Production Of Fatty Acid Methyl Esters Research Articles

Analysis of Improving the Quality of Fatty Acid Methyl Ester (FAME) Products Against Acid Value (AV) Levels Using the Six Sigma and Kaizen Methods

. PT XYZ is a palm oil derivative processing company that produces biodiesel / FAME (Fatty Acid Methyl Ester) products. However, there are several obstacles that still occur during the company's production process which causes the acid value (AV) level of FAME products to not meet specifications and there are 3% defective products. Therefore, this study aims to determine the improvement plan by applying kaizen to the Six Sigma improvement stage and reducing outspec products in the FAME production process. The results of the research conducted using the six sigma method show that the company has a DPMO value of 71,459 and a sigma value of 2.96 which is in the average position of the industry in Indonesia based on the results of data processing. While recommendations for improvement by implementing kaizen include training machine operators, making standard operating procedures (SOPs) for machine inspections on each shift, reducing the amount of strearin added to AV raw materials before pre-treatment, maintenance and machine calibration. This step are expected to overcome the main problems identified in the study.

Two-stage co-pyrolysis of Kraft lignin and palm oil mixture to biofuels: The role of lignin as a methylation agent for methyl ester formation

In this work pyrolysis of palm oil and lignin has been investigated using a two-stage process at 550 °C, with a first step configuration of continuous condensation for vapors and separation of gases, and a second step with distillation of vapors. Experiments were realized as pyrolysis of palm oil, palmitic acid, and Kraft lignin, as well as co-pyrolysis of palm oil/lignin, palmitic acid/lignin and palmitic acid/guaiacol. It has been shown that the addition of lignin improves the quality of palm oil pyrolysis bio-oil, thanks to the conversion of fatty acids coproduct to fatty acid methyl esters (FAME). The production of methyl esters in the reaction environment using palm oil and lignin was studied by conducting experiments with palmitic acid and lignin, as well as palmitic acid and guaiacol (the main product obtained from lignin pyrolysis). The results highlighted that during pyrolysis, the production of FAME is a consequence of a direct esterification reaction on palmitic acid. The formation of FAMEs during pyrolysis presents a promising avenue to optimize the utilization of palm oil by generating FAMEs as supplementary fuel products, Furthermore, it is possible to consider the application of the studied process for the conversion of free fatty acids into FAME.

Saccharomyces cerevisiae cellular engineering for the production of FAME biodiesel

The unsustainable and widespread utilization of fossil fuels continues to drive the rapid depletion of global supplies. Biodiesel has emerged as one of the most promising alternatives to conventional diesel, leading to growing research interest in its production. Microbes can facilitate the de novo synthesis of a type of biodiesel in the form of fatty acid methyl esters (FAMEs). In this study, Saccharomyces cerevisiae metabolic activity was engineered to facilitate enhanced FAME production. Initially, free fatty acid concentrations were increased by deleting two acetyl-CoA synthetase genes (FAA1, FAA4) and an acyl-CoA oxidase gene (POX1). Intracellular S-adenosylmethionine (SAM) levels were then enhanced via the deletion of an adenosine kinase gene (ADO1) and the overexpression of a SAM synthetase gene (SAM2). Lastly, the S. cerevisiae strain overproducing free fatty acids and SAM were manipulated to express a plasmid encoding the Drosophila melanogaster Juvenile Hormone Acid O-Methyltransferase (DmJHAMT). Using this combination of engineering approaches, a FAME concentration of 5.79 ± 0.56 mg/L was achieved using these cells in the context of shaking flask fermentation. To the best of our knowledge, this is the first detailed study of FAME production in S. cerevisiae. These results will provide a valuable basis for future efforts to engineer S. cerevisiae strains for highly efficient production of biodiesel.

