Review Article Coupling of Algal Biofuel Production …downloads.hindawi.com/journals/tswj/2014/210504.pdfphotosynthetic pigment [ ]. Algae can be divided into two main categories,

Review ArticleCoupling of Algal Biofuel Production with Wastewater

Neha Chamoli Bhatt Amit Panwar Tara Singh Bisht and Sushma Tamta

Algae Laboratory Department of Biotechnology Kumaun University Bhimtal Campus Bhimtal Nainital Uttarakhand-263136 India

Correspondence should be addressed to Neha Chamoli Bhatt nehachamoli2508gmailcom

Received 19 February 2014 Accepted 13 March 2014 Published 26 May 2014

Academic Editors Y-C Yong S-G Zhou and L Zhuang

Copyright copy 2014 Neha Chamoli Bhatt et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Microalgae have gained enormous consideration from scientific community worldwide emerging as a viable feedstock for arenewable energy source virtually being carbon neutral high lipid content and comparatively more advantageous to othersources of biofuels Although microalgae are seen as a valuable source in majority part of the world for production of biofuelsand bioproducts still they are unable to accomplish sustainable large-scale algal biofuel production Wastewater has organicand inorganic supplements required for algal growth The coupling of microalgae with wastewater is an effective way of wasteremediation and a cost-effective microalgal biofuel production In this review article we will primarily discuss the possibilities andcurrent scenario regarding coupling of microalgal cultivation with biofuel production emphasizing recent progress in this area

1 Introduction

World biofuel production has increased sevenfold since 2000but still meets only 23 of final liquid fuel demands [1]Worldwide energy consumption is projected to increase by49 from 522 exajoules (EJ) in 2007 to 780 EJ in 2035 [2]It is expected that two main energy resources crude oil andnatural gas will be diminished by 457 and 628 years andestimated energy requirement will be tripled in 2025 [3]Transportation is one of the fastest growing sectors using27 of primary energy in current scenario and in Indiaannual oil consumption is about 55 which is going toincrease in the next decade [4] Currently in India dieselalone meets an estimated 73 of transportation fuel demandfollowed by gasoline at 20 moreover it is estimated thatby the end of this decade the average demand for transportfuels will rise from an estimated 117 billion litres in 2013to 167 billion litres and would grow further to reach 195million liters by 2023 [5] Fossil fuels make up 88 and862 of the energy consumed by the world and USA [6]The transportation and energy sectors are the major sourcesin European Union (EU) responsible for more than 20and 60 of greenhouse gas (GHG) emissions respectively[7] It is fully accepted that global warming increases inresponse to (GHG) emissions [8] which reveals that there

is vital need for cleaner alternative to fossil fuels Due tocontinuous depletion of natural resources emerging energycrisis and increasing fuel prices demands for an alternativescalable and sustainable energy source Moreover the entireglobe is facing two major challenges of freshwater shortageand energy crisis [9] Recently renewable energies includingwater wind solar geothermal and especially biofuels havegained much attention as a substitute to conventional energyresources as they are sustainable ecofriendly and carbonneutral and have potential to fulfil the energy needs of thetransportation sector

Microalgae have potential to become an alternativesource of petrodiesel due to their sustainable photosyn-thetic efficiency ecofriendly approach increasing depletionof nonrenewable energy resources and use of nonarable landCoupling wastewater with microalgae cultivation can be apromising approach for biofuel production This integra-tion can offer an economically viable and environmentallyfriendly means for sustainable algal biofuel production sinceenormous amounts of water and nutrient (eg nitrogen andphosphorus) can be recycled for algal growth in wastewater-based algal cultivation system [10 11] Microalgae have dualapplication of biomass production for sustainable biofuelsproduction and phycoremediation [12] They have higherphotosynthetic efficiency and lipid content which can be

Hindawi Publishing Corporatione Scientific World JournalVolume 2014 Article ID 210504 10 pageshttpdxdoiorg1011552014210504

2 The Scientific World Journal

harnessed for biofuels including biodiesel bioethanol bio-hydrogen and combustible gases Microalgal biofuel systemsare capable of producing clean and sustainably produced fuelsfor the future while eradicating the food versus fuel and forestversus fuel concerns associated with first generation biofuelsand lignocellulosic processes based on wood feedstocks [13]Although there had been enough debate on algal biofuelsstill they are not commercialized as their economic viabilityis questionable Despite being so advantageous the technoe-conomics of present microalgal biofuel production systems isnot effective to compete with petroleum-based conventionalfuels as it is accompanied with high cost production Themajor expenditure of a current algae biofuel technologydepends on algae cultivation system harvesting and lipidextraction methods But certainly their outlook is promisingand both the developed nations and the emerging economiesare interested in algal fuels [14]

