Autor(es):
Rodrigues, Ana Cristina Costa ; Martins, Daniela Sofia Rodrigues ; Duarte, Maria Salomé Lira ; Carvalho, Ricardo Emanuel Silva ; Marques, Susana ; Cavaleiro, Ana Júlia Viana ; Gama, F. M. ; Dourado, Fernando
Data: 2025
Identificador Persistente: https://hdl.handle.net/1822/94590
Origem: RepositóriUM - Universidade do Minho
Assunto(s): Bacterial nanocellulose; Eucalyptus bark hydrolysate; Response surface methodology; BNC production optimization; Wastewater treatment; Water recycling; Anaerobic and aerobic digestion
Descrição
The production cost of bacterial nanocellulose (BNC) is a major limitation to its widespread use. However, this limitation can be addressed by using alternative low-cost substrates and high-yield strains. Agro-industrial waste-derived substrates offer a cost-effective and sustainable solution, but their high organic load often requires additional downstream wastewater treatments. Here, we optimized static BNC production using eucalyptus bark hydrolysate (EBH) as a low-cost carbon source and proposed a circular approach for wastewater management. Optimization was performed using response surface methodology - central composite design. The optimized EBH medium yielded a 39.7-fold increase compared to standard medium, with a maximum BNC production of 8.29±0.21g/L. Fermentation wastewater only (WaF) and combined with BNC washing streams (WaW) revealed high levels of organic matter, namely chemical oxygen demand (COD) of 159.0±2.0 and 41.1±0.3g/L, and volatile solids (VS) of 99.5±0.9 and 26.3±0.2g/L, respectively, requiring treatment before disposal. A sequential anaerobic-aerobic digestion was investigated for wastewater treatment and valorisation. Anaerobic digestion proved to be effective in treating the wastewater: methanization percentages over 87% were achieved, and methane productions of 486±2 and 544±30L/kg VS were obtained from WaF and WaW, respectively. Subsequent aerobic treatment was unsuccessful in further reducing COD levels (approximately 1.5g/L). Notably, treated wastewater was recycled into the production process up to 45% without affecting the BNC yield. This study provides valuable insights into the optimization of BNC production from lignocellulosic biomass and the management of wastewater streams, contributing to the development of a more sustainable and economically viable process.
