If biodegradable plastics tackle the marine plastic pollution problem sufficiently remains questionable. To gain more insight in degradability, performance, and the impact of degradation on the toxicity, commercial bags made from two biodegradable plastics and one conventional plastic (PE) were exposed for 120 days in a mesocosm featuring benthic, pelagic, and littoral habitat simulations. Degradability was assessed as weight loss, and specimens were tested for toxicity using Paracentrotus lividus sea-urchin larvae after different exposure times. Both biodegradable bags showed degradation within 120 days, with the littoral simulation showing the highest and the pelagic simulation the lowest decay. Disregarding habitat, the home-compostable plastic showed higher marine degradation than the industrial-compostable material. The relevant initial toxicity of both biopolymers was lost within 7 days of exposure, pointing towards easily leachable chemical additives as its cause. Interestingly, littoral exposed specimens gained toxicity after 120 days, suggesting UV- induced modifications that increase biopolymer toxicity.

Chitosan induces tolerance to abiotic stress agents in plants. However, studies on the different application forms of this biopolymer are limited. This study evaluated the effect of two forms of chitosan application on the morphophysiology of and metal accumulation by Talinum patens cuttings subjected to Cd to develop new cadmium (Cd) decontamination technologies. Cuttings from 75-day-old plants were transferred to a hydroponic system. For 30 days, three Cd concentrations (0, 7, and 14 mg L⁻¹) and three forms of chitosan application (without application, root, and foliar) were applied. The cuttings were tolerant to Cd because the metal did not influence biomass production or photosynthetic efficiency. Neither chitosan application nor Cd increased the modified chlorophyll content and fluorescence parameters. However, foliar chitosan reduced the transpiration rate. At the highest concentration of Cd, the application of chitosan in the root reduced the Mg content of the root system and shoots. The root application of chitosan increased the surface area and volume of thicker roots at the expense of finer ones. The foliar application resulted in greater total root length and surface area, mainly those finer. Furthermore, chitosan applied to the leaves activated catalase in the roots and leaves. In contrast to the root application, foliar application increased the accumulation of Cd in the roots. The action of catalase and the increase of fine roots may have favored a greater absorption of the nutrient solution and Cd in the chitosan foliar application treatment. It is concluded that chitosan foliar spraying can improve Cd rhizofiltration with T. patens.

Streams located in areas of sugarcane cultivation receive elevated concentrations of metal ions from soils of adjacent areas. This process may cause impacts on streams located in the adjacent areas. The contamination of stream sediments can lead to bioaccumulation of such metal by aquatic organisms, such as benthic invertebrates. Chitosan beads, a biopolymer that demonstrates a high affinity for metal, are simple to prepare under the laboratory, have a low overall cost, and can be used for removing metals from aquatic sediments. This work studied the use of Chitosan beads in metal adsorption from sediments of streams located in areas of sugarcane cultivation and evaluated the effects on the survival of Chironomus sancticaroli insect larvae. Acute bioassays were performed in two scenarios, in the presence and in the absence of chitosan beads. The bioassay consisted of the exposure of 10 IV instar of Chironomus sancticaroli larvae, for 96 h in five stream sediments. The results showed that chitosan beads (containing only 5.5% of chitosan) adsorbed metals in the order of Mg > Zn > Mn > Cd. The statistical results demonstrated that the addition of chitosan to the bioassays allowed a high larvae survival. The outcomes showed evidence of the viability of chitosan in remediating the metal impacts and showed a positive influence on aquatic biota.

