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Effect of Substrate and Intermediate Composition on Foaming in Palm Oil Mill Effluent Anaerobic Digestion System
Available online at www.sciencedirect.com
ScienceDirect Energy Procedia 79 (2015) 930 – 936
y Procedia 00 (2015) 000–000
2015 International Conference on Alternative Energy in Developing Countries and Emerging Economies
Effect of Substrate and Intermediate Composition on Foaming in Palm Oil Mill Effluent Anaerobic Digestion System Nantharat Wongfaeda, Prawit Kongjanb, Sompong O-Thanga,c,d* a
Biotechnology Program, Faculty of Science, Thaksin University, Phatthalung, Thailand Department of Science, Faculty of Science and Technology, Prince of Songkla University, Pattani,Thailand c Research Center in Energy and Environment, Faculty of Science, Thaksin University, Phatthalung, Thailand d Research Group for Development of Microbial Hydrogen Production Process from Biomass, Khon Kaen University, Khon Kaen, Thailand b
Abstract Anaerobic digestion (AD) process is a widely applied method for biogas production and wastewater treatment of palm oil mill effluent (POME). AD foaming is one of the major problems that occasionally occur in many biogas plants, since it affects negatively the overall digestion process. The effect of individual substrates and intermediate compounds on foaming potential in POME anaerobic digestion systems was investigated. Effect of interaction of each compound was investigated by fractional factorial design and tested ,for foaming potential in both pure water, POME and POME under AD. The results showed increased concentration of substrate and intermediate compounds in waster could create more foaming tendency but not effect on foaming stability. Each compound in a complex mixture showed that BSA, Na+, lactic acid and cellulose has foaming tendency in water while no created foaming stability. Na-oleate and Na2+ showed strong foaming tendency while butyric acid, acetic acid, Mg2+, SDS, peptone, gelatine and BSA showed more effect on foaming stability in POME. In AD systems found that highest methane production about 11.15-15.95 L-CH4/L-POME and yield about 179.05-256.08 mL- CH4/g-VS added. BSA, gelatine, oil palm and lactic acid has highest foaming stability in AD systems. © Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license © 2015 2015The The Authors. Published by Elsevier Ltd. (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the Organizing Committee of 2015 AEDCEE Peer-review under responsibility of the Organizing Committee of 2015 AEDCEE
Keywords: palm oil mill effluent, anaerobic digestion , foaming tendency, foaming stability
* Corresponding author. Tel.: +66-74-693-992; fax: +66-74-693-992 E-mail address: [email protected]
1876-6102 © 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 the Organizing Committee of 2015 AEDCEE doi:10.1016/j.egypro.2015.11.589
Nantharat Wongfaed et al. / Energy Procedia 79 (2015) 930 – 936
1. Introduction The production of palm oil, results in the generation of large quantities of polluted wastewater commonly referred to as palm oil mill effluent (POME). Typically, 1 ton of crude palm oil production requires 5–7.5 ton of water; over 50% of which ends up as POME [1]. POME is a viscous, brownish liquid containing about 95–96% water, 0.6–0.7% oil and 4–5% total solids (including 2–4% SS, mainly debris from fruit). It is acidic (pH 4–5), hot (80–90 o C) with average chemical oxygen demand (COD) and biological oxygen demand (BOD) values of 50,000 mg/L and 25,000 mg/L, respectively and contains appreciable amounts of plant nutrients [2,3]. Since POME contains high level of organic matters and thus, adoption of anaerobic digestion in the first stage of the treatment process is a necessity to convert the bulk of the wastes to biogas. Biogas production yield from POME was ranged 46350 mL-CH4/g-VS with methane content of 45-67% and organic reduction of 65-90% [4-7]. However AD foaming is one of the major problems that occasionally occur in many biogas plants, since it affects negatively the overall digestion process [8]. Foaming can also result in an inverse solids profile having higher solids concentrations at the top of a digester, creation of dead zones and reduction of the active volume of the digester hence resulting in sludge, which has not received the same degree of stabilization [9-12]. So far, there has never been a thorough investigation of a foaming problem in a POME-based digester, which is the main anaerobic digestion technology used in Thailand. There is a need for investigation of the foaming causes in this system in order to find the method to avoid as well as to resolve the problem. This work aims to identify the potential causes of foaming in POME digesters. The specific compounds commonly present in a POME digester are investigated for their effects on foaming potential in POME. 2. Materials and Methods 2.1 Preparation of the feedstock POME and anaerobic digester sludge used in this study were collected from palm oil mill plant, in southern of Thailand. POME was stored at the temperature of 4 o C for later use. The characteristics of POME are presented in Table 1. Sludge was prepared active in a container closed by lid and there was a constant production of biogas before being used as the mixed culture. 