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Energy aspects of microalgal biodiesel production

  • Algal biodiesel production will play a significant role in sustaining future transportation fuel supplies. A large number of researchers around the world are investigating into making this process sustainable by increasing the energy gains and by optimizing resource-utilization efficiencies. Although, research is being pursued aggressively in all aspects of algal biodiesel production from microalgal cell cultivation, cell harvesting, and extraction and transesterification steps to the final product separation and purification, there is a large disparity in the data presented in recent reports making it difficult to assess the real potential of microalgae as a future energy source. This article discusses some of the key issues in energy consumption in the process of algal biodiesel production and identifies the areas for improvement to make this process energy-positive and sustainable.

    Citation: Edith Martinez-Guerra, Veera Gnaneswar Gude. Energy aspects of microalgal biodiesel production[J]. AIMS Energy, 2016, 4(2): 347-362. doi: 10.3934/energy.2016.2.347

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  • Algal biodiesel production will play a significant role in sustaining future transportation fuel supplies. A large number of researchers around the world are investigating into making this process sustainable by increasing the energy gains and by optimizing resource-utilization efficiencies. Although, research is being pursued aggressively in all aspects of algal biodiesel production from microalgal cell cultivation, cell harvesting, and extraction and transesterification steps to the final product separation and purification, there is a large disparity in the data presented in recent reports making it difficult to assess the real potential of microalgae as a future energy source. This article discusses some of the key issues in energy consumption in the process of algal biodiesel production and identifies the areas for improvement to make this process energy-positive and sustainable.


    Coronavirus disease (COVID-19) is an infectious disease caused by a newly discovered coronavirus. Since its emergence in Wuhan, China in December 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) had rapidly spread throughout the world following an exponential growth curve prompting it to be characterized as a pandemic by the World Health Organization on March 11, 2020 [1],[2]. As of 12.00 pm on April 12, 2020, 1,780,315 cases of Coronavirus disease 2019, including 108,828 deaths, had been reported worldwide by more than 200 countries and territories [3]. Clinical presentations of COVID-19 may take up to 14 days to appear after exposure to the virus with the symptoms range from mild illness to severe pneumonia, and other life-threating complications which may lead to death [4],[5]. In Vietnam, a lower-middle-income country with the population of more than 96 million people, the first COVID-19 case was reported on 23rd January 2020. As of 12th April 2020 there were 258 infections, 144 of the affected patients have recovered and 0 death [3]. However, the threat of spreading COVID-19 in Vietnam is predicted to increase due to unidentified sources of infection in the community.

    Hand hygiene is considered as one of the most fundamental preventive measures against many infectious diseases. Several studies have indicated that the efficacy of keeping hands clean reduced significantly the rates of infectious illnesses in the community, including diarrhea [6][9], cholera [7],[10][12], and pneumonia [6]. Besides, poor handwashing may contribute greatly to the risk of foodborne illness [13]. However, handwashing has remained an infrequent practice, especially for those who live in the least developed countries [14]. Eighteen percent of the global population (approximately 1.4 billion) had no basic handwashing facilities with soap and water available at home in 2017 [14]. A recent study conducted in 2019 in Northern mountainous provinces and the Central Highlands of Vietnam indicated that only 10% of the studied population performed hand hygiene with soap and water after defecation and this number increased to 54% after intervention activities were implemented [15].

    World Health Organization (WHO) and the Vietnam Ministry of Health (MOH) has repeatedly emphasized that regularly and thoroughly performing hand hygiene with soap and water or alcohol-based hand rub is an effective way to prevent the spread of the new coronavirus SARS-CoV-2 [16],[17]. This virus spreads primarily through respiratory droplets when an infected person coughs or sneezes, or close personal contact, such as touching a contaminated surface and then touching eyes, noses or mouths before handwashing [5]. Therefore, promoting proper hand hygiene practices is a well-known preventive measure to control COVID-19 since effective treatment drugs and vaccines for COVID-19 are not currently available.

    Widely reporting of statistics and facts about the COVID-19 pandemic by the global media may lead to confusion and anxiety about the disease along with the preventive measures, including handwashing recommended by many organizations including WHO and MOH. This study describes the knowledge and practices of people in Vietnam about handwashing with soap and water or the alcohol-based hand rub, and the associated factors during the COVID-19 pandemic in March 2020.

    This was a cross-sectional study.

    Participants were eligible to participate if they were adults, currently lived in Vietnam, had internet connection, able to read, and understand the provided questions. Participants voluntarily participated in an online questionnaire administered through email and social networks.

    The study sample was calculated using the one-proportion sample size formula with an absolute precision d = 0.05, design effect DE = 2, and p was the proportion of handwashing people using soap at essential times (e.g., after going out). The calculated sample size was 277 people.

