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"Xylitol is a sugar alcohol used as a sweetener in the food industry. Xylitol can be produced from D-xylose using a fermentation process, but it then needs to be separated from the other components of the fermentation broth (e.g., metabolic products, residual substances, biomass cells, and mineral salts), before being purified as xylitol crystals. Therefore, to obtain high purity xylitol, various separation processes are required. One very promising downstream processing method is membrane separation. This study evaluated membrane-based processes for the separation of biomass cells and other impurities, determined the concentration of xylitol produced from Debaryomyces hansenii yeast fermentation broth, and proposed a polysulfone ultrafiltration (UF) membrane for biomass-cell separation followed by polyamide nanofiltration (NF) to remove low-molecular-weight compounds (e.g., acetic acids) from sugars. The effects of operating pressure were examined using a fermentation broth model solution. The results showed that a higher pressure caused a higher permeate flux; however, the permeate flux’s rate flow decreased over time due to concentration polarization, and fouling in the UF and NF membranes. Nevertheless, at all pressures, UF achieved a 99% rejection of biomass cells. In addition, microscope analysis showed that no biomass cells were detected in the permeates of UF. The resulting NF concentrates revealed high xylitol retention and a beneficially lower concentration of acetic acids. The operating pressures of the UF test conditions were 1 barg and 1.5 barg, illustrating that, at a pressure of 5.5 barg, the experiments achieved reasonably high xylitol retention (above 90%) indicating negligible losses of sugar in the permeate port. Moreover, this was proven to be a feasible way to concentrate xylitol up to three times from the initial concentration of the model fermentation broth (MFB). Therefore, the results demonstrated that a two-stage combination of UF and NF is a promising system for the downstream processing of microbial xylitol production."

"This book aims to disseminate the most current advances in the biotechnological production of D-xylitol and its applications in medical and health care. This book also provides essential information on hemicellulose hydrolysis to recover D-xylose, detoxification of hemicellulose hydrolysates, and improved fermentation methods for increased D-xylitol production. The highlights of strain improvement to increase the D-xylitol titers and downstream recovery of D-xylitol are also discussed in several sections. The current applications of D-xylitol in medical and health care have been used to justify the cost incurred for setting up the demonstration plant for D-xylitol production in the market. "

"This book will review the current status of the agriculture and agri-food sector in regard to green processing and provide strategies that can be used by the sector to enhance the use of environmentally-friendly technologies for production, processing. The book will look at the full spectrum from farm to fork beginning with chapters on life cycle analysis and environmental impact assessment of different agri-food sectors. This will be followed by reviews of current and novel on-farm practices that are more environmentally-friendly, technologies for food processing that reduce chemical and energy use and emissions as well as novel analytical techniques for R&D and QA which reduce solvent, chemical and energy consumption. Technologies for waste treatment, "reducing, reusing, recycling", and better water and energy stewardship will be reviewed. In addition, the last section of the book will attempt to look at technologies and processes that reduce the generation of process-induced toxins (e.g., trans fats, acrylamide, D-amino acids) and will address consumer perceptions about current and emerging technologies available to tackle these processing and environmental issues."

"Concerns over dwindling fossil fuel reserves and impending climate changes have focused attention worldwide on the need to discover alternative, sustainable energy sources and fuels. Biofuels, already produced on a massive industrial scale, are seen as one answer to these problems. However, very real concerns over the effects of biofuel production on food supplies, with some of the recent increases in worldwide food costs attributable to biofuel production, have lead to the realization that new, non-food substrates for biofuel production must be bought online. This book is an authoritative, comprehensive, up-to-date review of the various options under development for the production of advanced biofuels as alternative energy carriers. "

