**2. Assessment of production activities that leads to the generation of wastewater in the selected industries**

To determine wastewater characteristics, generation disposal processes and assessment of production activities that lead to wastewater generation within the

### *Adsorption Technique an Alternative Treatment for Polycyclic Aromatic Hydrocarbon (PAHs)… DOI: http://dx.doi.org/10.5772/intechopen.104789*

pharmaceutical and petroleum industries were conducted through interviews, observation, and experimental analysis. From the information gathered, most pharmaceutical industries in a country located in West Africa produced more syrups than any other form of drugs because it is cheaper to produce. Production of syrups takes more than 50% of production water and an average of 48,000 L of water per day is being discharged as effluent during the production of syrups. Syrups can be analgesic, antacids, or pain relievers. Effluent discharge may contain codeine phosphate, paracetamol, chlorpheniramine maleate, ephedrine HCl, parabens, etc. which are regarded as active pharmaceutical compounds. PAHs and PCBs can be found within the effluent as a result of chemical metabolites. Most of the pharmaceutical industries around the States visited in that country discharge their effluents through the drains into the surface water.

The petroleum industries visited were located within the Delta area of the country. The industries have two sources of liquid waste which are produced water and water pollutant with crude spills. Averagely about 30 million barrels of produced water are said to be discharged per day into the environment. Most of the oil and gas industries in the Delta region utilize the common treatment technique like the Induced Gas Flotation (IGF) or the Induced Air Flotation called WEMCO with the Enviro-cell as the latest technology of the group. The orthodox separation technique used the standard of gravity with variances in density between oil and water.

The oil and grease in the produced water can be classified as free, dispersed, and dissolved oil [21, 22]. The conventional method is seen to be effective in the removal of dispersed oil and grease and cannot be used in the removal of the dissolved oil and grease which are the PAHS (**Figure 1**).

### **2.1 Production of local Adsorbent using local Technology**

The production of local adsorbent from the natural agricultural material using local Technology is a crucial alternative to commercial absorbent since adsorbent is used in carrying out adsorption which is better than any other wastewater treatment methods due to its insensitivity to toxic substances and economically

**Figure 1.** *Concentrations of oil and grease in produced water at different days of sampling.*

based on types of materials employed as adsorbents [37]. But, the complete use of adsorption processes in purifying water is impeded by the insufficiencies of the commercial adsorbents like activated carbon and synthetic polymer resins, synthetic Nanomaterial. Hence, there is a need to develop a low-cost adsorbent for environmental research. So the adsorbent of agricultural products is becoming the popular alternative for commercial and synthetic adsorbents due to the hydrophobic-oleophilic potential that is needed for bioremediation processes [38]. The Activated Charcoal which is also known as activated carbon is a kind of carbon treated under heat to be extremely porous as processes very large surface area making room for adsorption or chemical reactions [39]. The activated carbons that are employed were formed from two different species of fresh bamboo culms that were cut at the height of 20 cm from the soil level and were chopped into 20 cm each as the peripheral materials were detached. The chopped bamboo culms were left to dry at the normal ambient temperature of 26-28°C and later cut down to 5 cm. The bamboo species were weighted and the aluminum foil was used to tightly cover in preparation for carbonization, the wrapping with the foil was done to complete deoxygenated processes. It was carbonized at 350°C for 2 hrs in an electric muffle furnace. Carbons were cooled and oven-dried at 105°C for 360 min. The carbonated samples were granulated and sieved to 1.18 m size and stored. Activation was done with Phosphoric acid (H3PO4) and Potassium chloride (KCl) as dehydrating agents. 26.25w/w of activator was used in the activation of the carbonated samples. Characterization was done chemically using Point of zero charge (pH pzc) and The Scanning Electron Microscopy (SEM) was used to view the surface structure of the samples at a magnification of 100, 300, 500, 2000, and 5000 times the original size to view the pore space development and reveal other information such as texture (external morphology) and structural orientation see **Figure 2** [10]. The point of zero charge (pH pzc) was used for further determination of pore and adsorption capacity. The point of zero charge is the point where the pH of the net total particle charge is zero. It is important in describing variable charge surface and it indicates the approximation equilibrium time at which the carbon is required to adsorb. Points of zero charge of the adsorbents were determined by measuring 20 ml of 0.01 m Nacl solutions into 9 separate beakers. The pH of each solution was adjusted to between 2 and 10 by adding 0.1 M of HCl or NaOH solution to each of the flasks. The flasks were thereafter placed in a water bath shaker at 25°C. The suspensions were agitated for 30 min and allowed to equilibrate for 48 hrs to ensure equilibrium point (pH pzc) after which the final pH(s) were measured see **Figure 3**. The differences between the initial and final were calculated as:

$$
\Delta pH = pH\_i - pH\_f \tag{1}
$$

Where ∆*pH* = Change in pH, *pHi* = Initial pH, and *pHf* = Final pH.

