Application of Aloe vera mucilage as bioflocculant for the treatment of textile wastewater: process optimization

Nano polysaccharides derived from aloe vera and guar gum as a potential fat replacer for a promising approach to healthier cake production

In recent years, there increment demand for healthier food options that can replace high-fat ingredients in bakery products without compromising their taste and texture. This research was focused on a formulation study of the blend of nano polysaccharides derived from aloe vera and guar gum at various concentrations. This study selected the blend concentration of 1 % aloe vera mucilage (AM) and 1 % guar gum (GG) due to its optimal gelling properties. Different magnetic stirring time durations were employed to formulate AGB (aloe vera guar gum blend). The particle size of AGB revealed the lowest nanoparticle size (761.03 ± 62 nm) with a stirring time of 4 h. The FTIR analysis found the presence of monomer sugars in AGB nano polysaccharide powder such as mannose, arabinose, and glucose. The thermogram results displayed an endothermic peak for all samples with a glass transition temperature (Tg) between 16 and 50 °C. The SEM image of the AGB indicated uniform spherical particles. The AGB powder exhibited good functional properties. The antimicrobial activity of AGB powder against Staphylococcus aureus, Escherichia coli, and Candida albicans was 22.32 ± 0.02, 21.56 ± 0.02, and 19.33 ± 0.33 mm, respectively. Furthermore, the effects of different levels of vegetable fat replacement with AGB powder on cake sensory properties, thermal stability, and texture characteristics were also examined. Notably, the cake containing a 50 % substitution of vegetable fat with AGB (C50) supplied desirable physicochemical, textural, and sensory properties. These results can provide advantages for the development of fat replacers in bakery products.

Effectiveness of a natural coagulant based on common mallow (Malva sylvestris) in urban wastewater treatment

This study evaluated the effectiveness of a natural coagulant based on common mallow (Malva sylvestris) to remove turbidity in urban wastewater. A 22 factorial design was selected to determine the optimal dose and the working pH of the natural coagulant. Its potential was studied in 50.0-450 mg/L and 4.00-10.0 ranges of doses and pH, respectively. A simplex lattice mixture evaluated its effectiveness as a coagulant aid combined with aluminum sulfate (conventional coagulant). Mixture proportions 0.000-1.00 were studied for each component, finding the proportion more effective. Results showed that the coagulation treatment could be feasible since a turbidity removal efficiency of 73.7% can be achieved under optimal conditions (50.0 mg/L and pH of 10.0). Likewise, a turbidity removal of 58.9% is obtained using 250 mg/L and maintaining wastewater pH (7.45). This efficiency can be increased using 31.0% natural coagulant mixed with 69.0% aluminum sulfate at 250 mg/L without modifying the wastewater pH. This improvement was associated with the natural coagulant's high molecular weight and long-chained structure since these properties enhance settling time, floc size and strength, and low sludge production. These results support using common mallow as a natural coagulant, making its use more feasible in alkaline water pH or as a coagulant aid combined with aluminum sulfate for urban wastewater treatment. A cost of USD 370/Kg of natural coagulant was estimated, which is higher than conventional coagulants. However, a cost-effectiveness analysis of its implementation should be performed since process scaling costs could significantly reduce its price.

Cocoyam powder extracted from Colocasia antiquorum as a novel plant-based bioflocculant for industrial wastewater treatment: Flocculation performance and mechanism

In the current investigation, the comparative study of cocoyam bioflocculant (CYBF) and chemical flocculant for the removal of heavy metals, COD, BOD, TDS, TSS, sulphate and nitrate from tannery effluent, and dyes from synthetic dye wastewater were examined. Different analytical techniques, including Fourier transforms infrared (FTIR), X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDX), were used to characterise the extracted bioflocculant. FTIR spectral measurement of the bioflocculant demonstrated the presence of hydroxyl, carboxyl, and amino groups. By using bioflocculant, the highest removal of TSS (85.5%), TDS (76.2%), BOD (74%), COD (50.5%), sulphate (54.4%), nitrate (52%), Lead (65%), Chromium (60%), Nickel (57.9%), from tannery effluent was achieved at pH 6 and bioflocculant dosage of 8 mg/L. While, 80% congo red, 79% methyl orange, 73% safranin, and 72% methylene blue were removed from synthetic dye wastewater by cocoyam bioflocculant. Two flocculation mechanisms were found for dye removal, electrostatic force of attraction, and hydrogen bonding. In the case of metal adsorption, only electrostatic interactions were observed between metal ions and functional groups of bioflocculant. The cocoyam bioflocculant exhibited excellent flocculation efficacy and thus can be used in wastewater treatment to remove heavy metals and other pollutants.

