Characterization of self-assembled bioflocculant from the microbial consortium and its applications

Green Synthesis, Characterization and Application of Silver Nanoparticles Using Bioflocculant: A Review

Nanotechnology has emerged as an effective means of removing contaminants from water. Traditional techniques for producing nanoparticles, such as physical methods (condensation and evaporation) and chemical methods (oxidation and reduction), have demonstrated high efficiency. However, these methods come with certain drawbacks, including the significant energy requirement and the use of costly and hazardous chemicals that may cause nanoparticles to adhere to surfaces. To address these limitations, researchers are actively developing alternative procedures that are cost-effective, environmentally safe, and user-friendly. One promising approach involves biological synthesis, which utilizes plants or microorganisms as reducing and capping agents. This review discusses various methods of nanoparticle synthesis, with a focus on biological synthesis using naturally occurring bioflocculants from microorganisms. Bioflocculants offer several advantages, including harmlessness, biodegradability, and minimal secondary pollution. Furthermore, the review covers the characterization of synthesized nanoparticles, their antimicrobial activity, and cytotoxicity. Additionally, it explores the utilization of these NPs in water purification and dye removal processes.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2019-2020

This review is the tenth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2020. Also included are papers that describe methods appropriate to analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. The review is basically divided into three sections: (1) general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, quantification and the use of arrays. (2) Applications to various structural types such as oligo- and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals, and (3) other areas such as medicine, industrial processes and glycan synthesis where MALDI is extensively used. Much of the material relating to applications is presented in tabular form. The reported work shows increasing use of incorporation of new techniques such as ion mobility and the enormous impact that MALDI imaging is having. MALDI, although invented nearly 40 years ago is still an ideal technique for carbohydrate analysis and advancements in the technique and range of applications show little sign of diminishing.

Environmental concentration PFOS as a light shield for lake exopolymers against photodegradation by formation of sandwiched supramolecular nanostructures

EPS (exopolymers) play a central role in global carbon cycling due to huger amount in aquatic environment, and PFOS (Perfluorooctane sulfonate) is also ubiquitous and persistent pollutant. Whether and how can PFOS of environmental concentrations affect behavior and fate of EPS was unclear. In this study, for the first time interaction between lake EPS and PFOS of environmental concentrations was visually probed by AFM-IR technique. It was found that EPS could effectively trap PFOS and the latter of environmental concentrations could trigger nanoscale reassembly of the former. Sandwiched PFOS-EPS nanostructures were formed via supramolecular interaction between EPS and PFOS, confirmed by fluorescence quenching titration and FTIR spectroscopy. The PFOS microlayers sandwiched in EPS was proven to be a light shield that could protect EPS from photodegradation because of its high reflectivity and nearly zero absorbance of UV-Vis light. The light shielding effect of PFOS was confirmed by evidences from photodegradation experiments, including change of concentrations of ions released and molecular weight distribution patterns. These novel findings provided valuable information for deep insight into environmental behavior of PFOS and its effects on biogeochemical carbon cycle of biopolymers in global waters.

Screening of bioflocculant and cellulase-producing bacteria strains for biofloc culture systems with fiber-rich carbon source

The biofloc technology (BFT) system has been widely applied in the shrimp and fish culture industry for its advantages in water-saving, growth improvement, and water quality purification. However, The BFT system usually takes a long time to establish, and the extra carbon source input increases the maintenance cost of the system. In this study, we aimed to develop a low-cost and high-efficient BFT system for Litopenaeus vannamei by applying bacteria that could promote the formation of BFT and utilize cheap carbon sources. Three bioflocculant-producing bacteria strains (M13, M15, and M17) have been screened from a cellulolytic strain collection. All three strains have been identified as Bacillus spp. and can use sugarcane bagasse (SB) as a carbon source, which is a cheap byproduct of the sucrose industry in the tropic area of China. Compared to sucrose, the addition of SB and the three strains could improve the biofloc formation rate, biofloc size distribution, ammonia removal rate, and the growth performance of the shrimps. These results suggest that the bioflocculant and cellulase-producing bacteria strains could promote the biofloc formation and the growth of shrimps by using SB as an economic substitute carbon source in the BFT shrimp culture system.