Sulfonated reduced graphene oxide catalyzed fatty acid methyl ester production from macroalgae Dictyota dichotoma in supercritical conditions

Despite proposed alternative fuels in the recent past, the race for a natural substitute still exists. In this research work, we suggest biodiesel preparation from the rarely explored macroalgae D. dichotoma using a supercritical fluid system of ethanol/ THF. Reduced graphene oxide was prepared using dried jasmine powder as bio-reductant. Reduced graphene oxide was sulphonated using sulfanilic acid, and the catalysts were characterized by XRD, BET surface area, FTIR, and SEM techniques. The reaction conditions for algal oil conversion into biodiesel in supercritical ethanolysis were optimized. FTIR, and GCMS were eployed as analytical tools to analyze the produced biodiesel. The optimized reaction conditions were 265 °C, ethanol: algal oil= 15:1, Reaction time = 10 min, catalyst loading = 5% GO, and THF: ethanol −0.4 for 78% FAEE yield using GO. 10 wt% S-rGO yielded a maximum of 89% FAEE; and 22.55% C18:2. The catalyst was efficient till five cycles. The work assures the utility of abundant macroalgae for alternative fuel production.

Maximizing the potential of commercial zinc stearate for one-pot esterification and transesterification for high-acidity biodiesel production

Meeting the growing demand for energy while combating the adverse effects of global warming remains challenging today, and biodiesel offers a potential solution to help mitigate the impact of global warming. In this scenario, our primary goal was to optimize biodiesel production from highly acidic soybean oil using a one-pot esterification and transesterification process, addressing the challenges associated with high-acidity substrates. To start, X-ray Diffraction (XRD) guaranteed us just one phase for each commercial catalyst, and we conducted catalytic experiments to select the most suitable Zn-based material for the process, choosing zinc stearate (ZnSt2) as the best candidate. Our study demonstrated that a nano-sized zinc oxide (ZnO) catalyst, which was anticipated to be the most suitable choice, did not exhibit optimal performance. Subsequently, a Full Factorial Design of Experiments (DOE) was employed to optimize reaction parameters, specifically, the reaction temperature and the oil-to-methanol (O:M) molar ratio. The results consistently showed that increased O:M ratio and temperature promoted enhanced fatty acid methyl esters (FAME) production and reduced acidity. Then, experiments were conducted to maximize FAME production and minimize free fatty acid (FFA) content. The results showed that increasing the catalyst concentration from 5 wt% to 10 wt% did not significantly impact FAME production or acidity reduction. Also, while increased methanol should theoretically enhance FAME production and reduce acidity, the results were inconsistent across all experiments. Excess methanol interfered with glycerol separation, leading to decreased FAME yield. Thus, this study underscores the complexity of biodiesel production and highlights the importance of selecting suitable catalysts and optimizing process parameters.

Enhanced Mixing Towards the Production of Fatty Acid Methyl Esters by In Situ Transesterification of Eucheuma Cottonii: Experimental and Computational Fluid Dynamics (CFD) Analysis

Biodiesel is one of the alternative replacements for the conventional fossil fuel-based diesel as the demand for energy is increasing with the increasing world population. The production of biodiesel (also known as fatty acid methyl esters (FAME)) from macroalgae (E. cottonii) is the focus in this study. Conventionally, production of FAME from macroalgae will be carried out through the two-step transesterification processes, which consists of extraction of algal oil (lipids and free fatty acids) and subsequent transesterification step. However, the two-step transesterification method is time and energy consuming processes and thus ways to enhance the production yield of the biodiesel produced are being studied. This paper concentrates on utilization of enhanced mixing technique via in situ transesterification (ISTE) process in FAME production which elucidate the effects of reaction time and mixing intensity. The ISTE reaction was carried out at the ratio of biomass: Methanol (MeOH): Hydrochloric Acid (HCl) (w/v/v) of 1:20:5 and a reaction temperature of 60 °C. The total reaction time for the reaction was 90 minutes, where samples were collected at 30 minutes interval. The increase in reaction time and mixing intensity gave a significant positive impact on the production of FAME. At 90 minutes of reaction time and impeller rotational speed of 900rpm, the maximum amount of methyl palmitate and methyl stearate produced were 0.5729 wt% and 0.0559 wt% respectively. The results of contour of volume fraction (VF) of palmitic acid obtained from Computational Fluid Dynamics (CFD) analysis from the Aspen Fluent Software is in good agreement to the experimental results of the study.

