Aquatic biomass has its own specificity and processing challenges compared to terrestrial resources. These resources are part of the EU's Blue Growth Strategy and are part of a knowledge-intensive bioeconomy ecosystem. Ensuring the processing of resources and finding the best available technological methods will promote environmentally friendly use of resources and increase the added value. The thesis examines the processing of aquatic resources by analysing the composition of resources, processing technologies and the products to be obtained, also evaluates the possible ways of processing with specific examples, carried out separate experiments. The aim of the work was to research aquatic bioresources, green processing of biomass resources into value-added products to find best use of aquatic origin feedstocks, and to support the transition to a more sustainable circular economy by leveraging renewable water resources. The Doctoral Thesis is based on seven thematically unified scientific publications published in various scientific journals and are available in international databases. The Thesis introduction outlines the goal and tasks, describes the organization of the work, and provides an overview of practical and scientific contributions. The first chapter summarizes the scientific literature, prior research, and concentrates on the features of aquatic bioresources. The third chapter contains the results and discussion. At the end of the thesis, conclusions are drawn.