Processing Of Microalgae Research Articles

Enhancing Scalability and Consistency in Pulsed Electric Field Processing of Microalgae: Integrating Single-Cell Suspension Rheology and Multiphysics Simulation

Emerging extraction technologies such as microsecond pulsed electric field (μsPEF) offer an energy-efficient and gentle method for downstream processing of single cells. However, attaining consistent processing outcomes in continuous PEF systems across different scales is challenging due to variations in cell residence times caused by cell concentration and flow-dependent rheological behavior. This study employed COMSOL Multiphysics® simulations to model rheological changes in high-density heterotrophically grown Auxenochlorella protothecoides microalgae suspensions. The model was designed to precisely estimate residence times for consistent μsPEF treatment and increased processing capacity at high flow rates and cell concentrations. Implementing the simulated residence times into experimental validations achieved consistent treatment outcomes, resulting in 86 ± 4% of cells being permeabilized and increased processing capacity from 21 to 300 mL min-1. Higher cell concentrations led to increased energy input and decreased protein extraction yields, indicating complex underlying permeabilization and diffusion processes during and after treatment. This work advances scalable and consistent μsPEF technology for single-cell downstream processing by applying cell suspension rheology and residence time simulations.

Impact of light spectrum on outdoors tubular photobioreactors used for microalgae-based wastewater treatment

Microalgae-based wastewater treatment involves various factors, including algal ecosystems and environmental conditions. Light spectral composition, particularly wavelength and intensity, is a key but underexplored under out-of-laboratory conditions. Therefore, this study investigates the effects of different light wavelengths on microalgae in wastewater treatment systems using filtered sunlight. It examines critical physiological and biochemical processes in microalgae, including pigment synthesis, carbon fixation, and nutrient uptake. A tubular photobioreactor (PBR) setup with two diameters, 4-inch (10.16 cm) and 6-inch (15.24 cm), was tested outdoors for three months using blue, green, and red filters. These filters transmitted radiation and were transparent to infrared light, ranging from 750 nm to blue-green-infrared light (peaking at 450 nm), green-infrared light (peaking at 520 nm), and red-infrared light (peaking at 600 nm). The study analyzed 56 absorption curves, finding that light color influences microalgae physiology even under the same radiation levels. Pigment production was enhanced with only 10 % of total solar radiation, avoiding photoinhibition. Chlorophyll production was highest in the 4-inch PBR with a green filter, while blue light filters promoted pigment accumulation in 6-inch PBRs. However, the 6-inch reactors exhibited a lower growth rate compared to the 4-inch reactors, with significant effects of light color seen only at extreme irradiance levels. Larger diameter PBRs also increased the nitrification process, regardless of the filter used. These results have important implications for biofuel production, wastewater treatment, and bioremediation, underscoring the role of filtered light in enhancing microalgae performance in environments requiring deeper sunlight penetration.

Artificial Intelligence and/or Machine Learning Algorithms in Microalgae Bioprocesses.

This review examines the increasing application of artificial intelligence (AI) and/or machine learning (ML) in microalgae processes, focusing on their ability to improve production efficiency, yield, and process control. AI/ML technologies are used in various aspects of microalgae processes, such as real-time monitoring, species identification, the optimization of growth conditions, harvesting, and the purification of bioproducts. Commonly employed ML algorithms, including the support vector machine (SVM), genetic algorithm (GA), decision tree (DT), random forest (RF), artificial neural network (ANN), and deep learning (DL), each have unique strengths but also present challenges, such as computational demands, overfitting, and transparency. Despite these hurdles, AI/ML technologies have shown significant improvements in system performance, scalability, and resource efficiency, as well as in cutting costs, minimizing downtime, and reducing environmental impact. However, broader implementations face obstacles, including data availability, model complexity, scalability issues, cybersecurity threats, and regulatory challenges. To address these issues, solutions, such as the use of simulation-based data, modular system designs, and adaptive learning models, have been proposed. This review contributes to the literature by offering a thorough analysis of the practical applications, obstacles, and benefits of AI/ML in microalgae processes, offering critical insights into this fast-evolving field.