Fatty acid methyl ester production from rainbow trout waste oil using microwave-assisted transesterification

The desirable oil content of Rainbow Trout waste makes it a valuable resource for the industrial-scale production of biodiesel. Limited research has been conducted regarding the utilization of microwave-assisted transesterification (MAT) as a cost-effective method for biodiesel production from this accessible resource. In this study, MAT was optimized in terms of reaction time (1–5 min), microwave power level (100–500 W), methanol/oil molar ratio (3−15), and catalyst concentration (0.3–1.5%). The optimal condition was reaction time of 4 min, microwave power 300 W, molar ratio of 12, and catalyst concentration of 1.2%, ensuring utmost efficiency and purity. In addition, MAT was compared to ohmic-, ultrasonic probe-, ultrasonic bath-, and magnetic stirrer-assisted transesterification techniques, assessing physicochemical properties, energy consumption, and thermal properties of produced methyl esters. The microwave, ohmic, and ultrasonic probe showed superior efficiency, briefest reaction time, and minimal pouring and cloudy values, respectively. Additionally, these techniques consumed only 5.3, 5.7, and 6.7 Wh/g, respectively, signifying the lowest energy usage. Conversely, magnetic stirrer and ultrasonic bath showed less desirable performance. Overall, MAT can be suggested as a novel and effective technique for enhancing efficiency, reducing reaction time, and decreasing energy consumption in the production of marine waste oil methyl esters.

Microalgal synthesis of the biodiesel employing simultaneous extraction and esterification via heterogeneous catalyst

Within the realm of biorefinery, the third generation of biodiesel production relies on extracting oil from Algae to create renewable fuels. Algae cultivation can occur under precise laboratory conditions, making them a sustainable substitute for Fatty Acid Methyl Ester or biodiesel production. Through analysis of the simultaneous extraction and (trans)esterification process of Algae Chlorella Minutissima utilizing sulfated carbonaceous catalysts, scientists have discovered an efficient technique for producing biodiesel. Various parameters, such as catalyst loading, oil-to-methanol ratio, reaction temperature, and reaction time for FFA reduction and FAME yields, were studied and optimized. Results indicate that utilizing a 10 wt% catalyst loading and a 70:30 volumetric oil to methanol ratio can achieve 67.59 % FFA reduction and a biodiesel yield of 44 mL. This method of producing biodiesel can occur in a single-unit operation, leading to higher yields of renewable fuel at a reduced cost and energy consumption. Finally, the quality of the biodiesel produced met ASTM D6751 standards, confirming its suitability for use.

Fatty acid methyl esters production from crude waste frying oil using modified coffee husk ash catalyst: Parameters optimization

In this study, a KNO3-loaded coffee husk (CH) ash catalyst was synthesized to produce waste frying oil methyl ester (WFOME) from crude waste frying oil (WFO). Taguchi method optimization was performed to identify the best set of reaction temperature, time, catalyst loading and methanol to WFO molar ratio for maximum WFOME yield. A catalyst composite material (CCM) which is a mixture of CH char and KNO3 (0–65 wt%) was calcined to obtain the catalyst. The KNO3 loading and CCM calcination time effects on the catalyst performance and physicochemical properties were examined. The combustion behavior of the CH and CCMs was investigated using thermal analysis techniques. Utilizing FTIR, XRD, BET, SEM, and pH measurements, the catalyst characterization was carried out. For analytical sample sizes (during thermal analysis) with high KNO3 loading, the thermal reactivity was higher. However, for larger sample sizes (during catalyst synthesis) higher KNO3 loading decreased the CCM global thermal reactivity due to an oxygen permeation resisting ash deposition on the top surface. Thus, KNO3 tuned the catalyst’s physicochemical properties as a function of its loading (optimum 45 wt%) by affecting the combustion characteristics of the CCMs and basic site concentration. The optimum WFOME yield was 97.99 wt% at a reaction temperature of 65 °C, a reaction time of 1.13 h, a catalyst loading of 5.42 wt%, and a methanol to WFO molar ratio of 13.55:1. The WFOME yield was dropped by 46.93 wt% in three consecutive catalyst reuse tests because of active components leaching.