2.2 Physicochemical effect of substrates and intermediate compounds in a complex mixture on foaming potential The effect of individual substrates and intermediate compounds on foaming potential was investigated in both water and POME. The foaming potential was measured as foaming tendency and foam stability. Nineteen compounds were chosen, which are proteins (bovine serum albumin (BSA), gelatine, peptone and casein), carbohydrates (cellulose, starch and sucrose), lipids (palm oil, sodium oleate and glycerol), Trace metal (Ca2+ and Mg2+), soluble microbial products (SMPs) (butyric acid, lactic acid and propionic acid) and ammonia. The concentration of each compound was chosen in the range of 0.0–8.0 g/L adding into 200 mL of pure POME and water. This is in accordance with its typical concentration that is commonly found in POME digesters. In a co-digestion system, several substrates and intermediate compounds are present in a digester at the same time, which can affect foaming in the digester differently. To investigate the effect of each compound in a complex mixture, a fractional factorial design of experiments was carried out, where all the compounds involved was tested at different concentrations. Assuming that the interaction between each compound is insignificant, the design matrix could be reduced to 20 combinations of 19 compounds in manure as shown in Table 2. From each test combination, the foaming potential was measured. Expert® software (Stat-Ease Inc., USA) used for
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experimental design the influence of each compound on foaming potential in POME. The foaming potential was determined as foaming tendency. Table 1. Characteristics of POME Parameter
Unit
pH
-
POME 4.71
TS
g/L
57.57
TVS
g/L
45.78
COD
g/L
22.30
Lipid
g/Kg
64.90
Nitrogen
g/Kg
44.00
VFA
g/L
9.73
Alkalinity
g-CaCO3/L
0.55
2.3 Physicochemical effect of intermediate compounds foaming potential under AD POME was evaluated for biochemical methanogenic potential (BMP) in a 500 mL serum vial with a working volume of 200 mL and intermediate compounds (Table 2) were and to BMP bottle [14]. Adjusting pH to neutral with NaHCO3 and fleshed with N2:CO2 mixed at 80:20 ratios. Incubate at 35±3oC for 45 day. All tests were carried out in duplicate. From each test combination, the foaming stability in system was measured. 2.4 Analysis and assay The foam formation inside the serum bottles was recorded daily. The volume of foam produced high multiplied with the surface area of the bottle, which can affect foaming in the serum bottle differently. All cumulative biogas production is measured via water displacement method, until less than 5% of biogas production was detected. Methane and carbon dioxide were analysed by GC-TCD fitted with 3.3 ft. stainless steel column packed with Porapak T (60/80 mesh). Helium was used as a carrier gas at a flow rate of 35 ml/min. The temperatures of the injection port, oven and detector were at 120, 40 and 100°C, respectively. The gas sample of 5 μL was injected in duplicate. Total solids (TS) were determined by drying the samples at 103–105 oC to constant weight according to [14]. There after the dried samples were ignited at 550 oC to constant weight in order to determine the volatile solids (VS) [14]. Total nitrogen (TKN) was measured Kjeldahl method. For physicochemical effect of substrates and intermediate compounds in a complex mixture. The foaming potential of the solution was determined by an aeration method modified from the Bikerman method described by [15]. The apparatus was comprised of an Imhoff settling cone with a diffuser placed at the bottom. A 50 mL sample was aerated in the settling cone with the air-flow rate of 30 mL/min. for 10 minutes. The foam height in the settling cone was measured right after aeration was stopped and again at 1 hour later. The foaming potential was defined using two parameters: foaming tendency and foam stability. The foaming tendency (mLfoam/(mL-air·min)) was calculated from the volume of foam (mL) right after aeration divided by air-flow rate (mL/ min). The foam stability was determined as percentage of foam remaining in the settling cone at 1 h after aeration compared with the volume of foam right after aeration. All tests were carried out in duplicate.