Kinetics, mechanisms and release of nitrogen-containing components during pyrolysis of Chlorella with potassium hydroxide addition

Pyrolysis integrated with KOH activation is the most frequently used and efficient method for microalgae to produce N-doped porous biochar. However, the effects of KOH to the pyrolysis process of microalgae are still unclear. Thus, the pyrolysis behavior, kinetics and the release of volatiles especially the nitrogen-containing components during Chlorella pyrolysis with KOH addition were investigated in this study. Results showed that KOH significantly changed the pyrolysis behavior by lowering the initial decomposition temperature and reducing the weight mean activation energy. KOH reacted with the solid matrix even at room temperature. CO2 was the dominant gas product, the release of which was postponed by KOH addition. KOH inspired the release of NH3 to lower temperatures (< 400 °C) while the reverse for HNCO. With the increase of KOH, the formation of hydrocarbons in volatiles shifted to higher temperatures while the yield of acids dramatically reduced and even vanished. The release of nitrogen-containing components was greatly inhibited at 600 °C by converting nitrogen in the feedstock to harmless N2. This study provided insights into the pyrolysis mechanisms of microalgae over KOH for biochar production and the essential environmental impact during the process.

Biohydrogen production from wastewater: Production technologies, environmental and economic aspects

Biohydrogen (bio-H2) production from wastewater can be a sustainable and innovative approach that uses biotechnological processes to convert organic waste into hydrogen, a clean energy source. Technologies such as dark fermentation, photo-fermentation, microbial electrolysis cells, and biophotolysis are widely utilized, with emerging technologies like anaerobic membrane bioreactors and microalgae processes also gaining prominence. Integration between these systems aims to enhance process efficiency. This study reviews the hydrogen production from wastewater, analyzing its potential as a source for bio-H2 production and evaluating environmental and economic issues. The performance of various processes in bio-H2 production from different wastewater sources is discussed, focusing on challenges, opportunities, and trends. Wastewater, including cassava (225.2 mL H2/gVS) and corn (265 mL H2/gVS) processing, dairy (54.5 mL H2/gVS), domestic (154–180 mL H2/gVS), fruit (104.9 mL H2/gVS) and starchy (153–200 mL H2/gVS), show promising potential for bio-H2 production. Economically, indirect biophotolysis is the most cost-effective technology per kg of bio-H2 produced, followed by microbial electrolysis cells, photo-fermentation, dark fermentation, and direct biophotolysis. Furthermore, from an environmental and sustainability perspective, bio-H2 production presents a strategic tool for global decarbonization efforts, reducing CO2 emissions and facilitating transformation towards clean energy solutions. Bio-H2 generation during wastewater treatment holds potential by concurrently producing clean fuel and enabling safe disposal of wastewater. Continued research and development efforts are essential to overcoming current challenges. Achieving this will require targeted investments, policy support, and technological innovations to make biohydrogen a viable and sustainable energy solution.

Injecting Sustainability into Epoxy-Based Composite Materials by Using Bio-Binder from Hydrothermal Liquefaction Processing of Microalgae.

We report a transformative epoxy system with a microalgae-derived bio-binder from hydrothermal liquefaction processing (HTL). The obtained bio-binder not only served as a curing agent for conventional epoxy resin (e.g., EPON 862), but also acted as a modifying agent to enhance the thermal and mechanical properties of the conventional epoxy resin. This game-changing epoxy/bio-binder system outperformed the conventional epoxy/hardener system in thermal stability and mechanical properties. Compared to the commercial EPON 862/EPIKURE W epoxy product, our epoxy/bio-binder system (35 wt.% bio-binder addition with respect to the epoxy) increased the temperature of 60% weight loss from 394 °C to 428 °C and the temperature of maximum decomposition rate from 382 °C to 413 °C, while the tensile, flexural, and impact performance of the cured epoxy improved in all cases by up to 64%. Our research could significantly impact the USD 38.2 billion global market of the epoxy-related industry by not only providing better thermal and mechanical performance of epoxy-based composite materials, but also simultaneously reducing the carbon footprint from the epoxy industry and relieving waste epoxy pollution.

