Scholarly article on topic 'Suspended Solid, Color, COD and Oil and Grease Removal from Biodiesel Wastewater by Coagulation and Flocculation Processes'

Suspended Solid, Color, COD and Oil and Grease Removal from Biodiesel Wastewater by Coagulation and Flocculation Processes Academic research paper on "Agriculture, forestry, and fisheries"

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Abstract of research paper on Agriculture, forestry, and fisheries, author of scientific article — Zawawi Daud, Halizah Awang, Ab Aziz Abdul Latif, Nazlizan Nasir, Mohd Baharudin Ridzuan, et al.

Abstract Coagulation and flocculation are essential processes in a number of diverse disciplines, including biochemistry, cheese manufacturing, rubber manufacturing, and in water and waste water treatment. Coagulation-flocculation is effective for removing high concentration organic pollutants and heavy metals in water and wastewater. However, limited information exists on the efficiency of this coagulation-flocculation process for biodiesel wastewater treatment. The biodiesel wastewater is basic (alkaline), with a high content of oil and grease, and a low content of nitrogen and phosphorus. As such, biological treatment of the biodiesel wastewater is expected to be very difficult. For this reason supportive physic-chemical methods are often used. Although one of the most frequently employed method is coagulation. Therefore, this study was conducted to investigate the efficiency of coagulation and flocculation processes for removing suspended solid (SS), color, COD and oil and grease from biodiesel wastewater. Aluminum sulfate, polyaluminum chloride, ferric chloride and ferric sulfate as a coagulant in biodiesel wastewater treatment were studied using a standard jar test apparatus. The result shows that, at the optimum dose of PAC (300mg/L), the percentage removal of SS, color, COD and oil and grease respectively 97%, 95%, 75% and 97% compared to only 92%, 92%, 53% and 99% at the optimal dose alum (500mg/L), 95%, 93%, 63% and 97% at the optimum dose of ferric chloride (350mg/L) and 88%, 88%, 54% and 94% at the optimum dose of ferric sulfate (450mg/L). The effect of coagulant dosages on suspended solid (SS), color, COD and oil and grease removal showed similar trend and PAC was found to be superior was observed at reasonable lower amount of coagulant i.e. 300mg/L. The results showed that coagulation-flocculation is effective as a pre-treatment for treating biodiesel wastewater.

Academic research paper on topic "Suspended Solid, Color, COD and Oil and Grease Removal from Biodiesel Wastewater by Coagulation and Flocculation Processes"

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Procedia - Social and Behavioral Sciences 195 (2015) 2407 - 2411

World Conference on Technology, Innovation and Entrepreneurship

Suspended Solid, Color, COD and Oil and Grease Removal from Biodiesel Wastewater by Coagulation and Flocculation Processes

Zawawi Daud*a Halizah Awangb Ab Aziz Abdul Latif Nazlizan Nasira Mohd Baharudin Ridzuana Zulkifli Ahmada

aFaculty of Civil and Environmental Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Batu Pahat, Johor, Malaysia bFaculty of Technical and Vocational Education, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Batu Pahat, Johor, Malaysia

Abstract

Coagulation and flocculation are essential processes in a number of diverse disciplines, including biochemistry, cheese manufacturing, rubber manufacturing, and in water and waste water treatment. Coagulation-flocculation is effective for removing high concentration organic pollutants and heavy metals in water and wastewater. However, limited information exists on the efficiency of this coagulation-flocculation process for biodiesel wastewater treatment. The biodiesel wastewater is basic (alkaline), with a high content of oil and grease, and a low content of nitrogen and phosphorus. As such, biological treatment of the biodiesel wastewater is expected to be very difficult. For this reason supportive physic-chemical methods are often used. Although one of the most frequently employed method is coagulation. Therefore, this study was conducted to investigate the efficiency of coagulation and flocculation processes for removing suspended solid (SS), color, COD and oil and grease from biodiesel wastewater. Aluminum sulfate, polyaluminum chloride, ferric chloride and ferric sulfate as a coagulant in biodiesel wastewater treatment were studied using a standard jar test apparatus. The result shows that, at the optimum dose of PAC (300 mg/L), the percentage removal of SS, color, COD and oil and grease respectively 97%, 95%, 75% and 97% compared to only 92%, 92%, 53% and 99% at the optimal dose alum (500mg/L), 95%, 93%, 63% and 97% at the optimum dose of ferric chloride (350 mg/L) and 88%, 88%, 54% and 94% at the optimum dose of ferric sulfate (450 mg/L). The effect of coagulant dosages on suspended solid (SS), color, COD and oil and grease removal showed similar trend and PAC was found to be superior was observed at reasonable lower amount of coagulant i.e. 300 mg/L. The results showed that coagulation-flocculation is effective as a pre-treatment for treating biodiesel wastewater.