Nantharat Wongfaed et al. / Energy Procedia 79 (2015) 930 – 936
3. Results and Discussion 3.1 Physicochemical effect of substrates and intermediate compounds in a complex mixture on foaming potential BSA, Na+, lactic acid and cellulose in water has foaming tendency potential but has no foaming stability. POME had a foaming tendency and stability around 51.67 mL-foam/mL-air min and 3.23 cm3. However addition of Na-oleate and Na2+ in POME show more foaming tendency. Addition of butyric acid, acetic acid, Mg2+, SDS, peptone, gelatine and BSA show strong foaming stability in POME. Foaming tendency of POME with addition of substrate and intermediates according to design in Table 2, all run create in ranged of 38.33-51.67 mL-foam/mL-air min. While foaming stability in the ranged of 7.74-52.17% which BSA, gelatine, peptone, SDS, Mg 2+, acetic acid and butyric acid showed more foaming stability. The effect on foaming potential of oil palm decrease foaming stability while all run increase foaming tendency. High protein, Ca2+, Mg2+, acetic acid, butyric acid, NH 4+ and SDS in POME increased strongly foaming (Fig. 2), while oil palm decrease foaming stability in POME (Fig. 3). For testing foaming potential in POME with the effect of individual (0.50, 1.00, 1.50 and 2.00 g/L) gelatine, (2.0, 4.0, 6.0 and 8.0) oil palm, (0.5,1.0, 1.5 and 2.0 g/L ) glycerol, (1.0, 2.0, 3.0 and 4.0) avicel, sucrose, (0.5,1.0, 1.5 and 2.0 g/L ) Ca2+ and (0.5,1.0, 1.5 and 2.0 g/L ) Mg2+ at difference concentration found that when increase concentration no effect foaming tendency, while when increase concentration has effect on foaming tendency accept Mg2+. Table 2. Experimental set-up for the effect of feedstock composition on foaming.
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Fig. 1 Comparison of foaming tendency of substrate and intermediates compounds in water and POME.
Fig. 2 Change in foaming stability of POME.
Fig. 3. Change in foaming tendency of POME.
3.2 Physicochemical effect of intermediate compounds foaming potential under AD In AD run 1, 2, 5, 10, 12, 13, 14 and 20 showed the highest foaming stability throughout the AD found that major compound were BSA, gelatine, oil palm and lactic acid. Run 3, 4, 6, 9, 15, 16, 17, 18 and 19 showed low foaming stability, found that few compound were casein, BSA, NH4+ and acetic acid. For Run 7, 8 and 11 showed the highest foaming tendency in the initial AD. The highest methane production obtains run 2, 5 and 7 about 11.15, 14.67 and 15.95 L-methane/L-POME and methane yield was obtained 179.05, 235.51 and 256.08 mL-methane/VS added respectively. While run 4, 6 12, 13, 14, 15, 16, 17, 18 and 19 were obtained low methane production in the rang 0.89-3.47 L-methane/L-POME and low methane yield were obtained in the rang 14.28-55.79 mL-methane/VS added respectively.
Fig. 4 Methane production of POME all run .
Fig. 5 Methane yield of POME all run.