Microalgae as a multibenefit natural solution for the wastewater industry: A UK pilot‐scale study

AbstractCommercialization of microalgae for wastewater treatment (WWT) is limited due to the large footprints and long hydraulic retention times (HRT) of standard systems, making integration into wastewater (WW) grey infrastructure unfeasible. Industrial Phycology Ltd has developed a process that manipulates the metabolic plasticity of microalgae for WWT. Initial batch trials in a 27 m3 demonstration plant treating municipal tertiary WW achieved a final effluent of 0.27 ± 0.2 mg/L and 0.009 ± 0.003 mg/L phosphate and ammonium, respectively, in 12 h HRT. A continuous flow‐through system was retrofitted onto a small rural WWT site owned by South West Water for tertiary treatment. Phosphate and emerging contaminants (ECs) were monitored over 12 months at an average flow of 1.5–2.2 m3/h. Consistent phosphate removal was observed with a reduction in ECs within a HRT of 16.5 h. This demonstrates that the microalgae process can retrofitted as a green infrastructure option, delivering benefits vital to sustainable development.

The aging of microplastics exacerbates the damage to photosynthetic performance and bioenergy production in microalgae (Chlorella pyrenoidosa)

The toxicity of microplastics (MPs) on freshwater plants has been widely studied, yet the influence of aged MPs remains largely unexplored. Herein, we investigated the influence of polyvinyl chloride (PVC) MPs, both before and after aging, at different environmentally relevant concentrations on Chlorella pyrenoidosa, a freshwater microalgae species widely recognized as a valuable biomass resource. During a 96-h period, both virgin and aged MPs hindered the growth of C. pyrenoidosa. The maximum growth inhibition rates were 32.40 % for virgin PVC at 250 mg/L and 44.72 % for aged PVC at 100 mg/L, respectively. Microalgae intracellular materials, i.e., protein and carbohydrate contents, consistently decreased after MP exposure, with more pronounced inhibition observed with aged PVC. Meanwhile, the MP aging significantly promoted the nitrogen uptake of C. pyrenoidosa, i.e., 1693.45 ± 42.29 mg/L (p < 0.01), contributing to the production of humic acid-like substances. Additionally, aged PVC induced lower chlorophyll a and Fv/Fm when compared to virgin PVC, suggesting a more serious inhibition of the photosynthesis process of microalgae. The toxicity of MPs to C. pyrenoidosa was strongly associated with intercellular oxidative stress levels. The results indicate that MP aging exacerbates the damage to photosynthetic performance and bioenergy production in microalgae, providing critical insights into the toxicity analysis of micro(nano)plastics on freshwater plants.

Resuspended freeze-dried Nannochloropsis as a model laboratory system for concentrated fresh Nannochloropsis in ultrasound cell disruption experiments

Microalgae have rigid, complex cell walls hindering direct lipid extraction. Cell disruption techniques are used to rupture these cellular structures to increase lipid extraction. Researchers investigating the downstream processing of microalgae do not always have access to microalgal cultivation systems to generate large amounts of fresh microalgal biomass. Using resuspended freeze-dried microalgal biomass as a model laboratory system for concentrated fresh biomass during cell disruption experiments offers greater flexibility in experimental planning and omits investment costs of microalgal cultivation equipment. So far, it however remains unclear whether freeze-dried resuspended biomass can be used as a model laboratory system to represent concentrated fresh biomass during cell disruption and lipid extraction experiments. This paper thus evaluated the suitability of resuspended freeze-dried Nannochloropsis as a model laboratory system for concentrated fresh Nannochloropsis during cell disruption. Ultrasound assisted cell disruption was used as example cell disruption technique and lipid extraction efficiency and free fatty acid content were investigated. Tap water and 3% sodium chloride are both suitable resuspension media for the resuspension of freeze-dried Nannochloropsis. Resuspension duration should be limited (&amp;lt; 120 min) to prevent the formation of free fatty acids. The condition of the biomass (concentrated fresh, or resuspended freeze-dried) prior to ultrasound assisted cell disruption did not influence the resulting lipid extraction efficiency. Resuspended freeze-dried Nannochloropsis biomass in tap water or 3% sodium chloride can thus be used as a model laboratory system for fresh microalgal biomass during research on ultrasound assisted lipid extraction. The generalization of the results to other cultivation conditions, cell disruption techniques, components of interest or microalgal species should be carefully assessed.

