| Abstract [eng] |
Controlled-release fertilizers are analyzed in this Master’s Final Degree project. The aim of this project is to develop a coating suitable for regulating the solubility of fertilizers using sulphur sludge, a waste product from other productions, to investigate its properties and to assess the feasibility of the application of the technology of regulated solubility fertilizers. Master’s Final Degree project is composed of four main parts: literature review, experimental and engineering parts and review of safety and health of employees. Trends in the production and use of controlled-release fertilizers, their classification, main advantages and disadvantages are analyzed in the literature review. The focus is on the research and production of coated (by sulphur or polymers) fertilizers. A lot of research is being carried out on coatings with biopolymers as they are fully degradable in the soil and environmentally friendly. Generation and potential use of sulphur sludge are also discussed in this part. Selection of right materials for coatings, their ratios and the best production conditions are discussed in the experimental part. It is decided to use the coat which has: 4 % polyvinyl alcohol (PVA), 6 % sulphur sludge, 6 % glycerol, 10 % starch, 6 % hydrochloric acid (0.1 N solution), 10 % sodium alkali solution (0.1 N) and 58 % water. This coat has the lowest solubility in water and the right rate of decomposition in soil. The chosen coating is proven effective because coated diammonium phosphate fertilizer tablets release 6 % less nitrogen and 14 % less P2O5 in water than the uncoated ones in 14 days. The engineering part of the report contains technological schemes and recommendations for the preparation of the polymer film and the coating of fertilizer granules. Finally, occupational hazards, safety equipment, hazard and precautionary statements of the used chemicals, warning signs, first-aid and fire-fighting measures are discussed. |