2 Microalgae Advantages asa Source of Biofuel

Microalgae are prokaryotic or eukaryotic photosyntheticmicroorganisms some of which can also form a chain orcolony ranging from a few micrometers to a few hundredmicrometers and are generally ubiquitous in nature Algae area broad category that has no proper taxonomic classification[15] They are primitive plants (thallophytes) that is lackingroots stems and leaves have no sterile covering of cellsaround the cells and have chlorophyll as their primaryphotosynthetic pigment [16] Algae can be divided into twomain categories that is macroalgae which are multicellularand size up to several meters and microalgae are small sizeorganisms ranging from sizes 02 120583m to 100 120583m or evenhigher [17] Microalgae have high rate of areal biomassproductivity compared to traditional agricultural crops likecorn and soya bean and oil content in microalgae can exceed80 dry weight of biomass [18] Generally algae are dividedinto five main groups

(i) blue-green algae (Cyanophyceae)(ii) green algae (Chlorophyceae)(iii) diatoms (Bacillariophyceae)(iv) red algae (Rhodophyceae)(v) brown algae (Phaeophyceae)

Although Cyanobacteria (blue-green algae) are classified tothe domain of bacteria being photosynthetic prokaryotesthey are often considered as ldquoalgaerdquo [19] There are manypromising attributes of microalgae which make them desir-able for biofuel production The main source of carbon forthe growth of microalgae is atmospheric carbon dioxide [20]Severalmicroalgae species can growwell onnonpotablewater(brackish wastewater and seawater) their is a possibilitythat biofuel production can be coupled with one of thesesystems in future This coupling does not compete for arableland which can be used for agricultural purpose and also foreliminating the use of freshwater resources The productionof biofuels from algae can be coupled with flue gas CO

2

mitigation wastewater treatment and production of high-value chemicals [21 22] Many species of microalgae producesignificant quantities of lipids which can be converted tobiodiesel through process of transesterification Microal-gal biodiesel has characteristics related to petroleum-baseddiesel including density viscosity flash point cold flow andcalorific valueMicroalgae can be harvested batch-wise nearlyall year round providing a reliable and constant supply ofoil [20] Microalgae does not require the use of chemicalunlike terrestrial plants requiring herbicides or pesticideswhich affect the environment adversely and increase thecost of production Lignin is generally absent in microalgaeand other large biopolymers (found in woody biomass) thatmay hinder with biomass processing and conversion [23]Apart from this the residual algal biomass mainly composedof proteins and carbohydrates can be processed to variousbiofuels including methane and alcohol fuels and it can alsoproduce other nonfuel coproducts which can be recoveredand formulated into products with high market value suchas nutriceuticals therapeutics and animal feeds [24]

3 Microalgal Farming Using Wastewater forBiofuel Production

Due to global expansion of human population and advancedliving standards of people a high level of water pollu-tion is generated worldwide Wastewater is basically endproduct generated by domestic municipal agricultural andindustrial sources [25] The composition of wastewater isa reflection of the life styles and technologies practiced inthe producing society [26] Wastewater generally containsorganic mass like proteins carbohydrates lipids volatileacids and inorganic content containing sodium calciumpotassium magnesium chlorine sulphur phosphate bicar-bonate ammonium salts and heavy metals [27] Excess ofthese nutrient loads in surrounding water bodies causeseutrophication or algal blooms often due to anthropogenicwaste production

More than 300 million tonnes of biodegradable house-hold and household-like wastes industrial wastes and otherwastes are generated every year in the European Unionand stay mostly unexploited [45] Human beings generateapproximatelysim3 billion tonnes of domesticwastewater everyyear [46] In India annually due to migration of people intocities the figures are expected to reach about 600 millionby 2030 making and simultaneously increasing pressure onurban return flow (wastewater) which is usually about 70ndash80 of the water supply [47] The recent reports of CentralPollution Control Board [48] NewDelhi India revealed thatthe wastewater generation in the nation is around 40 billionlitres per day largely from urban areas and ironically only 20ndash30 of the generated wastewater is subjected to treatmentIn majority of the developing nations the main sources ofwastewater generation are domestic municipal agriculturaland industrial activities which are foremost released intoenvironment without having sufficient treatment steps Manyspecies of microalgae are able to efficiently grow in waste-water environment through their capability to use abundant