Sustainable and efficient technologies for removal and recovery of toxic and valuable metals from wastewater: Recent progress, challenges, and future perspectives

Due to their numerous effects on human health and the natural environment, water contamination with heavy metals and metalloids, caused by their extensive use in various technologies and industrial applications, continues to be a huge ecological issue that needs to be urgently tackled. Additionally, within the circular economy management framework, the recovery and recycling of metals-based waste as high value-added products (VAPs) is of great interest, owing to their high cost and the continuous depletion of their reserves and natural sources. This paper reviews the state-of-the-art technologies developed for the removal and recovery of metal pollutants from wastewater by providing an in-depth understanding of their remediation mechanisms, while analyzing and critically discussing the recent key advances regarding these treatment methods, their practical implementation and integration, as well as evaluating their advantages and remaining limitations. Herein, various treatment techniques are covered, including adsorption, reduction/oxidation, ion exchange, membrane separation technologies, solvents extraction, chemical precipitation/co-precipitation, coagulation-flocculation, flotation, and bioremediation. A particular emphasis is placed on full recovery of the captured metal pollutants in various reusable forms as metal-based VAPs, mainly as solid precipitates, which is a powerful tool that offers substantial enhancement of the remediation processes' sustainability and cost-effectiveness. At the end, we have identified some prospective research directions for future work on this topic, while presenting some recommendations that can promote sustainability and economic feasibility of the existing treatment technologies.

Isolation, Identification and Characterization of Bioflocculant-Producing Bacteria from Activated Sludge of Vulindlela Wastewater Treatment Plant

The low microbial flocculant yields and efficiencies limit their industrial applications. There is a need to identify bacteria with high bioflocculant production. The aim of this study was to isolate and identify a bioflocculant-producing bacterium from activated sludge wastewater and characterise its bioflocculant activity. The identification of the isolated bacterium was performed by 16S rRNA gene sequencing analysis. The optimal medium composition (carbon and nitrogen sources, cations and inoculum size) and culture conditions (temperature, pH, shaking speed and time) were evaluated by the one-factor-at-a-time method. The morphology, functional groups, crystallinity and pyrolysis profile of the bioflocculant were analysed using scanning electron microscope (SEM), Fourier transform infrared (FTIR) and thermogravimetric (TGA) analysis. The bacterium was identified as Proteus mirabilis AB 932526.1. Its optimal medium and culture conditions were: sucrose (20 g/L), yeast extract (1.2 g/L), MnCl2 (1 g/L), pH 6, 30 °C, inoculation volume (3%), shaking speed (120 rpm) for 72 h of cultivation. SEM micrograph revealed the bioflocculant to be amorphous. FTIR analysis indicated the presence of hydroxyl, carboxyl and amino groups. The bioflocculant was completely pyrolyzed at temperatures above 800 °C. The bacterium has potential to produce bioflocculant of industrial importance.

Recent advances and perspectives in efforts to reduce the production and application cost of microbial flocculants

Microbial flocculants are macromolecular substances produced by microorganisms. Due to its non-toxic, harmless, and biodegradable advantages, microbial flocculants have been widely used in various industrial fields, such as wastewater treatment, microalgae harvest, activated sludge dewatering, heavy metal ion adsorption, and nanoparticle synthesis, especially in the post-treatment process of fermentation with high safety requirement. However, compared with the traditional inorganic flocculants and organic polymeric flocculants, the high production cost is the main bottleneck that restricts the large-scale production and application of microbial flocculants. To reduce the production cost of microbial flocculant, a series of efforts have been carried out and some exciting research progresses have been achieved. This paper summarized the research advances in the last decade, including the screening of high-yield strains and the construction of genetically engineered strains, search of cheap alternative medium, the extraction and preservation methods, microbial flocculants production as an incidental product of other biological processes, combined use of traditional flocculant and microbial flocculant, and the production of microbial flocculant promoted by inducer. Moreover, this paper prospects the future research directions to further reduce the production cost of microbial flocculants, thereby promoting the industrial production and large-scale application of microbial flocculants.