Nantharat Wongfaed et al. / Energy Procedia 79 (2015) 930 – 936
4. Conclusion The POME had a foaming tendency and stability around 51.67 mL-foam/mL-air min and 3.23 cm3. Low concentration of glycerol stronger increased of foaming tendency in water than gelatine, Mg2+ and sucrose respectively. Low concentration of Ca2+ stronger increased foaming stability in water than glycerol, Mg2+ and sucrose respectively. Effect of each compound in a complex mixture showed that BSA, Na+, lactic acid and cellulose has foaming tendency in water while no foaming stability. Na-oleate and Na2+ showed strong foaming tendency, while butyric acid, acetic acid, Mg2+, SDS, peptone, gelatine and BSA showed foaming stability in POME. In contrast oil palm had a decrease foaming stability in POME. In AD found that highest methane production about 11.15-15.95 L-CH4/L-POME and yield about 179.05-256.08 mL-CH4/g-VS added. Na+, acetic acid and NH4+ were obtained highest production and yield methane. While BSA, gelatine, oil palm and lactic acid was promoting foaming stability. Acknowledgements We would like to thank The Royal Golden Jubilee Ph.D. Program for financial supports and Microbial Resource Management Research Unit, Thaksin University support instrumental and assistance the conduct of research. References [1] Zinatizadeh AAL, Salamatinia B, Zinatizadeh SL, Mohamed A R, Hasnain Isa M. Palm oil mill effluent digestion in an up-flow anaerobic sludge fixed film bioreactor. Int. J. Environ. Res. 2007; 1, pp. 264-271. [2] Borja R., Banks CJ, Sanchez, E. Anaerobic treatment of palm oil mill effluent in a two-stage up-flow anaerobic sludge blanket (UASB). Biotechnol. J 1996; 45:2, p 125–135. [3] Singh G, Huan LK, Leng T, Kow DL. Oil palm and the environment. SDN. Bhd, Kuala Lumpur: Sp-nuda Printing. 1999. [4] Poh PE, Chong MF. Biomethanation of Palm Oil Mill Effluent (POME) with a thermophilic mixed culture cultivated using POME as a substrate. Chem. Eng. J 2010a.; 164, p 146–154. [5] Poh PE, Chong, MF. Thermophilic Palm Oil Mill Effluent (POME) treatment using a mixed culture cultivated from POME. Chem. Eng. J 2010b; 21, p 811-816. [6] Chotwattanasak J, Puetpaiboon, U. Full Scale Anaerobic Digester for Treating Palm Oil Mill Wastewater. Renew sust energy rev 2011; 2, p 133-136. [7] Chan JY, Chong, FM, Law LC. An integrated anaerobic–aerobic bioreactor (IAAB) for the treatment of palm oil mill effluent (POME): Start-up and steady state performance. Process Biochem 2012; 47, p 485–495. [8] Dalmau J, Comas J, Rodríguez-Roda I, Pagilla K, Steyer JP. Model development and simulation for predicting risk of foaming in anaerobic digestion systems. Bioresour Technol. 2010; 12: 4306-14. [9] Pagilla KR, Craney KC, Kido WH. Causes and effects of foaming in anaerobic sludge digesters. Water Sci. Technol 1997; 36, p 463-470. [10] Westlund AD, Hagland E, Rothman M. Operational aspects on foaming in digesters caused by Microthrix Parvicella. Water Sci. Technol 1998; 38, p 29-34. [11] Barjenbruch M, Hoffmann H, Kopplow O. Tränckner J. Minimizing of foaming in digesters by pre-treatment of the surplussludge. Water Sci. Technol 2000; 42, p 235-241. [12] Barber WP. Anaerobic digester foaming: causes and solutions. Water. 2005; 21: 5-49, IWA [Accessed at http://wwwuk1.csa.com/ids70/results.php?SID=4oo9hnkld4c223a8lr72q3vbb1&id=2, 11/06/08]. [13] Angelidaki I, Alves M, Bolzonella D, Borzacconi L, Campos JL, Guwy AJ, et al. Defining the biomethane potential (BMP) of solid organic wastes and energy crops: a proposed protocol for batch assays. Water Sci.Technol 2009;59:927–34.
