Scholarly article on topic 'The Performance of Jatropha Curcas Linn. Capsule Husk as Feedstocks Biogas in One Phase Anaerobic Digestion'

The Performance of Jatropha Curcas Linn. Capsule Husk as Feedstocks Biogas in One Phase Anaerobic Digestion Academic research paper on "Chemical engineering"

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{Biogas / biorefinery / "capsule husk" / "Jatropha curcas Linn."}

Abstract of research paper on Chemical engineering, author of scientific article — Praptiningsih G. Adinurani, S. Roy Hendroko, Satriyo K. Wahono, Anggi Nindita, Mel Mairziwan, et al.

Abstract Jatropa curcas Linn. (JcL) capsule husk was not recommended as biogas feedstocks. However for biorefinery purpose, several technologies have been conducting to solve this problem. This research reported quantity and quality comparison of Dry Husk Jcl (DH-JcL) in one phase system of batch digester compare with semi continuous digester. HDPE drum of 80 L working volume used as digester with 40 days hydraulic retention time. Feeding of DH-Jcl and solvent water was mixed on concentration of 1: 8. Research conclusion showed that semi continuous digester was better than batch digester. Biogas quality showed that methane content can reach 66.61% to 83.15% and biogas quantity in semi continuous digester can reach 0.016 m3 · kg–1 DH JcL. The result was not in optimize condition yet because ratio number of volatile fatty acids/ alkalinity showed 0.5, it was indicated unstable anaerobic degradation process of DH-JcL.

Academic research paper on topic "The Performance of Jatropha Curcas Linn. Capsule Husk as Feedstocks Biogas in One Phase Anaerobic Digestion"

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Procedia Chemistry 14 (2015) 316 - 325

2nd Humboldt Kolleg in conjunction with International Conference on Natural Sciences,

HK-ICONS 2014

The Performance of Jatropha curcas Linn. Capsule Husk as Feedstocks Biogas in One Phase Anaerobic Digestion

Praptiningsih G. Adinurania, Roy Hendroko S.b,c*, Satriyo K. Wahonode, Anggi Ninditaf, Mel Mairziwang, Andi Sasmitoh, Yogo A. Nugrohoh, Tony Liwangh

aFaculty of Agrotechnology University of Merdeka, Jl. Serayu, PO. Box 12, Madiun 63131, Indonesia bMa Chung Research Center for Photosynthetic Pigments, Villa Puncak Tidar N-01 Malang 65151, East Java, Indonesia c Indonesian Association of Bioenergy Scientist and Technologist. BPPTBuilding II, 22nd floor Jl. MH. Thamrin No. 8 Jakarta 10340 dTech. Implementation Unit for Development of Chemical Engineering Processes - Indonesian Institutes of Sciences, Yogyakarta 55861

eMawson Institute and School of Engineering, University of South Australia, Mawson Lakes SA 5095, Adelaide, Australia fDepartment of Agronomy and Horticulture, Bogor Agricultural University, Jl. Meranti, Kampus IPB Dramaga, Bogor 16680, Indonesia

gFaculty of Engineering, International Islamic University Malaysia (IIUM), Gombak, 50728 Kuala Lumpur, Malaysia. hPlant Production and Biotechnology Division, PT SMART Tbk. Sinar Mas Land Plaza, 2nd Tower, 10th Floor. Jakarta 10350, Indonesia

Abstract

Jatropa curcas Linn. (JcL) capsule husk was not recommended as biogas feedstocks. However for biorefinery purpose, several technologies have been conducting to solve this problem. This research reported quantity and quality comparison of Dry Husk Jcl (DH-JcL) in one phase system of batch digester compare with semi continuous digester. HDPE drum of 80 L working volume used as digester with 40 days hydraulic retention time. Feeding of DH-Jcl and solvent water was mixed on concentration of 1: 8. Research conclusion showed that semi continuous digester was better than batch digester. Biogas quality showed that methane content can reach 66.61 % to 83.15 % and biogas quantity in semi continuous digester can reach 0.016 m3 • kg-1 DH JcL. The result was not in optimize condition yet because ratio number of volatile fatty acids/ alkalinity showed 0.5, it was indicated unstable anaerobic degradation process of DH-JcL.

Keywords: Biogas; biorefinery; capsule husk; Jatropha curcas Linn.