Potential of algal oil production from secondary treated sewage: a study using Chlorella vulgaris and synthetic wastewater

ABSTRACTTo assess the potential of using the secondary treated wastewater for the production of algal biofuel, batch experiments were carried out in photobioreactors using indigenous Chlorella vulgaris isolated from the natural freshwater body. Secondary treated wastewater with partial nitrification was simulated using various proportions of NO3-N and NH4-N while keeping the total nitrogen the same. Experiments with similar concentrations of nitrate without the NH4-N were used for comparison. In the presence of only NO3-N in the concentration range of 9–37 mg/L, the growth and fatty acid methyl ester (FAME) production was similar to the literature reports. When NH4-N was present along with NO3-N, the biomass growth was adversely affected, indicating an impact on the metabolic activity. For the same initial concentrations of nitrate in the culture, the maximum biomass concentration was reduced by 50–60% in the presence of NH4-N. The FAME profile changed significantly and a new FAME was identified, suggesting an impact on the lipid synthesis pathway. Comparison and analysis with the help of existing literature indicated that the adverse effect due to NH4-N was a function of pH. The growth, biomass yield, and FAME production were unaffected by a wide range of phosphorus concentrations. Maximum fatty acid methyl ester (FAME) suitable for biodiesel production (fatty acid carbon chain length C16 to C18) was 381.01 mg/L (224.58 mg/g of dry biomass), produced at NO3-N concentration of 18.5 mg/L and initial nitrogen loading per unit biomass of 0.37 g NO3-N/g of dry biomass.

BaO as a heterogeneous nanoparticle catalyst in oil transesterification for the production of FAME fuel

Metal oxide-based catalysts play an important role in the transesterification reaction of vegetable oils for fatty acid methyl ester (FAME) production. Additionally, nanocatalysts demonstrate high efficiency due to their increased surface area, higher catalytic activity, and easy operational procedures. Thus, the main objective of this work is to investigate FAME production from sunflower oil using barium oxide (BaO) nanoparticles. BaO was synthesized through one-pot sol–gel reactions and was analysed by several techniques, such as X-ray diffraction (XRD), transform infrared spectrometry (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray fluorescence(EDXRF), N2 adsorption–desorption of liquid nitrogen at 77 K [Brunner–Emmett–Teller (BET)] for surface area measurement and UV–Vis spectroscopy. BaO behaved as an efficient catalyst in the transesterification of oils into FAMEs. Furthermore, the impacts of a variety of reaction parameters on the biofuel yield were explored. The catalyst with 4.7 wt% has the maximum yield of 78.38 % achieved under the optimized reaction conditions (70 °C, 1:20 M ratio of oil:methanol). The characteristics of the resulting methyl ester partially agreed with international FAME standards, making it suitable for use as a blend with petroleum diesel in proportions defined by volume according to the specifications of the American Society for Testing and Materials(ASTM). The catalyst was also evaluated for reusability tests, and the reusability through the reaction showed less than a 7 % conversion drop after 3 runs and 14.6 % after 5 runs.

