Contaminants of emerging concern (CECs) are chemicals or materials that are not under current regulation but there are increasing concerns about their possible occurrence in the environment because of their potential threat to human and environmental health, with wastewater perceived as their primary source. Although various techniques for their removal from water have been studied, it should be emphasized that the choice should also consider the use of resources and energy within the removal processes, which must be minimized to avoid additional carbon footprints and environmental impact. In this context, the use of biomass-based sorbents might represent a cost-effective and environmentally friendly approach for the removal of CECs from water because they are based on preferably local renewable resources with lower negative impacts on the global carbon cycle through greenhouse gas emissions than the conventional nonrenewable ones. This paper provides an overview of the studies dealing with the application of such so-called biosorbents for the removal of CECs from water and discusses the use of their different forms: sorbents after a minimal pretreatment of the original lignocellulosic biomass; sorbents extracted from lignocellulosic biomass and/or modified; and biochar-based sorbents obtained after thermochemical conversion of biomass. It explains possible modifications of biosorbents and discusses the efficiency of various biosorbents for the removal of selected emerging compounds that belong to the classes of pharmaceuticals, personal care products, and pesticides and compares the adsorption capacities, kinetic models, and mechanisms reported in the relevant literature. Biochar-based sorption has been studied more often if compared to other considered biosorbents. In some cases, removal efficiencies of contaminants greater than 90% were achieved, but nonetheless a wide range of efficiencies for different CECs indicates that for successful simultaneous multicompound removal, a combination of different processes seems to be a more appropriate approach than the stand-alone use of biosorbents. Finally, this review discusses the reasons behind the limited commercial application of the considered biosorbents and provides directions for possible further research, in particular the use of spent biosorbents from a perspective of circular systems.

The main objective of this work was to assess Eucalyptus globulus lignin as an adsorbent and compare the results with kraft lignin, which has previously been demonstrated to be an effective adsorbent. Eucalypt lignin was extracted (by the dioxane technique), characterised, and its adsorption properties for Cr(VI) ions were evaluated. The monomeric composition of both types of lignin indicated a high content of guaiacyl (G) and syringyl (S) units but low content of p-hydroxyphenyl (H), with an H:G:S ratio of 1:50:146 (eucalypt lignin) and 1:16:26 (kraft lignin), as determined by Py-GC/MS. According to elemental analysis, sulphur (2%) and sodium (1%) were found in kraft lignin, but not in eucalypt lignin. The adsorption capacity of the eucalypt lignin was notably higher than the kraft lignin during the first 8 h, but practically all the ions had been absorbed by both the eucalypt and kraft lignin after 24 h (93.4% and 95%, respectively). Cr(VI) adsorption onto both lignins fitted well using the Langmuir adsorption isotherm model, with capacities of 256.4 and 303.0 mg/g, respectively, for eucalypt and kraft. The study’s overall results demonstrate the great potential of eucalypt lignin as a biosorbent for Cr(VI) removal from aqueous solutions.

Wastewater treatment plants (WWTPs) have been identified as the major sources of contaminants of emerging concern (CECs) in water bodies, as they are not designed to remove organic micropollutants efficiently. Consequently, many technologies have been explored for WWTP upgrading, including activated carbon adsorption. However, the high production cost and environmental challenges associated with activated carbon production limit its application in industrial settings. Therefore, a wide range of alternative materials has been investigated as potential replacements. In this study, biochar produced from waste raspberry biomass was evaluated as an adsorbent for the removal of pharmaceuticals and pesticides quantified in the secondary effluent of municipal WWTP. The results showed that the biochar efficiently removed almost all detected compounds, except for three compounds (clarithromycin, propranolol, and linuron). The wastewater pH (6–8) did not significantly affect removal efficiency significantly, and kinetic tests demonstrated rapid adsorption. The potential for biochar reuse was confirmed through three consecutive batch adsorption cycles. A comparative study between biochar and powdered activated carbon (PAC) revealed some differences in efficiency, primarily attributed to the larger surface area of PAC. π-π interactions, hydrogen bonding, and pore-filling were proposed as possible adsorption mechanisms based on the adsorption efficiency and biochar characterization.

One of the major criteria for monitoring water and wastewater quality is turbidity, which is most often reduced using chemical coagulants and flocculants, such as alum and iron salts and acrylamide. However, due to their detrimental effects, intensive investigations into natural coagulants and flocculants have recently been conducted. These coagulants are biodegradable, derived from renewable sources, and do not pose health risks, making them a sustainable solution for water and wastewater treatment. Coagulation and flocculation using natural coagulants is a complex phenomenon influenced by multiple factors. In this study, the impact of the solvent used to extract the natural coagulant from Phaseolus vulgaris seeds on its coagulation effectiveness was examined, along with the effects of pH, the initial turbidity of the treated water, and the applied coagulant dose. The extract obtained using 0.5 mol/L NaCl demonstrated higher coagulation activity compared to the extract obtained with distilled water. Both extracts exhibited improved performance in water with higher initial turbidity (200 NTU) and at the lowest pH tested (pH 6). Under these conditions, the water extract achieved a maximum coagulation activity of 58.4% at a dose of 0.1 mL/L, while the NaCl extract reached an 83.5% turbidity reduction at a dose of 0.4 mL/L. The dominant coagulants in the NaCl extract of Phaseolus vulgaris seeds are anionic polyelectrolytes. In the presence of divalent cations, these coagulants destabilize negatively charged particles through either the bridging mechanism or the sweep coagulation mechanism.

Every year, crustacean shell waste amounts to nearly 8 million tons worldwide, representing both an environmental challenge and a valuable resource. Crustacean shells can be repurposed as raw material for products in various industries, including agriculture, construction, and biomedicine. They are a valuable resource for creating functional materials due to their high content of chitin, protein, and calcium carbonate. These compounds can be extracted and processed to create various products, such as the biopolymer chitosan, antioxidants like astaxanthin, and adsorbents for water treatment, aligning with a circular economy approach by converting waste into valuable by-products. Chitosan films from crustacean waste are promising active packaging materials developed over the last decade, featuring enhanced antimicrobial and antioxidant properties. Extensive research confirms that crustacean shell waste is an excellent, low-cost adsorbent for removing heavy metals from water. This review analyzes current trends and opportunities for crustacean shell waste utilization in packaging materials and wastewater treatment. Key applications include replacing conventional plastic in biodegradable packaging and improving water treatment, which enhances resource efficiency and minimizes environmental pollution.