A novel approach for harvesting the microalgae Chlorella vulgaris with sodium alginate microspheres using buoy-bead flotation method

In order to reduce the residue of buoy-beads and solve the problem of pollution caused by high flocculant consumption, SAMs¹(sodium alginate microspheres) with sodium alginate were used as the raw material to harvest microalgae for the first time. In addition, during the manufacturing of SAMs, the re-frying oil was used as the dispersion system, which not only reduced the cost, but also provided new ideas for the treatment of re-frying oil. Response surface methodology was used to explore the influence of different factors and the interaction of variables, and the harvesting process was optimized using the multi-objective optimization. Based upon the calculation of XDLVO (extended Derjaguin-Laudau-Verwey-Overbeek) theory and the characterization of Fourier Transform Infrared Spectroscopy, the harvesting mechanism of buoy-bead flotation method was clarified. The results showed that the combination of SAMs and a small amount of aluminum sulfate could replace air flotation and traditional buoy-bead flotation with solid particles as buoy-beads to harvest C. vulgaris (Chlorella vulgaris). For the multi-objective optimization with harvesting efficiency as the priority, the predicted pH, the concentrations of aluminum sulfate and buoy-beads and the dilution factor had values of 8.25, 56.09 mg/L, 17.46 mL/L, and 2.15, respectively. In the validation experiment, the harvesting efficiency and the enrichment ratio of C. vulgaris could reach the values of 97.51 % and 1.97 %, respectively. For the validation experiment of reverse optimization with focusing on enrichment ratio, the harvesting efficiency and the enrichment ratio of C. vulgaris had the values of 93.78 % and 2.65 %, respectively. The essence of improving the harvesting mechanism was the combination of carboxyl and hydroxyl groups between C. vulgaris and SAMs and the adsorption of positive ions by specific proteins on the surface of C. vulgaris to reduce electrostatic repulsion.

Utilization of Bioflocculants from Flaxseed Gum and Fenugreek Gum for the Removal of Arsenicals from Water

Mucilage-based flocculants are an alternative to synthetic flocculants and their use in sustainable water treatment relates to their non-toxic and biodegradable nature. Mucilage extracted from flaxseed (FSG) and fenugreek seed (FGG) was evaluated as natural flocculants in a coagulation-flocculation (CF) process for arsenic removal, and were compared against a commercial xanthan gum (XG). Mucilage materials were characterized by spectroscopy (FT-IR, ¹³C NMR), point-of-zero charge (pH_pzc) and thermogravimetric analysis (TGA). Box-Behnken design (BBD) with response surface methodology (RSM) was used to determine optimal conditions for arsenic removal for the CF process for three independent variables: coagulant dosage, flocculant dosage and settling time. Two anionic systems were tested: S1, roxarsone (organic arsenate 50 mg L^-1) at pH 7 and S2 inorganic arsenate (inorganic arsenate 50 mg L^-1) at pH 7.5. Variable arsenic removal (RE, %) was achieved: 92.0 (S1-FSG), 92.3 (S1-FGG), 92.8 (S1-XG), 77.0 (S2-FSG), 69.6 (S2-FGG) and 70.6 (S2-XG) based on the BBD optimization. An in situ kinetic method was used to investigate arsenic removal, where the pseudo-first-order model accounts for the kinetic process. The FSG and FGG materials offer a sustainable alternative for the controlled removal of arsenic in water using a facile CF treatment process with good efficiency, as compared with a commercial xanthan gum.

Aloe vera as Promising Material for Water Treatment: A Review

Aloe vera plant offers a sustainable solution for the removal of various pollutants from water. Due to its chemical composition, Aloe vera has been explored as coagulant/flocculant and biosorbent for water treatment. Most of the used materials displayed significant pollutants removals depending on the used preparation methods. AV-based materials have been investigated and successfully used as coagulant/flocculant for water treatment at laboratory scale. Selected AV-based materials could reduce the solids (total suspended solids (TSS), suspended solids (SS), total dissolved solids (TDS), and dissolved solids (DS)), turbidity, chemical oxygen demand (COD), biochemical oxygen demand (BOD), heavy metals, and color, with removal percentages varied depending on the coagulant/flocculant materials and on the wastewater characteristics. In the same context, AV materials can be used as biological flocculant for wastewater sludge treatment, allowing good solid–liquid separation and promoting sludge settling. Moreover, using different methods, AV material-based biosorbents were prepared and successfully used for pollutants (heavy metal dyes and phenol) elimination from water. Related results showed significant pollutant removal efficiency associated with an interesting adsorption capacity comparable to other biosorbents derived from natural products. Interestingly, the enzymatic system of Aloe vera (carboxypeptidase, glutathione peroxidase, and superoxide dismutase) has been exploited to degrade textile dyes. The obtained results showed high promise for removal efficiencies of various kinds of pollutants. However, results varied depending on the methodology used to prepare the Aloe vera based materials. Because of its valuable properties (composition, abundance, ecofriendly and biodegradable), Aloe vera may be useful for water treatment.