Multi-strain synergistic fermentation of waste biomass with bacterial cellulose fermentation wastewater to prepare sustainable detergents.

Abstract

Synthetic surfactants threaten the environment and public health due to their difficult degradation and high toxicity, creating a need for low-energy, high-efficiency green alternatives. Preparing natural surfactants is often expensive, inefficient, and complex, while the resource utilization of bacterial cellulose (BC) fermentation wastewater is still tricky. In this study, waste biomass, including pineapple peel and Sapindus mukorossi Gaertn., was combined with BC fermentation wastewater using synergistic fermentation by Saccharomyces cerevisiae, Lactobacillus sp., and Acetobacter sp. to extract triterpene saponins and proteases. This process was used to prepare green detergents enriched with surface-active substances. The results showed that after 10 days of fermentation, the saponin extraction efficiency reached 84.29%, significantly outperforming traditional methods such as ultrasound-assisted alcoholic extraction (16.17%), ultrasound-water immersion (19.00%), double extraction (31.72%), and cellulase-assisted extraction (38.98%). Protease activity reached 36.92 ± 0.20 U/mg. The fermentation broth reduced surface tension by 36.95 mN/m compared to pure water, which improved emulsification and dispersion. It exhibited high surface activity and foam stability with a low critical micelle concentration (CMC) of 0.163 ± 0.01 mg/mL. Green detergents showed a 20.71-45.87% higher efficiency than synthetic detergents in removing carbon black oil (90.38%), sebum (100%), and protein stains (89%). Saponins contributed to this advantage by reducing surface tension (P ≤ 0.01) and enhancing wettability (P ≤ 0.05). This study provides a sustainable new solution for the high-value utilization of waste biomass and BC fermentation wastewater and exhibits the broad prospects of green detergents for environmental and industrial applications.