The effect of cadmium on a semi-self-sustaining microalgal-bacterial granular sludge process for wastewater treatment

Microalgal-bacterial granular sludge (MBGS) is an innovative and sustainable technology for wastewater treatment. This research investigated the effect of Cd2+ on the performance and characteristics of such semi-self-sustaining MBGS reactors (with additional intermittent aeration). After 30 days of exposure to 0, 2, and 10 mg·l−1 Cd2+, the three reactors consistently exhibited robust removal efficiencies, achieving 89 % removal for chemical oxygen demand (COD) and 99 % removal for NH4+-N. However, the MBGS in control exhibited better performance in T-N removal compared to MBGS exposed to 10 mg·l−1 Cd2+ (especially during the light phase), indicating a potential impact of Cd2+ on the N-assimilation process of microalgae. The high concentration of Cd2+ also negatively affected the MBGS structure and increased the production of extracellular polymeric substances. Further investigations of the dissolved oxygen profile were conducted under phototrophic conditions, the maximum oxygen production rate contributed to microalgae in the control group was 20.9 % and 46.4 % higher than that of groups with 2 and 10 mg·l−1 Cd2+. The results show that Cd2+ mainly impacts the microalgae in the outer layer of the structure, and additional aeration helps compensate for the decrease in oxygen production caused by Cd2+ in MBGS, thereby making the system more stable in removing COD and NH4+-N.

Optically induced dielectrophoresis for continuous separation and purification of C. vulgaris and H. pluvialis

Marine microalgae are widely present in the natural environment, exhibiting a significant economic value. However, during the inoculation and cultivation process of microalgae, the introduction of unwanted algae is bound to trigger nutrient competition, leading to a decrease in the growth rate of microalgae and consequently impacting their economic value in production. To address this issue, this study integrates the optically induced dielectrophoresis (ODEP) manipulation technology based on the continuous flow in a microfluidic system. A two-stage cell filter, utilizing two virtual optical spots, is designed and manufactured. Leveraging the size differences between microalgae, continuous separation and purification of mixed samples containing Chlorella vulgaris and Haematococcus pluvialis are achieved within microchannels. Additionally, optimal ODEP manipulation conditions for mixed algal liquid samples, comprising C. vulgaris and H. pluvialis, are demonstrated, including appropriate alternating current voltage (6 V), alternating current frequency (100 kHz), light spot width (40 μm), and sample flow rate (0.9 μl/min). Analysis of mixed liquid samples collected at the chip's outlet reveals a reduction in the proportion of H. pluvialis from 37.5% to 1.2% after separation. In summary, this study proposes an ODEP microfluidic system capable of continuously separating and purifying microalgae with different biological characteristics, showcasing its potential as an alternative to traditional labor-intensive microalgae separation techniques.