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Masalah lingkungan seperti polusi sistem perairan telah mendorong urgensi penyusunan teknologi pengolahan limbah yang lebih baik. Nitrat adalah salah satu target pencemar yang digunakan dalam asesmen kualitas air. Saat ini, proses biologis untuk eliminasi nitrat dari sistem perairan sedang dikembangkan sebagai alternatif untuk proses-proses fisika-kimia yang sering digunakan. Microbial electrolysis cell (MEC) adalah teknologi baru yang diajukan untuk tujuan tersebut. Penelitian ini bertujuan memasangkan proses eliminasi nitrat dengan produksi biohidrogen (bio-H₂) di sistem MEC. Cakupan studi ini adalah dua sistem yang disebut mini-MEC dan MEC. Kedua sistem tersebut dibedakan berdasarkan volumenya. Parameter optimum operasi (V_ext dan sumber karbon) ditetapkan pada sistem mini-MEC sebelum beralih ke sistem MEC. Kondisi optimum ditentukan pada V_ext 0,7 V dengan asetat sebagai sumber karbon terbaik. Sistem dievaluasi berdasarkan performa luaran elektrikal (I_d, P_d), eliminasi nitrat (RE%, R_NO3-), dan produksi bio-H₂ (H_max, R_H2, dan Y_H2). Konsorsium desain (kode konsorsium: IS dan IW) disusun berdasarkan hasil penelitian sebelumnya dengan kinerja eliminasi nitrat dan lokasi isolasi sebagai kriteria desain. Konsorsium desain dibandingkan dengan konsorsium alam (S) di MEC skala 100 mL untuk proses simultan eliminasi nitrat dan produksi biohidrogen. Konsorsium IS memberikan hasil terbaik dari segi profil produksi biohidrogen dengan H_max 10,6515 mg L^-1, Y_H2 6,491 mg g^-1, dan R_max 0,0867 mg L^-1 jam^-1. Konsorsium alam S memberikan performa terendah dari ketiga konsorsium yang diuji. Data dari konsorsium IS dievaluasi terhadap model untuk pertumbuhan dan produksi biohidrogen. Model Gompertz dan logistik termodifikasi dapat mendeskripsikan data dengan baik berdasarkan parameter fit R². Estimasi parameter model dilakukan melalui metode non-linear least square. Hasil estimasi parameter model Gompertz yang telah dioptimasi adalah 0,1659 untuk R_max, 10,2495 untuk H_max, dan 30,0607 untuk l. Selanjutnya, studi ini dapat dikembangkan ke arah penyusunan model prediktif profil bio-H₂ pada sistem MEC berdasarkan hubungan linear antara profil bio-H₂ dan pertumbuhan sel.

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Environmental problems, especially pollution to water systems have urged research into cleaner wastewater treatment strategies. Nitrate is one of the main targets for water quality control. The use of biological processes to remove nitrate from water systems is being studied as alternatives to current physico-chemical practices. Microbial electrolysis cell (MEC) emerged as a new technology that is appropriate for this purpose. This research aim to pair nitrate elimination with biohydrogen production in MEC. The study worked on two scales of MECs, referred to as mini-MEC (20 mL) and MEC (100 mL). Operating parameters (V_ext and carbon source) was determined on mini-MEC using axenic cultures of known denitrifying bacteria. V_ext was set at 0.70 V and CH₃COONa was selected as carbon source for subsequent experiments. System was evaluated based on electrical outputs (I_d, P_d), nitrate elimination (RE%, R_NO3-), and biohydrogen production (H_max, R_H2, and yield). Synthetic microbial consortia were designed based on isolates obtained in a previous research using nitrate elimination and site characteristics as design criteria. Designed consortia (IS and IW) was compared against naturally occurring soil microbial consortium (S) in 100 mL MEC for simultaneous biohydrogen production and nitrate elimination. Consortium IS yield better biohydrogen production profile with H_max of 10.6515 mg L^-1, Y_H2 at 6.491 mg g^-1, and R_max 0.0867 mg L^-1 h^-1. Consortium S performed the worst out of three with declining H₂ concentration curves at later operation period. The data from consortium IS was evaluated against models for bio-H₂ production. Modified Gompertz model could describe the data well based on comparison of fit parameter R² against modified logistic model. Model optimization was carried out by non-linear least square methodology. Optimized parameter values were 0.1659 for R_max, 10.2495 for H_max, and 30.0607 for l. Future studies should explore the design of a predictive model for H₂ production based on microbial growth in MEC inoculated with microbes with similar profile to IS consortium.

