Conceptual design of a shell biorefinery for Aquaculture wastes valorization

• Grant number: 23/07775-0
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: July 01, 2023
• End date: July 31, 2026
• Field of knowledge: Engineering - Chemical Engineering
• Principal Investigator: Moisés Teles dos Santos
• Grantee: Ana Carolina Moreira Fonseca
• Host Institution: Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 22/02809-0 - Waste valorization and technological innovation in the agro-industrial and chitin supply chains by computational models, AP.PNGP.PI

Abstract

Shrimp farming is a technique for raising shrimp in captivity, whose production in Brazil in 2021 reached 120 thousand tons, even with the health crisis caused by the COVID-19 pandemic. The production of crustaceans represents around 10% of the aquaculture sector and the amount of waste generated by these species is significant, representing about 40% of the total weight of these animals. These residues are usually disposed of in landfills and inappropriate places, causing environmental problems and risks to human health. Based on knowledge about the use of lignocellulosic biomass, the concept of shell biorefinery was recently proposed to designate installations whose crustacean shells are separated into different fractions and transformed into value-added products. In this context, the present doctoral work proposes the elaboration of a conceptual proposal of a chitin biorefinery based on Brazilian shrimp farming residues. Chitin, which makes up about 15% to 40% of the shrimp shell, is the second most abundant biopolymer in nature, whose applicability ranges from the production of pharmaceutical and cosmetic products to the use of materials for water treatment. The chitosan biopolymer is the main derivative of chitin and has non-toxic characteristics, easy formation of gels and inhibitory action on the growth of microorganisms. However, to ensure the economic viability and environmental benefits of valuing shrimp farming waste, scientific and technological challenges will be addressed in this research, including: (i) improvement of existing conversion processes; (ii) technical, economic and environmental assessment of possible recovery routes with and without uncertainties in yield, conversions, prices and costs parameters and (iii) assessment of the environmental cost associated with such routes, such as effluent generation, energy consumption and gaseous emissions, among others. In this sense, this proposal intends to develop process flow diagrams with mass and energy balances to obtain environmental parameters and later use in economic evaluation of selected routes, using process synthesis techniques and estimation of operational and fixed costs. Therefore, information on process variables for different extraction methods (chemical, enzymatic or a combination of both) will be adapted from the literature to generate the biomass utilization superstructure. The possible routes will be evaluated simultaneously based on the concept of integrated biorefinery, whose objective is to maximize the yield and purity of the chitin obtained, as well as the recovery of nitrogenous components, pigments and minerals, minimizing the consumption of energy and reagents during the process biomass pre-treatment. With regard to the experimental part, the following activities are planned: (i) obtaining and characterizing shrimp shells of the species Litopenaeus vannamei, typical of shrimp farming; (ii) chitin extraction and conversion to chitosan; (iii) characterization of the obtained chitosan; (iv) evaluation of chitosan-based coatings as a coating on fruits and evaluation of their preservation capacity and (v) analysis of the adequacy of residual material from chitosan synthesis as food packaging. The proposal to investigate the by-product generated during the process of obtaining chitosan aims to maintain the focus on the sustainability of the entire production chain. (AU)