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Abstrak :
[ABSTRAK
Penggunaan bahan bakar oleh industri secara masif meningkatkan emisi karbon dioksida secara signifikan. Hal ini menyebabkan dua permasalahan besar, yakni pemanasan global dan krisis energi. Untuk mengatasi kedua masalah tersebut, mikroalga klorofita, seperti Chlorella vulgaris, dikenal memiliki kemampuan fiksasi karbon dioksida yang baik. Karbon dioksida yang terikat kemudian disintesis menjadi lipid. Lipid yang dihasilkan merupakan bahan baku biodiesel. Pada studi kali ini, mikroalga Chlorella vulgaris dikultivasi dalam fotobioreaktor 18 liter dan medium kompos pada pencahayaan 3000 lux selama 90 jam sebagai prototipe skala besar dengan variasi densitas sel awal dan konsentrasi karbon dioksida. Kultivasi pada densitas sel awal 0,137 g.dm-3 mampu memfiksasi karbon dioksida hingga 30,38 g.dm-3.hari-1 (93,56%) pada pengaliran karbon dioksida 23,80 g.jam-1 dengan produktivitas biomassa 0,44 g.dm-3.hari-1 dan yield lipid 0,0795 glipid.gsel-1, serta menunjukan potensi fiksasi karbon dioksida (31,51%) dan produksi lipid (0,0739g.g-1) yang baik pada pengaliran karbon dioksida 48,17 g.jam-1. Kultivasi pada densitas sel awal lebih tinggi (0,325 g.dm-3) menunjukan resistansi lebih baik pada pengaliran karbon dioksida 48,17 g.jam-1 dengan fiksasi karbon 37,95 g.dm-3.hari-1 (58%) , produksi biomassa 0,82 g.dm-3.hari-1 dan yield lipid 0,0834 g.g-1serta potensi yang baik pada pengaliran karbon dioksida 65,96 g.jam-1. Dengan efisiensi fotosintesis mencapai 26,3% pada densitas awal sel rendah dan 8,31% pada densitas awal sel tinggi, model kinetika Haldane mampu memberikan pendekatan (R=0,957) pada kurva pertumbuhan, mengindikasi besarnya pengaruh inhibisi substrat. Penelitian ini menunjukan potensi mikroalga klorophyta serta memberikan dasar empiris model dalam mereduksi karbon dioksida berkonsentrasi tinggi dan sekaligus memproduksi lipid sebagai bahan dasar biodiesel pada skala besar. Studi lebih lanjut diperlukan untuk adaptasi skala komersial.

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ABSTRACT
Massive use of fuels by industry increase carbon dioxide emission significantly. This leads to two big problems of the world, which are global warming and energy crsis. To deal with those problems, microalgae chlorophyta, especially Chlorella vulgaris, is wellknown for its ability to fixate carbon dioxide. Fixated carbon dioxide is then synthesized to lipid. Lipid produced is the raw material for biodiesel. In this study, microalgae Chlorella vulgaris is cultivated in photobioreactor (volume 18L) and in liquid organic compost based medium under illumination 3000 lux for 90 hours as prototype for scale up with varying initial density and carbon dioxide concentration. Cultivation with initial cell density 0.137 g.dm-3 shows ability to fixate carbon dioxide up to 30.38 g.dm-3.day-1 (93.56%) under carbon dioxide inflow 23.80 g.hour-1 with biomass productivity 0.44 g.dm-3.day-1 and lipid yield 0.0795 glipid.gcell-1, and shows potential to fixate carbon dioxide (31.51%) and produce high lipid (0,0739g.g-1) under carbon dioxide inflow 48,17 g.hour-1. Cultivation with higher initial cell density (0,325 g.dm-3) shows better resistance under carbon dioxide inflow 48.17 g.hour-1 with carbon fixation 37.95 g.dm-3.day-1 (58%) , biomass production 0.82 g.dm-3.day-1, lipid yield 0.0834 g.g-1, and good potential under carbon dioxide inflow 65.96 g.hour-1. With photosynthesis efficiency reaches 26.3% on lower initial cell density and 8,31% on higher initial cell density, Haldane kinetic model manages to give approach (R=0.957) on growth curve, indicating significance of substrate inhibition. This research shows potential of Chlorella vulgaris and empirical model base in reducing high concentration carbon dioxide and simultaneously producing lipid as raw material for biodiesel at larger scale. Further study is necessary for adapting this potential to commercial scale., Massive use of fuels by industry increase carbon dioxide emission significantly. This leads to two big problems of the world, which are global warming and energy crsis. To deal with those problems, microalgae