A comprehensive study of potential Arthrospira platensis cultivated in var‐ ious manure‐based media for biodiesel feedstock

Arthrospira platensis has emerged as a promising biodiesel feedstock due to its rapid growth and substantial biomass. In efforts to reduce production costs, researchers have explored alternative media derived from livestock waste to modify conventional mediums for Arthrospira platensis cultivation. The experimental design of this research employed a Completely Randomized Design, with treatments comprising inorganic fertilizer (A), chicken manure (B), cow manure (C), and goat manure (D). The livestock manures were macerated for seven days before being utilized as A. platensis medium. The results revealed significant ( p < 0.05) impacts of different media on peak growth values and biomass production, reaching 2.03 ± 0.06 g/L and 1.76 ± 0.05 g/ L, respectively for chicken manure. The highest peak lipid content was observed in A. platensis cultured in goat manure medium. This study recommends goat manure as the preferred medium for mass cultivation of A. platensis . Mass cultivation in goat manure medium yielded 1.53 kg of dried biomass, with a lipid content of 1.91% and a biodiesel yield of 1.65%. The predominant fatty acid in this biodiesel was heneicosane, constituting 26.4% of the total area.


Introduction
Arthrospira platensis is a type of cyanobacteria belonging to microalgae, which has been recognized as a food source in the future (Costa et al. 2019) because of its good nutri tional properties.The nutrients contained in A. platensis are very diverse (Braga et al. 2018) including protein, vi tamins and various other minerals (Trivedi et al. 2015; Lu patini et al. 2017; AbdelMoneim et al. 2022).Arthrospira platensis has a high lipid content which is consisted of es sential fatty acids and lipid soluble antioxidants, so it can be used as a lipid source for many purposes (Bhakar et al. 2013; Vo et al. 2017; Kalsum et al. 2019; Hindarti and Ayuningtyas 2020).
Arthrospira platensis as lipid source already be ex plored for its potential biodiesel feedstock.For the ex ample, Arthrospira maxima's lipid can be converted into biodiesel with the biodiesel yield is 86.1%.The qual ity of the biodiesel based on A. maxima is within the standards limit of biodiesel (Rahman et al. 2017).Fur thermore, A. platensis algae oil can be converted to 98.45% biodiesel through transesterification process with [Cu (H 2 S) (H 2 O) 2 ] complex as a catalyst (Haghighi et al. 2022).The certain research revealed that in situ trans esterification process applied to Arthrospira platensis's oil which could yield 84.7% of biodiesel (ElShimi et al. 2013).
The engineering microalgae becomes the concerned biodiesel feedstock that could be cultivated in wastewater.This microalgae biodiesel refinery should be conducted along with development of wastewater proposal industry (Chen et al. 2020).Therefore, utilization of wastewater in microalgae cultivation can reduce cost production during cultivation and pollution in environment.One of wastewa ter that provides huge amount of nutrients is livestock ma nure.
Livestock manure is waste generated from livestock activities.Chicken, cow, and goat are livestock types that are commonly raised by people for consumption purpose.The nutrients content in those livestock manures are po tential to fertilize the growth of A. platensis as biodiesel feedstock.However, the supplied nutrients are certainly different from each manure which is affected by each live stock feed.A study revealed that organic carbon, nitrogen, and kalium content were highest in goat manure among fertilizers from cow, chicken, and goat manures.Mean while, the chicken manure served highest phosphorus con tent.Then, cow manure contained higher amount of or ganic carbon, nitrogen, and potassium than chicken ma nure (Novitasari and Caroline 2021).
In general, the primary nutrients such as nitrogen and phosphorus in those manures are the main reason of their utilization as A. platensis media.A research showed that nitrogen content of cow manure, goat manure, and chicken manure are 1.12%, 2.09%, 2.09%, respectively.Nitro gen is primary nutrient that is important for microalgae growth and biomass production (Febtisuharsi 2016).Fur thermore, diminishing nitrogen concentration could affect to decreasing the cell growth, pigments and protein con tent of microalgae, specifically Isochrysis galbana.While that treatment could increase carbohydrate and poly un saturated fatty acids contents in I.s galbana cells.Beside nitrogen, livestock manure also contains phosphorus and some trace elements (Zarrinmehr et al. 2020).Another re search showed that phosphorus content in dairy manure and broiler litter were 7 and 14 g/kg of dry weight (Li et al. 2014).While the phosphorus content of goat manure ranged 350-500 mg/L (Mbatha et al. 2021).
Investigation of appropriate livestock manure based media to support biomass and lipid production of A. platensis becomes interesting to be conducted for produc ing biodiesel.Then, identification fatty acids methyl es ter of biodiesel from A. platensis feedstock cultivated in appropriate livestock medium is needed to fulfill the lim ited information of microalgalbased biodiesel.Based on this background, it is very important to do a study on A. platensis as potential biodiesel feedstock which is culti vated in livestock media in order to produce biodiesel in expensively and effectively.This study aimed to deter mine the growth, peak population, harvested biomass of A. platensis, lipid content, biodiesel yield, and quality of biodiesel yield of A. platensisbiodiesel feedstock.