The Scientific World Journal 3

organic carbon and inorganic N and P in the wastewater [11]Algae take up these nutrients along with CO

2and produce

biomass through the process of photosynthesis Microalgaeare the main microorganisms used in treatment of domesticwastewater in units such as oxidation ponds or oxidationditches Algae have also been deployed for low cost andenvironmentally friendly wastewater treatment [49ndash51] Theidea of coupling of wastewater as a medium for biofuelproduction from algae is not innovative as it was previ-ously suggested in report of the Aquatic Species Program(ASP) conducted from 1978 to 1996 USA [10] The mainconstraint for wastewater-based algae biofuel productionsystem is to find ideal microalgae strains which could beable to grow in wastewater environment with significantnutrient removal efficiency showing high biomass and lipidproductivity

Extensive work has been conducted by researchers [3537 40 52ndash54] from numerous parts of the world to explorethe feasibility of using microalgae for biofuel potentialfrom wastewater with nutrient removal property particularlynitrogen and phosphorus from effluents Researchers hadmore focus on microalgal culture for N and P removal fromdomestic sewage in comparison to industrial wastewaterThe reason behind this is that industrial wastewater such astannery wastewater and chemical industry wastewater hasmore metal ions in addition to various organic N and Pcompounds [39] and it is more toxic having heavy metalcontamination which does not facilitate the algal growthThe total biofuel potential of algae when grown in domesticwastewater generated by 1000 urban centres in India is sim016Mtannum considering the lipid fraction as 20 [55]

31 Biomass Production from Wastewater Grown MicroalgaeSpecies selection optimization of growth lipid content andharvesting at large scale are the important factors whichgovern the commercialization potential of algal biofuels Thealgal biomass produced and harvested from these wastewatertreatment systems could be transformed through a varietyof pathways to biofuels for example anaerobic digestion tobiogas transesterification of lipids to biodiesel fermentationof carbohydrate to bioethanol and high temperature alter-ation to biocrude oil [56] Economic feasibility of algal biofuelproduction from wastewater treatment can be achieved byhigh rate algal ponds (HRAPs) with low environmentalimpact compared to commercial algal production by HRAPswhich consume freshwater and fertilisers [57] The majorchallenge in themicroalgae research for the existing high rateponds is designing an efficient and economical carbonationsystem to fulfill the needs of high CO

2requirement that

might improve the biomass productivity [58] Viswanath andBux [59] isolated Chlorella sp from wastewater pond andscreened it for its efficiency in lipid production by culti-vating both photoautotrophic and heterotrophic conditionsin bioreactor Maximum amount of biomass was recoveredfrom the Chlorella sp grown under heterotrophic growthconditions with 890 gLminus1 compared to photoautotrophicgrowth conditions which were about 36-fold lesser thanthe former resulting in the accumulation of high lipid

3R998400OHCatalyst

Glyceride Alcohol Esters Glycerol

+ +

CH2ndashOOCndashR1

CHndashOOCndashR2

CH2ndashOOCndashR3

ndashndashndash ndash

CH2ndashOHCHndashOH

CH2ndashOH

R1ndashCOOndashR998400



Figure 1 The chemical reaction of transesterification process

content in cells compared to autotrophic growth by enhanc-ing lipid production by 44-fold This study suggested thatheterotrophic growth of microalgae is an efficient methodfor the production of biomass and high lipid content inthe cells which can reduce the cost of microalgal biomassproduction

4 Harvesting Methods of Microalgae

Dewatering and harvesting of algal biomass are a necessarystep for concentrating algal biomass and for further releasingtriacylglycerols (TAGs) which can then be transesterified toproduce biodiesel (as shown in Figure 1) Harvesting anddewatering are one of the challenging areas of current biofueltechnology as microalgae have small size and low densityincreasing the capital cost The difficulty is in releasing thelipids from their intracellular location in the most energy-efficient and economical way possible avoiding the use oflarge amounts of solvent such as hexane and utilising asmuch of the carbon in the biomass as liquid biofuel aspossible potentially with the recovery of minor high-valueproducts [60] The major techniques presently applied inmicroalgae harvesting and recovery include centrifugationflocculation filtration and flotation