Interpolyelectrolyte complexes (IPECs) formed by the interaction of two oppositely charged polyelectrolytes have been proposed as soil structure stabilizers. However, little is known about the environmental safety of IPECs. The goal of this study was to investigate the toxicity of a positively charged IPEC formed by two commercial polymers, namely the cationic biopolymer poly(diallyldimethylammonium chloride) (PDDA) and the anionic biopolymer lignohumate (LH), a humic-based plant growth promoter. Toxicity was assessed using cultures of the bacteria Escherichia coli, the ciliate Paramecium caudatum, mammalian (Bos taurus) spermatozoa in vitro, and three plant species (Sinapis alba, Raphanus sativus, and Triticum durum). The responses of test organisms were evaluated in contact with (1) polymer and water and (2) polymer and soil. In water, PDDA and IPEC were highly toxic to bacteria and ciliates at all concentrations and less toxic to mammalian cells. Higher plants were less sensitive to the polymers, and the toxicity progressively decreased in the order PDDA > IPEC > LH. In soil matrices; the phytotoxicity of PDDA and IPEC was found to be quite low, and none of the polymers was toxic to plants at concentrations that allowed the formation of polymeric soil crusts against erosion. This is because the toxicity of cationic polymers decreases as they enter the soil matrix and bind to organic matter and minerals.

Sewage treatment plants in Algeria produce huge quantities of sludge expressed in tons annually. This sludge produced is unfortunately contaminated because of the use of synthetic polyelectrolytes. Recently several kinds of research have been carried out on natural flocculants for sludge conditioning, because of several advantages they present such as their renewable source and their non-toxicity. This work aims to evaluate the potential use of protonated pectin extracted from orange waste of N’GAOUS juice factory as an eco-friendly flocculant in the chemical conditioning of sludge. Protonated pectin effectiveness was compared with synthetic cationic anionic and ionic polyelectrolytes (SUPERFLOC 8396, AF400, NF102). In this context, raw sludge samples from Bouira WWTP were tested. Specific resistance to filtration (SRF), cakes dry solid content were analyzed to determine filterability, dewatering capacity of conditioned sludge, and the optimum dose of each conditioner. So that our goal was to obtain greater dryness, which is the case with the addition of protonated pectin and even the addition of Superfloc, which allowed us to obtain dryness of 33.01% and 29.19%, respectively, for the same doses that gave the lowest SRF. Based on the results found and the analysis of the specific resistance to filtration (SRF) and the dryness, and compared with the values observed for the dewatered sludge by the method used in the Bouira WWTP. Band filters (18–22%) and raw sludge (4.8–5.7%).

Zein has drawn attention for its great potential for biodegradability and adsorption of hexavalent chromium Cr(VI) that is a carcinogenic industrial pollutant. Zein is a biopolymer extracted from corn and is used for many purposes, but because of its poor stability in aqueous solution, a novel composite of zein and nylon-6 was used to synthesize a nanofibrous membrane using electrospinning to improve its stability and tensile strength. The scanning electron microscope (SEM) image of the zein/nylon-6 (ZN6) nanofiber membrane showed a smooth, beadless, and continuous structure of the nanofibers, but the Fourier transform infrared (FTIR) spectrum of pristine and Cr(VI) saturated ZN6 showed that peaks of secondary amide, carbonyl, and hydroxyl functional groups were involved in adsorption. Optimized experimental parameters were obtained with pH 2.0, contact time 60 min, adsorbent dosage 25 mg, and adsorbate concentration 5.0 mg Cr-VI/mL. Experimental results show that the ZN6 nanofibers removed 87% Cr(VI) with an adsorption capacity of 4.73 mg/g at ambient temperature. Also, the Langmuir isotherm fits well, and the adsorption process followed a pseudo-2ⁿᵈ-order kinetics with r² of 0.90 and 0.99 respectively.