Materials and Methods
The study was conducted from August to October 2021 in Laboratory of Aquaculture Technology, Faculty of Agri culture, Malikussaleh University.Arthrospira platensis starter, as experimental object, was obtained from BBP BAP Ujung Batee, Banda Aceh.Then, observation of biodiesel quality was done in Syiah Kuala University, Banda Aceh.

Preparation of inorganic fertilized medium
Inorganic fertilized medium was a medium enriched by in organic fertilizers such as TSP, urea, and ZA.This medium was used to support the stock culture of A. platensis dur ing the research.The compositions of inorganic fertilized medium were seawater 30 ppt, TSP fertilizer 30 ppm, urea fertilizer 80 ppm and ZA fertilizer 20 ppm, EDTA 5 ppm, and FeCl 3 2 ppm, vitamin B1 0.001 ppm (Utomo et al. 2005).

Stock culture of Arthrospira platensis
Arthrospira platensis stock culture was carried out to in crease Arthrospira platensis population continuously as the object of research.Stock culture was initialized by cul turing 20% (600 mL) of Arthrospira platensis into 3,000 mL of inorganic fertilized medium.The culture was con ducted for five days, whereas in day 5, the stock culture would be renewed into new inorganic fertilized medium in same volume.

Preparation and maceration of livestock manures media
The livestock manures used were chicken, cow, and goat manures obtained from livestock activity in North Aceh Regency.The sterilized livestock manures were grinded into fine granules and sieved by small pore sieve.The livestock manures media were made by dissolving 100 g of each livestock manure into 1,000 mL of seawater sep arately (Astiani et al. 2016).Furthermore, the maceration process of livestock manures in media was conducted by allowing the media to stand for one week (7 days) in closed containers and without aeration.Then, the media were fil tered using cloth to separate the solution from its residue.The filtered livestock manure solutions in amount 150 mL were added into 2,850 mL of seawater 25 ppt.Further more, each livestock manure medium was aerated contin uously before using as culture medium.

Cultivation of Arthrospira platensis in the livestock manure media
Cultivation of A. platensis in livestock manures media was started by providing 3,000 mL of livestock manure me dia with continuous aeration.A total of 600 mL (20% starter) of A. platensis inoculum was added into each live stock manure medium.Furthermore, A. platensis cultiva tion was maintained for 7 days with 24hour lighting using a 20 watt TL lamp (intensity 2,000 lux).The containers of cultivation were closed with transparent cover to prevent contamination (Febtisuharsi 2016).
Harvesting of A. platensis was carried out in day 7 th of cultivation by flocculation method using 1 g/L of NaOH as flocculant agent.The flocculation process was carried out for 30 min then the flocs were filtered using filter papers.The filtered biomass of A. platensis was weighed as wet weight then it was dried for 24 h at 60 °C.After drying, the dried biomass was weighed again to determine its dry weight.

Lipid extraction of Arthrospira platensis
Arthrospira platensis lipid extraction was initiated by placing dried biomass into a Soxhlet flask and adding 200 mL of NHexane solvent.The lipid extraction process was carried out using the Soxhlet method with 4 h of immer sion time.Furthermore, the results of the lipid extraction from the extraction were carried out by separating the sol vent with the reactor for 30 min after that the lipid was put into the fume cupboard.The lipid content was calculated by formula:

Transesterification process of biodiesel
The transesterification process of A. platensis lipids in volved those several steps.Microalgae lipids were weighed and put into a 50 mL glass beaker.Furthermore, the KOH catalyst (1% of the pleated weight) was added to the erlenmeyer containing 1:6 methanol.Then, the mix ture of catalyst and methanol was put into a test tube and homogenized with lipids.The transesterification process was carried out for 180 min at a temperature of 50-60 °C.After that, the reaction mixture was put back into the beaker glass while the glycerol was separated.Then, the beaker glass was put into the fume cupboard to evaporate the solvent.Biodiesel yield was measured through this for mula:

Statistical Analysis
The analysis of variance was used a completely random ized design (CRD) with the significance level 0.05.The analysis of data was carried out by using SPSS 21 soft ware.Furthermore, the further test used was Tukey test to determine the significant different among the treatments.