    Participants were selected using non-probability, self-nominated sampling. The researchers sent the link contained online questionnaire to respondents through email, social networks (e.g., Facebook, Zalo, etc.). The online questionnaire was available from 0.00 am 25 March to 11.59 pm, 01 April 2020. At the time of the survey closing, 870 submissions were recorded. Among the submissions, 859 agreed to participate in the survey, making the response rate of 98.74%. Among those who agreed, 837 participants were included in the analysis, 22-excluded submissions were participants who had answered only 10% of total questions or fewer.

    We used Kobo Toolbox (kf.kobotoolbox.com) to develop the self-administered questionnaire and to collect data. The questionnaire could be easily accessed on any devices (e.g., computer, tablet, cellphones, etc.) with an internet connection through a link (https://ee.kobotoolbox.org/x/#Juy6CuzP). To prevent duplication, an email address was required for each time respondents submitting their responses. The average time to complete the questionnaire was approximately 10 minutes.

    The main dependent variable in this study was the correct reported practice of handwashing. It was a binary variable, which could be calculated by combining four following questions:

    1. Did the respondent choose water and soap as a primary mean to handwashing whenever it was available? (2 available choices: Yes/No).

    2. Could the respondent list ALL the 5 necessary times for handwashing? (2 available choices: Yes/No). Five mentioned necessary times were: 1) after going to the toilet, 2) after touching surfaces at public places (e.g.: elevator, doorknob, etc.), 3) before having meals, 4) before preparing meals for family and 5) after removing face mask.

    3. Did the respondent have handwashing with 6 steps? (2 available choices: Yes/No).

    4. Did the respondent have handwashing in at least 20 seconds? (2 available choices: Yes/No). (according to the United States Centers for Disease Control and Prevention recommendations [18]).

    A participant could be considered having a correct reported practice of handwashing when he/she has answered Yes for all four above questions.

    Independent variables were socio-economic information of respondents, including gender (male/female), age (in years), the highest educational level (high school or below, vocational/college/university), occupation (student/employee/other), marital status (single, married, separated/divorced/widowed)), a source where respondents get information about handwashing (friends, relatives, health staff, internet/social networks, newspaper/television, government/MOH), and knowledge of handwashing (in points). Knowledge variable was created through a combination of nine questions and the highest score would be 33, details were described as below:

    Table 1.  Details of questions regarding knowledge of handwashing.
    No. Question Correct answer Point
    1 Diseases that could be spread by dirty hands COVID-19, acute respiratory diseases, pneumonia, diarrhea, flu, helminth, hand-foot-mouth disease Each selected disease: 1 point (max. 7 points)
    Other or do not know/do not remember: 0 point
    2 Used soap/antiseptic solution when handwashing Water and soap
    Antiseptic solution (with alcohol)
    If each correct answer or both are selected: 1 point
    3 Conditions which need handwashing Before: having meals, cooking, feeding child
    After: leaving the toilet, childcare works, contacting patients or waste, touching pets
    Each selected condition: 1 point (max. 8 points)
    Other or do not know/do not remember: 0 point
    4 In COVID-19 pandemic, apart from mentioned above conditions, when handwashing should be done After touching surfaces at public places
    After taking off face mask
    Each selected choice: 1 point
    Other choices: 0 point
    5 Necessary time for handwashing At least 20 seconds
    At least 30 seconds
    0.5 point
    1 point
    6 Describe taken steps when handwashing by water 6 steps of handwashing according to Vietnam MOH recommendations [19] Each selected condition: 1 point (max. 6 points)
    Other or do not know/do not remember: 0 point
    7 Frequency of each step when handwashing by water 5 times 1 point
    8 Describe taken steps when handwashing by antiseptic solution (with alcohol) 6 steps of handwashing according to Vietnam MOH recommendations [19] Each selected condition: 1 point (max. 6 points)
    Other or don't know/don't remember: 0 point
    9 Frequency of each step when handwashing by antiseptic solution (with alcohol) 5 times 1 point

     | Show Table
    DownLoad: CSV

    Both descriptive and inferential statistics were performed in this study. All independent variables were described under the main outcome by calculating frequencies and percentages. Univariate linear regression was used for each independent variable with the main outcome with a significant level of 0.05. Multiple linear regression was conducted to provide a theoretical model with collected predictors.

    This study was approved by the Institutional Review Board of the Hanoi University of Public Health under the Decision No. 105/2020/YTCC-HD3 dated 20 March 2020. The study information about objectives, selection criteria, personal information privacy, data protection, advantages, and potential harm, were all provided to participants before doing the online questionnaire. Each participant was assigned a study number, no private data was collected, and all collected data was coded.

    The responses of 837 participants were included in the analysis. Out of 837 participants, 633 (75.7%) were female. The average age in years of the respondents was 33.3 (SD = 10.9), male respondents were older than females (35.7 vs. 32.6, respectively). Most respondents were employed, which accounted for about 60.5% while 25% of the respondents were students, and the rest of them were self-employed (4.4%), business/small business (3.8%), retired (2.8%), and other (2.3%). At the time of data collection, 23 of the63 provinces in Vietnam reported to have COVID-19 patients. In our survey, the proportion of respondents from the provinces with COVID-19 patients was about 72%. There was 64% of the respondents completing vocational/college/university as their highest educational level, while about 28% of total participants had completed postgraduate education. About half of the respondents were living with their spouse. The proportion of single respondents was 39.2%, and 3.8% of the respondents were separated/divorced/widowed.

