PTQ Q3 2026 Issue

Tank A Tank B

1.00E+10

1.00E+08

1.00E+06

28 27

1.00E+04

1.00E+02

1.00E+00

Jul/23

Dec/23

Jan/24

Feb/24 Aug/24

Sep/24

sustained microbiological control over time. The biocide’s mechanism of action involves controlled hydrolysis of the active component, promoting the gradual release of reactive species capable of penetrating microbial cells and interfering with essential metabolic processes, including inactivation of structural and enzymatic proteins, as well as degradation of microbial DNA. This mode of action provides high efficacy and broad-spectrum activity, covering aerobic and anaerobic bacteria, fungi and yeasts, which are microorganisms typi- cally associated with diesel biodeterioration and MIC. Defender SR 1664B differs from conventional biocides due to its partition coefficient, which favours the distri - bution of the biocidal active between the aqueous and oil phases of the system. Due to its log Kow value, the product exhibits affinity for both hydrophilic and hydrophobic envi - ronments, allowing the active agent to be simultaneously partitioned into free water and the fuel phase. The operational procedure included the application of the biocide to the diesel at a shock treatment rate (1,000 ppm) to rapidly reduce the microbial population. The biocide was applied only once to the tanks and provided long-term microbiological protection. Two tanks containing S10 Diesel (A and B) were evaluated simultaneously. Results The tanks were monitored for 16 months (from May 2023 to August 2024). The biocide was applied seven months after the start of monitoring (November 2023) and lasted for 10 months. Treatment performance was evaluated using two indicators: TAB concentration and diesel certification time. TAB concentration was periodically analysed throughout the treatment, and the results are presented in Figure 3 . The December 2023 analysis already showed a reduction in TAB concentration, one month after the application of this bespoke biocide in both tanks. This reduction became more pronounced over time, demonstrating that a robust microbi- ological treatment maintained over the long term effectively addresses microbial contamination in diesel storage tanks. The second performance indicator evaluated was the average diesel certification time. Figure 4 shows the aver- age time considering both evaluated tanks. The results demonstrate a clear trend of reduced diesel certification Figure 3 Monitoring of TAB over time. Treatment initiated in November 2023

time after biocide dosing, which was maintained through the end of the monitoring period. This reduction in certification time translates into improved operational efficiency, as diesel spends less time in storage tanks, thereby increasing the processing capacity of the unit. In addition, diesel quality improved with Defender SR 1664B treatment. According to Mataripe Refinery data, a 48% reduction in customer diesel rejection rates was observed. The certification time required of the stored fuel is directly limited by two fundamental operational factors: assuring the absence of turbulence within the tank and the intrin- sic lead time of the laboratory analyses. Any movement of the fuel can resuspend free water, sludge, and particles that had previously settled, making immediate sampling unrepresentative of the tank’s actual condition. Therefore, established best practices recommend allowing the fuel to remain at rest for the necessary period to enable complete sedimentation of contaminants. These practices also emphasise that sampling should be conducted only after turbulence has ceased and the physical equilibrium of the system has been restored, ensuring that the sample accurately reflects the condition of the stored fuel. Furthermore, even after it is collected, the sample remains subject to the technical processing time required in the lab- oratory (for example, stabilisation, execution of analytical tests, and emission of the corresponding reports), which together constitute the total lead time for quality certification prior to operational release of the inventory. To complement the evaluations, diesel samples col- lected before treatment and after 10 months of Defender SR 1664B application were compared in terms of visual appearance and the presence of corrosion-related solids using optical microscopy. Figures 5 and 6 show the appear- ance of the samples, in which it can be observed that the treatment visibly reduced fuel turbidity and the presence of suspended solids. Figure 7 highlights marked differences between untreated and biocide-treated samples. In the untreated sample (see Figure 7A ), a high concentration of solid par- ticles is observed, with a wide particle size distribution and irregular agglomerates with reddish-brown and dark col- ouration. This morphology is consistent with the presence Figure 4 Diesel monitoring certification time. Treatment ini - tiated in November 2023

PTQ Q3 2026