Synelnikov S. Environmentally safe utilization of polyethylene terephthalate waste using them for encapsulation of mineral fertilizers

In the thesis research actual scientific and practical task is solved: increasing environmental safety level of plant growing by applying the mineral fertilizers of the prolonged action encapsulated by the modified polyethylene terephthalate. Environmental and technological aspects of PET waste disposal in the production of encapsulated mineral fertilizers have been studied. The dependence of the required shell thickness on the duration of encapsulated ammonium nitrate at different values of the diffusion coefficient in the shell material is established. Diffusion of ammonium nitrate solution through a polymer film of different thickness was experimentally investigated. Separate stages of PET waste utilization in the production of encapsulated mineral fertilizers have been studied: collection of used PET products; primary collected waste processing; creation of a film-forming composition; granular mineral fertilizers encapsulation. The analysis of technological decisions in the process of mineral fertilizers encapsulation by a cover on the basis of the modified PET is carried out. The hydrodynamics and heat and mass transfer of coating on dispersed materials is investigated. Heat transfer studies were performed under the established hydrodynamic conditions of the encapsulation process. Test studies of encapsulated fertilizers have been carried out according to the method of EN 13266: 20. Under laboratory conditions, the effect of encapsulated PET mineral fertilizers on changes in soil pH, soil microbiota and growth kinetics of test plants were studied. A theoretical analysis of the balance ratios on the use of different types of mineral fertilizers in agroecosystems and the amount of undigested nutrients loss from these mineral fertilizers types in the environment. Field agroecological studies have been conducted on the use of encapsulated PET mineral fertilizers in agroecosystems of crops such as potatoes, soybeans and corn. The use of encapsulated mineral fertilizers with prolonged action showed significantly higher environmental and agronomic efficiency compared to granular fertilizers for all studied crops. The environmental and agronomic efficiency on the use of mineral fertilizers encapsulated in PET was evaluated. For all studied crops, the efficiency of fertilizer use is much higher for encapsulated fertilizers compared to granular (maximum - more than 4 times). With a smaller amount of applied active substance, the yield in areas where fertilized fertilizers are applied is much higher. Key words: environmental safety, encapsulated mineral fertilizers, agroecological researches, growth kinetics of test plants.