Search Results (108)

Flocculants are indispensable in water and wastewater treatment, enabling the aggregation and removal of suspended particles, colloids, and emulsions. However, the conventional development and application of flocculants rely heavily on empirical methods, which are time-consuming, resource-intensive, and environmentally problematic due to issues such as sludge production and chemical residues. Recent advances in machine learning (ML) have opened transformative avenues for the design, optimization, and intelligent application of flocculants. This review systematically examines the integration of ML into flocculant research, covering algorithmic approaches, data-driven structure–property modeling, high-throughput formulation screening, and smart process control. ML models—including random forests, neural networks, and Gaussian processes—have successfully predicted flocculation performance, guided synthesis optimization, and enabled real-time dosing control. Applications extend to both synthetic and bioflocculants, with ML facilitating strain engineering, fermentation yield prediction, and polymer degradability assessments. Furthermore, the convergence of ML with IoT, digital twins, and life cycle assessment tools has accelerated the transition toward sustainable, adaptive, and low-impact treatment technologies. Despite its potential, challenges remain in data standardization, model interpretability, and real-world implementation. This review concludes by outlining strategic pathways for future research, including the development of open datasets, hybrid physics–ML frameworks, and interdisciplinary collaborations. By leveraging ML, the next generation of flocculant systems can be more effective, environmentally benign, and intelligently controlled, contributing to global water sustainability goals. Full article

Phycosphere niches host rich, unique microbial consortia that harbor complex algae–bacteria interactions with fundamental significance in underpinning most functions of aquatic ecological processes. Therefore, harvesting the uncultured phycobacteria is crucial for understanding the intricate mechanisms governing these dynamic interactions. Here, we characterized and compared microbial community composition of the phycosphere microbiota from six harmful algal bloom-forming marine dinoflagellates, Alexandrium spp., and their bacterial associations. Furthermore, based on a combinational enhanced cultivation strategy (CECS) procedure for the selected isolation for cultivable phycobacteria, a new yellow-pigmented bioactive bacterium designated ABI-6-9 was successfully recovered from cultivable phycobacteria of the highly toxic A. minutum strain amtk4. An additional phylogenomic analysis fully identified this new isolate as a potential novel species of the genus Mameliella within the family Roseobacteraceae. The bioactivity evaluation observed that strain ABI-6-9 can significantly promote the cell growth of its algal host and altered the gonyautoxin accumulation profiles in the co-culture circumstance. Additionally, the bacterial production of active bioflocculanting exopolysaccharides (EPSs) by strain ABI-6-9 was also measured after culture optimization. Thus, these findings revealed the potential environmental and biotechnological implications of this new microalgae growth- promoting phycobacterium. Full article

The growing demand for the sustainable production of high-value compounds, such as biofuels, lipids, and pigments like carotenoids and phycobilin, has become the subject of numerous investigations. Furthermore, this has led to the exploration of renewable methods utilizing microalgae as feedstock to mitigate the challenges associated with producing these valuable compounds. Nevertheless, despite the numerous advantages of microalgae, the development of a microalgal biorefinery that employs sustainable, environmentally friendly, and economically efficient technologies remains a necessity. To address this challenge, the bio-flocculation process, and more specifically self-flocculation, is presented as a cost-effective and energy-efficient solution. This method is as easy and effective as chemical flocculation, which is applied at an industrial scale; however, in contrast, it is sustainable and cost-effective as no costs are involved in the pre-treatment of the biomass for oil extraction or in the pre-treatment of the medium before it can be re-used. In addition, microalgae possess molecular tools that would allow the efficiency of these processes to be increased. In the present review, we summarize the microalgal harvesting technologies used, with a particular focus on bio- and self-flocculation processes, and identify the improvements that could be made to enhance the production of high-added-value compounds while simultaneously reducing costs in microalgae biorefineries. Full article

This study systematically compared the harvesting efficiency and flocculation mechanisms of a bioflocculant (chitosan) and a chemical flocculant (Al₂(SO₄)₃) for Chlorella cells. For the first time, the divergent mechanisms underlying floc structure formation between the two flocculants were elucidated by analyzing the EPS distribution and dynamic changes in microalgal surface functional groups. By optimizing critical operational parameters—including flocculant dosage, flocculation time, pH, and biomass concentration—the optimal dosages of chitosan and Al₂(SO₄)₃ were determined as 0.5 mg/L and 90 mg/L, respectively. Under pH 6, both flocculants achieved over 99% flocculation efficiency within 30 min. Notably, at a dosage of 3 mg/L, chitosan-formed flocs exhibited denser structures, stronger adhesion, and a tendency to aggregate into spherical clusters compared to Al₂(SO₄)₃-induced flocs. Beyond identifying ideal conditions for Chlorella flocculation, this work provides novel insights into the role of EPS and surface functional groups in flocculation mechanisms, offering both theoretical foundations and practical guidance for efficient microalgal harvesting. The findings hold significant implications for optimizing bioflocculant applications and advancing environmentally sustainable harvesting technologies. Full article