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[14] APHA (American Public Health Association), (Ed.), “Standard Methods for the Examination of Water and Wastewater”, APHA. 2005, p 120-151. [15] Beneventi D, Carre B, Gandini A. Role of surfactant structure on surface and foaming properties. Colloids and Surfaces A: Colloids Surf. A 2001; 189;1–3,p 65–73.
ScienceDirect Energy Procedia 79 (2015) 930 – 936
y Procedia 00 (2015) 000–000
2015 International Conference on Alternative Energy in Developing Countries and Emerging Economies
Effect of Substrate and Intermediate Composition on Foaming in Palm Oil Mill Effluent Anaerobic Digestion System Nantharat Wongfaeda, Prawit Kongjanb, Sompong O-Thanga,c,d* a
Biotechnology Program, Faculty of Science, Thaksin University, Phatthalung, Thailand Department of Science, Faculty of Science and Technology, Prince of Songkla University, Pattani,Thailand c Research Center in Energy and Environment, Faculty of Science, Thaksin University, Phatthalung, Thailand d Research Group for Development of Microbial Hydrogen Production Process from Biomass, Khon Kaen University, Khon Kaen, Thailand b
Abstract Anaerobic digestion (AD) process is a widely applied method for biogas production and wastewater treatment of palm oil mill effluent (POME). AD foaming is one of the major problems that occasionally occur in many biogas plants, since it affects negatively the overall digestion process. The effect of individual substrates and intermediate compounds on foaming potential in POME anaerobic digestion systems was investigated. Effect of interaction of each compound was investigated by fractional factorial design and tested ,for foaming potential in both pure water, POME and POME under AD. The results showed increased concentration of substrate and intermediate compounds in waster could create more foaming tendency but not effect on foaming stability. Each compound in a complex mixture showed that BSA, Na+, lactic acid and cellulose has foaming tendency in water while no created foaming stability. Na-oleate and Na2+ showed strong foaming tendency while butyric acid, acetic acid, Mg2+, SDS, peptone, gelatine and BSA showed more effect on foaming stability in POME. In AD systems found that highest methane production about 11.15-15.95 L-CH4/L-POME and yield about 179.05-256.08 mL- CH4/g-VS added. BSA, gelatine, oil palm and lactic acid has highest foaming stability in AD systems. © Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license © 2015 2015The The Authors. Published by Elsevier Ltd. (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the Organizing Committee of 2015 AEDCEE Peer-review under responsibility of the Organizing Committee of 2015 AEDCEE
Keywords: palm oil mill effluent, anaerobic digestion , foaming tendency, foaming stability
* Corresponding author. Tel.: +66-74-693-992; fax: +66-74-693-992 E-mail address: [email protected]
1876-6102 © 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 the Organizing Committee of 2015 AEDCEE doi:10.1016/j.egypro.2015.11.589
Nantharat Wongfaed et al. / Energy Procedia 79 (2015) 930 – 936
1. Introduction The production of palm oil, results in the generation of large quantities of polluted wastewater commonly referred to as palm oil mill effluent (POME). Typically, 1 ton of crude palm oil production requires 5–7.5 ton of water; over 50% of which ends up as POME [1]. POME is a viscous, brownish liquid containing about 95–96% water, 0.6–0.7% oil and 4–5% total solids (including 2–4% SS, mainly debris from fruit). It is acidic (pH 4–5), hot (80–90 o C) with average chemical oxygen demand (COD) and biological oxygen demand (BOD) values of 50,000 mg/L and 25,000 mg/L, respectively and contains appreciable amounts of plant nutrients [2,3]. Since POME contains high level of organic matters and thus, adoption of anaerobic digestion in the first stage of the treatment process is a necessity to convert the bulk of the wastes to biogas. Biogas production yield from POME was ranged 46350 mL-CH4/g-VS with methane content of 45-67% and organic reduction of 65-90% [4-7]. However AD foaming is one of the major problems that occasionally occur in many biogas plants, since it affects negatively the overall digestion process [8]. Foaming can also result in an inverse solids profile having higher solids concentrations at the top of a digester, creation of dead zones and reduction of the active volume of the digester hence resulting in sludge, which has not received the same degree of stabilization [9-12]. So far, there has never been a thorough investigation of a foaming problem in a POME-based digester, which is the main anaerobic digestion technology used in Thailand. There is a need for investigation of the foaming causes in this system in order to find the method to avoid as well as to resolve the problem. This work aims to identify the potential causes of foaming in POME digesters. The specific compounds commonly present in a POME digester are investigated for their effects on foaming potential in POME. 2. Materials and Methods 2.1 Preparation of the feedstock POME and anaerobic digester sludge used in this study were collected from palm oil mill plant, in southern of Thailand. POME was stored at the temperature of 4 o C for later use. The characteristics of POME are presented in Table 1. Sludge was prepared active in a container closed by lid and there was a constant production of biogas before being used as the mixed culture. 