    Table 2.  Characteristics of respondents.
    Characteristics Total (n = 837) Males (n = 203) Females (n = 634)
    Age in years, mean (SD) 33.3 10.9 35.7 11.8 32.6 10.4
    Occupational status, n (%)
     Student 220 26.3 51 25.1 169 26.7
     Employee 506 60.5 112 55.2 394 62.2
     Self-employment 37 4.4 12 5.9 25 3.9
     Business/small business 32 3.8 15 7.4 17 2.7
     Retired 23 2.8 7 3.5 16 2.5
     Other (e.g., farmer, housewife) 19 2.3 6 3.0 13 2.1
    Provinces, n (%)
     Have COVID-19 patients 601 71.8 138 68.0 463 73.0
     Do not have COVID-19 patients 236 28.2 65 32.0 171 27.0
    Highest educational level, n (%)
     High school and below 63 7.5 23 11.3 40 6.3
     Vocational/College/University 536 64.0 114 56.2 422 66.6
     Postgraduate 234 28.0 65 32.0 169 26.7
    Marital status, n (%)
     Single 328 39.2 69 34.0 259 40.9
     Living with husband/wife 477 57.0 127 62.6 350 55.2
     Separated/Divorced/Widowed 32 3.8 7 3.5 25 3.9

     | Show Table
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    Overall, the rate of respondents with correct reported practices of handwashing was 26.3%. When looking into four aspects that assessed respondents correct reported practices, using water and soap as a primary choice for hand hygiene was the aspect with the highest correct proportion, which accounted for almost 80% of the total respondents. In this survey, only 60.6% of the respondents had a correct answer for the all necessary times for handwashing, and 42.8% of the respondents could list all six steps of proper hand hygiene practices. The aspect in which the respondents had the lowest correct level was the adequate handwashing time. Only 28.4% of participants reported washing their hands in at least 20 seconds as recommended by WHO.

    Figure 1.  Respondents' reported practice of handwashing (n = 837).

    Regarding the necessary time for handwashing, the popular times at which most respondents knew that they need to perform handwashing were: after going to the toilet (96.6%), after touching surfaces at places such as elevators, doorknobs, etc. (92.1%), and before having meals (92.1%). The proportion of respondents knew that they needed to wash hands before preparing meals for their families was 84.5% and only 69.3% of respondents answered that they needed to wash hands after removing their face masks.

    Figure 2.  Respondents' information of necessary time for handwashing (n = 837).
    Table 3.  Associations (both univariate and multivariate) between the reported practice of handwashing and respondent's characteristics.
    Characteristics Univariate analysis
    Multivariate analysis
    OR 95%CI p-value OR 95%CI p-value
    Age in years 1.02 1.01–1.04 0.002 1.02 0.99–1.05 0.24
    Gender
     Male Ref Ref
     Female 1.55 1.06–2.28 0.024 1.88 1.15–3.09 0.012
    Occupational status
     Student Ref Ref
     Employee 1.94 1.32–2.87 0.001 1.92 0.97–3.79 0.06
     Other (e.g., small business, retired, farmer, housewife) 1.14 0.64–2.02 0.65 1.60 0.61–4.15 0.34
    Provinces
     Do not have COVID-19 patients Ref Ref
     Have COVID-19 patients 0.81 0.58–1.14 0.22 1.21 0.77–1.90 0.40
    Highest educational level
     High school or below Ref Ref
     Vocational/College/University 1.37 0.72–2.60 0.33 1.30 0.54–3.14 0.56
     Postgraduate 1.51 0.77–2.96 0.23 1.26 0.48–3.28 0.64
    Marital status
     Single Ref Ref
     Married 1.64 1.18–2.28 0.003 0.91 0.48–1.73 0.77
     Separated/divorced/widowed 0.87 0.34–2.19 0.76 0.39 0.11–1.42 0.15
    Getting information from:
    Friends 1.47 1.08–2.00 0.015 0.96 0.51–1.81 0.89
    Relatives 1.31 0.96–1.79 0.09 1.09 0.58–2.06 0.78
    Health staffs 3.03 2.05–4.47 <0.001 2.96 1.70–5.13 <0.001
    Internet/social networks 0.78 0.48–1.25 0.30 0.44 0.21–0.96 0.04
    Newspaper/Television 0.79 0.51–1.24 0.31 0.41 0.20–0.87 0.019
    Government/MOH 2.16 1.20–3.87 0.01 1.64 0.76–3.53 0.21
    Knowledge of handwashing (points) 1.34 1.25–1.43 <0.001 1.30 1.20–1.41 <0.001