© 2015TheAuthors.PublishedbyElsevierB.V.This is an open access articleunder theCCBY-NC-NDlicense (http://creativecommons.Org/licenses/by-nc-nd/4.0/).

Peer-reviewunderresponsibilityof theScientificCommitteeofHK-ICQNS2014

* Corresponding author. Tel +62 815 9555 028. E-mail address: roy_hendroko@hotmail.com

1876-6196 © 2015 The Authors. Published by Elsevier B.V. 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 Scientific Committee of HK-ICQNS 2014 doi: 10.1016/j.proche.2015.03.044

Nomenclature

DH-JcL dried husk Jatropha curcas Linn. HRT hidraulic retention time

JcL Jatropha curcas Linn. VFA volatile fatty acids

VFA/alk volatile fatty acids/alkalinity

1. Introduction

Anaerobic Digestion (AD) is a convertion process of organic material into biogas, an energy rich gas containing 50 % to 70 % methane (CH4) and 30 % to 40 % carbon dioxide (CO2) and low amounts of other gases. In principle, all organic material can be anaerobic digested1. Prawira's statement1 was supported by several researchers2,3, indeed Annupukul4 stated organic wastes including domestic, industry, and agriculture wastes.

However Becker and Makkar5,6 , Halford and Karp7 stated that JcL husks, as crude jatropha oil (the biodiesel raw materials) wastes, is not suitable as substrates in biogas digesters due to very low digestibility. Moreover, some problems are also reported such as low density, high buffer capacity, and there are anti-nutrients e.g. phorbol ester in JcL husks8,9.

The research series in Indonesia about JcL husk as biogas source during 2010 to 2014 has been reported by several author, e.g.10-13. This article complete the previous research14 to show capsule husk JcL performance as feedstocks for one phase of small scale AD/household biogas digester system.

2. Material and method

The study was conducted at the research garden of PT Bumimas Ekapersada, Bekasi, West Java, Indonesia. JcL husk was collected from JatroMas toxic cultivar which drying under the sun directly, until the moisture content about 5 %. It is different from Danya15 which using fresh capsule husk. This research used Dry Husk (DH-JcL) for efficiency reason, as reported on previous study14. DGS and Ecofys16 stated AD systems can be considered under the following three categories i.e. continuous processes, semi continuous processes, and discontinuous processes (batch systems). According Pandey17 about household biogas digester, this research was focussed on batch systems and semi continuous processes.

(c) (d)

Fig. 1. Semi continuous digester (a) side view of 1st and 2nd holes (biogas outlet and feeding inlet); (b) top view of 1st and 2nd holes (c) feeding pipe submerged in slurry; (d) 3rd hole (slurry outlet).

HDPE (high-density polyethylene) drum with total volume 90 L and working volume 80 L was used as digester. On the batch digester, it was closed by drum with two hole and pipe. The first hole and pipe was used for flowing biogas into the holder, and the other was used for pH and temperature measurement. On the semi continuous digester, there are three holes (Fig. 1a and 1b). Two holes was closed by drum, the first was used for flowing biogas into the holder and the second hole was used for feeding DH-JcL (Fig. 1a and 1b). End of the feeding pipe submerge into slurry about 10 cm to prevent O2 from entering into digester (Fig. 1c). The third hole was located under the drum for dispensing slurry and taking sample of analysis (Fig. 1d).

On batch treatment, 1 500 g DH-JcL was entered into digester, mixed with rain water in composition 1 : 813 and starter by 10 % v/v4,18. Slurry from previous operated Dh-JcL digester was used as starter19 and then digester was closed tightly using seal. On semi continuous treatment, 80 L rain water and starter 10 % v/v4,18 was entered into digester and then it was closed tightly using seal. After that, the feeding of synthetic waste20 which containing 25 g ■ L-1 brown sugar was conducted. The feeding was conducted by draw and fill system21 on 3 000 cc per day. On the 10th day, the feeding was replaced by 54 g DH-JcL and 3 000 cc rain water per day which signed by biogas existence in the holder

pH and temperature determination was conducted every day during experiment by using digital measurement tools. Biogas volume was determined by water displacement method on the holder21, and methane determination was conducted using orsat apparatus. Volatile fatty acid (VFA) content and alkalinity was analyzed by distillation and titration based on APHA 232022. Batch digester observation was conducted until no production of DH-JcL and one phase system of semi continuous digester observation was continued until 84 d (based on two phase system of semi continuous digester which will be reported in another paper).