41 Flocculation Flocculation is a process of forming aggre-gates known as algae flocs that are often performed as a pre-treatment to destabilize algae cells fromwater and to increasethe cell density by natural chemical or physical meansChemicals called flocculants are usually added to induceflocculation and commonly used flocculants are inorganicflocculants such as alum [61 62] or organic flocculants such aschitosan [63] or starch [64] The surface charge of microalgalcells is generally negatively charged due to the ionizationof functional groups on the microalgal cell walls and alsoby the adsorption of ions from the culture medium whichcan be neutralized by applying positively charged electrodesand cationic polymers also commonly used to flocculatethe microalgal biomass This harvesting method is prettyexpensive because of the cost of flocculants hence flocculantsneed to be inexpensive easily produced and nontoxic

42 Centrifugation Centrifugation is a widely used methodof separation on the basis of particle size and density sep-aration Separation efficiency is dependent upon the size ofdesired algal species Numerous centrifugal techniques havebeen employed in various types and sizes depending on theuses such as tubular centrifuge multichamber centrifugesimperforate basket centrifuge decanter solid retaining disccentrifuge nozzle type centrifuge solid ejecting type disc


centrifuge and hydrocyclone [65] Despite being energyintensive method it is rapid and a preferred method formicroalgal cell recovery whereas cell viability was found tobe significantly dependent on the microalgal species and themethod of centrifugation [66] Even though it is very effec-tive centrifugation is considered unfeasible in large-scalealgal culture system due to the high capital and operationalcosts

43 Filtration Filtration harvests microalgal biomassthrough filters on which the algae accumulate forming thickalgae paste and allow the liquid medium to pass throughFiltration systems can be classified as macrofiltration (poresize ofgt10120583m)microfiltration (pore size of 01ndash10120583m) ultra-filtration (pore size of 002ndash2120583m) and reverse osmosis (poresize of lt0001120583m) [67] There are many different forms offiltration such as dead end filtration microfiltration ultrafil-tration pressure filtration vacuum filtration and tangentialflow filtration (TFF) [68] Nevertheless it is accompaniedwith extensive running costs and time consuming

44 Flotation Microalgae cells are trapped on microairbubbles and float at the surface of water [69] Generally theflotation efficiency is dependent on the size of the createdbubble nanobubbles (lt1120583m) microbubbles (1ndash999120583m) andfine bubbles (1ndash2mm) [70] Dissolved air flotation is awidely used technique in which microalgal cells are usuallyflocculated first and then air is bubbled through the liquidcausing the flocs to float to the surface for easier harvestingHydrophobic interaction and surface charge of microalgaeplay crucial role for attachment of microalgae to the bubbles

5 Lipid Extraction Methods

Lipid is polymer of fatty acids which is generally hydrophobicin nature and is classified as a polar (membrane lipids) andnonpolar lipid (neutral lipids) Polar lipids interact with polarsolvents like ethanol and methanol and similarly nonpolarlipids interact with nonpolar solvents like chloroform andbenzene which is the basis of designing solvent system forlipid extraction methods [71] This solvent system mainlydisrupts noncovalent interactions hydrophobic interactionsand hydrogen bonding between lipid and associated macro-molecule like protein Lipids are mainly composed of 90ndash98 (weight) of TAGs small amounts of mono- and diglyc-erides free fatty acids (1ndash5) and residual amounts ofphospholipids phosphatides carotenes tocopherols sulphurcompounds and traces of water [72] The majority of thelipid fraction is comprised of TAG content an importantparameter for biodiesel production The saturated (16 0)and monounsaturated (18 1) fatty acids also play essentialrole in determining the fuel properties of biodiesel such ascetane number oxidative stability and cold flow [73] Usuallyextraction of lipid from microalgae consists of dual stepscell disruption and solvent extraction The lipid extractionmethods might work differently on a variety of algal speciesas algae have an enormous variation in cell shape size cellwall composition and types of algal lipids

Microalgae cell disruption can be achieved by sonicationhomogenisation grinding bead beating or freezing [74]The Folch et al [75] method was originally optimized forisolation and purification of total lipids from animal tissuesis also used for the extraction of total lipids from microalgaeusing chloroform-methanol 2 1 The most commonly usedmethod for total lipid extraction from microalgae is theBligh and Dyer method [76] which uses chloroform andmethanol in 1 2 Another method for extraction of biooilor other molecule is to carry out extraction using safeand nonflammable solvent supercritical carbon dioxide (SC-CO2) which solubilizes non polar compounds when the