The values of changes in pH were then plotted against the initial pH values. From **Figure 3** above the pH pzc for carbon activated with salt is greater than pH value of the activated with acid, i.e., pH pzc < pHi COA KCl and pH pzc for CBV H3PO4 is lower than that pHi implying that pH > pH pzc This implies that the surfaces of these carbons are positively charged and this arises from the basic site that combines with protons from the medium. These results also confirmed [40, 41] *Adsorption Technique an Alternative Treatment for Polycyclic Aromatic Hydrocarbon (PAHs)… DOI: http://dx.doi.org/10.5772/intechopen.104789*

**Figure 2.** *SEM image of (a) CBV 350°C H3PO4 and (b) COA 350°C KCl at magnification of 2000.*

**Figure 3.**

*Potentiometric titration curves (pH pzc) for CBV H3PO4 and COA KCl.*

studies that a positive surface charged adsorbent would strongly attract to acidic compound in any polluted water, while a negative surface charge would strongly attract pollutant in a natural media.

### **2.2 Adsorption of PAH and PhACs from industrial wastewater**

The behavior of Adsorption for PhACs in pharmaceutical effluents and polycyclic aromatic hydrocarbon (PAHs) in petroleum wastewater onto activated carbon produced from bamboo was studied in a batch process. Experiments were done at room temperature and the adsorption efficiency of activated carbon made from bamboo was determined using contact time. Half a liter of Pharmaceutical effluent was poured into conical flasks with a capacity of 600 ml. Selected bamboo activated carbon of two grammes each was weighed into conical flasks to make an adsorbent/solute solution. Solutions were mixed at a stirring speed of 160 rpm to ensure propped contact of the adsorbent and solute in the solution. 6 hrs contact time was used to observe each solution before reaching a dynamic equilibrium. Thereafter, solutions were filtered with filter paper 0.45 μm size. 300 ml filtrate was poured into sampling bottles with a tie cap sealed with aluminum foils and kept at a temperature of 4°C for further analysis of extraction, clean-up, and Vis-UV. For accuracy, all experimental analysis was repeated. Similarly, 200 ml of petroleum wastewater simulated, was poured into different conical flasks of 250 ml capacity. 1 g of each selected bamboo activated carbon was weighed into the conical flasks to form an adsorbent/solute solution. Solutions were mixed at a stirring speed of 160 rpm to ensure propped contact of the adsorbent and solute in solution while observing each solution in equilibrium for 5 hrs contact-time

to attain dynamic equilibrium. After 5 hrs of clean up and solutions were filtered with filter paper 0.45 μm and the filtrate of 150 ml was poured into amber bottles with a Teflon cap and kept at a temperature of 4°C for further analysis of and extraction were done before analying with GC-MS. The 5 hrs contact time was informed based on the experiment performed at the terminal station of the oil and gas industry. To obtain accuracy, all experimental analysis was duplicated [10]. The amount of PhACs (qe) and PAHs (qe) adsorbed by bamboo activated carbons can be expressed mathematically as:

$$qe = ((Co-Ce)/M) \times v \tag{2}$$

The percentage removal is evaluated using.

$$\text{96\getsRecall} = \text{((Co} - \text{Ce}) \, / \, M \,\text{)} \times \text{100} \tag{3}$$

Where V is the volume of PAHs and PhACs in solution (L), Co is initial concentrations of PAHs and PhACs ( <sup>−</sup><sup>1</sup> *mg L* ), Ce is equilibrium concentrations of PAHs and PhACs ( <sup>−</sup><sup>1</sup> *mg L* ), M is the mass of the adsorbent (g).

The Spectra in **Figure 4** shows, 16 priority PAHs in Simulated Petroleum wastewater. The efficiency of adsorbent based on contact time in the removal of PAHs from simulated petroleum wastewater by COA KCl and CBV H3PO4 are stated in **Figures 5** and **6**. The various contact times used were 30 min, 2 hrs, and 12 hrs, and there were otnotany changes differences in the adsorption rate with time. It was deduced that the percentage removal efficiency of PAHs with time by COA KCl was not consistent. At 30 min of adsorption rate; the percentage removal efficiency was 49.8% of total PAHs, while 39.1% of total PAHs were adsorbed at 2 hrs and about 72.3% of total PAHs were adsorbed at 12 hrs contact time.