Evaluating nutrient limitation in co-culture of Chlorella pyrenoidosa and Rhodobacter sphaeroides

The influence of nitrogen deficiency on microalgae-bacteria co-culture has been studied mostly with nitrogen-fixing bacteria. Photosynthetic bacteria (PSB), which are non-nitrogen-fixing bacteria, the impact of N deficiency on its co-culture with microalgae is unknown. In this study, Chlorella pyrenoidosa and Rhodobacter sphaeroides co-culture was cultivated photoheterotrophically with acetate. The impact of N starvation and different P supply levels on oil production were examined. When phosphorus was sufficient, N starvation increased the fatty acid methyl ester (FAME) content from 21.7 % to 28.2 %, and also increased the FAME yield (g CODFAME/g CODAcetate) from 0.17 to 0.22. However, the biomass and FAME productivities decreased. Sufficient phosphorus was also essential for a high growth rate and FAME productivity. Deficiencies in either N or P led to a decrease in the proportion of unsaturated FAMEs. iTRAQ analysis indicated N starvation promoted oil accumulation by driving the carbon flow to fatty acid synthesis in microalgae from co-culture. This study improves the understanding of biomass and lipid production via microalgae-PSB co-culture in photoheterotrophic cultivation. The mechanism of interaction between microalgae and bacteria needs further study.

Using ZnAl–LDH@SiO2 as a catalyst for the electrocatalytic conversion of waste frying oil into biodiesel

In this study, a novel electrocatalytic conversion system via simultaneous esterification and transesterification, based on a ZnAl–layered double hydroxide (LDH)@SiO2, was investigated for fatty acid methyl ester (FAME) production from waste frying oil (WFO). A mechanism is proposed for the (trans)esterification process to generate CH3O− and OH− on the ZnAl–LDH@SiO2 as the semiconductor heterogeneous catalyst. The inclusion of SiO2 enhanced the catalyst's basicity and caused a better exposure of atoms of oxygen atoms on the catalyst's surface which contributed to the formation of methoxides as a nucleophilic attack on the triglyceride's carbonyl. Also, ZnAl–LDH@SiO2 as an electrocatalyst reduces the beginning potential rate and increases the charge carriers transport. The results showed that 98.4% FAME yield was obtained at higher water content from WFO after 90 min of reaction at 25 °C using 2 wt% of the ZnAl–LDH@SiO2 catalyst, and a methanol to WFO (M:WFO) molar ratio of 6:1. ZnAl–LDH@SiO2 was also effective for WFO containing 3.3 wt% of free fatty acid (FFA), and indicated high stability for WFO (trans)esterification after 5 runs. The electrocatalytic conversion system has the potential to advance a new process development for the conversion of feedstock containing high FFA and water to produce the second generation of biodiesel.

Kaolinite and Illite Based Clay Supporting Nickel: its Synthesis, Characterization, and Catalytic Optimazion in a Lab-Scale Fatty Acid Methyl Ester Production

The increasing world energy needs are not matched by the limited availability of fossil fuels thus the development of clean and sustainable fuels is the right solution. Biodiesel is one of these fuels and can be produced through transesterification reactions of vegetable oils in the presence of a catalyst. Acidic natural clay can be an option because of its large abundance, especially in the Indonesia and is heterogeneous in the solution it catalyzes. In this study, clay samples were obtained from an area in Bukittinggi City, West Sumatra Province, and then combined by wet impregnation with nickel as a catalyst in the transesterification reaction of used cooking oil to produce fatty acid methyl esters. Based on X-Ray diffraction (XRD) analysis, the presence of nickel ions does not affect the diffraction pattern of clay minerals contained in the soil consisting of kaolinite and illite. Measurements with X-Ray fluorescence (XRF) showed that the silicon-aluminum mole ratio also did not show a significant change where before mixing the value was 2.0 and after that it only decreased about 5 % to 1.9. The pore diameter of the catalyst was 3.03 nm known by Surface Area Analyzer (SAA). Several variations have been carried out to optimize the catalytic performance of the nickel supported clay and the best conditions were obtained when the catalyst concentration was 3 wt %, the methanol-oil mole ratio was 6:1, the reaction temperature was 70 °C and the reaction carried out for 3 hours. Under these conditions, the yield of methyl ester produced was 63 %

Strategy for lipid extraction and transesterification to enhance Chlorella sorokiniana strain BV 12 feedstock utilization

