

via (membrane) filtration.

**3.2 Membranes processes**

COD and 99% BOD reduction from a 10 m3

further to degrade the more concentrated form of PhACs.

Due to incomplete elimination pharmaceutical products, the residues of these products can enter the aquatic environment [19]. The typical concentration of PhACs in water and solid wastes is summarized in **Table 1**. However, the concentration in untreated industrial wastewater varies from ppb to ppm levels. Different pathways for initiation of pharmaceuticals and their metabolites in the environment are shown in **Figure 1**. The typical values of different parameters of pharmaceutical

The efficiency of adsorption process is studied by numerous workers for treatment of wastewater containing varieties of drugs. Especially the porosity and surface area of adsorbent shows the extent of adsorption [19]. Dutta et al. [21] reported that both adsorption and desorption efficiency of 6-aminopenicillanic acid (6-APA) in aqueous effluent using activated carbon as an adsorbent was found to be 93% and the process is highly reversible in nature. About greater than 90% of oestrogens is removed from both powdered activated carbon (PAC) (5 mg/L) and granular activated carbon (GAC) can remove [22]. However, dissolved organic compounds (DOC), surfactants and humic acids participate with binding sites to block the pores within activated carbon structures [22]. A filtration step is important to increase removal efficiency before treating micro pollutants using PAC [23, 24].

High molecular weight compounds reduce the blocking of micropores that leads to decrease in carbon demand. Thus, PAC will be suitable for the treatment of pretreated effluent with a low organic loading [23]. Separation of fine carbon particles is the general difficulty with PAC treatment. An additional step of separation is usually needed such as sedimentation, which necessitates the use of precipitants, or

Membrane-based separation methods like MBR (membrane bioreactor), MBR/RO (MBR followed by reverse osmosis) and UF/RO (ultra-filtration followed by RO) are used for the removal of PhACs from wastewater [22]. Maeng et al. [25] suggested that PhACs like ibuprofen, naproxen, caffeine and acetaminophen and can be expressively removed using MBR and the degradation efficiency can be as high as 82%. However, the adaptation of microorganisms to less degradable compounds can occur due to its enhanced sludge retention time (SRT) in MBRs. MBR treatment has a better performance (removal >80%) than the conventional processes for diclofenac, ketoprofen, ranitidine, gemfibrozil, bezafibrate, pravastatin and ofloxacin. Chang et al. [17] obtained about 95%

a pharmaceutical facility. Nano filtration (NF) and RO membranes are more efficient in eliminating PhACs having different physico-chemical properties. The removal using NF is mostly over 85%, except for gemfibrozil (50.2%), bezafibrate (71.8%), atenolol (66.6%), mefenamic acid (30.2%) and acetaminophen (43%) [26]. Short circuiting of membrane or failure of membrane support is responsible for the reduction of permeate quality. However, the retentate must be treated

per day capacity MBR operated at

**3. Techniques for treatment of pharmaceutical wastewater**

**2.3 Surface water and ground water**

**358**

These processes use to remove contaminants by assimilating them and it has long been a support of wastewater treatment in chemical industries using bacteria and other microorganisms. In any biological system, the main factor is the supply of an adequate oxygen as cells need not only organic materials as food but also oxygen to breathe. A wide range of natural and xenobiotic chemicals in pharmaceutical wastewater are recalcitrant and non-biodegradable in nature. Anaerobic processes are not always effective in removing such substances [23]. Conventional activated sludge treatment (AST) with a long hydraulic retention time (HRT) generally is the choice for pharmaceutical industry wastewater [27]. It needs a lower capital cost than advanced treatment methods and a limited operational requirement. However, it suffers from the production of large amounts of sludge [22]. Removal efficiencies are decreased due to development of more resistant microorganisms towards many PhACs [28]. Ibuprofen, naproxen, bezafibrate and estrogens (estrone, estradiol and ethinylestradiol) showed a high degree of removal while sulfamethoxazole, carbamezapine and diclofenac displayed limited removal efficiency [29]. A few studies are carried out using sequence batch reactors (SBRs) and MBRs to improve the efficiency of AST [29]. Ileri et al. [30] achieved removal efficiency of 82% biochemical oxygen demand (BOD), 88% chemical oxygen demand (COD), 96% NH3 and 98% suspended solids (SS) from domestic and pharmaceutical wastewater in a SBR operated for 4 h aeration followed by 60 min sedimentation. In another study, slightly lower COD removal efficiencies between 63 and 69% are reported [31]. MBRs are known to be effective for the removal of bulk organics and can replace traditional methods when operated in combination with a conventional AST [32]. The main advantage of MBRs over AST is that they require less space and can also treat variable wastewater compositions [17]. Biologically active filters are also used for pharmaceutical wastewater treatment and can remove PhACs [33].

