Aida Nur Ramadhani
Universitas Sebelas Maret

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Biofilm Formation and Bio Corrosion of Carbon Steel in Diesel-Biodiesel Storage Tank Aida Nur Ramadhani; Ardiyan Harimawan; Hary Devianto
Jurnal Presipitasi : Media Komunikasi dan Pengembangan Teknik Lingkungan Vol 18, No 1 (2021): March 2021
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1651.131 KB) | DOI: 10.14710/presipitasi.v18i1.45-55

Abstract

Biodiesel is potential to blend with petroleum diesel as an alternative blended fuel. Biodiesel is usually stored in carbon steel storage tank which easily corroded by microorganisms. Microorganisms can use blended fuels as carbon source and water from biodiesel which is hygroscopic for growth and metabolism. Thus, degradation of fuel may occur and lead to biocorrosion by microorganisms such as Bacillus megaterium. This research was conducted to determine the effect of biodiesel concentration of blended fuel on biofilm formation and biocorrosion by Bacillus megaterium. The experiments were carried out by immersing carbon steel specimens in immersion medium for 21 days with variation of biodiesel concentration (B0, B20, B30, and B100). Biofilms that form on the metal surface cause areas with non-uniform oxygen concentrations and form anodic/cathodic conditions, raised to potential differences and biocorrosion occurred. The average corrosion rates were 0,035 ± 0,03; 0,533 ± 0,33; 0,642 ± 0,28; 0,109 ± 0,04 mm/year achieved by B0, B20, B30 and B100 respectively. These rates increased when compared to the control medium. Microorganism activity also caused damage to the metal surface by forming pitting corrosion on B30 and B100.
Optimization of Fermentable Sugar Production from Pineapple Leaf Waste (Ananas comosus [L.] Merr) by Enzymatic Hydrolysis Yohanita Restu Widihastuty; Sutini Sutini; Aida Nur Ramadhani
Jurnal Presipitasi : Media Komunikasi dan Pengembangan Teknik Lingkungan Vol 18, No 1 (2021): March 2021
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1113.951 KB) | DOI: 10.14710/presipitasi.v18i1.73-80

Abstract

Pineapple leaf waste is one agricultural waste that has high cellulose content. Pineapple leaf waste's complex structure contains a bundle of packed fiber that makes it hard to remove lignin and hemicellulose structure, so challenging to produce reducing sugar. Dried pineapple leaf waste pretreated with a grinder to break its complex structure. Delignification process using 2% w/v NaOH solution at 87oC for 60 minutes has been carried out to remove lignin and hemicellulose structure so reducing sugar could be produced. Delignified pineapple leaf waste has been enzymatic hydrolyzed using cellulase enzyme (6 mL, 7 mL, and 8 mL) to produce reducing sugar. The sample was incubated in an incubator shaker at 155 rpm at 45, 55, and 60oC for 72 hours. Determination of reducing sugar yield had been carried out using the Dubois method and HPLC. The model indicated that the optimum operating condition of enzymatic hydrolysis is 7 mL of cellulase enzyme at 55oC to produce 96,673 mg/L reducing sugar. This result indicated that the enzymatic hydrolysis operating condition improved the reducing sugar yield from pineapple leaf waste. The optimum reducing sugar yield can produce biofuel by the saccharification process.