Nanotechnology offers effective solutions for removing contaminants and harmful bacteria from polluted water. This study synthesized copper nanoparticles using a carbohydrate-based bioflocculant derived from Proteus mirabilis AB 932526.1. The bioflocculant is a natural polymer that facilitates the aggregation of particles, enhancing the efficiency of the nanoparticle synthesis process. Characterization of the bioflocculant and copper nanoparticles was conducted using Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, Energy-Dispersive X-ray Spectroscopy, Ultraviolet-Visible Spectroscopy, X-ray Diffraction, and Transmission Electron Microscopy techniques to assess their properties, flocculation efficiency, and antibacterial characteristics. The optimal flocculation efficiency of 80% was achieved at a copper nanoparticle concentration of 0.4 mg/mL, while a concentration of 1 mg/mL resulted in a lower efficiency of 60%. The effects of biosynthesized copper nanoparticles on human-derived embryonic renal cell cultures were also investigated, demonstrating that they are safe at lower concentrations. The copper nanoparticles effectively removed staining dyes such as safranin (90%), carbol fuchsine (88%), methylene blue (91%), methyl orange (93%), and Congo red (94%), compared to a blank showing only 39% removal. Furthermore, when compared to both chemical flocculants and bioflocculants, the biosynthesized copper nanoparticles exhibited significant nutrient removal efficiencies for nitrogen, sulfur, phosphate, and total nitrates in coal mine and Vulindlela domestic wastewater. Notably, these biosynthesized copper nanoparticles demonstrated exceptional antibacterial activity against both Gram-positive and Gram-negative bacteria. Full article

Spirulina platensis is a promising microalga, but biomass harvesting remains a challenge. Fungal bioflocculation offers a potential solution, facilitating the production of valuable bioproducts like bioethanol. Effective cell disruption methods, including physical-chemical and enzymatic treatments, can enhance biomass utilization. However, commercial enzymes are not optimized for microalgae, necessitating research on ideal operational conditions. This study evaluated physical and enzymatic processes to hydrolyze bioflocculated microalgae for bioethanol production. The microalga was harvested using a fungal bioflocculant produced via submerged fermentation. Biomass hydrolysis involved physical methods (autoclaving, ultrasound + autoclaving, ultrasound + gelatinization, and gelatinization) combined with enzymes (amylase, amyloglucosidase, cellulase, and xylanase), optimized for pH, temperature, and enzyme load. Hydrolysates were then used for bioethanol production. Results showed a microalgae harvest efficiency of 99.7% with a 1:8 fungus-to-microalgae ratio. Enzyme optimization identified ideal conditions (e.g., pH 4.5; 60 °C for amylase/amyloglucosidase, 70 °C for cellulase, and 50 °C for xylanase). Combined enzymatic treatments achieved approximately 70% hydrolysis efficiency, yielding 19.06 g/L glucose and 7.29 g/L ethanol (~79% conversion). Ethanol productivity was ~0.6 g per 1 g bioflocculated biomass L⁻¹·hr. These findings highlight the potential of enzymatic hydrolysis for complex biomasses, although further studies are needed to refine enzyme applications for better biomass utilization. Full article

Phenolic compounds are harmful organic pollutants found in wastewater from the chemical and pharmaceutical industries, which are frequently accompanied by high saline concentrations. Microorganism-based biodegradation represents an environmentally friendly and cost-effective strategy for phenol removal. In this study, we isolated a bioflocculant-producing Bacillus paralicheniformis BL-1 that is capable of phenol degradation in high-salinity conditions. Differential gene expression analysis revealed the down-regulation of genes related to the synthesis of extracellular polymeric substances and the up-regulation of poly-γ-glutamate biosynthesis in 10% NaCl conditions. These findings indicate that poly-γ-glutamate is the main large biomolecule produced by B. paralicheniformis BL-1. A further investigation suggested that salinity stress resulted in the down-regulated expression of the genes involved in iron homeostasis. Therefore, alleviating iron limitation by supplying excess iron could improve cell growth and, thus, increase the phenol removal rate and flocculating activity. The productivity of poly-γ-glutamate reached 2.23 g/L, and the phenol removal rate reached 73.83% in the synthetic medium supplemented with 10% NaCl, 500 mg/L phenol, and 250 μM FeCl₃. Full article