     | Show Table
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    Some characteristics were found to be statistically significant with reported practices of handwashing among the participants in the univariate analysis including age, gender, occupational status, marital status, getting COVID-19 information from friends, health staff, government/MOH, and knowledge of handwashing (in points). When adjusting all variables in multivariate analysis, female respondents were found likely to be 1.88 times (95% CI: 1.15–3.09) higher to have correct reported practices of handwashing than males. We also found that respondents who received information regarding handwashing from health staff had the odds of reported handwashing correctly 2.96 times (95% CI: 1.70–5.13) higher than those who did not. This survey also revealed the negative impacts of internet/social networks and newspaper/television on the reported practice of handwashing among the respondents. In detail, the participants who received hand hygiene information from the internet/social networks had 56% (95% CI: 4–79%) chances lower to wash hands correctly than those who did not. The same trend was observed among the respondents getting information from newspaper/television with a proportion of 59% (95% CI: 13–80%). At last, respondents who had more knowledge of handwashing correctly could have correct reported practices of this behavior, for each point increased in knowledge, the odds of reported practices correctly increased 1.3 times (95% CI: 1.2–1.41).

    Our multivariate analysis did not found characteristics including age, occupational status, original provinces, educational level, marital status, getting information from friends, relatives, government/MOH to be associated with correct reported practices of handwashing among participants.

    The study results showed that the prevalence of people reported washing their hands with clean water and soap as their primary choice was remarkably high (79.3%). This result was relevant with the recommendation from the Vietnamese MOH that people should perform handwashing with soap and clean water. This method is considered as the priority measure for handwashing and the sterilized sanitizer is recommended only when soap and water are not available [20]. Our study found that participants' reported practices on handwashing (including handwashing with soap and with sterilized sanitizers) were rather high (60.6%) at essential times such as after defecation, before meals, before processing meals for family members, after contact with public places such as lifts, public corridors or doorknobs, and after removing masks during the time of the COVID-19 pandemic. This prevalence was significantly higher comparing to that during the non-pandemic time in which the prevalence of handwashing with soap and water among the community was reported to be very low at 10% after defecation [21]. The group of mothers of children under 5 years old is considered as a priority target group in all health communication programs in Vietnam, however, the handwashing practice rate among this group was only 24.3% at the essential times [22]. The remarkably high prevalence of reported handwashing of the community during the COVID-19 pandemic could be due in part to the fact that the Vietnamese Government did a very comprehensive communication strategy about COVID-19. The communication strategy included frequent delivery of information about the danger of COVID-19, its rapid transmission, and the prevention methods, including handwashing with soap and water, and with sterilized sanitizers to all mobile and Zalo users in Vietnam. As of January 2020, there were 145.8 million mobile users in Vietnam which is about 150% of the total population of the country. The number of internet users was 68.17 million, of whom, 74% used Zalo-the number three popular social media in Vietnam after Facebook and YouTube [23]. Therefore, it could be concluded that COVID-19 related information was disseminated to almost Vietnamese people. Also, mass media and the internet presented COVID-19 information at an exceedingly high frequency. These together might have contributed to the high prevalence of the reported handwashing practice. Another reason that may contribute to the explanation of the high frequency of reported handwashing was due to the unawareness of the community about the COVID-19, as it is the emerging infectious disease that happened in late 2019 in China. The unawareness might lead to the community's panic and outrage about the disease, especially when the number of cases surge daily, with 1,780,315 cases and 108,828 deaths in 211 countries and territories in the world at 12.00 pm of 12th April 2020 [3]. According to Sandman (2012), the risk was characterized as hazard and outrage [24], therefore, people might have considered COVID-19 as a seriously dangerous disease and might have paid a lot of attention to the disease, including handwashing as a prevention measure.

    However, the high frequencies of reported handwashing at essential times in this study might not have implied that the actual handwashing practices of the participants were that high, as many of the studies around the world have shown that the reported handwashing practices were much higher than observational handwashing behaviors [25],[26], even higher than 40 times in reported handwashing practices versus actual practices [25]. Therefore, the Vietnamese Government needs to regularly focus on the importance of handwashing with soap in prevention of COVID-19 disease and other infectious diseases transmitted via contaminated hands to maintain the high prevalence of handwashing at essential times, not only during the pandemic time but also in all the time, and therefore could contribute to the decrease of various preventable infectious diseases.

    The study revealed that only 42.8% of the participants reported practicing all six steps during handwashing and only 28.4% performed hand hygiene for at least 20 seconds recommended by WHO [27], making the total prevalence of correct reported handwashing practice was only 26.3%. Although the Government had implemented comprehensive measures to prevent and control the disease, including the “Nationwide Social Distancing” Decree in 15 days, starting from 0.00 1st April 2020 [28], this result implies that the intervention strategy of the Vietnamese Government to improve community's awareness and practices on COVID-19 prevention should also focus on how to guide the community to practice proper handwashing to effectively prevent of the spread of the disease in the community.

