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Preparation and Identification of Local Microorganisms (LMOs) using Lake Toba Water and Their Utilization for Plastic Biodegradation Lumbantoruan, Chintya Sinar; Misran, Erni; Masyithah, Zuhrina
Reaktor Volume 24 No.2 August 2024
Publisher : Department of Chemical Engineering, Faculty of Engineering, Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/reaktor.24.2.41-51

Abstract

Local microorganisms (LMOs) are solutions made from anaerobic fermentation of sugar and complex carbohydrate sources using a local microorganism source medium. Generally, LMO solution possesses the potential to perform plastic biodegradation. This research aims to analyse the variation of the volume of Lake Toba water as a source of microorganisms in the preparation of LMO and to identify plastic degrading local microorganisms. The research steps consisted of making standard curves and growth curves, LMO preparation, testing the biodegradation of low-density polyethylene (LDPE) plastic, isolating microorganisms, performing biochemical test, testing the clear zone for plastic degrading microorganisms, and identifying microorganisms. LMO was made by mixing raw materials according to the ratio of Lake Toba water volume to substrate, namely 20:80 (% v/v); 30:70 (% v/v); and 40:60 (% v/v) which were fermented for 99 hours at 37 °C. The results showed that LMO pH before and after fermentation changed from 4.75; 4.9; and 4.94. to 3.46; 3.45; and 3.48. The decrease in pH was likely due to the activity of microorganisms that produce organic acids. The LDPE plastic degradation percentage of the resulting LMOs were 2.353% w/w; 3.012% w/w; and 4.023% w/w, respectively. For that reason, five microbe isolates obtained from fermentation of Lake Toba water volume to substrate ratio of 40:60 (% v/v) were further screened to validate their potential in degrading LDPE, which 2 isolates produced clear zones and identified as Staphylococcus aureus and Streptococcus sp.
A Comparative Review on Polyhydroxybutyrate (PHB) Production by Bacillus megaterium Using Different Substrates under Batch Fermentation Lumbantoruan, Chintya Sinar; Fitriani, F.B.A.
Reaktor Volume 25 No.3 December 2025
Publisher : Department of Chemical Engineering, Faculty of Engineering, Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/reaktor.25.3.%p

Abstract

The use of non-degradable plastics as packaging has led to significant environmental issues because they are resistant to degradation and contributes to environmental pollution. The application of biodegradable plastics offers a potential solution to this problem. Polyhydroxybutyrate (PHB) is an environmentally friendly thermoplastic polyester polymer that exhibits advantageous properties compared to conventional plastics, especially its biodegradability. The synthesis of PHB can be achieved through three main routes: synthetic polymerization, genetic engineering, and microbial fermentation. This paper aims to explore most suitable substrate used for PHB biosynthesis via batch microbial fermentation based on the highest yield. The microorganism employed in PHB biosynthesis was Bacillus megaterium, which utilized substrates, such as cheese whey, sugarcane molasses, glucose, and glycerol. The highest PHB yield, 8.29 g/L, was obtained when cheese whey was used as the substrate. These finding indicates that cheese whey provides an excellent nutrient source for PHB production.
Pemanfaatan Serbuk Sekam Padi sebagai Katalis Basa Heterogen pada Pembuatan Biodiesel dari Minyak Kelapa Fitriani, FBA; Togatorop, Elgrini; Lumbantoruan, Chintya Sinar
Jurnal Teknik Kimia USU Vol. 15 No. 1 (2026): Jurnal Teknik Kimia USU
Publisher : Talenta Publisher (Universitas Sumatera Utara)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32734/jtk.v15i1.23521

Abstract

High rice production in Indonesia generates rice husk waste of approximately 0.53–5.8 million tons in 2024, most of which has not been optimally utilized. According to the Ministry of Agriculture (2022), this waste is generally stockpiled or openly burned without further valorization. This study aims to analyze the effect of calcination temperature on the characteristics of rice husk–based heterogeneous catalysts, the effect of catalyst concentration on biodiesel yield, and the reusability of the catalyst. The results show that a calcination temperature of 600°C produces a porous catalyst with a larger number of active sites. The highest biodiesel yield of 91 mL was obtained using a catalyst concentration of 9% w/v. Catalyst reuse for up to two cycles resulted in a decrease in biodiesel yield due to the reduction of active sites; however, the yield remained above 50%. Catalyst pore characteristics were analyzed using Scanning Electron Microscopy  and the produced biodiesel met the requirements of SNI 7182:2015, including a density in the range of 850–890 kg/m³, copper strip corrosion rating of No. 2, and an acid value not exceeding 0.5 mg KOH/g.
Pemanfaatan Serbuk Sekam Padi sebagai Katalis Basa Heterogen pada Pembuatan Biodiesel dari Minyak Kelapa Fitriani, FBA; Togatorop, Elgrini; Lumbantoruan, Chintya Sinar
Jurnal Teknik Kimia USU Vol. 15 No. 1 (2026): Jurnal Teknik Kimia USU
Publisher : Talenta Publisher (Universitas Sumatera Utara)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32734/jtk.v15i1.23521

Abstract

High rice production in Indonesia generates rice husk waste of approximately 0.53–5.8 million tons in 2024, most of which has not been optimally utilized. According to the Ministry of Agriculture (2022), this waste is generally stockpiled or openly burned without further valorization. This study aims to analyze the effect of calcination temperature on the characteristics of rice husk–based heterogeneous catalysts, the effect of catalyst concentration on biodiesel yield, and the reusability of the catalyst. The results show that a calcination temperature of 600°C produces a porous catalyst with a larger number of active sites. The highest biodiesel yield of 91 mL was obtained using a catalyst concentration of 9% w/v. Catalyst reuse for up to two cycles resulted in a decrease in biodiesel yield due to the reduction of active sites; however, the yield remained above 50%. Catalyst pore characteristics were analyzed using Scanning Electron Microscopy  and the produced biodiesel met the requirements of SNI 7182:2015, including a density in the range of 850–890 kg/m³, copper strip corrosion rating of No. 2, and an acid value not exceeding 0.5 mg KOH/g.