D. Ariyanti
Center of Biomass and Renewable Energy (CBIORE), Diponegoro University,

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Batch and Fed-Batch Fermentation System on Ethanol Production from Whey using Kluyveromyces marxianus Hadiyanto, H; Ariyanti, D.; Aini, A.P.; Pinundi, D.S.
International Journal of Renewable Energy Development Vol 2, No 3 (2013): October 2013
Publisher : Center of Biomass & Renewable Energy, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/ijred.2.3.127-131

Abstract

Nowadays reserve of fossil fuel has gradually depleted. This condition forces many researchers to  find energy alternatives which is renewable and sustainable in the future. Ethanol derived from cheese industrial waste (whey) using fermentation process can be a new perspective in order to secure both energy and environment. The aim of this study was  to compare the operation modes (batch and fed-batch) of fermentation system on ethanol production from whey using Kluyveromyces marxianus. The result showed that the fermentation process for ethanol production by fed-batch system was higher at some point of parameters compared with batch system. Growth rate and ethanol yield (YP/S) of fed-batch fermentation were 0.122/h and 0.21 gP/gS respectively; growth rate and ethanol yield (YP/S) of batch fermentation were 0.107/h, and 0.12 g ethanol/g substrate, respectively. Based on the data of biomass and ethanol concentrations, the fermentation process for ethanol production by fed-batch system were higher at some point of parameters compared to batch system. Periodic substrate addition performed on fed-batch system leads the yeast growth in low substrate concentrations and consequently  increasing their activity and ethanol productivity. 
Heavy Metal Waste Using Ch/AgNPs Synthesized by Gamma Radiolysis: Preliminary Study Ariyanti, D.; Basuki, K. T.; Megasari, K.; Ismail, I; Abimanyu, A.; Hamadi, H.; Rozana, K.
Atom Indonesia Vol 51, No 1 (2025): APRIL 2025
Publisher : National Research and Innovation Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55981/aij.2025.1181

Abstract

Environmental issues had always been a problem for all countries in the world. Within a certain threshold, heavy metal waste in water and air must be considered. Various methods and instruments could be used for analysis of heavy metal waste levels. However, quick and accurate method needs to be upgraded in order to improve the efficiency of analysis. Ag nanoparticle is an alternative that could be used to detect the presence of heavy metal waste. Ag nanoparticles can be synthesized through reduction reaction with reductant agents from chemicals, biological compounds, and gamma irradiation. This research used qualilative analysis, utilizing chitosan stabilizer for Ag nanoparticles with gamma irradiation reductant in various doses, such as 7.5, 15, and 20 kGy. The results showed that AgNPs/chitosan was formed in the peak absorption range of 390-500 nm with optimum gamma irradiation dose of 15 kGy. In addition, AgNPs/chitosan has good sensitivity to detect Cr and Hg metals and was not sensitive to Cu and Pb metals.