    It revealed from our study that female participants had better reported practices on handwashing than male participants (Table 3), which was consistent with other studies' results in Vietnam among child caretakers [22], a group of adolescents in Malaysia [29], and in an online survey in Hong Kong [30] although these studies did not collect data during the pandemic while our study was conducted during the COVID-19 pandemic.

    Many international studies [31] and studies in Vietnam [22],[32] showed that educational level was an important factor affecting handwashing practices. However, a contrast result was obtained in our study. As discussed above, the frequent delivery of information about COVID-19 prevention and control measures to every mobile and Zalo users in Vietnam by the Vietnamese MOH and the Vietnamese Government could be a feasible reason to explain this result.

    Besides, various studies showed that better knowledge associated with better reported handwashing practices [29],[33]. A similar trend was also observed in this study, with an increase of 1 knowledge score on handwashing contributed to the odds ratio of 1.3 (95% CI: 1.20–1.41) in reported handwashing practices. Intervention studies on sanitation and hygiene also confirmed that intervention to increase knowledge on handwashing would contribute to the increase in handwashing practices [21],[34].

    One interesting finding from this study was that participants who obtained knowledge on handwashing from the internet sources (internet/social network) or newspapers/television had poorer handwashing practices that those who did not receive knowledge from these sources. The participants who gained knowledge from healthcare staff had better reported handwashing practices than those who did not get information from this staff. As suggested by Sandman (2012) above, due to the uncertain of the COVID-19 disease, the community's outrage for this disease increased and therefore contributed to the increased perception on the risk of the disease [24]. Based on the increased community outrage, fake news about the disease was quite common, especially on the internet and social media, which might have led to the poorer reported handwashing practices.

    Although certain interesting results were found in this study, our study is subject to several limitations. First, our sample was not representative because we only collected data online, which might have resulted in most of the respondents were at higher educational levels (more than 90% had the college/university levels or higher). Other studies found that users of the internet were not representative of the general population, and not all felt familiar with the online protocol [35]. However, during the COVID-19 pandemic with social distancing suggestion and later ordered by the Government Decree on the 1st of April 2020 [28], an online survey was the most convenient and feasible method for data collection. Secondly, all the study team members worked for a public health education institution, therefore, many of their social media friends might also interrelate to public health or medicine. This might lead to a higher chance of giving “right options” in the questionnaire as they know clearly interrelate to public health or medicine. We must accept this bias and consider it as a limitation for this study. Thirdly, due to the social distancing Decree of the Vietnamese Government, only online data collection was undertaken, and therefore we could only collect reported handwashing practices. This might have implied that the prevalence of reported handwashing practices might have much higher than the actual practice, as shown by various studies in the world [25],[26]. However, as explained earlier, due to the fear of acquiring COVID-19 during the pandemic, people tended to follow and undertake preventable measures, including handwashing practices [23], therefore these reported practices might have been relatively higher than that of the non-pandemic time. Last but not least, we did not collect data about respondents' income, place of living (urban, rural) in the data collection, the presence of handwashing places, and soap in their houses, although these variables are considered important indicators for handwashing practices. However, as we explained earlier, the data collection was undertaken during the COVID-19 pandemic, and handwashing with soap was not the only measure to be encouraged by the Vietnamese Government. Alcohol-based hand rub was also encouraged to be used to prevent COVID-19, especially when water and soap were not available. Therefore, we could only focus on collecting data by provinces/cities where there were COVID-19 patients and on educational messages that our respondents received from the MOH and the Government during the time of data collection.

    Although handwashing practices at all essential times recorded in this study was rather high, the prevalence of practiced washing hand correctly was low, mainly due to the incorrect practice on the six handwashing steps and the minimum required time for handwashing. The Government should pay attention to the communication strategy on COVID-19 prevention measures to the citizens, with a focus on the six steps of handwashing and the minimum required time for handwashing. Also, the Government should remind the Vietnamese people to select appropriate and reliable information on COVID-19 pandemic for references, especially information on the internet, social media, newspapers, etc.