2.2 Physicochemical effect of substrates and intermediate compounds in a complex mixture on foaming potential The effect of individual substrates and intermediate compounds on foaming potential was investigated in both water and POME. The foaming potential was measured as foaming tendency and foam stability. Nineteen compounds were chosen, which are proteins (bovine serum albumin (BSA), gelatine, peptone and casein), carbohydrates (cellulose, starch and sucrose), lipids (palm oil, sodium oleate and glycerol), Trace metal (Ca2+ and Mg2+), soluble microbial products (SMPs) (butyric acid, lactic acid and propionic acid) and ammonia. The concentration of each compound was chosen in the range of 0.0–8.0 g/L adding into 200 mL of pure POME and water. This is in accordance with its typical concentration that is commonly found in POME digesters. In a co-digestion system, several substrates and intermediate compounds are present in a digester at the same time, which can affect foaming in the digester differently. To investigate the effect of each compound in a complex mixture, a fractional factorial design of experiments was carried out, where all the compounds involved was tested at different concentrations. Assuming that the interaction between each compound is insignificant, the design matrix could be reduced to 20 combinations of 19 compounds in manure as shown in Table 2. From each test combination, the foaming potential was measured. Expert® software (Stat-Ease Inc., USA) used for
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Nantharat Wongfaed et al. / Energy Procedia 79 (2015) 930 – 936
experimental design the influence of each compound on foaming potential in POME. The foaming potential was determined as foaming tendency. Table 1. Characteristics of POME Parameter
Unit
pH
-
POME 4.71
TS
g/L
57.57
TVS
g/L
45.78
COD
g/L
22.30
Lipid
g/Kg
64.90
Nitrogen
g/Kg
44.00
VFA
g/L
9.73
Alkalinity
g-CaCO3/L
0.55
2.3 Physicochemical effect of intermediate compounds foaming potential under AD POME was evaluated for biochemical methanogenic potential (BMP) in a 500 mL serum vial with a working volume of 200 mL and intermediate compounds (Table 2) were and to BMP bottle [14]. Adjusting pH to neutral with NaHCO3 and fleshed with N2:CO2 mixed at 80:20 ratios. Incubate at 35±3oC for 45 day. All tests were carried out in duplicate. From each test combination, the foaming stability in system was measured. 2.4 Analysis and assay The foam formation inside the serum bottles was recorded daily. The volume of foam produced high multiplied with the surface area of the bottle, which can affect foaming in the serum bottle differently. All cumulative biogas production is measured via water displacement method, until less than 5% of biogas production was detected. Methane and carbon dioxide were analysed by GC-TCD fitted with 3.3 ft. stainless steel column packed with Porapak T (60/80 mesh). Helium was used as a carrier gas at a flow rate of 35 ml/min. The temperatures of the injection port, oven and detector were at 120, 40 and 100°C, respectively. The gas sample of 5 μL was injected in duplicate. Total solids (TS) were determined by drying the samples at 103–105 oC to constant weight according to [14]. There after the dried samples were ignited at 550 oC to constant weight in order to determine the volatile solids (VS) [14]. Total nitrogen (TKN) was measured Kjeldahl method. For physicochemical effect of substrates and intermediate compounds in a complex mixture. The foaming potential of the solution was determined by an aeration method modified from the Bikerman method described by [15]. The apparatus was comprised of an Imhoff settling cone with a diffuser placed at the bottom. A 50 mL sample was aerated in the settling cone with the air-flow rate of 30 mL/min. for 10 minutes. The foam height in the settling cone was measured right after aeration was stopped and again at 1 hour later. The foaming potential was defined using two parameters: foaming tendency and foam stability. The foaming tendency (mLfoam/(mL-air·min)) was calculated from the volume of foam (mL) right after aeration divided by air-flow rate (mL/ min). The foam stability was determined as percentage of foam remaining in the settling cone at 1 h after aeration compared with the volume of foam right after aeration. All tests were carried out in duplicate.
