Production of methane from anaerobic digestion of jatropha and pongamia oil cakes

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    Keywords:Jatropha

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    259.2 kg of input volatile solids, with an average total volatile solids mass removal efciency of 59.6%.

    s sustanturyepletioergy e

    derived diesel. Presently, more than 95% of bio-diesel of the worldis produced from edible oil, which is available at large scale fromthe agricultural industry. However, continuous and large-scaleproduction of bio-diesel from edible oil without proper planningmay cause negative impact such as depletion of food supply leadto economic imbalance. A possible solution to overcome this prob-lem is to use non-edible oil for production of bio-diesel [1].

    from the bio-diesel resource results in generation of huge unuti-lized biomass. In general, 50% (dry weight basis) of the collectedfruits of bio-diesel resource are seeds (kernels). Out of these seeds,at the most 35% is converted into vegetable oil and remaining 65%material is rejected as toxic oil seed cake. In short, more than 85%of cultivated bio-resource (seeds pericoat and oil seed cake) isremaining unutilized in bio-diesel production. This toxic oil seedcake can neither be used as cattle feed nor as a bio-fertilizer forgrowing plants, due to presence of phorbol ester (a toxic com-pound). The current annual production of toxic jatropha oil seedcake alone has been estimated to be about 60,000 tonnes [4]. The

    Corresponding author. Tel./fax: +91 3592 251390.

    Applied Energy 93 (2012) 148159

    Contents lists availab

    lseE-mail address: ram.chandra6dec@gmail.com (R. Chandra).are searching for supplementing the fossil fuel energy resourceswith cultivated bio-fuel energy resources. Development of sustain-able and commercially viable technologies for production of alco-hols, biogas, producer gas and bio-diesel are good examples onthis scenario. The commercial viability of any bio-resource energytechnology strongly depends on level of utilization of the culti-vated resources and the amount of energy consumption for pro-duction of useful fuel.

    Bio-diesel has high potential as a new and renewable energysource in forthcoming future as a substitution fuel for petroleum

    been launched in the year 2003 under demonstration phase withthe objective to produce enough bio-diesel to meet 20% blendingof total diesel requirement using various non-edible oils by theyear 20112012 [3]. In this context, cultivation of jatropha andpongamia (non-edible oil seed bearing plants) on 40 million hect-are waste land has been started to meet the oil seed requirement.

    However, there are critical issues, which need to be addressedto make the production of bio-diesel as a techno-economically via-ble and ecologically acceptable renewable substitute or additive todiesel. Present method of utilization of only extracted vegetable oilPongamiaOil seed cakeAnaerobic digestionBiogasMethane

    1. Introduction

    One of the major thrust towarddevelopment of the world in 21st ceresources and technologies as the dat alarming level. The associated en0306-2619/$ - see front matter 2010 Elsevier Ltd. Adoi:10.1016/j.apenergy.2010.10.049However, in case of pongamia oil seed cake average specic methane production was observed as0.427 m3/kg TS and 0.448 m3/kg VS. The average value of methane and carbon dioxide content in the pro-duced biogas over 30 days of retention was found as 62.5% and 33.5%, respectively. Cumulative methaneyield over 30 days of retention time period was found as 147.605 m3 with a 255.9 kg of input volatile sol-ids, with an average total volatile solids mass removal efciency of 74.9%.

    2010 Elsevier Ltd. All rights reserved.

    inable socio-economicis cultivation of energyn of petroleum fuel isxperts over the world

    India is endowed with more than 100 species of tree born non-edible oil seeds occurring in wild or cultivated sporadically to yieldoil in considerable quantities [2]. The country has a huge potentialof tree born non-edible oil seeds. Therefore, the attempts are beingmade for utilization of non-edible and under-exploited oils for bio-diesel production. A National Mission on bio-diesel in India hasthe produced biogas over 30 days of retention time period was found as 66.6% and 31.3%, respectively.Cumulative methane yield over 30 days of retention time period was found as 131.258 m3 with aProduction of methane from anaerobic di

    R. Chandra a,, V.K. Vijay b, P.M.V. Subbarao c, T.K. KhaDepartment of Farm Power and Machinery, College of Agricultural Engineering and PoSikkim 737 135, IndiabCentre for Rural Development and Technology, Indian Institute of Technology Delhi, HacDepartment of Mechanical Engineering, Indian Institute of Technology Delhi, Hauz Kha

    a r t i c l e i n f o

    Article history:Received 14 November 2009Received in revised form 30 July 2010Accepted 12 October 2010Available online 7 January 2011

    a b s t r a c t

    The experimental study wamia (Pongamia pinnata) oitemperature condition. Theobserved as 0.394 m3/kg T