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"Tofu waste can be used as a raw material for bioethanol production due to its high carbohydrate content in the form of starch. A microbial consortium, consisting of Aspergillus niger and Saccharomyces cerevisiae. The study’s first objective wasto capture the amount of sugar produced from starch hydrolysis using single cultures of Aspergillus niger.The study’s second objective wasto determine the amount of ethanol produced by the SSF technique. Aspergillus niger was used to produce an amylase enzyme that hydrolyzes starch into simple sugar.Then, Saccharomyces cerevisiae was used to produce bioethanol from the sugar produced earlier.The synthesis of bioethanol consists of two main stages, hydrolysis and fermentation. In previous studies, the hydrolysis and fermentation processes were performed separatelyusing a separated hydrolysis and fermentation (SHF)technique. This studyprocesses via a simultaneous saccharification and fermentation (SSF) technique which produced higher substrate efficiency, cell yield, and product yield compared to the SHF process.The characterization process showed that tofu waste flour was mainly composed of carbohydrates, which comprised 52.82±0.01% (dw) and had a starch content of 35.1±0.2% (dw). Sugar from the starch of the tofu waste was produced by batch system cultivation for 84 hours using Aspergillus niger. The highest sugar production (14.48 g/L) was achieved during the 48th hour. Then, Saccharomyces cerevisiae was used to convert the produced sugar into bioethanol. The production of bioethanol by SSF using a microbial consortium for 72 hours was 7.69 g/L of bioethanol, with a yield of bioethanol per substrate use (Yp/s) of 0.23 g ethanol/g substrate and a substrate conversion efficiency of 88%."

"Teknologi Microbial Fuel Cell (MFC) berpotensi dikembangkan sebagai sumber energi listrik alternatif karena dapat mengkonversi berbagai substrat dari sumber yang dapat diperbaharui menjadi energi listrik menggunakan bakteri sebagai biokatalis. Limbah cair tempe merupakan salah satu bahan yang dapat dimanfaatkan sebagai substrat MFC. Penggunaan limbah cair tempe sebagai substrat MFC memberikan keuntungan dalam mengurangi biaya pembelian bakteri dan pengolahan limbah cair tempe. Saat ini, aplikasi MFC masih terbatas karena produksi listrik yang dihasilkan relatif kecil, sehingga banyak penelitian yang dilakukan untuk meningkatkan produksi listrik oleh MFC. Penelitian ini berfokus dalam meneliti pengaruh waktu pembentukan biofilm dan penggunaan makromolekul sebagai substrat tambahan terhadap produksi listrik dari sistem MFC dengan reaktor tubular membranless dan substrat limbah cair tempe. Hasil penelitian menunjukkan bahwa karbohidrat merupakan makromolekul dalam limbah cair tempe yang paling berpengaruh dalam produksi listrik ditandai dengan nilai penurunan kadar terbesar, yaitu 1,82%, setelah eksperimen MFC dilakukan selama 50 jam. Pembentukan biofilm pada anoda dapat meningkatkan produksi listrik hingga 10 kali lipat, sedangkan penggunaan glukosa sebagai substrat tambahan menurunkan produksi listrik hingga 60%. Hasil keluaran listrik terbesar diperoleh dari variasi waktu pembentukan biofilm 14 hari dengan kandungan EPS pada biofilm sebesar 0,13 mg/cm2. Nilai tegangan dan densitas daya maksimum yang dihasilkan berturut turut 34,81 mV dan 0,26 mW/m2.

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Microbial Fuel Cell (MFC) technology has the potential to be developed as an alternative energy source since it can convert various substrates from renewable sources into electricity using bacteria as biocatalyst. Tempe wastewater is one of the material which can be utilized as MFC substrate. The use of tempe wastewater as MFC substrate gives advantages in reducing the purchasing cost of bacteria and tempe wastewater treatment. Currently, the applications of MFCs are still limited due to the relatively low electricity production, so many studies have been conducted to improve the electricity production by MFC.

This study focused on investigating the influence of biofilm formation time and the use of macromolecule as additional substrate towards electricity production from MFC system with tubular membranless reactor.