Reactive oxygen species mediated extracellular polymeric substances production assisting the recovery of Thalassiosira pseudonana from polystyrene micro and nanoplastics exposure

As emerging pollutants in the aquatic environments, micro- and nano-plastics (MNPs) aroused widespread environmental concerns for their potential threats to the ecological health. Previous research has proved that microalgae growth could recover from the MNPs toxicities, in which the extracellular polymeric substances (EPS) might play the key role. In order to comprehensively investigate the recovery process of microalgae from MNPs stress and the effecting mechanisms of EPS therein, this study conducted a series of experiments by employing two sizes (0.1 and 1 μm) of polystyrene (PS) MNPs and the marine model diatom Thalassiosira pseudonana during 14 days. The results indicated: the pigments accumulations and photosynthetic recovery of T. pseudonana under MPs exposure showed in the early stage (4–5 days), while the elevation of reactive oxygen species (ROS) and EPS contents lasted longer time period (7–8 days). EPS was aggregated with MNPs particles and microalgal cells, corresponding to the increased settlement rates. More increase of soluble (SL)-EPS contents was found than bound (B)-EPS under MNPs exposure, in which the increase of the protein proportion and humic acid-like substances in SL-EPS was found, thus facilitating aggregates formation. ROS was the signaling molecule mediating the overproduction of EPS. The transcriptional results further proved the enhanced EPS biosynthesis on the molecular level. Therefore, this study elucidated the recovery pattern of microalgae from MNPs stress and linked “ROS-EPS production changes-aggregation formation” together during the growth recovery process, with important scientific and environmental significance.

Biogas Purification through the use of a Microalgae-Bacterial System in Semi-Industrial High Rate Algal Ponds.

In recent years, a number of technologies have emerged to purify biogas into biomethane. This purification entails a reduction in the concentration of polluting gases such as carbon dioxide and hydrogen sulfide to increase the content of methane. In this study, we used a microalgal cultivation technology to treat and purify biogas produced from organic waste from the swine industry to obtain ready-to-use biomethane. For cultivation and purification, two 22.2 m3 open-pond photobioreactors coupled with an absorption-desorption column system were set up in San Juan de los Lagos, Mexico. Several recirculation liquid/biogas ratios (L/G) were tested to obtain the highest removal efficiencies; other parameters, such as pH, dissolved oxygen (DO), temperature, and biomass growth, were measured. The most efficient L/Gs were 1.6 and 2.5, resulting in a treated biogas effluent with a composition of 6.8%vol and 6.6%vol in CO2, respectively, and removal efficiencies for H2S up to 98.9%, as well as maintaining O2 contamination values of less than 2%vol. We found that pH greatly determines CO2 removal, more so than L/G, during cultivation because of its participation in the photosynthetic process of microalgae and its ability to vary pH when solubilized due to its acidic nature. DO, and temperature oscillated as expected from the light-dark natural cycles of photosynthesis and the time of day, respectively. Biomass growth varied with CO2 and nutrient feeding as well as reactor harvesting; however, the trend remained primed for growth.

Structure evolution characteristic of hydrochar and nitrogen transformation mechanism during co-hydrothermal carbonization process of microalgae and biomass

Co-hydrothermal carbonization (co-HTC) of microalgae and lignocellulosic biomass has high potential for producing nitrogen-rich carbon materials (hydrochar) with relatively high yield. The synergistic effect, hydrochar structure evolution and nitrogen transformation mechanism during the co-HTC process were depicted in depth. The results of the co-HTC process showed that the positive synergy between biomass and microalgae could improve the hydrochar yield and facilitate incorporation of nitrogen into the hydrochar aromatic heterocycles structures. Moderate reaction conditions were beneficial for co-HTC hydrochar nitrogen enrichment and porosity increment, and the optimal nitrogen content and specific surface area reached 3.50% and 5.91 m2/g in co-HTC hydrochars at 240 °C and 1 h. Severe reaction conditions could enhance the formation of stable heterocyclic nitrogen species (reaching 54% at 300 °C). The hydrochar structure evolution and nitrogen transformation mechanism during co-HTC process could be generally divided into two stages. The first stage took place from 180 to 260 °C, and the nitrogen-rich secondary chars could be formed by the interaction of the hydrolysis intermediates. The second stage occurred from 260 to 300 °C, and the previously formed secondary char would be gradually decomposed. This study provides theoretical guidance for regulating the co-HTC process to produce nitrogen-rich carbon materials.