Nantharat Wongfaed et al. / Energy Procedia 79 (2015) 930 – 936
3. Results and Discussion 3.1 Physicochemical effect of substrates and intermediate compounds in a complex mixture on foaming potential BSA, Na+, lactic acid and cellulose in water has foaming tendency potential but has no foaming stability. POME had a foaming tendency and stability around 51.67 mL-foam/mL-air min and 3.23 cm3. However addition of Na-oleate and Na2+ in POME show more foaming tendency. Addition of butyric acid, acetic acid, Mg2+, SDS, peptone, gelatine and BSA show strong foaming stability in POME. Foaming tendency of POME with addition of substrate and intermediates according to design in Table 2, all run create in ranged of 38.33-51.67 mL-foam/mL-air min. While foaming stability in the ranged of 7.74-52.17% which BSA, gelatine, peptone, SDS, Mg 2+, acetic acid and butyric acid showed more foaming stability. The effect on foaming potential of oil palm decrease foaming stability while all run increase foaming tendency. High protein, Ca2+, Mg2+, acetic acid, butyric acid, NH 4+ and SDS in POME increased strongly foaming (Fig. 2), while oil palm decrease foaming stability in POME (Fig. 3). For testing foaming potential in POME with the effect of individual (0.50, 1.00, 1.50 and 2.00 g/L) gelatine, (2.0, 4.0, 6.0 and 8.0) oil palm, (0.5,1.0, 1.5 and 2.0 g/L ) glycerol, (1.0, 2.0, 3.0 and 4.0) avicel, sucrose, (0.5,1.0, 1.5 and 2.0 g/L ) Ca2+ and (0.5,1.0, 1.5 and 2.0 g/L ) Mg2+ at difference concentration found that when increase concentration no effect foaming tendency, while when increase concentration has effect on foaming tendency accept Mg2+. Table 2. Experimental set-up for the effect of feedstock composition on foaming.
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Fig. 1 Comparison of foaming tendency of substrate and intermediates compounds in water and POME.
Fig. 2 Change in foaming stability of POME.
Fig. 3. Change in foaming tendency of POME.
3.2 Physicochemical effect of intermediate compounds foaming potential under AD In AD run 1, 2, 5, 10, 12, 13, 14 and 20 showed the highest foaming stability throughout the AD found that major compound were BSA, gelatine, oil palm and lactic acid. Run 3, 4, 6, 9, 15, 16, 17, 18 and 19 showed low foaming stability, found that few compound were casein, BSA, NH4+ and acetic acid. For Run 7, 8 and 11 showed the highest foaming tendency in the initial AD. The highest methane production obtains run 2, 5 and 7 about 11.15, 14.67 and 15.95 L-methane/L-POME and methane yield was obtained 179.05, 235.51 and 256.08 mL-methane/VS added respectively. While run 4, 6 12, 13, 14, 15, 16, 17, 18 and 19 were obtained low methane production in the rang 0.89-3.47 L-methane/L-POME and low methane yield were obtained in the rang 14.28-55.79 mL-methane/VS added respectively.
Fig. 4 Methane production of POME all run .
Fig. 5 Methane yield of POME all run.