Daily growth of Arthrospira platensis in different media
The daily growth of A. platensis cultivated in chicken, goat and cow manure media showed the better increment of growth than in inorganic fertilized medium.The daily growth of A. platensis cultured in different media had dif ferent peak value and life curve tendency.This life curve was determined by dried biomass harvested in each day for seven days of cultivation.The life curve of A. platen sis cultured in different media is shown by Figure 1.The result of experiment showed that A. platensis achieved its full life cycle.Most A. platensis in inorganic fertilizer, chicken manure, and goat manure media might suffer adaptation phase from day 0 until day 1 st .Then, A. platensis in inorganic fertilizer and chicken manure media achieved its exponential phase from day 1 st until day 2 nd , meanwhile A. platensis in goat manure medium needed longer time to get exponential phase than those two media, namely in day 3 rd .Stationary phase of A. platensis in in organic fertilizer and chicken manure media was achieved after day 2 nd to day 3 rd , while A. platensis in goat manure medium achieved its stationary phase after day 3 rd to day 4 th .Finally, the declining phase was reached in day 5 th for cultivation in chicken and goat manure media and in day 6 th for cultivation in inorganic fertilizer.However, the growth of Arthrospira platensis's cells in cow manure medium was slight increase during experiment.
The life cycle of A. platensis in inorganic and chicken manure media showed abnormal growth tendency which suffered the decrease of cells after reaching lag phase in day 2 nd .This condition might be caused by proportion of nitrogen and phosphorus in both of media could not sup port the growth of A. platensis.The data of nitrate as ni trogen source and phosphate as phosphorus source in each medium is shown by Table 1.
Figure 2 shows the peak value of A. platensis's growth in this experiment.The peak value of growth of A. platen sis cultured in chicken manure added medium became the highest value, namely 2.03 g/L in dried biomass.Then, A. platensis cultured in goat manure added medium re sulted the second highest value of growth peak for seven days cultivation.Meanwhile, the lowest peak value of A. platensis growth was shown by cow manure added medium which was not significant different from inor ganic fertilized medium (p > 0.05).In general, different media affected significantly on peak value of Arthrospira platensis's growth at confidence level of 95% (p < 0.05).

Biomass production of Arthrospira platensis
Based on the experiment, different media in cultivation of A. platensis also significantly affected the biomass pro duction of A. platensis (p < 0.05).Biomass production of A. platensis cultured in inorganic fertilized medium was different from A. platensis cultured in livestock manure media.The highest biomass production was shown by chicken manure medium with the value 1.76 g/L (dried biomass).Then it was followed by A. platensis biomass production from cow manure medium.Meanwhile, the lowest biomass production of A. platensis was shown by inorganic fertilized medium which was 1.37 g/L (dried biomass).The biomass production of A. platensis cultured in different media can be seen on Figure 3.

Daily lipid content
Daily lipid content of A. platensis was evaluated after de termining the potential media based on its growth and biomass production.The measurement of daily lipid con tent purposed to determine the appropriate time of harvest ing A. platensis that had the best lipid productivity.Daily lipid content of Arthrospira platensis cultivated in live stock manure media is shown by Figure 4.
Based on the graph, production of lipid content in A. platensis's cells fluctuated during cultivation.In general, lipid content dropped in exponential phase until station ary phase, namely from day 2 to 5. Then it dramatically increased in phase of mortality of A. platensis's life cy cle, which was in day 6.This phenomenon was related to biomass production of A. platensis.According to its lipid content and biomass production, the day which showed the best lipid productivity could be determined.
Different from cow and goat media, chicken manure medium showed the peak lipid content in day 5 th , then it decreased drastically after day 5 th .This result implied that accumulation of lipid in A. platensis's cells was used as energy to adapt for lack nutrition in medium and to re generate its new cells in its exponential phase.Lipid con tent peak (Figure 4) showed different tendency from cell growth of A. platensis (Figure 1).During its reproduction from lag phase to exponential phase, the cells would con  sume much energy, therefore energy accumulated in lipid form would be limited in the cells of A. platensis.It means that highest cells production in medium, lowest lipid con tent in cells.Therefore, lipid content pattern of A. platen sis in chicken manure medium would adjust its life cycle pattern in that medium.
Beside of determining the appropriate harvesting time based on its lipid productivity, this result was also useful to determine the best cultivation medium used for huge cul tivation purpose.The goat manure added medium was the good medium which supported lipid production at 4.215% in A. platensis's cells.While, the chicken manure and cow manure showed less lipid content than goat manure.Therefore, the chosen medium was goat manure added medium.