Synergistic development of nonvascular species microalgae for bio-hydrogen production featured with nano titanium dioxide additive

With technological growth, renewable biofuel energy sources, extracted from organic materials and microalgae feedstock's rich energy substance, have the potential for future energy applications. Moreover, syngas production is limited due to microalgae processing. The prime aim of this research is to enhance the bio-hydrogen extraction by the source of sewage sludge and harvesting of microalgae from non-vascular species (Bryothyta) water with the integration of 0.05, 0.1, 0.15, and 2vol% of titanium dioxide (TiO2) nano additive. Influences of TiO2 concentration on synergistic specific microalgae growth are monitored concerning day and observed that the higher content (2vol%) of TiO2 own 0.87 microns/day, which involves hydrothermal gasification process configured with potassium hydroxide catalyst operating with 400, 500, 600, and 700 ⁰C gasification temperature under 60min time gap. Gasification temperature influencing molar fraction, bio-methane & and hydrogen yield, low heating value, hydrogen selectivity, and gasification efficiency is experimentally studied. With the importance KOH adopted hydrothermal gasifier functioned with higher gasification temperature of 700⁰C operated by 60min offered higher molar fractions of 62% in hydrogen & 17% in bio-methane, superior bio-methane & hydrogen yield of 9.1& 23mol/kg, reduced low heating value of 9.3 MJ/Nm3, higher hydrogen selectivity of 18.5, and superior gasification efficiency of 66%.

Coupling anaerobic co-digestion of winery waste and waste activated sludge with a microalgae process: Optimization of a semi-continuous system

Wine production represents one of the most important agro-industrial sectors in Italy. Wine lees are the most significant waste in the winery industry and have high disposal and storage costs and few applications within the circular economy. In this study, anaerobic digestion and a microalgae coupled process was studied in order to treat wine lees and waste activated sludge produced within the same facility, with the aim of producing energy and valuable microalgae biomass that could be processed to recover biofuel or biostimulant. Chlorella vulgaris was cultivated on liquid digestate in a semi-continuous system without biomass recirculation. The best growth and phytoremediation performance were achieved applying a hydraulic retention time (HRT) of 20 days with a stable dry weight, lipid and protein storage of 1.85 ± 0.02 g l−1, 33.48 ± 7.54 % and 57.85 ± 10.14 % respectively. Lipid characterization highlighted the potential use in high quality biodiesel production, according to EN14214 (<12 % v/v linolenic acid). The microalgae reactor’s liquid output showed high removal of ammonia (95.72 ± 2.10 %), but low organic soluble matter reduction. Further semi-continuous process optimization was carried out by increasing the time between digestate feeding and biomass recovery at HRT 10. These operative changes avoided biomass wash-out and provided a stable phytoremediation of the digestate with 84.58 ± 4.02 % ammonia removal, 33.01 ± 1.44 % sCOD removal, 38.06 ± 2.65 % of polyphenols removal.

Study of life cycle assessment: Transforming microalgae to biofuel through hydrothermal liquefaction and upgrading in organic or aqueous medium

Hydrothermal liquefaction (HTL) is a promising method for the utilization of low-lipid microalgae. For the upgrading of biocrude obtained from hydrothermal liquefaction of Dunaliella salina, two different catalysts for hydrodeoxygenation (HDO), which could function in organic solvents and aqueous phases respectively, were published in our previous work (Lin et al., 2023; Lin et al., 2022). Corresponding to quite different upgrading processes based on these catalysts, two systems for resource utilization of low-lipid microalgae were established, including microalgae growth & collection, HTL, HDO upgrading, and catalysts recovery, which were named case 1 and case 2, respectively. Through life cycle assessment (LCA), the product yield, energy consumption, and different environmental impact categories of the two systems were compared. It was found that both conversion processes of microalgae had significant environmental benefits for the reuse of wastewater in terms of global warming potential (GWP) and eutrophication (EP) by reducing up to a maximum value of 8.73 kg PO4-eq and 158.80 kg CO2-eq, respectively. In two systems, case 2 has more significant advantages in terms of low energy consumption, high product yield, and less hazardous substance emissions, which achieves 62 % total production yield and complete self-heating. The annual profits of case 2 increased by 41 % compared to case 1. Remarkably, the carbon-based catalysts contribute to the sustainability of the system due to the easy procedure of catalyst recovery. Through this work, the significance of technological innovation for environmental protection and economic development was emphasized.