molecule of interest is not soluble the solvent power can beincreased using a safe and polar modifier such as ethanol[77] But it has few disadvantages it is uneconomical forlarge-scale energy-consuming step of drying pretreatmentwhich limits its application for biofuel production Rycke-bosch et al [78] optimized procedure for extraction of totaland nonpolar lipids from microalgae showing chloroform-methanol 1 1 to be the best solvent mixture for extraction oftotal lipids frommicroalgae Sathish and Sims [79] developedwet lipid extraction procedure capable of extracting 79 oftransesterifiable lipids fromwet algal biomass (84moisture)via acid and base hydrolysis (90∘C and ambient pressures)and 76of extracted lipids were further converted to FAMEsUltimately it is necessary to develop extraction methodhaving less organic solvent use reduce contamination andavoid drying of algae to obtain significant cost reduction forscaling upmass algal culture system for biodiesel production

51 Lipid Analysis Methods After lipid extraction it isimportant to identify and quantify lipid contents to screenthe desirable algal strains for their biofuel efficiency Furtherquantification of lipids requires separation of the crudeextract and quantification of the lipid fraction by thin-layerchromatography (TLC) HPLC or gas chromatography (GC)[80] The Nile red fluorescence method is also employed forthe determination of both neutral and polar lipids in algaebut has been unsuccessful in many others particularly inthose with thick rigid cell walls that prevent the penetrationof this lipid soluble fluorescence dye [81] Mostly microalgallipid profiling is done by gas chromatography with flameionization detector (GC-FID) and is carried out using themethylated ester form of the lipid [82]

52 Transesterification Transesterification or alcoholysis isthe reaction of a lipid with an alcohol to form esters and a by-product glycerol [71] This reaction actually converts highlyviscous raw lipidoil into low molecular weight molecules inthe form of fatty acid alkyl esters which can be used as analternative fuel for diesel engines Biodiesel is a term used todescribe ldquofuel comprised of monoalkyl esters of long-chainfatty acids that are derived from vegetable oils or animalfatsrdquo [83] In a typical biodiesel reaction TAGs enter intoa reaction with methanol which yields fatty acid methylesters (biodiesel) and glycerol as a waste product (as shownin Figure 1) Mainly three approaches are used to producebiodiesel they are base catalyzed transesterification acid


catalyzed transesterification (with simultaneous esterificationof free fatty acids) and noncatalytic conversion [84 85]

6 Lipid Productivity from WastewaterGrown Algae

Lipid productivity takes into account both the lipid concen-tration within cells and the biomass produced by these cellsand is therefore a more useful indicator of the potential costsof liquid biofuel production [86] High lipid productivityis a key characteristic of a microalgal species for biodieselproduction [87] Generally algae produce lipids betweenC14

and C20

in length During stressful conditions likenutrient limitation algae change their biosynthetic pathwaysand produce TAGs which accumulate in the cytoplasmfor the purpose of energy and carbon storage [88 89]Nevertheless deliberately cultivation of algae in stressfulconditions can inhibit cell division leading to decrease inoverall lipid productivity [33 90] This is one of the reasonsthat it is difficult to maximize both high biomass and lipidproductivity simultaneously But still to achieve substantialcost reduction for the commercialization of biofuel pro-duction it is suggested that the near-term research shouldbe focused on maximizing lipid content with the help ofaltering the phycological metabolism of the microalgal celland manipulation of cultivation system with the applicationof advanced engineering and design system

Although in many cases most of the microalgal speciesreported with high lipid content does not adapt well to growin wastewater many researchers had screened microalgalisolates able to grow in wastewater effluents showing highlipid content Xin et al [54] isolated a freshwater microalgaScenedesmus sp LX1 with high lipid content (around 25ndash35) from low nutrient environment and they comparedScenedesmus sp LX1 with other reported 11 oily microalgalspecies based on the growth and lipid accumulation prop-erties while growing in the secondary effluent of domesticwastewater Scenedesmus sp LX1 showed best growth andaccumulated the maximum lipid content in microalgal cellsin comparison to other microalgal species which couldnot grow in the secondary effluent of domestic wastewaterZhou et al [35] screened 17 top-performing strains iso-lated from water bodies including wastewater from Min-nesota which grew well in centrate (highly concentratedmunicipal) wastewater Five strains were promising thatis Chlorella sp Heynigia sp Hindakia sp Micractiniumsp and Scenedesmus sp regarding their ability to adaptto centrate municipal wastewater showing high growthrates (0455ndash0498 dminus1) and higher lipid productivities (745ndash778mg Lminus1 dminus1) Bhatnagar et al [52] isolated three robustmixotrophic microalgae isolated from industrial wastewaterand evaluated their growth potential in media supplementedwith different organic carbon substrates and wastewaterswhich showed 3ndash10 times more biomass production relativeto phototrophy Devi et al [53] evaluated the effect of sequen-tial growth phase (GP) and starvation phase (SP) on the lipidproductivity of heterotrophically grown mixed microalgaeusing domestic wastewater as a substrate The mixotrophic