    [1] Chisti Y (2007) Biodiesel from microalgae. Biotechnol Adv 25: 294-306. doi: 10.1016/j.biotechadv.2007.02.001
    [2] Mata TM, Martins AA, Caetano NS (2010) Microalgae for biodiesel production and other applications: A review. Renew Sust Energ Rev 14: 217-232.
    [3] Moody JW, McGinty CM, Quinn JC (2014) Global evaluation of biofuel potential from microalgae. Proc Natl Acad Sci 111: 8691-8696. doi: 10.1073/pnas.1321652111
    [4] Lardon L, Helias A, Sialve B, et al. (2009) Life-cycle assessment of biodiesel production from microalgae. Environ Sci Technol 43: 6475-6481. doi: 10.1021/es900705j
    [5] Uduman N, Qi Y, Danquah MK, et al. (2010) Dewatering of microalgal cultures: a major bottleneck to algae-based fuels. J Renew Sustain Energy 20: 12701-12715.
    [6] Batan L, Quinn J, Willson B, et al. (2010) Net Energy and Greenhouse Gas Emission Evaluation of Biodiesel Derived from Microalgae. Environ Sci Technol 44: 7975-7980. doi: 10.1021/es102052y
    [7] Stephenson AL, Kazamia E, Dennis JS, et al. (2010) Life-Cycle Assessment of Potential Algal Biodiesel Production in the United Kingdom: A Comparison of Raceways and Air-Lift Tubular Bioreactors. Energ Fuel 24: 4062-4077. doi: 10.1021/ef1003123
    [8] Sturm BSM, Lamer SL (2011) An energy evaluation of coupling nutrient removal from wastewater with algal biomass production. Appl Energ 88: 3499-3506.
    [9] Liu X, Saydah B, Eranki P, et al. (2013) Pilot-scale data provided enhanced estimates of the life cycle energy and emissions profile of algae biofuels produced via hydrothermal liquefaction. Bioresource Technol 148: 163-171.
    [10] Ozkan A, Kinney K, Katz L, et al. (2012) Reduction of water and energy requirement of algae cultivation using an algae biofilm photobioreactor. Bioresource Technol 114: 542-548.
    [11] Molina Grima E, Belarbi EH, AciénFernández FG, et al. (2003) Recovery of microalgal biomass and metabolites: process options and economics. Biotechnol Adv 20: 491-515.
    [12] Jorquera O, Kiperstok A, Sales EA, et al. (2010) Comparative energy life-cycle analyses of microalgal biomass production in open ponds and photobioreactors. Bioresour Technol 101: 1406-1413. doi: 10.1016/j.biortech.2009.09.038
    [13] Slade R, Bauen A (2013) Microalgae cultivation for biofuels: cost, energy balance, environmental impacts and future prospects. Biomass bioenerg 53: 29-38.
    [14] Singh M, Shukla R, Das K (2013) Harvesting of microalgal biomass in Biotechnological applications of microalgae. CRC Press: 77-88.
    [15] Vandamme D, 2013. Flocculation based harvesting processes for microalgae biomass production (Doctoral dissertation, UGent).
    [16] Sanghi R, Singh V, Green Chemistry for Environmental Remediation. John Wiley & Sons; 2012. Chapter 8.4.
    [17] Reddy HK, Muppaneni T, Patil PD, et al. (2014) Direct conversion of wet algae to crude biodiesel under supercritical ethanol conditions. Fuel 115: 720-726. doi: 10.1016/j.fuel.2013.07.090
    [18] Ali M, Watson IA (2015) Microwave treatment of wet algal paste for enhanced solvent extraction of lipids for biodiesel production. Renew Energy 76: 470-477.
    [19] Martinez-Guerra E, Gude VG, Mondala A, et al. (2014) Extractive-transesterification of algal lipids under microwave irradiation with hexane as solvent. Bioresource Technol 156: 240-247.
    [20] Martinez-Guerra E, Gude VG, Mondala A, et al. (2014b) Microwave and ultrasound enhanced extractive-transesterification of algal lipids. Appl Energ 129: 354-363.
    [21] Patil PD, Gude VG, Mannarswamy A, et al. (2012) Comparison of direct transesterification of algal biomass under supercritical methanol and microwave irradiation conditions. Fuel 97: 822-831.
    [22] Chen CL, Huang CC, Ho KC, et al. (2015) Biodiesel production from wet microalgae feedstock using sequential wet extraction/transesterification and direct transesterification processes. Bioresource Technol 194: 179-186.
    [23] Cheng J, Yu T, Li T, et al. (2013) Using wet microalgae for direct biodiesel production via microwave irradiation. Bioresource Technol 131: 531-535.
    [24] Koberg M, Cohen M, Ben-Amotz A, et al. (2011) Bio-diesel production directly from the microalgae biomass of nannochloropsis by microwave and ultrasound radiation. Bioresource Technol 102: 4265-4269.
    [25] Araujo GS, Matos LJBL, Fernandes JO, et al. (2013) Extraction of lipids from microalgae by ultrasound application: prospection of the optimal extraction method. Ultrason Sonochem 20: 95-98. doi: 10.1016/j.ultsonch.2012.07.027
