Tri Widjaja

Production of Ethanol as a Renewable Energy by Extractive Fermentation

One issue with batch fermentation is that product inhibition causes low yields and ethanol productivity. The objective of this study was to increase the yield and ethanol productivity via continuous fermentation in a packed bed bioreactor with both an integrated extraction process and recycling of the raffinate into the fermenter. Molasses was used as the feedstock, and the immobilized cells were supported by ĸ-carrageenan. This process used n-amyl alcohol, 1-octanol, and 1-dodecanol as solvents. The yield and ethanol productivity increased from 8.79% to 20.03% and 34.54 g/L·h to 118.16 g/L·h for experiments using n-amyl alcohol, 9.05% to 12.67% and 35.59 g/L·h to 74.71 g/L·h, for 1-dodecanol, 8.89% to 13.45% and 34.93 g/L·h to 84.62 g/L·h, for1-octanol by increasing recycle ratio from 0 to 0.5. Based on these results, n-amyl alcohol was the best solvent for the extractive fermentation process.

Technique of ethanol food grade production with batch distillation and dehydration using starch-based adsorbent

Development and innovation of ethanol food grade production are becoming the reasearch priority to increase economy growth. Moreover, the government of Indonesia has established regulation for increasing the renewable energy as primary energy. Sorghum is cerealia plant that contains 11-16% sugar that is optimum for fermentation process, it is potential to be cultivated, especially at barren area in Indonesia. The purpose of this experiment is to learn about the effect of microorganisms in fermentation process. Fermentation process was carried out batchwise in bioreactor and used 150g/L initial sugar concentration. Microorganisms used in this experiment are Zymomonas mobilis mutation (A3), Saccharomyces cerevisiae and mixed of Pichia stipitis. The yield of ethanol can be obtained from this experiment. For ethanol purification result, distillation process from fermentation process has been done to search the best operation condition for efficiency energy consumption. The experiment for purification was divided into two parts, which are distillation with structured packing steel wool and adsorption (dehydration) sequencely. In distillation part, parameters evaluation (HETP and pressure drop) of distillation column that can be used for scale up are needed. The experiment was operated at pressure of 1 atm. The distillation stage was carried out at 85 °C and reflux ratio of 0.92 with variety porosities of 20%, 40%, and 60%. Then the adsorption process was done at 120°C and two types of adsorbent, which are starch – based adsorbent with ingredient of cassava and molecular sieve 3A, were used. The adsorption process was then continued to purify the ethanol from impurities by using activated carbon. This research shows that the batch fermentation process with Zymomonas mobilis A3 obtain higher % yield of ethanol of 40,92%. In addition to that, for purification process, the best operation condition is by using 40% of porosity of stuctured packing steel wool in distillation stage and starch-based adsorbent in adsorption stage, which can obtain ethanol content of 92,15% with acetic acid percentage of 0,001% and the rest is water. This result is qualified for ethanol food grade specification which is between 90 - 94 % of ethanol with maximum percentage of acetic acid is 0,003%, and passes in fusel oil and isopropyl alcohol test.

Extractive Fermentation of Sugarcane Juice to Produce High Yield and Productivity of Bioethanol

Ethanol production by batch fermentation requires a simple process and it is widely used. Batch fermentation produces ethanol with low yield and productivity due to the accumulation of ethanol in which poisons microorganisms in the fermenter. Extractive fermentation technique is applied to solve the microorganism inhibition problem by ethanol. Extractive fermentation technique can produce ethanol with high yield and productivity. In this process raffinate still, contains much sugar because conversion in the fermentation process is not perfect. Thus, to enhance ethanol yield and productivity, recycle system is applied by returning the raffinate from the extraction process to the fermentation process. This raffinate also contains ethanol which would inhibit the performance of microorganisms in producing ethanol during the fermentation process. Therefore, this study aims to find the optimum condition for the amount of solvent to broth ratio (S: B) and recycle to fresh feed ratio (R: F) which enter the fermenter to produce high yield and productivity. This research was carried out by experiment. In the experiment, sugarcane juice was fermented using Zymomonasmobilis mutant. The fermentation broth was extracted using amyl alcohol. The process was integrated with the recycle system by varying the recycle ratio. The highest yield and productivity is 22.3901% and 103.115 g / L.h respectively, obtained in a process that uses recycle to fresh feed ratio (R: F) of 50:50 and solvents to both ratio of 1.