The rising global energy demand and environmental concerns associated with fossil fuels have intensified interest in sustainable biofuel sources, with microalgae emerging as a viable candidate due to its high biomass yield and efficient CO₂ conversion. However, the economic feasibility of microalgal biofuels is currently challenged by costly harvesting processes. This study investigates the use of exopolysaccharides (EPSs) derived from Klebsiella sp. as an environmentally friendly bioflocculant for harvesting two microalgae species: Raphidocelis subcapitata and Dunaliella salina. Comparative flocculation experiments revealed that Klebsiella EPS promotes efficient aggregation in R. subcapitata, achieving over 90% flocculation efficiency, while performance with D. salina was impacted by high salinity, which reduced charge neutralization and bridging effects. Structural analyses using FTIR, 3D-EEM, CLSM, and XPS elucidated the EPS composition, underscoring the roles of polysaccharides and proteins in facilitating microalgal aggregation. The findings indicate that Klebsiella EPS offers a sustainable alternative to chemical flocculants, supporting eco-friendly biofuel production and potential applications in wastewater treatment. This approach provides insights into optimizing EPS-based flocculation for diverse environmental conditions, paving the way for more sustainable biomass recovery practices. Full article

The intriguing characteristics of nanoparticles have fueled recent advancement in the field of nanotechnology. In the current study, a microbial-based bioflocculant made from the SCOBY of Kombucha tea broth was purified, profiled, and utilized to biosynthesize iron nanoparticles as a capping and reducing agent. UV–visible absorption spectroscopy, transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and TGA were used to characterize the Fe nanoparticles. The FT-IR spectra showed functional groups such as hydroxyl, a halogen (C-Br), and carbonyl, and the alkane (C-H) functional groups were present in both samples (bioflocculant and FeNPs) with the exception of the Fe-O bond, which represented the successful biosynthesis of FeNPs. The TEM investigation revealed that the sizes of the produced iron nanoparticles were between 2.6 and 6.2 nm. The UV-vis spectra revealed peaks at 230 nm for the bioflocculant and for the as-fabricated FeNPs, peaks were around 210, 265, and 330 nm, which confirms the formation of FeNPs. X-ray diffraction presented planes (012), (104), (110), (113), (024), (116), and (533) and these planes correspond to 17.17, 32.58, 33.75, 38.18, 45.31, 57.40, and 72.4° at 2Ө. The presence of Fe nanoparticles presented with 0.82 wt% from the EDX spectrum of the biosynthesized FeNPs. However, Fe content was not present from the bioflocculant. SEM images reported cumulus-like particles of the bioflocculant, while that of FeNPs were agglomerated and hexagonal with sizes between 18 and 50 nm. The TGA of FeNPs showed thermal stability by retaining above 60% of its weight at high temperatures. It can therefore be deduced that the purified bioflocculant produced by a yeast Pichia kudraivzevii can be utilized to synthesize FeNPs with the current simple and effective method. Full article

With the aim to establish clean and sustainable sludge treatment, green conditioning using natural flocculants has recently gained a growing interest. In this study, a variety of plant materials, namely Moringa (Moringa oleifera) seeds, Fenugreek (Trigonella foenum-graecum) seeds, Potato (Solanum tuberosum) peels, Aloe (Aloe vera) leaves, Cactus (Opuntia ficus indica) cladodes, and Phragmites (Phragmites australis) stems, were evaluated for their potential bioflocculant activity in conditioning sewage sludge. They were thoroughly characterized to determine their active flocculating compounds. Sludge dewaterability was evaluated by assessing various sludge parameters, including specific resistance to filtration (SRF), dryness of filtration cake (DC), and total suspended solid removal (TSS) from sludge filtrate. The collected results from various physicochemical characterizations of plant materials suggest that the main flocculating agents are carbohydrates in Cactus and Fenugreek and proteins in Moringa, Potato, and Phragmites. Additionally, all tested plant-based flocculants demonstrated effective dewatering performance. Interestingly, compared to the chemical flocculant polyaluminum chloride, Moringa and Cactus showed superior conditioning effects, yielding the lowest SRF values and the highest DC. As a result, the use of these natural flocculants improved sewage sludge filterability, leading to a significant removal of total suspended solids from the filtrate. The conditioning properties of Moringa and Cactus can be attributed to their high protein and sugar content, which facilitates the effective separation of bound water from solids through charge neutralization and bridging mechanisms. Thus, green conditioning using plant-based flocculants, particularly Moringa and Cactus materials, presents a promising and eco-friendly approach to enhance sewage sludge dewatering for safer disposal and valorization. Full article