chlorophyta, especially Chlorella vulgaris, is wellknown for its ability to fixate carbon dioxide. Fixated carbon dioxide is then synthesized to lipid. Lipid produced is the raw material for biodiesel. In this study, microalgae Chlorella vulgaris is cultivated in photobioreactor (volume 18L) and in liquid organic compost based medium under illumination 3000 lux for 90 hours as prototype for scale up with varying initial density and carbon dioxide concentration. Cultivation with initial cell density 0.137 g.dm-3 shows ability to fixate carbon dioxide up to 30.38 g.dm-3.day-1 (93.56%) under carbon dioxide inflow 23.80 g.hour-1 with biomass productivity 0.44 g.dm-3.day-1 and lipid yield 0.0795 glipid.gcell-1, and shows potential to fixate carbon dioxide (31.51%) and produce high lipid (0,0739g.g-1) under carbon dioxide inflow 48,17 g.hour-1. Cultivation with higher initial cell density (0,325 g.dm-3) shows better resistance under carbon dioxide inflow 48.17 g.hour-1 with carbon fixation 37.95 g.dm-3.day-1 (58%) , biomass production 0.82 g.dm-3.day-1, lipid yield 0.0834 g.g-1, and good potential under carbon dioxide inflow 65.96 g.hour-1. With photosynthesis efficiency reaches 26.3% on lower initial cell density and 8,31% on higher initial cell density, Haldane kinetic model manages to give approach (R=0.957) on growth curve, indicating significance of substrate inhibition. This research shows potential of Chlorella vulgaris and empirical model base in reducing high concentration carbon dioxide and simultaneously producing lipid as raw material for biodiesel at larger scale. Further study is necessary for adapting this potential to commercial scale.]

Abstrak :
Krisis energi menyebabkan kebutuhan akan biodiesel meningkat secara signifikan setiap tahunnya. Untuk mengatasi hal tersebut, Chlorella vulgaris diteliti karena memiliki lipid yang potensial untuk sintesis biodiesel. Akumulasi lipid pada mikroalga dapat ditingkatkan dengan mengontrol kandungan nitrogen. Salah satu pengontrol kandungan nitrogen alami ialah cyanobacteria seperti Spirulina platensis. Penggunaan S. platensis sebagai agen simbiosis dapat memungkinkan akumulasi lipid pada produksi skala pabrik menggunakan medium komersiil seperti kompos dan limbah organik. Pada studi ini, C. vulgaris dan S. platensis dikultur dengan medium BG-11 pada fotobioreaktor datar dengan melihat biomassa dan produktivitas lipid. Komposisi koloni optimum ditentukan dengan intensitas pencahayaan kontinu tertentu untuk menghasilkan lipid tertinggi. Penggunaan S. platensis meningkatkan laju pertumbuhan akibat biosintesis simbiotik dengan yield lipid yang lebih tinggi. Koloni 3:2 (S. platensis 40%wt) menghasilkan yield 6,72% pada intensitas pencahayaan 3000 lux, lebih tinggi dibandingkan kontrol 100% C. vulgaris (5,13%). Hal ini mengkonfirmasi bahwa keberadaan S. platensis menginduksi akumulasi lipid pada mikroalga. Studi lebih lanjut diperlukan untuk memahami proses biosintesis dalam koloni. ...... Due to energy crisis, demand on biodiesel inclines significantly year by year. In order to cope with that, Chlorella vulgaris is often observed for having potential amount of lipid for synthesizing biodiesel. Lipid accumulation in potential C. vulgaris could be induced by controlling nitrogen concentration in optimum level. One of natural nitrogen controller is cyanobacteria. The use of Spirulina platensis as symbiosis agent could enable higher lipid content in non-synthetic, more economic, plant scale medium such as compost and bio-waste. In this study, C. vulgaris and Spirulina platensis were cultured in BG-11 medium in microalgal flat plate photobioreactor to assess biomass and lipid productivity. We also determine optimum colony composition on certain light intensity to yield highest lipid amount. Colony composition 3:2 (40%wt S. platensis) gives highest lipid yield (6.72%) in continuous illumination 3000 lux compare to control sampel (100% C. vulgaris) which only yields 5,13%. This confirms that the existence of cyanobacteria induces lipid accumulation in microalgae Chlorella vulgaris. Further study is needed to understand better biosynthesis in colony and optimum parameters for plant scale establishment.