Offering a potential solution for global food security and mitigating environmental issues caused by the expansion of land-based food production, the carbon-hunger and nutrient-rich microalgae ...emerged as a sustainable food source for both humans and animals. Other than as an alternative source for protein, microalgae offer its most valuable nutrients, omega-3 and 6 long-chain polyunsaturated fatty acids where the content can compete with that of marine fish with lower chemicals contamination and higher purity. Furthermore, the colorful pigments of microalgae can act as antioxidants together with many other health-improving properties as well as a natural colorant. In addition, the supplementation of algae as animal feed provides plentiful benefits, such as improved growth and body weight, reduced feed intake, enhanced immune response and durability towards illness, antibacterial and antiviral action as well as enrichment of livestock products with bioactive compounds. The significant breakthrough in algal biotechnology has made algae a powerful “cell factory” for food production and lead to the rapid growth of the algal bioeconomy in the food and feed industry. The first overview of this review was to present the general of microalgae and its potential capability. Subsequently, the nutritional compositions of microalgae were discussed together with its applications in human foods and animal feeds, followed by the exploration of their economic feasibility and sustainability as well as market trends. Lastly, both challenges and future perspectives were also discussed.
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•Microalgae offer solutions for a sustainable food source.•Microalgae contain vast nutritional compounds for food and feed products.•Microalgal-based feed and food provide better growth and health benefits.•The market trend of algal-based products enables sustainable bioeconomy.•Biotechnology breakthrough made algae a powerful “cell factory” for food production.
Utilizing wastewaters as feedstock for microalgal cultivation has the dual benefits of water-saving and low nutrient costs, with simultaneous remediation of pollutants and generation of value-added ...biochemical products. This study employed two different strategies to treat raw dairy wastewaters with moderate and high chemical oxygen demand (COD) levels. For moderate-COD dairy wastewater, the wastewater was directly utilized as feedstock for algal cultivation, in which the effects of wastewater dilution ratios and algal inoculum sizes were investigated. The results show that the microalga strain used (Chlorella sorokiniana SU-1) was capable of obtaining a high biomass concentration of 3.2 ± 0.1 g/L, accompanied by 86.8 ± 6%, 94.6 ± 3%, and 80.7 ± 1%, removal of COD, total phosphorus (TP) and total nitrogen (TN), respectively. Meanwhile, the obtained microalgal biomass has lipids content of up to 12.0 ± 0.7% at a wastewater dilution ratio of 50% and an inoculum size of 2 g/L. For high-COD dairy wastewater, an integrated process of anaerobic digestion and microalgal phycoremediation was employed, and the effect of inoculum sizes was also studied. The inoculum size of 2 g/L gave highest biomass production of 4.25 ± 0.10 g/L with over 93.0 ± 2.0% removal of COD, TP, and TN. The harvested microalgal biomass has lipids and protein content of 12.5 ± 2.2% and 18.0 ± 2.2%, respectively. The present study demonstrated potential microalgal phycoremediation strategies for the efficient COD removal and nutrients recovery from dairy wastewater of different COD levels with simultaneous production of microalgal biomass which contains valuable components, such as protein and lipids.
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•C. sorokiniana SU-1 can treat dairy wastewater with simultaneous biomass production.•High-strength dairy wastewater was treated by combining AD and algal cultivation.•4.25 g/L biomass concentration and 93% pollutants removal was obtained.•Highest biomass productivity of 0.37 g/L/d was obtained at 1 g/L inoculums size.•The harvested microalgal biomass had 12% lipids and 18% proteins content.
Microalgae are a potential solution to supersede fossil fuels and produce renewable energy. The major obstacle to the commercialization of microalgae-based biofuels is the high production cost, ...including nutritional requirements, photobioreactor design, and downstream processes. As for the photobioreactor design, open ponds have been adopted by major commercial plants for their economic advantages. Raceway is a popular type among open ponds. Nevertheless, the fluid dynamics of the raceway operation is quite complex. Software simulation based on Computational Fluid Dynamics is an upcoming strategy for optimizing raceway design. The optimization intends to affect light penetration, particle distribution, mass transfer, and biological kinetics. This review discusses how this strategy can be helpful to design a highly productive raceway pond-based microalgal culture system.