Removal of Heavy Metals during Primary Treatment of Municipal Wastewater and Possibilities of Enhanced Removal: A Review

Resource reuse has become an important aspect of wastewater management. At present, use of sludge in agriculture is one of the major reuse routes. Conventional municipal wastewater treatment does not involve any designated process for removal of heavy metals, and these distribute mainly between effluent and sludge. Enhanced removal of heavy metals during primary treatment may decrease the heavy metal concentrations in both effluent and sludge from secondary treatment and promote long-term reuse of secondary sludge. This review considers heavy metal occurrence and removal during primary settling, together with possible treatment technologies for heavy metal removal in primary settlers and their theoretical performance. The variation in total heavy metal concentrations and dissolved fraction in raw municipal wastewater points to a need for site-specific assessments of appropriate technologies for improved heavy metal removal. Studies examining the heavy metal speciation beyond dissolved/particulate are few. Missing or disparate information on process parameters such as hydraulic retention time, pH and composition of return flows makes it hard to generalize the findings from studies concerning heavy metal removal in primary settlers. Coagulation/flocculation and use of low-cost sorbents were identified as the most promising methods for enhancing heavy metal removal during primary settling. Based on the available data on heavy metal speciation and removal during primary settling, sorption technologies may be most effective for enhancing the removal of Cu and Ni, while coagulation may be efficient for Cd, Cr, Cu, Pb, Zn and Hg removal (but not as efficient for Ni removal).

Wastewater treatment using plant-derived bioflocculants: green chemistry approach for safe environment

The rapid expansion of global trade and human activities has resulted in a massive increase in wastewater pollution into the atmosphere. Suspended solids, organic and inorganic particles, dissolved solids, heavy metals, dyes, and other impurities contained in wastewater from various sources are toxic to the atmosphere and pose serious health risks to humans and animals. Coagulation-flocculation technology is commonly used in wastewater treatment to remove cell debris, colloids, and contaminants in a comfortable and effective manner. Flocculants, both organic and inorganic, have long been used in wastewater treatment. However, because of their low performance, non-biodegradability, and associated health risks, their use has been limited. The use of eco-friendly bioflocculants in wastewater treatment has become essential due to the health implications of chemical flocculants. Because of their availability, biodegradability, and protection, plant-derived coagulants/flocculants and plant-based grafted bioflocculants have recently made significant progress in wastewater treatment. This study will undoubtedly provide a clearer understanding of the current state, challenges, and solutions for bioflocculation in wastewater remediation using green materials for the sake of a cleaner climate.

An overview of organic matters in municipal wastewater: Removal via self-assembly flocculating mechanism and the molecular level characterization

On considering the critical issues in attaining stringent water quality standards and not creating any environmental impacts, we focused for the first time the economically feasible, emerging technology known as Self-assembly flocculating (Saf process). In which, the study investigated the applicability of bioflocculant (a biopolymer-self-assembly in nature) act as a surrogates on relying the removal of broad spectrum of substances under optimized conditions (Dosage: 90 mg/L; pH: 7; CaCl₂). On using different techniques, the results have proved in removing the organic matter such as pharmaceuticals (Gentamycin, Cholecalciferol, Fluvoxamine, 3-OH Desogestrel, and Pheniramine), endocrine disturbing compounds [Phthalic acid, Benzene, 1, 2, 4 -Trimethoxy-5-(1-Propenyl)-, Benzene, 1, 2-Dimethoxy-4-(2-Propenyl)-, 1, 2-Benzenedicarboxylic Acid, 3-Cyclohexen-1-ol], fluorescent components (Polysaccharide like material), and others. The toxicological assessment of self-assembly bioflocculant implemented on zebra fish were statistically correlated [r = 0.95, p < 0.01 and 0.05 for P₁WW; r = 0.91, p < 0.01 and 0.05 for P₂WW] and [r = 0.7 5, p < 0.05 for P₁WT; r = 0.095, p < 0.01 and 0.05 for P₂WT]. This integrated approach supplemented further information of zeta potential (-16 mV in P₁WW and -14.6 mV in P₂WW decreased to -1.05 mV and -1.56 mV) with particle size distribution to explain via Saf process. In this research, the new insight has established non-toxic, self-assembly, biodegradable, bioflocculant for effective bioremediation.