Retno Ambarwati Sigit Lestari


2 Kinetics of Growth Rate of Microalga: The Effect of Carbon Dioxide Concentration

Authors: Retno Ambarwati Sigit Lestari


Microalga is one of the organisms that can be considered ideal and potential for raw material of bioenergy production, because the content of lipids in microalga is relatively high. Microalga is an aquatic organism that produces complex organic compounds from inorganic molecules using carbon dioxide as a carbon source, and sunlight for energy supply. Microalga-CO₂ fixation has potential advantages over other carbon captures and storage approaches, such as wide distribution, high photosynthetic rate, good environmental adaptability, and ease of operation. The rates of growth and CO₂ capture of microalga are influenced by CO₂ concentration and light intensity. This study quantitatively investigates the effects of CO₂ concentration on the rates of growth and CO₂ capture of a type of microalga, cultivated in bioreactors. The works include laboratory experiments as well as mathematical modelling. The mathematical models were solved numerically and the accuracy of the model was tested by the experimental data. It turned out that the mathematical model proposed can well quantitatively describe the growth and CO₂ capture of microalga, in which the effects of CO₂ concentration can be observed.

Keywords: Photobioreactor, mathematical model, CO2 concentration, Microalga

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1 Sulfide Removal from Liquid Using Biofilm on Packed Bed of Salak Fruit Seeds

Authors: Wahyudi Budi Sediawan, Retno Ambarwati Sigit Lestari, Sarto Sarto


This study focused on the removal of sulfide from liquid solution using biofilm on packed bed of salak fruit seeds. Biofilter operation of 444 hours consists of 6 phases of operation. Each phase lasted for approximately 72 hours to 82 hours and run at various inlet concentration and flow rate. The highest removal efficiency is 92.01%, at the end of phase 7 at the inlet concentration of 60 ppm and the flow rate of 30 mL min-1. Mathematic model of sulfide removal was proposed to describe the operation of biofilter. The model proposed can be applied to describe the removal of sulfide liquid using biofilter in packed bed. The simulation results the value of the parameters in process. The value of the rate maximum spesific growth is 4.15E-8 s-1, Saturation constant is 9.1E-8 g cm-3, mass transfer coefisient of liquid is 0.5 cm s-1, Henry’s constant is 0.007, and mass of microorganisms growth to mass of sulfide comsumed is 30. The value of the rate maximum spesific growth in early process is 0.00000004 s-1.

Keywords: Biofilm, removal, packed bed, sulfide, salak fruit seeds

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