Ensuring sustainability has increasingly become a significant concern not only in aquaculture but in the general agrifood sector. Therefore, it is imperative to investigate pathways to feed substitutes/best practices to enhance aquaculture sustainability. The application of fungi in aquaculture provides innovative methods to enhance the sustainability and productivity of aquaculture. Fungi play numerous roles in aquaculture, including growth, immunity enhancement and disease resistance. They also play a role in bioremediation of waste and bioflocculation. The application of fungi improves the suitability and utilization of terrestrial plant ingredients in aquaculture by reducing the fibre fractions and anti-nutritional factors and increasing the nutrients and mineral contents of plant ingredients. Fungi are good flotation agents and can enhance the buoyancy of aquafeed. Pigments from fungi enhance the colouration of fish fillets, making them more attractive to consumers. This paper, via the relevant literature, explores the multifaceted roles of fungi in aquaculture, emphasizing their potential to transform aquaculture through environmentally friendly and sustainable techniques. The effectiveness of fungi in reducing fibre fractions and enhancing nutrient availability is influenced by the duration of fermentation and the dosage administered, which may differ for various feed ingredients, making it difficult for most aquaculture farmers to apply fungi approximately. Therefore, the most effective dosage and fermentation duration for each feed ingredient should be investigated. Full article

Copper nanoparticles (CuNPs) are tiny materials with special features such as high electric conductivity, catalytic activity, antimicrobial activity, and optical activity. Published reports demonstrate their utilization in various fields, including biomedical, agricultural, environmental, wastewater treatment, and sensor fields. CuNPs can be produced utilizing traditional procedures; nevertheless, such procedures have restrictions like excessive consumption of energy, low production yields, and the utilization of detrimental substances. Thus, the adoption of environmentally approachable “green” approaches for copper nanoparticle synthesis is gaining popularity. These approaches involve employing plants, bacteria, and fungi. Nonetheless, there is a scarcity of data regarding the application of microbial bioflocculants in the synthesis of copper NPs. Therefore, this review emphasizes copper NP production using microbial flocculants, which offer economic benefits and are sustainable and harmless. The review also provides a characterization of the synthesized copper nanoparticles, employing numerous analytical tools to determine their compositional, morphological, and topographical features. It focuses on scientific advances from January 2015 to December 2023 and emphasizes the use of synthesized copper NPs in wastewater treatment. Full article

Microbial flocculants (MBFs), a class of eco-friendly and biodegradable biopolymers produced by various microorganisms, have gained increasing attention as promising alternatives to conventional chemical flocculants in wastewater treatment and pollutant removal. This review presents a comprehensive overview of the current state of MBF research, encompassing their diverse sources (bacteria, fungi, and algae), major categories (polysaccharides, proteins, and glycoproteins), production processes, and flocculation performance and mechanisms. The wide-ranging applications of MBFs in removing suspended solids, heavy metals, dyes, and other pollutants from industrial and municipal wastewater are critically examined, highlighting their superior efficiency, selectivity, and environmental compatibility compared to traditional flocculants. Nonetheless, bioflocculants face significant challenges including high substrate costs, low production yields, and intricate purification methodologies, factors that impede their industrial scalability. Moreover, the risk of microbial contamination and the attendant health implications associated with the use of microbial flocculants (MBFs) necessitate thorough evaluation. To address the challenges of high production costs and variable product quality, strategies such as waste valorization, strain improvement, process optimization, and biosafety evaluation are discussed. Moreover, the development of multifunctional MBF-based flocculants and their synergistic use with other treatment technologies are identified as emerging trends for enhanced wastewater treatment and resource recovery. Future research directions are outlined, emphasizing the need for in-depth mechanistic studies, advanced characterization techniques, pilot-scale demonstrations to accelerate the industrial adoption of MBF, and moreover, integration with novel wastewater treatment processes, such as partial nitrification and the anammox process. This review is intended to inspire and guide further research and development efforts aimed at unlocking the full potential of MBFs as sustainable, high-performance, and cost-effective bioflocculants for addressing the escalating challenges in wastewater management and environmental conservation. Full article

The optimization of wastewater treatment technologies using biological processes is no longer limited to improving the removal of organic matter and nutrients, as it is possible to reduce area and energy consumption, and recover value-added by-products. In this context, the microalgae–bacteria consortium is an alternative for reducing costs, as microalgae produce the oxygen required by bacteria to oxidize organic matter through photosynthesis. Additionally, it is possible to extract different by-products such as lipids, biofertilizers, biogas, alginate-type exopolymers, and others. Furthermore, bioflocculation occurs naturally through the adhesion of microalgae to the surface of bacterial flocs, without the addition of chemical products. This review discusses the main systems that utilize the microalgae–bacteria consortium, the metabolism of the microalgae–bacteria consortium, and its performance in removing organic matter and nutrients, as well as the effect of operating conditions on the physical properties of the biomass. Among the highlighted systems are sequencing batch and single-batch reactors, high-rate ponds, and continuous flow reactors. Among the systems discussed in this work, the sequential batch reactor configurations found better biomass formation and production of extracellular polymeric substances and the continuous flow reactors showed lower installation and operating costs. From this perspective, the potential for full-scale application of each system can be evaluated once the optimum operating conditions have been defined and the limitations of each system have been understood. Full article

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. Full article