3. Result and discussion

3.1. Temperature andpH observation

Fig. 2. The dynamic of slurry temperature in batch digester and semi continuous digester.

Fig. 2 showed that temperature in batch digester (31.62 °C in average with range between 28.7 °C to 35.2 °C) is higher than in semi continuous digester (29.88 °C in average with range between 27.8 °C to 32.5 °C). Hendroko23 said that this research temperature include in normal range by 30 °C to 38 °C. Based on Fig. 2, actually batch digester is potency to produce more biogas because Deublein and Steinhauser24 stated that high temperature is better condition for archaea methanogen. The dynamic of slurry pH is showed by Fig. 3.

V ♦ Batch —■—Semi continuous

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39

Fig. 3. The dynamic of slurry pH in batch digester and semi continuous digester.

Fig. 3 showed that pH in batch digester (6.18 in average with range between 5.4 to 6.8) is lower than in semi continuous digester (6.51 in averages with range between 5.2 to 7.0). Hendroko23 said that this research pH include in normal range, because some references stated that the normal pH is between 6.0 to 8.5.

The daily pH in batch digester is lower than semi continuous digester, although pH after the 28th day is higher than semi continuous digester. It was expected negative impact on biogas production of batch digester, because some references24,25 state that only Methanosarcina is able to withstand lower pH values (pH = 6.5 and below). With the other bacteria, the metabolism is considerably suppressed at pH < 6.7.

3.2. Biogas production

ml/g 4

—♦—Batch —■— Semi continuous

/ \----

20 25 d

Fig. 4. The dynamic of biogas production in batch digester and semi continuous digester.

Fig. 4 showed biogas dynamic production. In the beginning, one phase system of semi continuous digester produces highly, but decreases gradually and stable on the 30th day. Biogas production of batch digester was low in the beginning and then increase. After that, it decreased gradually on the 14 day until the 36 day. The decreasing biogas production on the 14th day is normal condition because Wellinger said that degradation of anaerobic agriculture residue will decrease on the (10th to 14th) day. Furthermore, the finishing of biogas production on the 36th day was appropriate with 40 d HRT (Hydraulic Retention Time) which reported several researchers26-28 in the one phase system of digester.

One phase of semi continuous digester data on the Fig. 4 supports Susilo and Caroko29 which stated that archaea methanogen mobility in substrate/slurry was blocked gradually by increasing solid content, so it obstruct biogas production. The observation elucidated that demolition of semi continuous digester on the 84th day has proved 80 L working volume of digester which fulfilled by DH-JcL solid, moreover some of solids have attended on above substrate/slurry (detail report will be published on other paper). DH-JcL solids could not degrade and dissolved due to its high lignin content which showed in previous research14.

The Graph of batch digester on Fig. 4 was similar with Fry curve30; Setiana and Prasetyani31. The decreasing of biogas production on the 14th day happened because there are unbalance growths between acidogens bacteria and archaea methanogens. The presumption stated that acidogens - bacteria which producing acid grow over fprompt, therefore acid production impact will be more than the numbers of archaea methanogens consumption, so the substrate will be too acid. Fig. 3 supported this condition because batch digester pH is more acid than semi continuous digester. The increasing and accumulation of short chain fatty acid (SCFA) or volatile fatty acid (VFA) gave negative impact for archaea methanogens living, and then on biogas productions32,33.

0.6 0.5 0.4 ml/g 0.3

0.2 0.1 0

I Batch ■ Semi continuous -045-

I Batch ■ Semi continuous _18.03

Fig. 5. (a) Daily biogas production (40 d HRT); (b) Total biogas production (40 d HRT).

Fig. 5a and Fig. 5b support statement before about biogas production in semi continuous digester is higher than batch digester. The last observation day on Fig. 4, based on batch digester, is 40 d and is supported by Karki26 which stated that cow dung HRT in one phase digester is 40 d to 100 d. Furthermore, 40 d HRT was appropriate with several references27,28,34. Daily biogas production on Fig. 5a is 0.000 24 m3 ■ d-1 in one phase system of batch digester and 0.000 4 m3 ■ d-1 in semi continuous digester. This production number of DH-JcL is higher than research at Lagos University in Nigeria35,36 which reporting cow dung by 0.0230 dm3 ■ d-1 or 0.000 0230 m3 ■ d-1 and 0.023 8 dm3 ■ d-1 or 0.000 023 8 m3 ■ d-1. Statistical test using t test with level of trust on 95 % is provided on Table 1.