The present study investigated the effect of light intensity and mixing on microalgae growth in a raceway by comparing the performance of a paddlewheel to a combination of paddlewheel and CO2 ...spargers in a 20 L raceway. The increase of light intensity was known to be able to increase the microalgal growth rate. Increasing paddlewheel rotation speed from 13 to 30 rpm enhanced C. vulgaris growth by enhancing culture mixing. Simulation results using computational fluid dynamics (CFD) indicated that both the turnaround areas of the raceway and the area opposite the paddlewheel experienced very low flow velocities (dead zones) of less than 0.1 m/min, which could cause cell settling and slow down growth. The simulated CFD velocity distribution in the raceway was validated by actual velocity measurements. The installation of CO2 spargers in the dead zones greatly increased flow velocity. The increase of paddlewheel rotation speed reduced the dead zones and hence increased algal biomass production. By complementing the raceway paddlewheel with spargers providing CO2 at 30 mL/min, we achieved a dry cell weight of 5.2 ± 0.2 g/L, which was about 2.6 times that obtained without CO2 sparging.
•Comparing the performance of a paddlewheel to a combination of paddlewheel and CO2 spargers.•Simulation results using computational fluid dynamics (CFD).•Installation of CO2 spargers in the dead zones greatly increased flow velocity.•Rotation speed from 13 to 30 rpm enhanced Chlorella vulgaris growth by enhancing culture mixing.
In this work silver nano/micro-particles have been synthesized using sambiloto (Andrographis paniculata) plant extract as a bio-reducing agent. The effects of different plant extract concentrations, ...AgNO3 precursor concentrations, and reaction time on the synthesized silver nano/micro-particles were investigated. The silver nano/micro-particles samples were then analyzed using UV-Vis spectrophotometer (UV-Vis), X-Ray Diffractometer (XRD), Field Emission Scanning Electron Microscopy (FESEM), Particle Size Analyzer (PSA), and Fourier Transform Infra-Red (FTIR) spectroscopy. The UV-Vis absorbance spectrum of the colloid silver nano/micro-particles exhibited that all samples had absorbance peaks at a wavelength around 450 nm, confirming the formation of silver nano/micro-particles. It was also found that the UV-Vis absorbance peak of the silver nano/micro-particles inversely increased with decreasing AgNO3 solution concentration. Whereas, the higher the sambiloto extract concentration the higher the UV-Vis absorbance peaks. The UV-Vis absorbance peak increased with increasing synthesis time, suggesting that silver nano/micro-particles became more prominent. The UV-Vis absorbance peaks of the silver nano/micro-particles were about 0.0462, 0.0637, 0.0729, and 0.0936 at reaction time of 5, 10, 20, and 40 min, respectively. The XRD analysis result confirmed that the synthesized silver nano/micro-particles were in the form of nanocrystals with a face-centered cubic centered without any impurities. Additionally, the FESEM images showed that the silver nano/micro-particles had the primary particle size of 150-300 nm. There was the formation of some secondary particles with the size of about 0.7-1.5?m due to the agglomeration of primary particles. The particle size distribution analysis further confirmed the presence of primary and secondary particles. Meanwhile, the FTIR analysis confirmed the presence of four main peaks, linked to functional groups in the sambiloto extract and involved in the creation of silver nano/micro-particles.
•Swine wastewater (SWW) is rich in ammonia-N with potential environmental threats.•Natural treatment systems employ simple ponds with indigenous flora.•Biological methods are carried out in closed ...systems with effective nutrient removal.•Microalgae can assimilate the nutrients in SWW under hetero/mixo-trophic conditions.•Microalgae-based SWW treatment is beneficial compared to other methods.
There is an exponential increase in swine farms around the world to meet the increasing demand for proteins, resulting in a significant amount of swine/piggery wastewater. The wastewater produced in swine farms are rich in ammonia with high eutrophication potential and negative environmental impacts. Safe methods for treatment and disposal of swine wastewater have attracted increased research attention in the recent decades. Conventional wastewater treatment methods are limited by the high ammonia content and chemical/biological oxygen demand of swine wastewater. Recently, microalgal cultivation is being proposed for the phytoremediation of swine wastewater. Microalgae are tolerant to high ammonia levels seen in swine wastewater and they also ensure phosphorus removal simultaneously. This review first gives a brief overview on the conventional methods used for swine wastewater treatment. Microalgae-based processes for the clean-up of swine wastewater are discussed in detail, with their potential advantages and limitations. Future research perspectives are also presented.
