The use of biosorbents for the decontamination of industrial effluent (e.g., wastewater treatment) by retaining non-biodegradable pollutants (antibiotics, dyes, and heavy metals) has been investigated in order to develop inexpensive and effective techniques. The exacerbated water pollution crisis is a huge threat to the global economy, especially in association with the rapid development of industry; thus, the sustainable reuse of different treated water resources has become a worldwide necessity. This review investigates the use of different natural (living and non-living) microbial biomass types containing polysaccharides, proteins, and lipids (natural polymers) as biosorbents in free and immobilized forms. Microbial biomass immobilization performed by using polymeric support (i.e., polysaccharides) would ensure the production of efficient biosorbents, with good mechanical resistance and easy separation ability, utilized in different effluents’ depollution. Biomass-based biosorbents, due to their outstanding biosorption abilities and good efficiency for effluent treatment (concentrated or diluted solutions of residuals/contaminants), need to be used in industrial environmental applications, to improve environmental sustainability of the economic activities. This review presents the most recent advances related the main polymers such as polysaccharides and microbial cells used for biosorbents production; a detailed analysis of the biosorption capability of algal, bacterial and fungal biomass; as well as a series of specific applications for retaining metal ions and organic dyes. Even if biosorption offers many advantages, the complexity of operation increased by the presence of multiple pollutants in real wastewater combined with insufficient knowledge on desorption and regeneration capacity of biosorbents (mostly used in laboratory scale) requires more large-scale biosorption experiments in order to adequately choose a type of biomass but also a polymeric support for an efficient treatment process.

In this paper, a novel resin-based crystallisation method was developed for the recovery of succinic acid (SA) crystals from fermentation broths (FB) using Actinobacillus succinogenes. Direct crystallisation of synthetic fermentation broths was firstly investigated and the results indicated that the synthetic fermentation broth consisting of a mixture of organic acids (in the free acid form rather than in the salt form) could significantly benefit in succinic acid recovery. Therefore, a commercially available cation-exchange resin Amberlite IR 120H was employed to convert the fermentation end-products such as succinate, formate, acetate and pyruvate from the salt form into the free acid form. Then, succinic acid was selectively separated from the acid mixture by vacuum evaporation and crystallisation. Highly purified SA crystals were successfully recovered from both synthetic and real fermentation broths using this method. A higher SA crystal purity (99%) and yield (89.5%) were obtained in the direct crystallisation method using an ion-exchange resin as compared to the direct acid addition method (46% and 35%, respectively). The work presented here sets the stage for the development of an efficient resin-based vacuum-distillation and crystallisation system for the recovery of succinic acid crystals from fermentation broths.

The beetroot peels can be a sustainable source of betalains that can dye the wool materials through green processes based on low water and energy consumption. Green chemistry in the extraction of betalains from colored food waste/peels from red beetroot involved the use of water as a solvent, without other additives. In order for the extract obtained to be able to dye the wool, it was necessary to functionalize betalains or even the wool. Three types of sustainable functionalizations were performed, with (1) acetic acid; (2) ethanol; and (3) arginine. For each functionalization, the mechanism that can justify dyeing the wool in intense colors was elucidated. The characterization of the extract was performed with the data provided by UV-VIS and HPLC-MS analyses. The characterization of the wool dyed with the extract obtained from the red beetroot peels was possible due to the information resulting from the FTIR and CIELab analyses. The functionalizations of betalains and wool in acid environments lead to the most intense red colors. The color varies depending on the pH and the concentration of betalains.