Composite coagulants of polyaluminum chloride (PAC) and natural polyelectrolytes have attracted considerable attention in recent years due to their outstanding properties in drinking water treatment. However, the selection of polyelectrolytes grafted into PAC and aluminum forms distribution in the coagulant composite is under continuous evaluation and update. This study evaluated the effectiveness of new composite coagulants based on polyaluminum chloride (PAC) and sodium alginate (SA) to remove the colloidal matter from dam water. Optimization of the basicity (OH to Al ratios) and the sodium alginate ratio was performed by experimental design to control aluminum speciation in the composites coagulants. The Al-Ferron timed spectrophotometric method, density Functional Theory (DFT), and FTIR analysis were performed to explore PAC and SA’s interaction mechanism. The monitoring of aluminum speciation in the composite coagulant PAC-SA revealed that the basicity and SA ratios in the PAC-SA affected the distribution of aluminum forms (mononuclear Ala, medium polymeric Alb, colloidal, and highly polymeric Alc). The theoretical analysis identified the medium and high aluminum polymer species as the most sensitive species to react with SA. The coagulation performance revealed that the increasing percentage of the SA and the prevalence of Alb and Alc species over Ala species in the PAC-SA are beneficial for turbidity and oxidable matter removal. Incorporating biopolymer (SA) into the PAC reduced the concentration of inorganic coagulant consumed and increased the attraction efficiency of suspended pollutants compared to PAC. At an AlCl₃ concentration of 10 mg.L⁻¹, the incorporation of PAC (66.6% of basicity) into 20% of SA removed 99.9% of turbidity and 78.67% of oxidizable matter. This study provided new insights into the intramolecular interaction between PAC and SA and its influence on aluminum’s speciation in the PAC-SA to increase surface water treatment efficiency.

Large quantities of waste biomass are generated annually worldwide by many industries and are vastly underutilized. However, these wastes contain sugars and other dissolved organic matter and therefore can be exploited to produce microbial biopolymers. In this study, four selected Halomonas strains, namely, Halomonas caseinilytica K1, Halomonas elongata K4, Halomonas smyrnensis S3, and Halomonas halophila S4, were investigated for the production of exopolysaccharides (EPS) using low-cost agro-industrial wastes as the sole carbon source: cheese whey, grape pomace, and glycerol. Interestingly, both yield and monosaccharide composition of EPS were affected by the carbon source. Glucose, mannose, galactose, and rhamnose were the predominant monomers, but their relative molar ratio was different. Similarly, the average molecular weight of the synthesized EPS was affected, ranging from 54.5 to 4480 kDa. The highest EPS concentration (446 mg/L) was obtained for H. caseinilytica K1 grown on cheese whey that produced an EPS composed mostly of galactose, rhamnose, glucose, and mannose, with lower contents of galacturonic acid, ribose, and arabinose and with a molecular weight of 54.5 kDa. Henceforth, the ability of Halomonas strains to use cost-effective substrates, especially cheese whey, is a promising approach for the production of EPS with distinct physicochemical properties suitable for various applications.

The major biomass burning tracers are thermal degradation products from the biopolymer cellulose, namely the didehydromonosaccharide derivatives levoglucosan, galactosan, and mannosan and the resin acid derivative dehydroabietic acid, with a minor contribution from β-sitosterol. Levoglucosan, galactosan, and mannosan were measured at two sites in Silesia, a rural (Rokitno) and industry region (Zabrze), during the winter of 2017/2018. The results showed that mean concentrations of the total tracers determined were 737 ng/m³ for Zabrze and 465 ng/m³ for Rokitno. Levoglucosan was the most abundant tracer; it was 83.2% of the determined tracers in Zabrze and 78.1% in Rokitno. The relative proportions of levoglucosan to mannosan have been used for source reconstruction of combustion-derived byproducts in atmospheric aerosols. The levoglucosan to mannosan ratio for Zabrze was 8.9 and for Rokitno 5.3; the levoglucosan to sum of mannosan and galactosan ratio was 6.2 and 3.8 for Zabrze and Rokitno, respectively. The correlation between tracers is high (0.73 to 0.97) and shows linearity. In order to compare the fuel type (by the coefficient of divergence (CD)) between different sites, the results from a previous work in health resort Krynica were used. The CD between Krynica and Rokitno as well as Krynica and Zabrze was equal to 0.633 and 0.712, respectively. The CD between Rokitno and Zabrze was equal to 0.175. Despite the biomass burning tracer measurements are mostly local, they have a huge impact on air pollution and climate changes.