    [26] Wiyarno B, Yunus RM, Mel M (2010) Ultrasound Extraction Assisted (UEA) of oil from microalgae (nannochloropsis sp.). Int J Sci Eng Technol 3: 65-71.
    [27] Ranjan A, Patil C, Moholkar VS (2010) Mechanistic assessment of microalgal lipid extraction. Ind Eng Chem Res 49: 2979-2985.
    [28] Adam F, Abert-Vian M, Peltier G, et al. (2012) Solvent-free ultrasound-assisted extraction of lipids from fresh microalgae cells: A green, clean and scalable process. Bioresource Technol 114: 457-465.
    [29] Lee JY, Yoo C, Ju SY, et al. (2010) Comparison of several methods for effective lipid extraction from microalgaemicroalgae. Bioresource Technol 101: S75-S77.
    [30] Balasundaram B, Skills SC, Llewellyn CA (2012) A low energy process for the recovery of bioproducts from cyanobacteria using a ball mill. Biochem Eng J 69: 48-56.
    [31] McGarry MG (1970) Alga flocculation with aluminium sulfate and polyelectrolytes. J Water Pollut Control Fed 42: R191-201.
    [32] Benemann JR, Kopman BL, Weissman DE, et al. Development of microalgae harvesting and high rate pond technologies in California. In: Shelef G, Soeder CJ, editors. Algal biomass. Amsterdam: Elsevier; 1980, 457.
    [33] Moraine R, Shelef G, Sandbank F, Bar-Moshe Z, Shvartzbard I. Recovery of sewage borne algae: flocculation and centrifugation technique. In: Shelef G, Soeder CJ, editors. Algae biomass. Amsterdam: Elsevier; 1980, 531-546.
    [34] Koopman B, Lincoln EP (1983) Autoflotation harvesting of algae from high rate pond effluents. Agric Wastes 5: 231-246. doi: 10.1016/0141-4607(83)90038-0
    [35] Lincoln EP (1985) Resource recovery with microalgae. Arch Hydrobiol 20: 25-34.
    [36] Buelna G, Bhattarai KK, de la Nuoe J, et al. (1990) Evaluation of various flocculants for the recovery of algal biomass grown on pig-Waste. Biol Waste 31: 211-222. doi: 10.1016/0269-7483(90)90160-T
    [37] Harith ZT, Yusoff FM, Mohamed MS, et al. (2009) Effect of different flocculants on the flocculation performance of microalgae, Chaetoceroscalcitrans, cells. Afr J Biotechnol 8: 5971-5978.
    [38] Bosma R, van Spronsen WA, Tramper J, et al. (2003) Ultrasound, a new separation technique to harvest microalgae. J Appl Phycol 15: 143-153.
    [39] Zhang X, Hu Q, Sommerfeld M, et al. (2010) Harvesting algal biomass for biofuelsusing ultrafiltration membranes. Bioresour Technol 101: 5297-5304. doi: 10.1016/j.biortech.2010.02.007
    [40] Zou S, Gu Y, Xiao D, et al. (2011) The role of physical and chemical parameters on forwardosmosis membrane fouling during algae separation. J Membr Sci 366: 356-362. doi: 10.1016/j.memsci.2010.10.030
    [41] Mohn F (1980) Experiences and strategies in the recovery of biomass from mass cultures of microalgae. Algae Biomass: 547-571.
    [42] Bilad MR, Vandamme D, Foubert I, et al. (2012) Harvesting microalgal biomass using submerged microfiltration membranes. Bioresource Technol 111: 343-352.
    [43] Milledge JJ, Heaven S (2013) A review of the harvesting of micro-algae for biofuel production. Rev Environ Sci Bio 12: 165-178.
    [44] Supple D. MIT Energy Club (https://mitei.mit.edu/research). Accessed February 5, 2016.
    [45] University of Washington (http://www.ocean.washington.edu). Accessed February 5, 2016.
    [46] Singh J, Gu S (2010) Commercialization potential of microalgae for biofuels production. Renew Sust Energ Rev 14: 2596-2610.
    [47] Gude VG, Patil PD, Deng S, et al. (2011) Microwave enhanced methods for biodiesel production and other environmental applications. Green chemistry for environmental remediation. New York: Wiley Interscience, 209-249.
    [48] Gude VG, Patil P, Martinez-Guerra E, et al. (2013). Microwave energy potential for biodiesel production. Sustainable Chemical Processes 1: 1-31. doi: 10.1186/2043-7129-1-1
    [49] Ma G, Hu W, Pei H, et al. (2016) In situ heterogeneous transesterification of microalgae using combined ultrasound and microwave irradiation. Energ Convers Manage 90: 41-46.
    [50] Kanitkar AV, Master’s Thesis. Lousiana State University, Baton Rougue, LA.2010
    [51] Kanitkar A, Balasubramanian S, Lima M, et al. (2011) A critical comparison of methyl and ethyl esters production from soybean and rice bran oil in the presence of microwaves. Bioresource Technol 102: 7896-7902.
    [52] Balasubramanian S, Allen JD, Kanitkar A, et al. (2011) Oil extraction from Scenedesmusobliquus using a continuous microwave system--design, optimization, and quality characterization. Bioresource Technol 102: 3396-3403.
    [53] Stavarache C, Vinatoru M, Maeda Y, et al. (2007) Ultrasonically driven continuous process for vegetable oil transesterification. Ultrason Sonochem 14: 413-417.