Cyanobacteria and microalgae as potential sources of biofertilizers: a review

Cyanobacteria and microalgae represent promising sources for sustainable production of biofertilizers and biostimulants, which can improve crop yield and quality and contribute to food security. However, despite their potential, their exploration remains incomplete, hindered by technical and economic challenges that arise when attempting to scale up production. The primary focus of this review is to delve into the active chemical compounds responsible for the biofertilizing and biostimulating roles of cyanobacteria and microalgae. In addition, it explores the essential unit operations involved in transforming their biomass into potential bioproducts. Moreover, this review highlights studies that have employed cyanobacteria and microalgae as sources of biofertilizer in various crops, describing their mode of action and application. By integrating cyanobacteria and microalgae processing with other advanced biotechnological, the viability of these products for sustainable agriculture can be significantly enhanced.

HEAVY METAL BIOREMEDIATION BY ALGAE: A REVIEW OF REMOVAL METHODS, BY-PRODUCT RECOVERY, OBSTACLES, AND POTENTIAL FUTURE APPLICATIONS.

Due to the constant discharge of many pollutants into the aquatic environment, water pollution is a major environmental concern on a global level. The treatment of heavy metals found in wastewater has attracted attention to novel technologies in recent years. The utilization of biological processes has been investigated because they are dependable, straightforward, and eco-friendly. Through this review, the researchers attempt to disseminate information regarding the environmental dangers posed by heavy metals, the function of bioremediators employed in heavy metal processing, the many microalgae strains utilized for heavy metal removal, and their modes of action for remediation. Different external and intracellular processes are used by diverse microalgae species to remove heavy metals. In-depth discussion is provided on the assessment of microalgae's processing potential and the usage of biochar generated from algae in the removal of heavy metals. It is obvious that bioremediation of heavy metals alone is not a viable business plan. As a result, additional work is being done to create integrated treatment plans to make this procedure more affordable and long-lasting. This review describes recent developments in the use of microalgae for heavy metal therapy. Additionally, the challenges that must be met in order to improve this process efficiency, economy, sustainability, and cleanliness are covered. From the comments in this review, it can be inferred that bioremediation can be crucial to the sustainable processing of heavy metals and the development of the bio-economy.

Study of the interaction mechanism between the components of microalgae by thermal behaviors and pyrolysis characteristics

There is significant effect on thermal behaviors pyrolytic characteristics of the interactions between microalgal components. In order to understand the reaction process, interaction mechanism, and better utilization of microalgae, co-pyrolysis of microalgal model compounds (soybean protein (PT), sunflower oil (OL) and sucrose (SC)) was carried out with TG-FTIR and Py-GC/MS. The results showed that co-pyrolysis of PT and SC significantly changed the thermal behaviors, and accelerated decomposition at lower temperature to generate CO, CO2 largely. And it could promote the generation of linear O-compounds (such as acetic acid), and inhibit the formation of N-heterocycles and furans. Moreover, OL co-pyrolysis with PT or SC could significantly promote the formation of long-chain acid and inhibit the generation of aliphatics. Meanwhile, co-pyrolysis of PT and OL inhibited the generation of N-heterocycles. And co-pyrolysis of SC and OL accelerated the generation of furans. Furthermore, co-pyrolysis of model compounds reduced the average activation energy of the pyrolysis process, and changed the reaction kinetic model.