Preparation of slow-release microencapsulated fertilizer-Biostimulation remediation of marine oil spill pollution

Occasional marine oil spills can have considerable negative effects on the environment and economy. Using biotechnology to clean up oil is more reliable and environmentally friendly. Biostimulation can greatly enhance the hydrocarbon degradation activity of native microorganisms. In this study, slow-release microencapsulated fertilizers with alginate and bentonite as base, nitrogen and phosphorus as release elements, and double-coated with ethyl cellulose and vegetable wax were developed for biostimulation to improve the degradation of petroleum hydrocarbons. The prepared material had a macroporous structure resembling a honeycomb, in which nitrogen and phosphorus elements were scattered according to results from scanning electron microscopy and element mapping images. Additionally, the success load of nitrogen and phosphorus was further verified by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The effects of additional quantities of bentonite on the slow-release of nutrients were examined, and the findings indicated that the slowrelease process benefited from the rise in bentonite. More excellent slow-release behavior was obtained after coating material, and the release process conformed to the Fickian diffusion model. The results of biostimulation repair experiments of oil spill show that the slow-release microencapsulated fertilizer can improve the degradation effect of petroleum hydrocarbons, particularly high molecular weight polycyclic aromatic hydrocarbons (PAHs). Further researches on the microbial community revealed that biostimulation altered microbial community structure following the oil spill, making Cycloclasticus prevalent, which in turn improved native microorganisms' ability to degrade PAHs. The alginate/bentonite composite aerogels were promising to be used as biocompatible carriers for microbial nutrition delivery.