Biodiesel production of Arthrospira platensis cultivated in goat manure added media
The experiment was continued to massive scale cultiva tion of A. platensis in goat manure added medium.The purpose of this step was to evaluate the biodiesel yield of A. platensis cultivated in goat manure added media.The result of this study was shown by Table 2.
A. platensis cultured in goat manure added medium in volume 1,000 L and harvested in day 4 th could result 11,800 grams of wet biomass then it became 1,300 g of dried biomass.The water content of Arthrospira platen sis in this study was 88.98%.Lipid content resulted by A. platensis was 1.91% which was categorized as low lipid source.Then, biodiesel yield of A. platensis through trans esterification process was 1.65% from its lipid content.

Quality of Arthrospira platensis based biodiesel
Biodiesel resulted from A. platensis biomass was mea sured to evaluate the fatty acids composition in the biodiesel.The result of biodiesel quality is shown by Fig ure 5.
The highest peak was achieved by fatty acid hene icosane with area 26.4%.Then, the second highest peak in biodiesel quality was achieved by 9octadedecenoic acid methyl ester (CAS) with area 24.92%.Furthermore, it was followed by linoleic acid ethyl ester with area 17.47%.

Discussion
This study showed that the livestock manures could af fect A. platensis growth and biomass production which are shown by Figure 2 and Figure 3.Those impacts were bet ter than was in inorganic fertilized medium that contained nutrients compounds in such as nitrogen, phosphorus, and some trace elements in inorganic form.The reason was that the total number of nutrients and their forms sup plied by livestock manures and inorganic fertilizer were different.The restricting factor which was important for cyanobacteria's life was carbon (C), in where the propor tion of carbon in inorganic fertilized medium was sus pected lower than was in livestock manures media.These conditions actually could affect nutrients uptaking ability of A. platensis.
The growth of microalgae basically is affected by some factors.The important factors that should be con sidered are light intensity, salinity, pH, temperature, nu trients availability, CO 2 , and dissolved oxygen concen tration.Those factors can be optimized to gain the opti mal biomass productivity of microalgae (Chowdury et al. 2020).The nutrients availability mentioned is the avail ability of inorganic nutrients mainly nitrogen and phos phorus, and also organic and inorganic carbon, which are absorbed by microalgae (Lage et al. 2021).
Indonesian Journal of Biotechnology 29(1), 2024, 8-17  Arthrospira platensis cultured in inorganic fertilized and chicken manure added media had peak value of growth on day2 of cultivation (Figure 1).While, A. platensis cul tivated in goat manure added medium had a peak value of growth on day3 of cultivation.However, the growth of A. platensis cultivated in cow manure added medium had a slight growth during seven days of cultivation.In gen eral, the exponential phase of A. platensis occurred in day 2 nd to day 3 rd then it is continued in second cycle in day 6 th to day 7 th during the experiment.Increment of life curve of A. platensis was a characteristic of exponential phase of A. platensis's life.It meant that producing biomass was highest compared to other phases of life.
The life cycle of Arthrospira platensis in normal pH 8.0 showed the exponential phase on day 3 to day 5.Meanwhile, increment of medium pH would extend the lag phase of A. platensis (Putri 2019).Furthermore, Arthrospira platensis cultured in vannamei culture waste water showed the exponential phase in day 3 rd to day 6 th of cultivation, while the stationary phase was on day 7 th and the declining phase was on day 8 th (Hartami et al. 2022).Generally, peak value of Arthrospira platensis's biomass is started on day 3 rd of cultivation which consider in the exponential phase.
Based on the Figure 1, livestock manures added into media gave better performance of A. platensis's growth than inorganic fertilized medium.This result was caused by micro nutrients of livestock manures which were more complete than inorganic fertilizer.Using livestock ma nure could help forming ion particles in medium so that A. platensis could absorb the nutrients easily.The growth performance of A. platensis in this study was similar to the experiment conducted by Astiani et al. (2016).Those experiment showed that the different livestock manures, namely chicken manure, bird manure, buffalo manure and cow manure could give significantly to affect (pvalue < 0.05) on growth rate and biomass production of A. platen sis.
The growth of A. platensis in the inorganic fertilized medium and chicken manure added medium increased in the first day to second days, then decreased on the third to fifth day.Meanwhile, for goat manure added medium, the daily growth of A. platensis increased on the first up to third days, then decreased on the fourth and fifth days.This life cycle showed that A. platensis cultured in inor ganic fertilized medium and livestock manure added me dia needed five days for its life period.Life cycle of A. platensis related to the activity of A. platensis cell division phase.Whereas the cell division phase indicated the avail ability of nutrients in the media fulfilling the Arthrospira platensis's life needs.Muliani et al. (2018) stated that the growth of microal gae is strongly influenced by several factors, including nutrient content in the media, water quality, quantity and quality of microalgae starter.Another study got the sim ilar results to this study, in where the exponential phase of Arthrospira platensis occurred on the second day.Fur thermore, for the stationary phase, Arthrospira platensis's growth decreased on the third to fifth day which indicated that the nutrients contained in the media had begun to de crease and caused the cell division process to be hampered (Astiani et al. 2016).Rusydi (2018) revealed that nitrogen and phosphate contained in animal manure can stimulate the growth kinetics of microalgae and cyanobacteria (including A. platensis).Then nitrogen, phosphorus and potassium in livestock manure are very important nutrients for growth of microalgae (Febtisuharsi 2016).The experi ment suggests that the use of waste especially livestock waste becomes potential to be explored in microalgae and cyanobacteria development as biodiesel feedstock.
