Slow-release nutrient capsules for microorganism stimulation in oil remediation

As the concern towards environmental deterioration grows worldwide, new technological achievements become essential for all countries. Among the technologies with great potential of bioremediation is microencapsulation of active material. Several studies have investigated the use of controlled release of active materials as a way of biostimulation and supplying the nutrients necessary for the bioremediation process. In fact, as the use of microorganisms has a great potential in degrading crude oils, this work aims to use that technology and to associate it to produce controlled-release capsules of nitrogen, phosphorus, and potassium (N, P, and K) for bioremediation purposes. For the capsule formulation, polymers of sodium alginate, Capsul®, and the commercial fertilizer NPK from Sempre Verde Inc. were used. Crude oil was the only carbon source and mineral medium for microorganism growth. Controlled-release nutrient capsules, with 4 mm in diameter, made of 3.0 % alginate (w/v) and 4.0 % Capsul® (w/v) were produced. Those capsules were used in association with a microbial consortium, in a liquid phase bioremediation process, having degraded 43.6 % of the total hydrocarbon within 240 h, evidencing thus as a promising tool for hydrocarbon bioremediation.