Nantharat Wongfaed et al. / Energy Procedia 79 (2015) 930 – 936
4. Conclusion The POME had a foaming tendency and stability around 51.67 mL-foam/mL-air min and 3.23 cm3. Low concentration of glycerol stronger increased of foaming tendency in water than gelatine, Mg2+ and sucrose respectively. Low concentration of Ca2+ stronger increased foaming stability in water than glycerol, Mg2+ and sucrose respectively. Effect of each compound in a complex mixture showed that BSA, Na+, lactic acid and cellulose has foaming tendency in water while no foaming stability. Na-oleate and Na2+ showed strong foaming tendency, while butyric acid, acetic acid, Mg2+, SDS, peptone, gelatine and BSA showed foaming stability in POME. In contrast oil palm had a decrease foaming stability in POME. In AD found that highest methane production about 11.15-15.95 L-CH4/L-POME and yield about 179.05-256.08 mL-CH4/g-VS added. Na+, acetic acid and NH4+ were obtained highest production and yield methane. While BSA, gelatine, oil palm and lactic acid was promoting foaming stability. Acknowledgements We would like to thank The Royal Golden Jubilee Ph.D. Program for financial supports and Microbial Resource Management Research Unit, Thaksin University support instrumental and assistance the conduct of research. References [1] Zinatizadeh AAL, Salamatinia B, Zinatizadeh SL, Mohamed A R, Hasnain Isa M. Palm oil mill effluent digestion in an up-flow anaerobic sludge fixed film bioreactor. Int. J. Environ. Res. 2007; 1, pp. 264-271. [2] Borja R., Banks CJ, Sanchez, E. Anaerobic treatment of palm oil mill effluent in a two-stage up-flow anaerobic sludge blanket (UASB). Biotechnol. J 1996; 45:2, p 125–135. [3] Singh G, Huan LK, Leng T, Kow DL. Oil palm and the environment. SDN. Bhd, Kuala Lumpur: Sp-nuda Printing. 1999. [4] Poh PE, Chong MF. Biomethanation of Palm Oil Mill Effluent (POME) with a thermophilic mixed culture cultivated using POME as a substrate. Chem. Eng. J 2010a.; 164, p 146–154. [5] Poh PE, Chong, MF. Thermophilic Palm Oil Mill Effluent (POME) treatment using a mixed culture cultivated from POME. Chem. Eng. J 2010b; 21, p 811-816. [6] Chotwattanasak J, Puetpaiboon, U. Full Scale Anaerobic Digester for Treating Palm Oil Mill Wastewater. Renew sust energy rev 2011; 2, p 133-136. [7] Chan JY, Chong, FM, Law LC. An integrated anaerobic–aerobic bioreactor (IAAB) for the treatment of palm oil mill effluent (POME): Start-up and steady state performance. Process Biochem 2012; 47, p 485–495. [8] Dalmau J, Comas J, Rodríguez-Roda I, Pagilla K, Steyer JP. Model development and simulation for predicting risk of foaming in anaerobic digestion systems. Bioresour Technol. 2010; 12: 4306-14. [9] Pagilla KR, Craney KC, Kido WH. Causes and effects of foaming in anaerobic sludge digesters. Water Sci. Technol 1997; 36, p 463-470. [10] Westlund AD, Hagland E, Rothman M. Operational aspects on foaming in digesters caused by Microthrix Parvicella. Water Sci. Technol 1998; 38, p 29-34. [11] Barjenbruch M, Hoffmann H, Kopplow O. Tränckner J. Minimizing of foaming in digesters by pre-treatment of the surplussludge. Water Sci. Technol 2000; 42, p 235-241. [12] Barber WP. Anaerobic digester foaming: causes and solutions. Water. 2005; 21: 5-49, IWA [Accessed at http://wwwuk1.csa.com/ids70/results.php?SID=4oo9hnkld4c223a8lr72q3vbb1&id=2, 11/06/08]. [13] Angelidaki I, Alves M, Bolzonella D, Borzacconi L, Campos JL, Guwy AJ, et al. Defining the biomethane potential (BMP) of solid organic wastes and energy crops: a proposed protocol for batch assays. Water Sci.Technol 2009;59:927–34.
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