### **Figure 4.** *Spectra of 16 priority PAHs in Simulated Petroleum wastewater.*

*Adsorption Technique an Alternative Treatment for Polycyclic Aromatic Hydrocarbon (PAHs)… DOI: http://dx.doi.org/10.5772/intechopen.104789*

**Figure 6.**

*Effect of contact time on adsorption rate of PAHs by CBVH3PO4 at (a) 30 mins, (b) 2 hrs and (c) 12 hrs.*

Also, the adsorption rate of PAHs by CBV H3PO4 was seen not to follow the adsorption pattern wherein the adsorption rate increased with time. About 85.1% was adsorbed at 30 min; with an increase in contact time to 2 hrs its shows a reduction in adsorption rate to 25.1% but a further increase in time to 12 hrs increases adsorption efficiency to 87.7% which is the maximal contact time for CBV H3PO4 in adsorbing PAHs. It was deduced that adsorption patterns do not follow the norms of adsorption, hence adsorption of PAHs is in two stages. In the first stage, the PAHs were adsorbed easily onto the accessible hydrophobic site within the adsorbent or granular activated carbon matrix for the first 30 min. These may have resulted from the chemical interaction between the PAHs and the adsorbent. The reduction in adsorption rate implies that in the second stage, the adsorption rate may be restricted by the slow movement of PAHs to less available sites associated with the microspores within the adsorbents matrix which could take hours [10].

**Figure 7a-c** revealed the adsorption trend of PhACs, it was deduced that a slight reduction of adsorption rate was observed before an increase after which equilibrium was observed for COA KCl adsorbent. Similarly, the adsorption trend of CBV H3PO4 shows a sharp reduction to a level, and thereafter an increase was seen before an equilibrium point was reached. These observations are similar to [42–45] findings. It can be explained that absorption of PhACs with COA KCl and CBV H3PO4 occurred in two different stages. The first stage occurred during the first 30-360mins

**Figure 7.** *(a-c). Effect of contact time on adsorption rate of PhACs by COA KCl and CBVH3PO4 at 30, 180, 360, 720, and 1440 mins.*

*Adsorption Technique an Alternative Treatment for Polycyclic Aromatic Hydrocarbon (PAHs)… DOI: http://dx.doi.org/10.5772/intechopen.104789*

contact time, with a high number of active binding sites on the adsorbent's surfaces. The adsorption rate is rapid in this stage and the points to adsorption are being controlled by diffusion processes of paracetamol, salbutamol, and chlorpheniramine molecules from the bulk phase to the adsorbent surface. The second stage of adsorption is an attachment-controlled process due to a decrease in the number of the active sites available for Paracetamol, salbutamol, and chlorpheniramine. Adsorptions graphs showing the rate and removal efficiency of PhACs by COA KCl and CBV H3PO4 at varying contact times of 30, 180, 360, 720, and 1440 min are shown below.

### **3. Conclusion**

The ever-growing human population cannot do without water; hence clean water becomes a critical issue. Therefore, the various conventional ways of treating water have been established by existing researchers, most of which are said to be inadequate in the removal of organic contaminants. This study showed that adsorbents made from Oxytenanthera Abyssinia and Bambusa vulgaris can efficiently adsorb selected PhACs and PAHs in industrial Contaminated Water. *Oxytenanthera abyssinica* (COA 350°C KCl) had a Removal efficiency of (73.3%, 78.1%, and 86.2%) for PhACs while *B. vulgaris* (CBV 350°C H3PO4) had (63.9%, 66.7%, and 82.2%) in remediating Pharmaceutical actives contaminants such as paracetamol, salbutamol, and chlorpheniramine, respectively. For polycyclic aromatic hydrocarbons (PAHs) Removal efficiency of COA and CBV ranged from 42.5–81.2% and 8.9–65.5% respectively. The adsorption mechanism of trace organics followed the same pattern though with little differences. For all organic pollutants, adsorption rate is in two stages viz.: optimization and reduction followed by equilibrium. In comparison, COA showed the highest removal efficiency for PhACs and PAHs. The characterization of the adsorbent developed from agricultural materials was also revealed by Scanning Electron Microscopy (SEM) and point of zero charge (pH pzc)

### **Acknowledgements**

The author expresses her heart of gratitude to all organizations and industries that afford her access to their facilities and environment to carry out the study.