This study suggested that carbohydrate is the macromolecule contained in tempe wastewater which is the most influential for electricity production marked by the biggest decrease in macromolecule content, which is 1.82%, after MFC experiment had been carried out for 50 hours. In addition, biofilm formation on anode could improve the electricity production up to 10-folds while the use of glucose as substrate addition reduce the electricity production. The biggest electricity output was obtained from the experiment of biofilm formation for 14 days with EPS content in biofilm 0,13 mg/cm2 where the maximum voltage and power density produced was respectively 34,81 mV dan 0,26 mW/m2."

"ABSTRACTPenggunaan bahan bakar fosil berujung pada berbagai macam kerusakan lingkungan. Salah satu bahan bakar alternatif potensial untuk menggantikan penggunaan bahan bakar fosil ialah hidrogen, dikarenakan tingginya nilai kalorifik hidrogen dan emisinya yang hanya berupa uap air dan oksigen apabila dikonsumsi sebagai bahan bakar. Namun demikian, mayoritas proses produksi hidrogen masih bergantung pada sumber fosil dan sangat mengonsumsi energi, seperti pirolisis bahan bakar fosil. Selama dua dekade terakhir, penggunaan potensial sistem Microbial Electrolysis Cell MEC telah banyak diteliti sebagai sarana produksi hidrogen. Selain konsumsi energi yang sangat rendah, sistem MEC ini mampu menggunakan limbah lumpur sebagai substrat bagi komunitas bakteri di dalamnya. Satu masalah besar yang senantiasa timbul dalam penggunaan sistem MEC ialah keberadaan metanogen, yaitu bakteri penghasil metana. Metanogen ini mengonsumsi biohidrogen yang diproduksi pada katoda MEC sehingga menurunkan yield produksi biohidrogen. Penelitian ini mengemukakan metode kontrol biologis melalui pengenalan koloni terisolasi bakteri denitrifikasi ke dalam sistem MEC dalam wujud bioelektroda diperkaya sebagai kompetitor alami metanogen, dengan tujuan akhir untuk menginhibisi pertumbuhan metanogen. Penelitian akan dilakukan dalam konfigurasi MEC satu-ruang single-chamber. Komposisi gas headspace reaktor yang diperkaya dengan denitrifier akan dibandingkan dengan reaktor kontrol untuk menguji kebenaran hipotesis. Hipotesis akan diuji melalui analisis komposisi gas masing-masing reaktor. Hasil penelitian menunjukkan bahwa reaktor yang telah diperkaya dengan denitrifier mampu meningkatkan produksi H2 dalam beberapa siklus pengerjaan, dimana pada siklus kedua produksi H2 meningkat sebesar 100 apabila dibandingkan terhadap reaktor kontrol.

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ABSTRACTThe intense usage of fossil fuel has led to the release of pollutants that are closely linked with the global warming phenomena, causing a variety of irreconcilable environmental destruction. One potential alternative fuel to replace fossil based fuels is hydrogen, as it possesses high calorific content and only emits water vapor and oxygen on usage. However, the majority of hydrogen production processes still rely on fossil based resources as well as energy consuming such as fossil fuel pyrolysis. In the past two decades, the potential use of microbial electrolysis cell MEC reactor to produce biohydrogen has been continuously researched. Aside from a very low energy input, it can utilize wastewater sludge as a feed for the bacterial community. A persistent problem present in all MEC usage is the presence of methanogens or methane producing bacteria. The methanogens consumes produced biohydrogen at the cathode of the MEC, reducing significant net biohydrogen yield. Numerous methods based on antibiotics, chemicals, and physical manipulations have been attempted. However, biological methods are still left largely unexplored. This research proposes the introduction of biological control method through bioelectrode enrichment with isolated colony of denitrifying bacteria to the MEC system as natural competitor to methanogens, ultimately aiming for inhibition of methanogenic, hydrogenotrophic microbial growth. The research will be done based on a single chambered MEC configuration. Composition of headspace gas in a denitrifier enriched reactor will be compared with control one to confirm the hypothesis. Hypothesis will be tested through analyzing the composition of evolved gas in each reactor. The experiment proves that in several consequent cycles, denitrifier enriched reactor increases H2 production such as in the second cycle, where H2 production increases 100 when compared to control reactor. "