Efficient production and recovery of fatty acid methyl esters (FAMEs) from lipid containing feedstock is the key step of biodiesel production. This enhances the utilization of feedstock and improves the final economics of the process. Currently, direct and indirect transesterification strategies are being employed for biodiesel production from microalgae with few reports of tailoring the process to a specific feedstock. In this study, Chlorella sorokiniana strain BV 12 was grown in modified BG-11 medium and biomass was harvested. This was subjected to different physical, chemical and physico-chemical strategies for increasing the transesterification yield. The transesterified lipid was evaluated for various biodiesel properties like iodine value, saponification value, acid value, peroxide value and cetane number. After harvesting, gravimetric lipid yield of 161.7 mg/g and 4117.5 µg/g of FAME were obtained. Extraction of lipid was dependent on the cell disruption technique as it is accumulated intracellularly as droplets. Sonication resulted in maximum FAME production using either dry (4724.2 µg/g) and wet (4835.8 µg/g) biomass which shows that wet biomass is more suitable for processing. Gravimetric results favour the extraction by sonication showing a 63.22% increase in lipid recovery. Testing of different solvents for extraction showed methanol as most favourable for FAME analysis with acidic catalyst like HCl and H2SO4 giving FAME with better ignition value (∼51, Cetane number).

Multifunctional halloysite and hectorite catalysts for effective transformation of biomass to biodiesel

Halloysite surface was modified with tetrabutylammonium iodide, and then the obtained nanomaterial was used as support for ZnO nanoparticles. After characterization, the nanomaterial was used as a catalyst for fatty acid methyl esters (FAMEs) production. The recyclability of the nanomaterial was also investigated, and the optimization of reaction conditions by the design of experiments approach was performed as well. In addition, the synthesized nanomaterial was tested as a catalyst for FAME production from a series of waste lipids affording biodiesel in moderate to good yields (35–95%), depending on the matrix. To fully exploit the feasibility of clay minerals as catalysts in biodiesel formation, a screening of different clays and clay minerals with different morphologies and compositions, such as sepiolite, palygorskite, bentonite, and hectorite was also performed in the esterification of FFAs (a mixture of 1:1 palmitic and stearic acids). Finally, hectorite, chosen as a model of 2:1 clay minerals, was covalently modified, and tested as a catalyst in the esterification of FFAs.

Batch and continuous γ-alumina-catalyzed FAME production from soybean oil deodorizer distillate by interesterification

This paper presents data for a batch and continuous fatty acid methyl esters (FAME) production through heterogeneous catalysis interesterification with methyl acetate, using soybean oil deodorizer distillate (SODD) as feedstock, a high-acid by-product of problematical destination, generated during the soybean oil refining process. As a reaction catalyst, γ-alumina with high catalytic activity, acid character, and an interesting specific area was synthesized and used in the processes. The SODD presented a significant FFA content of 35.2 ± 0.4 wt% and low convertibility in esters (48.0 ± 0.9 %) pointing to high impurity content. By statistical design, the parameters optimization (temperature, methyl acetate:SODD mass ratio, and catalyst load) of the batch reactor returned results that indicated the reliability and reproducibility of the proposed model, allowing predicting the system behavior at autogenous pressure, where around 80.0 wt% of ester yield and 5.4 wt% of triacetin (TA) yield was obtained after 2 h. By kinetics analysis, a FAME yield higher of 90 wt% and TA yield of 13.90 wt% were achieved after 4 h. From these results, continuous production of FAME and TA could be evaluated, where the results obtained permitted to affirm that the acid heterogeneous interesterification can be an interesting process to biodiesel synthesis from SODD.