    Applied

    journal homepage: www.ell rights reserved.stion of jatropha and pongamia oil cakes

    a a

    arvest Technology (Central Agricultural University), Ranipool, Gangtok,

    has, New Delhi 110 016, Indiaew Delhi 110 016, India

    arried out on anaerobic digestion of jatropha (Jatropha curcas) and pong-ed cakes in a 20 m3/d capacity oating drum biogas plant under mesophilicerage specic methane production potential of jatropha oil seed cake wasd 0.422 m3/kg VS. The average content of methane and carbon dioxide in

    le at ScienceDirect

    Energy

    vier .com/ locate/apenergy

  • OLR organic loading rate

    Eneestimated amount of jatropha oil seed cake could be a signicantsource of bio-energy production if it is utilized in a planned man-ner. Further, waste-to-energy provides a solution to waste man-agement and energy generation. An integrated anaerobic wastevalorization process is an interesting option for energy generationfrom non-edible oil seed cakes [5].

    Anaerobic digestion is considered to be a sustainable bio-con-version technology as it produces biogas a renewable gaseous fueland it also stabilizes and reduces the volume of waste. As a part ofan integrated waste management system anaerobic digestion re-duces the emission of green house gases into the atmosphere.The degradation process or digestion of solids in an anaerobic di-gester takes place in three stages. The rst stage is the hydrolysisof particulate and colloidal wastes to solublise the waste in theform of organic acids and alcohols. The second stage is the conver-sion of the organic acids and alcohols to acetate, carbon dioxide,and hydrogen. The third stage is the production of gases mostlymethane and new bacterial cells or sludge from acetate and hydro-gen. In an anaerobic digester a great diversity of bacteria are re-quired to perform phases of hydrolysis, acidogenesis andmethanogenesis of the input substrate feed that contains diversi-ed wastes in term of carbohydrates, fats and proteins [6].

    The yield and constituents of biogas are greatly affected by car-bohydrates, fats and proteins contents of the feed material. Anaer-obic digestion of carbohydrates, fats and protein yields 886 l ofbiogas (with methane content of around 50%), 1535 l of biogas(with methane content of around 70%) and 587 l of biogas (withmethane content of around 84%) per kg of VS destroyed, respec-tively [7]. The oil seed cakes of jatropha and pongamia are rich in

    Nomenclature

    C carbonC/N carbonnitrogen ratioCD cattle dungd daydb dry basisDR dilution ratiog gramh hourH hydrogenJC jatropha oil seed cakekg kilo gram

    R. Chandra et al. / Appliedfat and protein and therefore, are considered to be good feed mate-rial for biomethanation.

    The governing factors of anaerobic digestion process such as pH,retention time (RT), total solids (TS), volatile solids (VS) and organ-ic loading rates (OLR) inuence the sensitivity of bacteria, the re-sponse to toxicity and acclimatization characteristics [8].Methanogens are sensitive to both high and low pH and performwell within pH of 6.58.0 [9]. Long retention time increases the po-tential for acclimatization and also minimizes the severity of re-sponse to toxicity. The heavy metals at higher concentrationhave toxic effect on bacterial activity. Further, at higher OLRnon-toxic organic or inorganic substances become inhibitory tobacterial growth. The threshold toxic levels of inorganic substancesdepend on the conditions that whether these substances act aloneor in combination. Certain combinations have a synergistic effect,whereas other display an antagonistic effect [10,11]. The carbon/nitrogen (C/N) ratio of the feedstock has been found to be a usefulparameter in providing optimal nitrogen level for bacterial growth.The optimal C/N ratio is 30 [12]. The actual available C/N ratio is afunction of feedstock characteristics and digestion operationalparameters and may vary from less than 10 to above 90. Since allof the carbon and nitrogen present in the feedstock are not avail-able for digestion. Furthermore, it has been reported that at 37 Ctemperature the amount of biogas production is reaches at maxi-mum from each category of waste material under anaerobic diges-tion process [13].

    Most of the experimental studies have been performed to ndout the biogas generation potential of various feedstock mixtureand its individual components of various categories of waste mate-rials like animal dung, kitchen wastes, waste owers, etc. In theanaerobic digestion, the pre-treated substrate produce higheramount of biogas as well as considerably reduce the total and vol-atile solids content in the digester. Furthermore, the chemical anal-ysis of substrates indicates an improvement in nitrogen contentafter anaerobic digestion [14]. The potential biogas productionfrom municipal garbage under batch anaerobic digestion at roomtemperature conditions (26 4 C) for 240 days of retention timewas reported 0.661 m3 kg1 of volatile solids. Total biogas yieldfrom municipal garbage per kg dry matter was observed 0.50 m3

    with an average methane content of the biogas of 70% by volume[15].