The experiment revealed that different media in cultivation of A. platensis significantly affected the biomass production of A. platensis (p < 0.05) (Figure 3).Arthrospira platensis cultured in inorganic fertil ized medium produced a distinct biomass compared to that which was cultivated in livestock manure media.The medium composed of poultry manure exhibited the greatest biomass production, measuring 1.76 g/L (dry biomass).The production of biomass by A. platensis in a medium containing bovine manure followed.Con versely, inorganic fertilized medium exhibited the least biomass production of A. platensis, measuring 1.37 g/L (dried biomass).
The highest biomass production was reached by Arthrospira platensis in chicken manure was not dif ferent significantly (p > 0.05) from Arthrospira platen sis's biomass from cow and goat manure added me dia.In general, livestock manure media could support the biomass production better than inorganic fertilizer medium.Utilization of livestock manures known as poul try waste exactly could optimize the biomass production of Arthrospira platensis.
Utilization of wastewater as Arthrospira platensis's medium was also done by Zhai et al. (2017).Their ex periment showed that using synthetic municipal wastew ater (SWW) could enhance the biomass production of Arthrospira platensis in total of number 262.5 mg/L.This strategy was a good choice for optimizing the microalgal production and treating the wastewater in controlled envi ronment Zhai et al. (2017).
The growth of Arthrospira platensis in various me dia during experiment was evaluated for seven days of cultivation.Generally, Arthrospira platensis needed five days for its full life cycle and continued to conduct the next life cycle along the availability of nutrients in me dia.Therefore, limited nutrients in those used media af fected the biomass production which was harvested on day 7 th .However, chicken manure medium still supplied the enough nutrients supporting the biomass production of Arthrospira platensis.
At harvested time (day 7 th ), Arthrospira platensis gen erally already reached the stationary phase in its life.The absorbance of nutrients during stationary phase in fluenced the forming new cells of Arthrospira platensis to form biomass.This statement was similar to certain study, in where the longer the stationary phase needed by Arthrospira platensis in absorbing the nutrient content in the media, the more the amount of biomass will increase (Jati et al. 2012).
Beside of determining the biomass production of Arthrospira platensis, the evaluation of lipid content dur ing cultivation was also important tobe considered for lipid productivity of Arthrospira platensis.Analysis of the lipid content was conducted on Arthrospira platensis cultured in livestock manures media.In general, daily lipid con tent of Arthrospira platensis suffered fluctuation during seven days of cultivation.The goat manure added medium reached a peak at 4.215% in day 6 th and became the high est lipid content among the media else.Lipid content of those Arthrospira platensis can be seen on Figure 4.The potential of goat manure as material for microal gae medium is also revealed by Sopandi et al. (2020).Adding goat compost give an effect to biomass produc tion, in where 25 g/L of goat manure certainly result low biomass and high lipid content of Arthrospira platensis.Meanwhile, 100 g/L of goat manure encourage biomass and protein production of Arthrospira platensis but its lipid content was lower than was in 25 g/L of goat manure.
Different livestock manures added media resulted dif ferent daily lipid content of Arthrospira platensis.Daily lipid content curve showed that the lowest lipid content occurred on day 2 until day 5 whereas on those days Arthrospira platensis started to grow fastly called expo nential phase.Energy obtained from absorbed nutrients was used to form new cells of Arthrospira platensis and yielded huge biomass during exponential phase and sta tionary phase.Availability of abundant nitrogen and other nutrients leaded growth of cells of Arthrospira platensis.Therefore, forming lipid content was less during that time.
In contrast, lipid content was growing up after station ary phase ended, namely on day 5 to day 7. Tendency of forming new cells in stationary phase was low, so energy was accumulated as lipid content in its cells.Rusydi et al. (2015) revealed that the relation of both nitrogen consump tion rate and specific growth rate on Nostoc muscorum was a linear positive.The decreasing of total lipid in N. musco rum implied that there was a good growth of cells of Nos toc muscorum.The previous study of Mata et al. (2016) also showed contrast tendency of both biomass and lipid content.Their study resulted that stress condition could induce lipid accumulation in A. platensis and C. vulgaris but it was also followed by decreasing the biomass pro ductivity of both microalgae.
The next investigation was determining biodiesel yield of A. platensis cultured in goat manure added medium in large scale.The experimental result showed that biodiesel yield of A. platensis was very low, namely 1.65% from its lipid yield.This result could be caused by low lipid content extracted from Arthrospira platensis, therefore fatty acids that could be converted into biodiesel were also low.This result is not in same line with the result revealed by El Shimi et al. (2013).That study showed that the biodiesel yield of A. platensis by in situ transesterification is 84.7%.
Biodiesel yield resulted through transesterification process is actually affected by molar ratio of alcohol, presence of water and free fatty acid content, reaction temperature, catalyst concentration and agitation speed (Mathiyazhagan and Ganapathi 2011).Therefore, low yield of biodiesel from feedstock Arthrospira platen sis could be caused by low free fatty acid content in Arthrospira platensis's lipid and presence of hexane as lipid extraction solvent.
Characteristics of fatty acid methyl ester in biodiesel is one of important measurement for suitable biodiesel.Based on this findings, heneicosane became the dominant fatty acid in A. platensis based biodiesel with the area 26.4%.Then, it was followed by 9octadedecenoic acid methyl ester (CAS) and linoleic acid ethyl ester with each area 24.92% and 17.47%.
This result was not similar to the findings of ElShimi et al. ( 2013).The biodiesel from A. platensis had high palmitic acid (C16:0) with percentage 48.35%.Then, the study of (Pradana et al. 2020), the composition of fatty acids in biodiesel produced from A. platensis were con sisted of high methyl oleate, methyl palmitate, and low methyl stearate.