Biodiesel Fuel Production from Soybean Oil Using a Microreactor

The synthesis of fatty acid methyl ester from soybean oil was examined. A microreactor was used as a reactor, and the results were compared with those by batch reaction. In a batch reaction experiment, the concentration of by-product glycerol was large when methanol/soybean oil ratio was low, which inhibited the mass transfer between methanol and oil, and as a result, reduced fatty acid methyl ester yield. On the other hand, when the reaction was conducted under an emulsion state using a microreactor, the initial reaction rate was significantly increased, achieving a specific interfacial area about 7 times larger than that of the batch reaction. Furthermore, the decrease in reaction rate was suppressed and the space-time fatty acid methyl ester yield was successfully increased. When the reaction was conducted under a segmented flow state, the initial reaction rate decreased because of the smaller specific interfacial area. However, the mass transfer coefficient increased about 30-fold, and furthermore, the phase separation was completed immediately after the reaction. Finally, the high temperature and high-pressure flow operation was conducted using a microreactor, which enabled an efficient fatty acid methyl ester production from soybean oil at 2 – 3 times higher space-time yield with less amount of catalyst and/or methanol use compared to the conventional batch production method.

Decoupling solid and hydraulic retention times in microalgal biofilm reactors treating primary wastewater: performance and biodiesel potential

AbstractBACKGROUNDMicroalgal biofilm systems are a promising approach for wastewater treatment and for production of biodiesel precursors through simple biomass harvesting. However, the low concentration of nutrients in wastewater limits possible approaches for microalgal growth. The effective decoupling of the solid retention time (SRT) and the hydraulic retention time (HRT) in biofilm reactors as an alternative for increasing microalgae growth and biodiesel performance in low‐strength wastewater has not been investigated. In this study, we tracked how decoupling the SRT and the HRT influences the removal of organics and nutrients, the biomass productivity and the production of fatty acid methyl esters (FAME).RESULTSThree perturbations of the HRT, SRT and liquid level (LL) with regards to the base case condition (HRT 2.6 h; SRT 21 days, LL 5 mm) performance were analyzed. The base case showed the highest TN and TP removal (>50%) outcomes with high pH values (>10). A decrease of HRT and SRT from 2.6 to 1.3 h and 21 to 10 days, respectively, promoted an increment of microalgal productivity ≤5.8 ± 0.7 g m−2 day−1. A short HRT of 1.3 h enhanced the nitrogen removal rate up to 1.2 g N m−2 day−1, which triggered an increase in the FAME productivity and microalgal density on the biofilms without affecting their productivity.CONCLUSIONOur study demonstrated that the strategy of decoupling HRT and SRT allows operation at shorter HRTs, promoting microalgal growth without affecting FAME production in low‐strength municipal wastewater. © 2023 Society of Chemical Industry (SCI).

A closed-loop approach for enhanced biodiesel recovery from rapeseed biodiesel-based byproducts through integrated glycerol recycling by black soldier fly larvae

The present study evaluated an innovative zero-waste approach for efficient recycling of byproducts from rapeseed-based biodiesel industry including lipid-free rapeseed cake (RSC) and waste glycerol by black soldier fly larvae (BSFL). RSC showed high organic matter and protein contents of 92.7 dw% and 32.1 dw%, respectively. Therefore, it was utilized as the main feed source for BSFL rearing, while waste glycerol was supplemented at different concentrations (0–10%, w/w). Application of 5.0% waste glycerol significantly enhanced larval biomass gain rate and areal productivity by 13.0% and 17.2%, respectively, over the control. Interestingly, lipid content also increased by 25.9% over the control. The study suggested a synergistic action in the mixture, where RSC is digested to achieve the growth and development, while waste glycerol can be integrated directly into fatty acid biosynthesis pathway to accumulate lipids. In addition to being a carbon source, morphological examination and FTIR analysis showed that waste glycerol has the potential to penetrate RSC biomass fibers easing its decomposition. Overall, the highest recorded fatty acid methyl esters (FAMEs) productivity of 98.0 mg m−2 was recorded in BSFL treated with 5.0% waste glycerol, which represented 57.7% higher than the control. Comparing to rapeseed biodiesel, saturated fatty acids proportion in the BSFL-based FAMEs at all studied treatments was much higher, leading to 11.9–12.9% higher cetane number. In conclusion, findings of this study provide new insights to BSFL as a promising mini-livestock for biodiesel production through innovative recirculation route of biodiesel byproducts towards waste reduction and sustainable development.