© 2015TheAuthors. Publishedby ElsevierLtd. This is an open access article under the CC BY-NC-ND license

(http://creativecommons.Org/licenses/by-nc-nd/4.0/).

Peer-review under responsibility of Istanbul Univeristy.

Keywords: Biodiesel wastewater; Coagulation-flocculation; Coagulant

Corresponding author. Tel.: +607-4564460 E-mail address: zawawi@uthm.edu.my

1877-0428 © 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

(http://creativecommons.org/licenses/by-nc-nd/4.0/).

Peer-review under responsibility of Istanbul Univeristy.

doi: 10.1016/j.sbspro.2015.06.234

1. Introduction

Since fossil fuels such as petroleum, natural gas and coal are non-renewable and limited together with the increasing energy demands of the present day, there is an increasing urgency to search for new sustainable and renewable power sources that can produce a sufficient quantity of power with acceptable safety (environmental and human), efficiency and reliability criteria (Ngamlerdpokin et al., 2011). Biodiesel has recently attached much attention, given that it has various advantages (Rattanapan, Sawain, Suksaroj & Suksaroj, 2011). It provides an alternative to petroleum- based fuel, it is renewable and non-toxic fuel, it allows a favorable energy balance, biodegradable, nontoxic, burns with a low sulphur, carbon monoxide and aromatic-free emission profile and it is fewer harmful emissions (Jaruwat, Kongjao, & Hunsom, 2010; Rattanapan et al., 2011).Biodiesel is produced from the transesterification reaction of triglycerides from vegetable oils or fats with alcohols like methanol and ethanol in the presence of a homogenous base catalyst like NaOH or KOH to yield fatty acid alkyl esters (i.e., biodiesel) and glycerol (Rattanapan, Sawain, Suksaroj & Suksaroj, 2011). In the final process of biodiesel production, water is usually introduced into the biodiesel to remove impurities such as suspended matter and catalysts present in it (Chavalparit & Ongwandee, 2009; Mohana, Gowda, Pramila, & Prasanna, 2011). This washing step is repeated 2-5 times dependent on the quantity of impurities in the methyl ester. A large amount of wastewater, 20-120 liters per 100 liters of biodiesel, is generated in this process (Chavalparit & Ongwandee, 2009).The biodiesel wastewater was dark yellowish cream in color, highly turbid, pungent smelling and has high organic load as seeds are used as a chief raw material in the production, with high levels of chemical oxygen demand, biological oxygen demand, oil, high suspended and dissolved solids, high amount of sodium, nitrogen, phosphorus and potassium content (Mohana et al., 2011). As such, biological treatment of the biodiesel wastewater is expected to be very difficult (Suehara et al., 2005; Chavalparit & Ongwandee, 2009). For this reason supportive physic-chemical methods are often used. Although one of the most frequently employed method is coagulation.Coagulation/flocculation is a commonly used process in water and wastewater treatment in which compounds such as coagulant are added to wastewater in order to destabilize the colloidal materials and cause the small particles to agglomerate into larger settleable flocs (Aygun & Yilmaz, 2010). Aim of this study was to determine efficiency of coagulation/flocculation process for the removal of suspended solids (SS), color, COD and oil and grease (O&G) from biodiesel wastewater using Aluminum sulfate, polyaluminum chloride, ferric chloride and ferric sulfate. This study also investigates optimum coagulant dosage on the coagulant process. The optimization of these factors may significantly increase the process coagulation and flocculation efficiency.

2. Material and Method

2.1. Wastewater

Biodiesel wastewater was used as feed in this study. It was collected from UTHM Biodiesel Pilot Plant which is situated in University Tun Hussein Onn Malaysia. This Plant uses palm oil as a feedstock and alkali-catalyzed transesterification process. The sample then kept in a cold room at temperature of 4°C to avoid further biodegradation. The characteristic of this biodiesel wastewater were analyzed according to the standard methods for examination of water and wastewaters (APHA, AWWA & WEF, 2012) are shown in Table 1.

Table 1. Biodiesel wastewater Characteristic.

Characteristic

COD SS

Oil and grease

mg/L mg/L PtCo mg/L

4.5- 5.5

2.2 Experimental Set-up

Coagulation and flocculation studied were performed in standard jar-test apparatus, Jar Tester Model CZ150 comprises of six paddle motors (24.5mm x 63.5mm), equipped with 6 beakers of 1 liter volume. Twelve beakers positioned on magnetic stirrer and specified dosage of coagulant. The pH value of 500 milliliter biodiesel wastewater sample was adjusted to pH 7 respectively, by using 1.0 M H2SO4 or 1.0 M NaOH. 50,100,150, 200, 250, 300, 350, 400, 450, 500, 550 and 600 mg/L coagulant such as aluminum sulfate was added to 500 mililiter biodiesel wastewater sample. After rapid mixing for 4 min at 150 rpm and slow mixing for 20 min at 20rpm, the liquid was clarified for 30 min, then the supernatant was withdrawn from a point located about 2cm below the top of the liquid level of the beaker to determined COD, SS, color, and oil and grease (O&G) by using standard methods (APHA, AWWA & WEF, 2012) so that the effect of coagulant dosage could be studied. This experiment is repeated for the other coagulant (polyaluminum chloride, ferric chloride and ferric sulfate).