Simulation and optimization of continuous extractive fermentation with recycle system

Extractive fermentation is continuous fermentation method which is believed to be able to substitute conventional fermentation method (batch). The recovery system and ethanol refinery will be easier. Continuous process of fermentation will make the productivity increase although the unconverted sugar in continuous fermentation is still in high concentration. In order to make this process more efficient, the recycle process was used. Increasing recycle flow will enhance the probability of sugar to be re-fermented. However, this will make ethanol enter fermentation column. As a result, the accumulated ethanol will inhibit the growth of microorganism. This research aims to find optimum conditions of solvent to broth ratio (S:B) and recycle flow to fresh feed ratio in order to produce the best yield and productivity. This study employed optimization by Hooke Jeeves method using Matlab 7.8 software. The result indicated that optimum condition occured in S: B=2.615 and R: F=1.495 with yield = 50.2439 %.

Biogas production from pretreated coffee-pulp waste by mixture of cow dung and rumen fluid in co-digestion

Coffee is an excellent commodity in Indonesia that has big problem in utilizing its wastes. As the solution, the abundant coffee pulp waste from processing of coffee bean industry has been used as a substrate of biogas production. Coffee pulp waste (CPW) was approximately 48% of total weight, consisting 42% of the coffee pulp and 6% of the seed coat. CPW holds good composition as biogas substrate that is consist of cellulose (63%), hemicellulose (2.3%) and protein (11.5%). Methane production from coffee pulp waste still has much problems because of toxic chemicals content such as caffeine, tannin, and total phenol which can inhibit the biogas production. In this case, CPW was pretreated by ethanol/water (50/50, v/v) at room temperature to remove those inhibitors. This study was to compare the methane production by microbial consortium of cow dung and rumen fluid mixture coffee pulp waste as a substrate with and without pretreatment. The pretreated CPW was fermented with mixture of Cow Dung (CD) and Rumen ...

Studi Awal PRA Desain Pabrik Bioetanol dari Nira Siwalan

Bioetanol kini banyak dikembangkan sebagai bahan bakar alternatif pengganti bahan bakar fosil. Bioetanol untuk campuran bensin harus memiliki kemurnian sebesar 99,5-100%. Bioetanol dapat diperoleh dengan proses fermentasi yang melibatkan mikroorganisme. Pra desain pabrik bioetanol dari nira siwalan ini menggunakan proses fermentasi. Bahan baku berupa nira siwalan diasamkan dengan menggunakan H2SO4, kemudian disterilisasi sebelum difermentasi di fermentor selama 36 jam. Adapun mikroorganisme yang digunakan adalah Saccharomyces cereviceae. Bakteri ini mampu mengurai gula tanpa kehadiran oksigen dan menghasilkan etanol dan karbondioksida. Bioetanol dapat diperoleh dengan proses fermentasi yang melibatkan mikroorganisme. Pra desain pabrik bioetanol dari nira siwalan ini menggunakan proses fermentasi. Bahan baku berupa nira siwalan diasamkan dengan menggunakan H2SO4, kemudian disterilisasi sebelum difermentasi di fermentor selama 36 jam. Adapun mikroorganisme yang digunakan adalah Saccharomyces cereviceae. Setelah dari fermentor nira yang sudah difermentasi dinetralkan pH nya menggunakan NH4OH di tangki netralisasi. Dari tangki netralisasi nira dipompakan melewati preheater sebelum masuk ke kolom distilasi. Pemurnian dilakukan dengan menggunakan kolom distilasi sebanyak 2 buah. Pada distilasi yang pertama diperoleh kadar etanol sebesar 60% dan pada distilasi yang kedua diperoleh kadar 96%. Dari kolom distilasi 2 larutan didinginkan menggunakan cooler untuk didapatkan suhu 32oC agar sesuai dengan suhu proses dehidrasi dengan menggunakan Molecular Sieve yang diinginkan. Proses dehidrasi dilakukan untuk mendapat kadar etanol 99,5%. Etanol 99,5% yang dihasilkan kemudian disimpan dalam tangki penampung. Kebutuhan bioetanol dalam negeri pada tahun 2018 diperkirakan 3.166.015,13 kL/tahun. Berdasarkan analisa ekonomi yang dilakukan, diperoleh hasil sebagai berikut internal rate of return 26,53 % per tahun, pay out time 4,73 tahun, dan BEP 34,62 % Ditinjau dari uraian di atas, maka secara teknis dan ekonomis, pabrik etanol dari nira siwalan layak untuk didirikan.