ACTIVITIES OF BIOSURFACTANTS F7 AS AGENTS ANTI-BIOFILM AND ANTI-CORROSION IN CARBON STEELS ST37 IN WATER COOLING SYSTEM

• Main Author: Dewantoro, Fajar
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/52263
• Institution: Institut Teknologi Bandung

Water is used in the cooling process in a cooling water system or in the cooling process to cool an operating engine or reactor. Water has an important characteristic in cooling water systems in nuclear reactors, where water has a high thermal conductivity value, namely the ability to absorb heat and heat transfer. One of the problems commonly found in cooling water systems is the occurrence of biocorrosion. The treatment of bicorrosion with synthetic biocide compounds is toxic to the environment because it is not biodegradable. Several studies have shown that biosurfactant compounds can be used to overcome biocorrosion problems because they have anti-biofilm properties on steel surfaces. In addition, biosurfactants are biodegradable and non-toxic to the environment so they can be potential alternative compounds to overcome biocorrosion. This study aims to evaluate the biosurfactant activity produced by Bacillus sp. F7 on the structure of the microbial community forming biofilms in BATAN cooling water systems, Bandung, West Java. This research was conducted using biosurfactant F7 isolated from Bacillus sp. F7 uses SMSSe + 5% (v/v) petroleum as medium. Then the Minimum Inhibitory Concentration (MIC), Minimum Biofilm Inhibition Concentration (MBIC) and Minimum Biofilm Eradication Concentration (MBEC50) values were determined from biosurfactant F7. The formation of biofilms from the bacterial consortium from cooling water on Carbon Steels ST37 was carried out using a hydrostatic system. The dynamic analysis of the bacterial community on the biofilm was determined using total plate numbers using Nutrient Agar (NA) medium for aerobic microbes. Corrosion rate analysis was determined by the Weight Loss method. Visualization of Biofilms and Corrosion Products was carried out using Scanning Electron Microscopy and Scanning Electron Microscopy: Energy-Dispersive X Ray Spectroscopy (SEM-EDS). The results showed that the MIC, MBIC and MBEC50 values for biosurfactant F7 were 31.25; 62.5 and 500 ?g / ml. The biofilm formation curve showed that the mature biofilm on day 14 was indicated by the cell density of the biofilm and the high weight of the biofilm using the Wet weight method. The study showed that there were 4 isolates isolated on the biofilm. Of the 4 isolates, it is known that 3 isolates are Gram positive rod-shaped bacteria with 1 isolate being Gram negative rod-shaped bacteria. The results showed that F7 biosurfactant was more effective in eradicating Gram positive bacteria in biofilms. Based on the results of the Weight Loss analysis, it shows that biosurfactant F7 is able to reduce the number of microbial communities on the biofilm, thereby reducing the corrosion rate of steel. These results prove that biosurfactant F7 is a potential compound that can be used to eradicate biofilms on Carbon Steels ST37 steels.