2.3 Sampling and Analysis

Analyses undertaken in triplicates. The pH measured by pH meter (Cyberscan 20), while oil and grease measured according standard method 1164, EPA. Suspended solid, color and COD measured by DR 5000 HACH spectrophotometer that is adapted from Standard Method for Water and wastewater. All water color measures described in this work report as true color values using the platinum-cobalt (Pt-Co) method, the unit of color being that produced by 1 mg platinum/L in the form of the chloroplatinate ion (APHA, AWWA & WEF, 2012). The samples were filtered using 0.45^m filter paper before colors were measured.

3. Result and Discussion

Dosage was one of the most important parameters that been considered to determine the optimum condition for the performance of coagulant in coagulation and flocculation. Basically, insufficient dosage or overdosing would result in the poor performance in flocculation (Hassan, Tan, & Noor, 2009). Therefore, it was crucial to determine the optimum dosage in order to minimize the dosing cost and obtain the optimum performance in treatment. The optimum dosage of coagulant is defined as a value above which there is no significant increase in removal efficiency with further addition of the coagulant (Zainol, Aziz, Yusoff, & Umar, 2011).

Each type of coagulant has its own optimal dose range. A coagulant is defined as the substance or chemical that is added into water to begin and accomplish the coagulation-flocculation process (Zainol et al., 2011). The effect of dosage was analyzed at pH 7, rapid mixing for 4 min at 150 rpm and slow mixing for 20 min at 20rpm and 30 minutes of settling time for a range of coagulant dosage which varied from 50,100,150, 200, 250, 300, 350, 400, 450, 500, 550 and 600 mg/L coagulant.The results of the effects of different dosages of aluminum sulfate, polyaluminum chloride, ferric chloride and ferric sulfate as coagulant on the removal of SS, color, COD and oil and grease in biodiesel wastewater are as presented in Fig. 1. Fig. 1, Fig. 2, Fig. 3 and Fig. 4 respectively. The results showed that PAC provides removal more effective than other coagulant. The optimum dose for the PAC, alum, ferric chloride and ferric sulfate respectively at 300 mg / L, 500mg / L, 350 mg / L and 450 mg / L. PAC poses a good structure and higher charge density which leads to decrease in dosage requirements and hence lesser sludge production (Zainol et al., 2011).Percentage removal of SS, color, COD and oil and grease, respectively 97%, 95%, 81% and 97% of PAC, 92%, 92%, 53% and 99% of alum, 95%, 93%, 63% and 98% of ferric chloride and 88%, 88%, 54% and 94% for ferric sulphate at the optimum dosage. Results showed that the removal increased with an increase in coagulant dosage until it reached an optimum value, the removal started to decrease. This could be attributed by the restabilization of colloidal particulates when coagulants were used at dosages in excess of the optimum value (Aygun & Yilmaz, 2010). With the addition of larger dosage of the coagulant, the surface charge of the particles gets reversed due to continued adsorption of mono- and polynuclear hydrolysis species of coagulant. As

the colloidal particles become positively charged, they cannot be removed by perikinetic flocculation (Verma, Prasad, & Mishra, 2010).

Fig. 1 Percentage Of SS Removal Against Coagulant Dosage.

Fig. 2 Percentage Of Color Removal Against Coagulant Dosage.

Fig. 3 Percentage Of COD Removals Against Coagulant Dosage.

Fig. 4 Percentage Of COD Removals Against Coagulant Dosage.

4. Conclusion

This study has shown that coagulation and flocculation is a useful method as a pre-treatment of biodiesel wastewater. Coagulation and Flocculation is very effective in the suspended solids, color, and Oil and Grease removal and moderately effective in the COD removal of the biodiesel wastewater. Polyaluminum chloride was superior to other coagulant at 300 mg/l, removal of suspended solids, color, COD and Oil and Grease. In order to achieve better percentage removal for COD, suspended solids, color and oil and grease, further treatment is needed.

Acknowledgements

The authors would like acknowledgment the Ministry of Higher Education Malaysia and University Tun Hussein Onn Malaysia (UTHM) for financially supporting this study.

References

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Abu Hassan, M. A., Tan, P. L., & Zainon Noor, Z. (2009). Coagulation and Flocculation Treatment of Wastewater in Textile Industry Using

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