Conclusions
Different media influenced significantly (pvalue < 0.05) on peak value of growth and biomass production of A. platensis.The livestock manures media supported the better daily growth of A. platensis than inorganic fertil ized medium.The highest peak value of growth and biomass production were produced by chicken manure added medium.The daily lipid content of A. platensis cul tivated in livestock manures media showed different day of peak lipid content.The highest peak value of lipid con tent was showed by A. platensis cultured in goat manure added medium.However, the biodiesel yield of A. platen sis cultivated in goat manure added medium was low.He uneicosane was the most predominant fatty acid in this biodiesel derived from Arthrospira platensis.

FIGURE 3
FIGURE 3Biomass production of Arthrospira platensis in different media.

FIGURE 4
FIGURE 4Daily lipid content of Arthrospira platensis in different media.

FIGURE 5
FIGURE 5Fatty acids peaks contained in Arthrospira platensis based biodiesel using GC-MS.

TABLE 1
Nitrate and phosphate content of each medium for Arthrospira platensis cultivation.
Phosphate (mg/L) 1.9 32.2 7.45 7.65 1.3 25.25 4.75 4.95 Note: A : Inorganic medium B : Chicken manure medium C : Cow manure medium D : Goat manure medium FIGURE 1 Daily growth of Arthrospira platensis in different media.FIGURE 2 Peak value of Arthrospira platensis's growth in different media.

TABLE 2
Biomass, lipid, and biodiesel production of Arthrospira platensis cultured in goat manure added medium.

TABLE 3
Fatty acids composition in Arthrospira platensis based biodiesel.