Harvesting Nannochloropsis sp. using PES/MWCNT/LiBr membrane with good antifouling properties

Harvesting marine microalgae Tetraselmis sp. using cellulose acetate membrane

This study presents the development and application of a cellulose acetate phase-inversion membrane for the efficient harvesting of Tetraselmis sp., a promising alternative for aquaculture feedstock. Once fabricated, the cellulose acetate membrane was characterized, and its performance was evaluated through the filtration of Tetraselmis sp. broth. The results demonstrated that the developed membrane exhibited exceptional microalgae harvesting efficiency. It showed a low intrinsic resistance and a high clean water permeability of 1100 L/(m2·h·bar), enabling high-throughput filtration of Tetraselmis sp. culture with a permeability of 400 L/(m2·h·bar) and a volume reduction factor of 2.5 ×. The cellulose acetate -based membrane demonstrated robust filtration performance over a 7-day back concentration filtration with minimum irreversible fouling of only 22.5 % irreversibility even without any cleaning. These results highlighted the potential of cellulose acetate as a versatile base polymer for custom-membrane for microalgae harvesting.

Microalgae harvesting for wastewater treatment and resources recovery: A review

Microalgae-based wastewater treatment has been conceived to obtain reclaimed water and produce microalgal biomass for bio-based products and biofuels generation. However, microalgal biomass harvesting is challenging and expensive, hence one of the main bottlenecks for full-scale implementation. Finding an integrated approach that covers concepts of engineering, green chemistry and the application of microbial anabolism driven towards the harvesting processes, is mandatory for the widespread establishment of full-scale microalgae wastewater treatment plants. By using nature-based substances and applying concepts of chemical functionalization in already established harvesting methods, the costs of harvesting processes could be reduced while preventing microalgae biomass contamination. Moreover, microalgae produced during wastewater treatment have unique culture characteristics, such as the consortia, which are primarily composed of microalgae and bacteria, that should be accounted for prior to downstream processing. The aim of this review is to examine recent advances in microalgal biomass harvesting and recovery in wastewater treatment systems, considering the impact of consortia variability. The costs of available harvesting technologies, such as coagulation/flocculation, coupled to sedimentation and differential air flotation, are provided. Additionally, promising technologies are discussed, including autoflocculation, bioflocculation, new filtration materials, nanotechnology, microfluidic and magnetic methods.

Performance of modified hollow fiber membrane silver nanoparticles-zeolites Na-Y/PVDF composite used in membrane bioreactor for industrial wastewater treatment

Membrane bioreactor (MBR) deteriorates due to fouling on the membrane pores, which can reduce the membrane performance. To reduce membrane fouling, the addition of inorganic filler can enhance the antifouling properties. This study investigates two different membrane preparation by thermally induced phase separation (TIPS) and dip coating methods to modify hollow fiber membrane with Silver Nanoparticles (AgNPs)-Zeolites used in MBR for industrial wastewater treatment. Performance was evaluated by analyzing the flux of water and wastewater, rejection, water content, and antifouling properties. Characterization result represented the synthesized silver nanoparticles had similar diffraction peak with commercial AgNPs, then the micrograph of AgNPs and zeolites addition membrane showed that the inorganic material had an octahedral shape representing zeolite crystal and irregular shape representing AgNPs. The addition of zeolites and AgNPs resulted in satisfying performance, increased flux, rejection, and antifouling properties.

Bromelain extraction using single stage nanofiltration membrane process

Pineapple (Ananas Comosus) is a tropical fruit having exceptional juiciness, vibrant tropical flavor and immense health benefits. Pineapples are not only taken fresh but they have been commercialized in the canning industry. Morris cultivar is mostly supplied to the canning industry where only the flesh is utilized and the rest of the pineapple (50 wt%) such as the core, stem, peels and crown are discarded as wastes. In the extraction of bromelain which is a vital proteolytic enzyme the whole pineapple including its peels, core, stem and crown can be utilized. This enzyme is very valuable and considered as a food supplement with a wide range of therapeutic benefits. Thus, in this study, bromelain is extracted from the flesh, crown, stem, core and peel of pineapples using simple one stage hollow fiber nanofiltration membrane process. The different parts of the pineapple were crushed to extract the juice. The juice was then centrifuged and the supernatant was then passed through a nanofiltration membrane. Results revealed the retentates from the different pineapple parts contain high amounts of bromelain in descending order flesh > peel > core > crown > stem. The amount of bromelain activity increased after every process especially after freeze drying.

Sustainable production of EPA-rich oil from microalgae: Towards an algal biorefinery

Utilization of sustainable natural resources such as microalgae has been considered for the production of biofuels, aquaculture feed, high-value bioactives such as omega-3 fatty acids, carotenoids, etc. Eicosapentaenoic acid (EPA) is an omega-3 fatty acid present in fish oil, which is of physiological importance to both humans and fishes. Marine microalgae are sustainable sources of lipid rich in EPA and different species have been explored for the production of EPA as a single product. There has been a rising interest in the concept of a multi-product biorefinery, focusing on maximum valorization of the algal biomass. Targeting one or more value-added compounds in a biorefinery scenario can improve the commercial viability of low-value products like triglycerides for biofuel. This approach has been viewed by technologists and experts as a sustainable and economically feasible possibility for the large-scale production of microalgae for its potential applications in biodiesel and jet fuel production, nutraceuticals, animal and aquaculture feeds, etc. In this review paper, we describe the recent developments in the production of high-value EPA-rich oil from microalgae, emphasizing on the upstream and downstream bioprocess techniques, and the advantages of considering an EPA-rich oil based biorefinery.

Membrane-Based Harvesting Processes for Microalgae and Their Valuable-Related Molecules: A Review

The interest in microalgae production deals with its role as the third generation of feedstock to recover renewable energy. Today, there is a need to analyze the ultimate research and advances in recovering the microalgae biomass from the culture medium. Therefore, this review brings the current research developments (over the last three years) in the field of harvesting microalgae using membrane-based technologies (including microfiltration, ultrafiltration and forward osmosis). Initially, the principles of membrane technologies are given to outline the main parameters influencing their operation. The main strategies adopted by the research community for the harvesting of microalgae using membranes are subsequently addressed, paying particular attention to the novel achievements made for improving filtration performance and alleviating fouling. Moreover, this contribution also gives an overview of the advantages of applying membrane technologies for the efficient extraction of the high added-value compounds in microalgae cells, such as lipids, proteins and carbohydrates, which together with the production of renewable biofuels could boost the development of more sustainable and cost-effective microalgae biorefineries.

Current and novel approaches to downstream processing of microalgae: A review

Biotechnological application of microalgae cultures at large scale has significant potential in the various fields of biofuels, food and feed, cosmetic, pharmaceutic, environmental remediation and water treatment. Despite this great potential application, industrialisation of microalgae culture and valorisation is still faced with serious remaining challenges in culture scale-up, harvesting and extraction of target molecules. This review presents a general summary of current techniques for harvesting and extraction of biomolecules from microalgae, their relative merits and potential for industrial application. The cell wall composition and its impact on microalgae cell disruption is discussed. Additionally, more recent progress and promising experimental methods and studies are summarised that would allow the reader to further investigate the state of the art. A final survey of energetic assessments of the different techniques is also made. Bead milling and high-pressure homogenisation seem to give clear advantages in terms of target high value compounds extraction from microalgae, with enzyme hydrolysis as a promising emerging technique. Future industrialisation of microalgae for high scale biotechnological processing will require the establishment of universal comparison-standards that would enable easy assessment of one technique against another.