    Anaerobic digestion of olive oil mill wastewater (OMW) mixedwith diluted poultry manure (DPM) in pilot plant reactor of 100 l,containing 40% volatile solids produces biogas at a rate of 1.53 l/d per unit volume of reactor with a methane content of 65% by vol-ume. Co-digestion of wastewater together with local agriculturalresidues is a sustainable and environmentally attractive methodto treat wastes and convert to useful resources. The biogas pro-duced can be used for the generation of heat or electricity; apart

    PC pongamia oil seed cakeSTP standard temperature and pressureTS total solidsTVSMRE total volatile solids mass removal efciencyVS volatile solidsl litrem3 cubic metreN nitrogen

    rgy 93 (2012) 148159 149from this energy co-digestion results in liquid and solid efuentsthat are also valuable as they retain all their nutrient constituents(nitrogen, phosphorus, trace elements, etc.). Thus, it can be used asbio-fertilizers and soil organic matter improvers [16].

    The review of the literature showed that no study has been re-ported on anaerobic digestion of jatropha and pongamia oil seedcakes. Although, the production of these two oil seed cakes is ex-pected to be very high in India. These feed materials could be a po-tential source of biogas production which would be used tosupplement the petroleum demand in substantial amount.

    2. Analysis of feed materials and experimental details ofanaerobic digestion process

    2.1. Proximate and ultimate analysis of feed material

    The proximate and ultimate analysis of jatropha and pongamiaoil seed cakes were carried out as per standard procedure de-scribed below.

  • Ene2.1.1. Proximate analysis2.1.1.1. Moisture content. The moisture content of the feed materialwas determined as follows: the initial weight of the samples of50 g biomass with pre-weighed moisture boxes were taken byusing an electronic balance with least count of 0.001 g. The sam-ples were rst heated at 60 C for 24 h and then at 103 C for 3 husing a hot air oven. The nal weight or dried samples weight withpre-weighed moisture boxes were recorded. The percentage mois-ture content of the sample was then calculated by using:

    MC Ww WdWw

    100 1

    where MC is the moisture content, % (wet basis); Ww is the weightof wet sample, g; and Wd is the weight of oven dried sample, g.

    2.1.1.2. Oil content. The oil content of the mechanically expelled oilseed cakes of jatropha and pongamia were determined by Soxhletextraction method. The samples of 200 g of jatropha and pongamiaoil seed cakes were crushed using mechanical blender. The crushedsamples of oil seed cake were packed in a thimble and the oil wasextracted with the solvent n-hexane. The solvent n-hexane was -nally removed by rotary evaporator (Laborta 4000-HeidolphInstruments, Germany) to recover the oil.

    2.1.1.3. Total solids content. The total solids content of feed materi-als were determined as per the standard method [17]. The initialweight of the samples of 50 g biomass with pre-weighed porcelainboxes were taken by using an electronic balance with least count of0.001 g. The samples were rst heated at 60 C for 24 h and then at103 C for 3 h using a hot air oven. The nal weight or dried sam-ples weight with pre-weighed porcelain boxes were recorded. Thepercentage total solids content of the sample was then calculatedby using:

    TS WdWw

    100 2

    where TS is the total solids, %; Wd is the weight of oven dried sam-ple, g; and Ww is the weight of wet sample, g.

    2.1.1.4. Volatile solids content and non-volatile solids content. Thevolatile solids content and non-volatile solids content of feedmaterials were determined as per the standard method [17]. Theoven dried samples used for determination total solids contentwere further dried at 550 C 50 C temperature for 1 h in a mufefurnace and allowed to ignite completely. The dishes were thentransferred to a desiccator for nal cooling. The weight of thecooled porcelain dishes with ash were taken by the electronic bal-ance. The volatile solids content and non-volatile solids content ofthe sample were calculated using:

    VS Wd WaWd

    100 3

    NVS WaWd

    100 4

    where VS is the volatile solids in dry sample, %; NVS is the non-vol-atile solids in dry sample, %; Wd is the weight of oven dried sample,g;Wa is the weight of dry ash left after igniting the sample in a muf-e furnace, g.

    2.1.2. Ultimate analysisCarbon, hydrogen and nitrogen contents in feed materials (cat-

    tle dung, jatropha oil seed cake and pongamia oil seed cake) were

    150 R. Chandra et al. / Applieddetermined using fully automatic instrument Vario EL elementalanalyzer (Perkin Elmer, USA Made) which enables speedy andaccurate quantitative analysis of CHN in the sample. The instru-ment works on the principle of thermal conductivity detector(TCD).

    2.2. Start up of anaerobic digester

    The major challenge in anaerobic digestion of jatropha andpongamia oil seed cakes is lack of inherent bacteria like in cattledung. Apart from the existing bacteria in a digester, fresh cattledung continuously ad...

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