#### **3.4 Advanced oxidation processes (AOPs)**

Advanced Oxidation Processes (AOPs) those are generating the very reactive radicals, such as hydroxyl radicals (HO• ) which are able to react with most of the organic compounds. The pollutants and by-products are degraded through a series of complex reactions. In the first step, HO• radicals react with organic compounds through electron transfer leading to formation of organic intermediates and after that species react with dissolved oxygen to form peroxyl (ROO• ) radicals which undergo rapid decomposition. The overall process leads to partial or total mineralization of pollutants [34].

#### *3.4.1 Fenton processes (FP)*

Fenton's reagent, a mixture of Fe2+ (catalyst) and hydrogen peroxide (H2O2) which produces HO• radical, a strong oxidizing agent (E0 = 2.8 vs. NHS). The mechanism of FP is studied by several workers [17, 35]. The main reactions occurring in Fenton oxidation of organics are appended bellow (Eqs. 1–4):

$$\text{Fe}^{2+} + \text{H}\_2\text{O}\_2 \rightarrow \text{Fe}^{3+} + \text{OH}^- + \text{HO}^\* \tag{1}$$

$$\text{Fe}^{2+} + \text{HO}^{\bullet} \rightarrow \text{Fe}^{3+} + \text{OH}^{\bullet} \tag{2}$$

$$\text{HO}^\* + \text{RH} \rightarrow \text{H}\_2\text{O} + \text{R}^\* \tag{3}$$

$$\mathbf{R}^\* + \mathbf{F}\mathbf{e}^{3\*} \to \mathbf{R}^\* + \mathbf{F}\mathbf{e}^{2\*}\tag{4}$$

where, R• is alkyl free radical.

The major parameters like solution pH, amount of ferrous ion, concentration of H2O2, initial concentration of pollutants/ PhACs and presence of other background ions [36] that are affecting FP. The optimum pH for FP generally ranges from 2 to 4. At pH > 4, Fe2+ ions are unstable, and they are easily transformed to Fe3+ forming complexes with hydroxyl ion. Moreover, under alkaline conditions H2O2 loses its oxidative power as it breakdowns to water [17]. An effluent pH was Adjusted usually before addition of Fenton reagent. Increase of Fe2+ ions and H2O2 concentration boosts up the degradation rate [37]. The use of excess amount of H2O2 can deteriorate the overall degradation efficiency of FP coupled with biological treatment due to toxic nature of H2O2 to microorganisms [38]. Fenton oxidation of organics/ PhACs can be inhibited by PO4 3−, SO4 2−, F− , Br− and Cl− ions. The inhibition may be due to precipitation of iron, scavenging of HO• radicals or coordination with Fe3+ to form a less reactive complex [39].

## *3.4.2 Photo-Fenton processes (PFP)*

Photo-Fenton process (H2O2/Fe2+/UV) involves formation of HO• radicals through photolysis of hydrogen peroxide (H2O2/UV) by UV-irradiation along with the Fenton reaction (H2O2/Fe2+). In presence of UV irradiation, ferric ions (Fe3+) are also photo-catalytically converted to ferrous ions (Fe2+) with formation of additional HO• radicals (Eq. 5) [40].

$$\text{Fe(OH)}\_{2}^{\cdot \text{ } + \text{ hv} \rightarrow \text{Fe}^{2+} + \text{HO}^{\cdot}} \tag{5}$$

Likewise, PFP gives faster rates and higher degree of mineralization compared to conventional FP [39]. The reaction can be driven by low energy photons and it also can be achieved using solar irradiation [39]. The employment of solar light significantly reduces the operational cost. Another important advantage of PFP is that iron-organic complexes formed during Fenton oxidation can be broken under the illumination of UV light [41].