    [54] Santos FFP, Rodrigues S, Fernandes FAN (2009) Optimization of the production of biodiesel from soybean oil by ultrasound assisted methanolysis. Fuel Process Technol 90: 312-316. doi: 10.1016/j.fuproc.2008.09.010
    [55] Cintas P, Mantegna S, Gaudino EC, et al. (2010) A new pilot flow reactor for high intensity ultrasound irradiation. Application to the synthesis of biodiesel. Ultrason Sonochem 17: 985-989. doi: 10.1016/j.ultsonch.2009.12.003
    [56] Chisti Y (2013) Constraints to commercialization of algal fuels. J biotechnol 167: 201-214.
    [57] Brentner LB, Eckelman MJ, Zimmerman JB (2011) Combinatorial Life Cycle Assessment to Inform Process Design of Industrial Production of Algal Biodiesel. Environ Sci Technol 45: 7060-7067. doi: 10.1021/es2006995
    [58] Campbell PK, Beer T, Batten D (2011) Life cycle assessment of biodiesel production from microalgae in ponds. Bioresour Technol 102: 50-56. doi: 10.1016/j.biortech.2010.06.048
    [59] Chowdhury R, Viamajala S, Gerlach R (2012) Reduction of environmental and energy footprint of microalgal biodiesel production through material and energy integration. Bioresour Technol 108: 102-111.
    [60] Clarens AF, Nassau H, Resurreccion EP, et al. (2011) Environmental Impacts of Algae-Derived Biodiesel and Bioelectricity for Transportation. Environ Sci Technol 45: 7554-7560. doi: 10.1021/es200760n
    [61] Frank ED, Palou-Rivera I, Elgowainy A, et al. (2011) Life- Cycle Analysis of Algal Lipid Fuels with the GREET Model; Argonne National Laboratory: Argonne, IL, 2011.
    [62] Khoo HH, Sharratt PN, Das P, et al. (2011) Life cycle energy and CO2 analysis of microalgae-to-biodiesel: Preliminary results and comparisons. Bioresour Technol 102: 5800-5807.
    [63] Razon LF, Tan RR (2011) Net energy analysis of the production of biodiesel and biogas from the microalgae Haematococcus pluvialis and Nannochloropsis. Appl Energy 88: 3507-3514. doi: 10.1016/j.apenergy.2010.12.052
    [64] Sander K, Murthy G (2010) Life cycle analysis of algae biodiesel. Int J Life Cycle Assess 15: 704-714.
    [65] Sawayama S, Minowa T, Yokoyama SY (1999) Possibility of renewable energy production and CO2 mitigation by thermochemical liquefaction of microalgae. Biomass Bioenergy 17: 33-39. doi: 10.1016/S0961-9534(99)00019-7
    [66] Shirvani T, Yan X, Inderwildi OR, et al. (2011) Life cycle energy and greenhouse gas analysis for algae-derived biodiesel. Energy Environ Sci 4: 3773-3778. doi: 10.1039/c1ee01791h
    [67] Vasudevan V, Stratton RW, Pearlson MN, et al. (2012) Environmental Performance of Algal Biofuel Technology Options. Environ Sci Technol 46: 2451-2459. doi: 10.1021/es2026399
    [68] Chisti Y (2008) Biodiesel from microalgae beats bioethanol. Trends in Biotechnology 26: 126-131. doi: 10.1016/j.tibtech.2007.12.002
    [69] Fast SA, Kokabian B, Gude VG (2014) Chitosan enhanced coagulation of algal turbid waters–Comparison between rapid mix and ultrasound coagulation methods. Chem Eng J 244: 403-410. doi: 10.1016/j.cej.2014.01.081
    [70] Fast SA, Gude VG (2015) Ultrasound-chitosan enhanced flocculation of low algal turbid waters. J Ind Eng Chem 24: 153-160. doi: 10.1016/j.jiec.2014.09.023
    [71] Patil PD, Gude VG, Mannarswamy A, et al. (2011) Optimization of direct conversion of wet algae to biodiesel under supercritical methanol conditions. Bioresource Technol 102: 118-122. doi: 10.1016/j.biortech.2010.06.031
    [72] Patil PD, Gude VG, Mannarswamy A, et al. (2011) Optimization of microwave-assisted transesterification of dry algal biomass using response surface methodology. Bioresource Technol 102: 1399-1405. doi: 10.1016/j.biortech.2010.09.046
    [73] Martinez-Guerra E, Gude VG (2016) Energy analysis of extractive transesterification of algal lipids for biocrude production. Biofuels, in press.
    [74] Yang J, Xu M, Zhang X, et al. (2011) Life-cycle analysis on biodiesel production from microalgae: water footprint and nutrients balance. Bioresource Technol 102: 159-165.
    [75] Bligh EG, Dyer WJ (1959) A rapid method of total lipid extraction and purification. Biochem Cell Bio 37: 911-917
    [76] Folch J, Lees M, Sloane Stanley GH (1957) A simple method for the isolation and purification of total lipides from animal tissues. J Biol Chem 226: 497-509.
    [77] Gude VG (2015) Synergism of microwaves and ultrasound for advanced biorefineries. Resource-Efficient Technologies 1: 116-125. doi: 10.1016/j.reffit.2015.10.001
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