Development of immobilized matrix from durian rind waste in cultivation of microalgae for biofertilizer production

Abstract

Conventional fertilizers have a negative impact on environment and are not economically efficient. This is because the fertilizers are lost by volatilization in the atmosphere, leaching into the groundwater or fixation in the soil. The aim of this project is to produce a new generation of biofertilizers, using an eco-friendly coating based on biomass and biopolymers derived from pectin. In this study, pectin from durian rind was obtained after a treatment with an acidified solution followed by purification through alcohol precipitation. The durian pectin was found to be 3.22 ± 0.065% of methoxyl content which is classified as a low methoxyl pectin. Therefore, it is suitable to be used as a biopolymeric matrix to produce a slow-release soil fertilizer added with microalgal (Scenedesmus sp.) biomass residue. The incorporation of sodium alginate as a gelling mixture was found to enhance the formation of rigid bead structure. The morphology of encapsulated Scenedesmus-beads were then examined using scanning electron microscopy and the growth of Abelmoschus esculentus (Okra plant) was observed for its potential use as biofertilizer. The results obtained for the morphology of the beads shows that the beads have a porous structure. In just two weeks, the significant growth of plant treated with biofertilizer was shown by having a much greater height (7.17 + 1.04 cm), number (4 leaves) and size of leaves (3.67 ± 0.32 cm) compared to the control (5.17 + 0.35 cm high, 3 leaves, and 2.67 ± 0.20 cm in size, respectively). However, further research is needed on the optimal biofertilizer concentration and dosage as well as on the kinetic study of the release compounds from the beads. Overall, this article exhibits a good perspective for alternative fertilizer for agriculture applications and represent an innovative solution for durian rind final disposal.