The oleic acid solubility in methanol is low due to two phase separation, and this causes a slow reaction time in biodiesel production. Tetrahydrofuran as co-solvent can decrease the interfacial ...surface tension between methanol and oleic acid. The objective of this study was to investigate the effect of co-solvent, methanol to oleic acid molar ratio, catalyst amount, and temperature of the reaction to the free fatty acid conversion. Oleic acid esterification was conducted by mixing oleic acid, methanol, tetrahydrofuran and Amberlyst 15 as a solid acid catalyst in a batch reactor. The Amberlyst 15 used had an exchange capacity of 2.57 meq/g. Significant free fatty acid conversion increments occur on biodiesel production using co-solvent compared without co-solvent. The highest free fatty acid conversion was obtained over methanol to the oleic acid molar ratio of 25:1, catalyst use of 10%, the co-solvent concentration of 8%, and a reaction temperature of 60°C. The highest FFA conversion was found at 28.6 %, and the steady state was reached after 60 minutes. In addition, the use of Amberlyst 15 oleic acid esterification shows an excellent performance as a solid acid catalyst. Catalytic activity was maintained after 4 times repeated use and reduced slightly in the fifth use.
The environmental impact of fossil fuel consumption has shifted the focus of research toward biomass and bioenergy. Renewable biomass, such as microalgae, has several benefits, including growth in ...wastewater, sequestration of carbon dioxide, economic feasibility, and environmental friendliness. This study investigated the feasibility of using Chlorella sorokiniana SU-1 biomass cultivated on a swine-amended medium as a renewable feedstock to produce biocrude oil. Microalgal cultivation under optimal conditions of 50 % swine wastewater (SW), inoculum sizes of 1 g/L, CO2 concentration of 2 %, and light intensity of 300 μmol m−2 s−1 obtained a high biomass concentration (6.53 g/L), biochemical production (56.65 % carbohydrate content, 33.5 % protein content, and 4.35 % lipid content) and wastewater treatment performance 92.29 % chemical oxygen demand (COD) removal, 93.7 % total phosphorus (TP) removal, and 95.64 % ammonia removal. Subsequently, hydrothermal liquefaction (HTL) of the obtained microalgal biomass achieved a 29.45 % biocrude oil yield with a composition of 34.3 % esters, 23.5 % hydrocarbons, 5.14 % aldehydes, 7.54 % furans, and 11.1 % phenolic derivatives, making it a promising choice for biofuel production. Thus, the findings confirmed that C. sorokiniana SU-1 could be effectively utilized for the phycoremediation of SW with simultaneous biomass production as a renewable feedstock for biocrude oil production.
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•C. sorokiniana effectively treated swine wastewater and produce significant biomass.•Algal biomass concentration of 6.53 g/L was achieved.•Residual COD, TP, and ammonia removal archived were 92.29 %, 93.7 %, and 95.64 %.•C. sorokiniana had 56.65 % carbohydrate, 33.5 % protein, and 4.35 % lipid content.•Hydrothermal liquefaction (HTL) of algal biomass yielded 29.45 wt% of biocrude oil.
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•Dairy wastewater was treated with combined AD and microalgal cultivation.•COD, TN and TP were removed during cultivation of a bacterial-algal consortium.•Highest nutrient removal & ...biochemicals production were obtained using 25% wastewater.•Co-digestion with 25% resulting algal biomass enhanced biomethane production.
A sequential anaerobic digestion and phycoremediation process was employed to recover nutrients and remove pollutants from dairy wastewater (DW), while simultaneously producing biomethane and biochemicals. Anaerobic digestion of 100% DW achieved a methane content and production rate of 53.7% and 0.17 L/L/d, respectively. This was accompanied by the removal of 65.5% chemical oxygen demand (COD), 86% total solid (TS), and 92.8% volatile fatty acids (VFAs). The anaerobic digestate was then used to grow Chlorella sorokiniana SU-1. Using 25% diluted digestate as the medium, SU-1 could reach 4.64 g/L biomass concentration, with total nitrogen (TN), total phosphorus (TP) and COD removal efficiencies of 77.6%, 87.1% and 70.4%, respectively. The obtained microalgal biomass (contained 38.5% carbohydrates, 24.9% proteins, 8.8% lipids) was used to co-digest with DW, resulting in good methane production performance. Co-digestion with 25% (w/v) algal biomass obtained a higher CH4 content (65.2%) and production rate (0.16 L/L/d) than other ratios.
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