Table 1. T test for biogas production ■ d-1 in one phase system of batch and semi continuous digester with DB-JcL as feedstocks .

Treatment Average Sig

Batch 0.2403 0,03

Semi continuous 0.4040*

*) Significant difference with the level of trust on 95 %

Table 1 also supports Fig. 5 wherein semi continuous system productivity is higher than batch system. Some causes of low production in batch system are unstable microbe populations37 and stability effect in discontinuous digester is relatively small and very sensitive to inhibition38. Total biogas production in one phase system of batch digester for 40 d is 0.010 m3 ■ kg-1 DH-JcL, whereas in semi continuous system is 0.016 m3 kg-1 DH-JcL (Fig. 4b). This productivity number is lower than Karki report26 which stated that biogas production from cow dung by (0.023 to 0.04) m3 kg-1 cow dung and is supported by some references39,40.

However, comparation between biogas productivity from DH-JcL and cow dung is not relevant. Cow dung is ideal raw material for biogas because it has characteristic such as forming cream, forming very wet, forming a colloidal solution, containing high capacity of bicarbonate buffer, containing high ammonia content, having stable pH on 7.5 to 8.0, containing enough of macro and micro compounds, and containing microbe so anaerobic degradation process can happen easily41,42. Productivity of biogas from agricultural wastes, such as rice husk, is reported by Bond and Templeton3 on (0.014 to 0.018) m3 ■ kg-1 DM. This data indicate Fig. 4b in semi continuous system by 0.016 still on biogas production range of rice husk. For annotation, lignin of rice husk is 12 % to 16 %43,44 and it is lower than DH-JcL by 20 %14. Methane content, which determined by orsat app., is showed on Table 2.

Table 2. Methane content of biogas from DH-JcL on comparation between one phase system of batch than semi continuous digester.

Treatment Methane content of biogas (%)

Average Minimum Maximum

Batch 68.61 66.50 69.67

Semi continuous 83.15 72.83 91.83

Table 2 showed methane content in semi continuous system is higher than batch system, as a result of better process which explained before. Moreover, methane content on this research is higher than methane content of biogas from several wastes, namely cow dung : 50 % to 70 %26; solid waste of tapioca process : 32 % to 50 %45; cassava leather : 57 %46; fruits and vegetables wastes : 51 % to 53 %47. It happens because fat content of DH-JcL14.

3.3. Review of volatile fatty acids content and alkalinity

Fig. 3 showed pH average in semi continuous digester is 6.51 (with range on pH 5.2 to pH 7.0). This condition categorize in normal23, because the ideal range of digester on pH 6.0 to pH 8.5. However several researchers48-50 stated that pH is bad indicator and it is not recommended. Similar opinion is expressed on DH-JcL substrate12,13. Several researchers 1,4 51-52 stated that volatile fatty acids (VFA) observation, which expressed on acetic acid content L-1 substrate, is very important indicator on determination of digester performance. Because of the weakness of pH, VFA is suggested as monitoring tools. The observation data of VFA content average for 36 samples in one phase system of semi continuous digester is showed on Table 3.

Table 3. VFA, Alkalinity, and VFA/alkalinity data in one phase of semi continuous digester from DH-JcL.

Content

Analysis average

VFA - volatile fatty acids Alkalinity

volatile fatty acids/alkalinity

1 532 mg acetic acid ■ L 3 211 mg CaCÜ3 ■ L-1 0.5

Table 3 showed VFA content average in semi continuous digester from DH-JcL by 1 532 mg acetic acid ■ L 1. This result is over the thresholds which defined by several researchers. Schnaars53 recommended on range (50 to 300) mg ■ L-1; Gerardi54 said on range (50 to 500) mg ■ L-1; Labatut and Gooch54 stated the best VFA content < 500 mg ■ L-1; whereas Bulcher55 stated the best VFA content < 250 mg ■ L-1. Based on previous statements, Andrews and Graef56 said extreme number of VFA is 2 000 mg ■ L-1; Gerardi54 said VFA on range (500 to 2 000) mg ■ L-1 is marginal; Labatut and Gooch51 said that there is degradation process disturbance when digester has VFA content on range (1 500 to 2 000) mg ■ L-1. Based on Table 3, which showing VFA content average by 1 532 mg ■ L 1, therefore it can be concluded that one phase system of semi continuous digester performance is not optimize to manage DH-JcL substrate although observation of pH number (Fig. 3) shows on normal condition. This result supported previous research which stated that pH number could not be used as reference for digester from DH-JcL12,13.

