Optimization Bacterial Density and Fertilizer Dosage for Bioremediation of Oil Contaminated Sandy Beach: A Case of Cilacap, Indonesia

Abstract

Bioremediation, involving biostimulation and/or bioaugmentation, is a promising method to overcome oil spills in Cilacap coastal waters. Cilacap coastal area has high risk on oil pollution. This study investigated the stimulatory effect of nitrogen concentration, bacterial density and the composition of bacterial culture in enhancing oil degradation in this area. The applications of 4 different concentrations of Slow Release Fertilizer (SRF) and 2 different densities of bacterial cells in the form of single (RCO/B/08_008) and mixed culture were employed in microcosm experiments for 28 days. The efficacy of combining bacterial culture and fertilizer application in various concentrations was also tested. Oil degradation, bacterial growth and environmental parameters were monitored periodically during the experiments. The results showed that oil degradation rate was more influenced by nutrient concentration (biostimulation) than bacterial number or culture composition (bioaugmentation) added. The efficacy of biostimulation in degrading oil was better than that of bioaugmentation. Biostimulation increased oil degradation up to 6.4 times higher than the control. The optimum of fertilizer concentration added was 7.5 mg N/g (C:N ratio of 1,000 : 75), which increased depletion rate both in biostimulation-only and the combination of biostimulation with bioaugmentation up to 6.4 and 7.5 times higher than the control, respectively. It is suggested that bioremediation of oil-contaminated sandy beach in Cilacap would be optimal by employing a combination of Slow Release Fertilizer at 8 concentration having C/N ratio = 1,000 : 75 and RCO/B/08_008 culture at density of 0.5 x 10 cells/mL (100% homology with Alcanivorax sp. TE-9).

Production and toxicological evaluation of poly(butylene succinate)–urea microspheres targeting bioremediation

“…62,63 The excessive loss of nitrogen compounds by volatilization, especially in places subject to high temperatures, would be another adversity, which like the aforementioned environmental problems has motivated research in this area. [16][17][18]64 In this study, the controlled release of urea was carried out in seawater since this environment is prone to accidental spills in which biostimulation could be applied with the encapsulated matrices in order to accelerate bioremediation. Sterile seawater was used to avoid possible interferences by the action of natural microbiota, for better control of the process, since it used a pure culture of Pseudomonas sp.…”

“…Among the topics mainly addressed is the study of the mechanism of nutrient release required for the growth of petroleum-degrading microorganisms in the environment, either through their direct availability 14,15 or through their encapsulation and controlled release. [16][17][18][19] In environments where bioremediation will be conducted or where HC derivatives are present, the presence of a microbial population with the ability to degrade these compounds has been detected and Pseudomonas sp. has often been isolated from these environments.…”

“…28,29 For example, some authors 16 studied the use of nitrogen and phosphorus sources encapsulated in alginate spheres and Capsul® (biopolymers) for the process of bioremediation via biostimulation of media polluted with oil. Some works 17,18 applied commercial biostimulants in the biodegradation of HCs and obtained removal percentages of more than 60%.…”

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“…Recently, studies have evaluated the use of slow-release fertilizer, as a form of bio stimulus, to provide the concentrations of nutrients necessary for the bioremediation process. However, the majority of products that have been applied are usually used for different agricultural cultivars and provide nutrients (Darmayati et al, 2017;Becker et al, 2016). There are few studies on this line of bioremediation and the use of polymers such as encapsulation matrix has been reported for application mainly in the area of food and drugs.…”