BackgroundEthanol production from paper sludge (PS) by simultaneous saccharification and fermentation (SSF) is considered to be the most appropriate way to process PS, as it contains negligible lignin. In this study, SSF was conducted using a cellulase produced from PS by the hypercellulase producer, Acremonium cellulolyticus C-1 for PS saccharification, and a thermotolerant ethanol producer Saccharomyces cerevisiae TJ14 for ethanol production. Using cellulase of PS origin minimizes biofuel production costs, because the culture broth containing cellulase can be used directly.ResultsWhen 50 g PS organic material (PSOM)/l was used in SSF, the ethanol yield based on PSOM was 23% (g ethanol/g PSOM) and was two times higher than that obtained by a separate hydrolysis and fermentation process. Cellulase activity throughout SSF remained at around 60% of the initial activity. When 50 to 150 g PSOM/l was used in SSF, the ethanol yield was 21% to 23% (g ethanol/g PSOM) at the 500 ml Erlenmeyer flask scale. Ethanol production and theoretical ethanol yield based on initial hexose was 40 g/l and 66.3% (g ethanol/g hexose) at 80 h, respectively, when 161 g/l of PSOM, 15 filter paper units (FPU)/g PSOM, and 20% inoculum were used for SSF, which was confirmed in the 2 l scale experiment. This indicates that PS is a good raw material for bioethanol production.ConclusionsEthanol concentration increased with increasing PSOM concentration. The ethanol yield was stable at PSOM concentrations of up to 150 g/l, but decreased at concentrations higher than 150 g/l because of mass transfer limitations. Based on a 2 l scale experiment, when 1,000 kg PS was used, 3,182 kFPU cellulase was produced from 134.7 kg PS. Produced cellulase was used for SSF with 865.3 kg PS and ethanol production was estimated to be 51.1 kg. Increasing the yeast inoculum or cellulase concentration did not significantly improve the ethanol yield or concentration.

Cellulase production was investigated in pH-controlled cultures of Acremonium cellulolyticus. The response to culture pH was investigated for three cellulolytic enzymes, carbomethyl cellulase (CMCase), avicelase, and β-glucosidase. Avicelase and β-glucosidase showed similar profiles, with maximum activity in cultures at pH 5.5–6. The CMCase activity was highest in a pH 4 culture. At an acidic pH, the ratios of CMCase and avicelase activity to cellulase activity defined by filter paper unit were high, but at a neutral pH, the β-glucosidase ratio was high. The pH 6.0 culture showed the highest cellulase activity within the range of pH 3.5–6.5 cultures. The saccharification activity from A. cellulolyticus was compared to those of the cellulolytic enzymes from other species. The A. cellulolyticus culture broth had a saccharification yield comparable to those of the Trichoderma enzymes GC220 and Cellulosin T2, under conditions with the same cellulase activity. The saccharification yields from Solka floc, Avicel, and waste paper, measured as the percent of released reducing sugar to dried substrate, were greater than 80% after 96 h of reaction. The yields were 16% from carboxymethylcellulose and 26% from wood chip refiner. Thus, the A. cellulolyticus enzymes were suitable for converting cellulolytic biomass to reducing sugars for biomass ethanol production. This study is a step toward the establishment of an efficient system to reutilize cellulolytic biomass.

ABSTRAK Pemanfaatan minyak jelantah sebagai bahan baku pembuatan biodiesel memberikan beberapa manfaat seperti mengurangi pencemaran lingkungan di began air. Karena masyarakat sekarang ini cenderung membuang minyak jelantah dengan kualitas yang sangat rendah. Selain itu, bahan baku minyak jelantah ini sudah bukan lagi dikategorikan sebagai bahan pangan mengingat bentuknya yang hitam dan encer. Pembuatan biodiesel dengan transesterifikasi suasana basa ini bisa dilakukan dengan biaya yang murah dengan mengggunakan NaOH teknis yang banyak dijual dipasar dan ethanol teknis. Optimasi dilakukan dengan mempertimbangkan parameter jumlah NaOH teknis 2N mulai dari 10, 25, 40, 55 dan 70 ml dan exces ethanol 0, 25, 50, 75 dan 100%. Proses transesterifikasi dilakukan pada suhu 80°C selama tiga jam dalam pengadukan yang homogen. Kondisi optimum didapatkan dengan menggunakan 10 ml NaOH 2M dan 0% exces ethanol sebesar 196.64 gr/200 gr minyak jelantah. Kondisi ini juga mampu meminimalkan volume glycerol yang hanya berjumlah 79.79 ml. Secara keseluruhan FFA biodiesel ini sudah dibawah 0.5% sesuai dengan yang diharapkan. Adapun kualitas biodiesel melalui pengamatan masa jenis yang menunjukan 0.937 gr/ml masih harus dilakukan perlakukan lebih lanjut dari target yang diharapkan 0.900 gr/ml, yaitu dengan melakukan penguapan air dalam oven pada suhu lebih tinggi dan durasi yang lebih panjang. Kata kunci: biodiesel, minyak jelantah, transesterifikasi, Fatty Acid Ethyl Ester (FAEE)

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Cellulase was produced by Acremonium cellulolyticus using untreated waste paper sludge (PS) as the carbon source. The clay present in PS did not show any inhibitory effect on cellulase production but did alter the pH during fermentation. On the flask scale, the maleate buffer concentration and pH were key factors that affected the efficiency of cellulase production from PS cellulose. Optimum cellulase production in a 3-L fermentor of working volume 1.5 L was achieved by controlling the pH value at 6.0 using 2 M NaOH and 2 M maleic acid, and the productivity reached 8.18 FPU/mL. When 40.89 g/L PS cellulose, 2.2 g/L (NH(4) )(2) SO(4) , and 4.4 g/L urea were added to a 48-h culture, the cellulase activity was 9.31 FPU/mL at the flask scale and 10.96 FPU/mL in the 3-L fermentor. These values are ∼80% of those obtained when pure cellulose is used as the carbon source. The method developed here presents a new route for the utilization of PS.