The previous guidance of maximum threshold stated that VFA on range (1 500 to 2 000) mg ■ L-1. However, several researchers defined higher maximum threshold. Ikbal et al.57 set maximum threshold on 3 000 mg L-1. Taiganides58 said VFA no more than (2 000 to 3 000) mg L-1. Furthermore, APHA59 said generally that digester performance is still on good condition when VFA content on range (1 500 to 5 000) mg L-1 as acetic acid. Angelidaki and Ahring60 said that from the many different levels of VFA found in different reactor systems, it can be concluded that it is not feasible to define an absolute VFA level indicating the state of the process. Different anaerobic systems have their own "normal" levels of VFA, determined by the composition of the substrates digested or by the operating conditions.

Ogejo et al.61 stated that digester stability is enhanced by alkalinity concentration. Therefore, some researchers1,33,49 suggest to use alkalinity content as monitoring tools. Table 3 showed analysis average of alkalinity in one phase system of semi continuous digester by 3 211 mg CaCO3 ■ L-1. This number is than several references52,54 on range (1 500 to 3 000) mg ■ L-1 or (2 000 to 3 000) mg ■ L-1 CaCO3 like a reference56. On Gerardi54 criteria, alkalinity number by 3 211 mg CaCO3 ■ L-1 is said marginal, whereas Andrews and Graef56 said on extreme criteria range. This results support Angelidaki and Ahring48 which stated that agriculture residue as high capacity buffer with small changing impact on pH number and this acidity indicator come up lately33,49,50.

However, references show several researchers defined alkalinity threshold higher than 3 000 mg ■ L-1 CaCO3 References53,55 said that ideal alkalinity on range (1 500 to 5 000) mg ■ L-1. Durkin62 suggested higher than 4 000 mg ■ L-1. For example, reference56 said that cow dung alkalinity on range (2 500 to 5 000) mg ■ L-1; Labatut and Gooch51 stated 5 500 mg CaC03 L-1. Furthermore, Crolla et al.63 reported on 9 000 mg CaC03 ■ L-1.

Advanced reference review shows that VFA number and alkalinity is related. Based on this consideration, total volatile acid (acetic acid) ratio to total alkali (calsium carbonate) - VFA/Alk is important indicator to check acid and base balancing or process stability of digester4,64,65. VFA/Alk ratio on Table 3 shows on 0.5 which concluded higher than some references. Juanga66 said that VFA/Alk ratio threshold is 0.1. Melnyk et al.67 said that ideal range on 0.1 to 0.3; Bulcher55 suggested lower than 0.25; Schnaars53 said on range 0.1 to 3.5; Durkin62 said on range 0.2 to 0.5; and Kurian et al.68 stated comparation between VFA content and bicarbonate alkalinity must be < 0.5. Based on previous statements and VFA/Alk. ratio on Table 3, one phase system of semi continuous digester from DH-JcL in this research categorized failed66; and/or categorized unstable19. It happenned on biogas productivity on 0.016 m3 kg-1 DH-JcL feed only.

4. Conclusion

DH-JcL was able to use for biogas substrate in one phase digester. Quality of biogas from DH-Jcl was higher than several agriculture residues (tapioca process wastes, vegetables, and fruits). Methane content of DH-JcL biogas

in semi continuous digester (83.15 %) was higher than batch digester (68.61 %). Biogas quantity in semi continuous digester (0.016 m3 ■ kg-1 DH-Jcl) was higher than batch digester (0.010 m3 ■ kg-1 DH -JcL). The biogas productivity was lower than cow dung, but similar relatively with agricultural residue, such as rice husk. The production quantity was not optimum yet due to VFA/Alk ratio in semi continuous digester was 0.5. This indicator showed degradation process of DH-JcL in one phase system of semi continuous digester was unstable. It is needed advance research to solve these problems.

Acknowledgements

The authors would like to thank PT Sinar Mas Agro Resources and Technology (PT SMART Tbk.) Jakarta, Indonesia for supporting this study. Special thanks to Agus Setyo Yudhanto, and also to the research technicians, Ata Atmaja WKD, Acam Are Hikman, and Dewi Tiara Sagita for their assistance.

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