microalgae used in this studywereChlorella Scenedesmus spCosmarium sp and facultative heterotrophs (centric and pin-nate diatoms) alongwith few photoautotrophs (Cyclotella andOedogonium) and obligate photoautotrophs (P boryanum)Effect of nutrient supplementation and the results showedthat in growth phase (GP) operation with maximum N+ P condition higher biomass (169mgmL) was observedwhile higher lipid productivity was observed in starvationphase with maximum in C condition (282) showinggood wastewater treatment efficiency in terms of substratedegradation and nutrient removal during the growth phaseoperationMoreover when supplemented with CO

2sparging

period and interval it influences growth and lipid accumula-tion of microalgae cultivated in domestic wastewater undermixotrophic microenvironment Sparging period of 120 sdocumentedmaximumbiomass growth (GP 34mgmL) andlipid productivity (SP 273) while in intervals 4 h (120 s)condition showed maximum biomass (32mgmL) and lipidproductivity (278) Fatty acid composition revealed highdegree of saturated fatty acids (SFAs) varied with theexperimental variations signifying their utility as biodiesel[91] They also documented microalgal efficiency to utilizeacid-rich effluents from biohydrogen production process ascarbon source for lipid accumulation under heterotrophicnutritional mode Two types of substrates namely syntheticvolatile fatty acids (SVFAs) and fermentative fatty acids(FFAs) collected from acidogenic H

2producing bioreactor

were used for evaluating the lipid accumulation potentialin microalgae Comparatively FFAs documented higherbiomass and lipid productivity (142mgmL (wet weight)264) than SVFAs 060mgmL 231) [92]

In another study fatty acid methyl ester (FAME) analysisof A protothecoides UMN280 showed that the microalgallipids were mainly composed of C

16C18fatty acids (account-

ing for over 94 of total fatty acid) making it suitablefor high-quality biodiesel production [36] He et al [93]checked the feasibility of cultivating Chlorella vulgaris withwastewater containing high ammonia nitrogen concentra-tions This study found that increasing NH

4

+-N from 17 to207mg Lminus1 yielded additional short-chain and saturated fattyacids Lipid productivity peaked in its value of 233mg Lminus1 dminus1at 39mgLminus1 NH

4

+-N Hence microalgae components couldbemanipulated by NH

4

+-N concentration of the initial feedsThe biomass and lipid productvities of some of themicroalgalspecies grown in different wastewater resources reported tilldate is given in Table 1

7 Nutrient Removal Efficiency

Growing algae depends on the availability of principalnutrients like nitrogen phosphorus carbon sulphur andmicronutrients including silica calcium magnesium potas-sium iron manganese sulphur zinc copper and cobaltAlgal cells have the capability to uptake nitrogen and phos-phorus fromwater [94 95]Microalgae can be efficiently usedto remove significant amount of nutrients because they needhigh amounts of nitrogen and phosphorus for protein (45ndash60 of microalgae dry weight) nucleic acid and phospho-lipid synthesis [12] The nitrogen in sewage effluent arises


Table 1 Biomass and lipid productivities of microalgae grown in different wastewater resources

Microalgae species Wastewater typeBiomass

productivity(mg Lminus1 dminus1)

Lipid content( DW)

Lipidproductivity(mg Lminus1 dminus1)

Reference

Chlorella pyrenoidosa Activated sludge extract 1155 NA NA [28]

Chlorella pyrenoidosa Digested sludgeExtract 5182 NA NA [28]

Chlorella pyrenoidosa Settled sewage 275 NA NA [29 30]Chlorella pyrenoidosa and Scenedesmus sp Activated sewage 9231 NA NA [29 30]Botryococcus braunii Secondarily treated sewage 3500 NA NA [31]

Scenedesmus sp ArtificialWastewater 12654 1280 162 [32]

Polyculture of Chlorella spMicractinium spActinastrum sp Dairy Wastewater NA 2900 17 [33]

Polyculture of Chlorella spMicractinium spActinastrum sp

Primary clarifierEffluent NA 900 244 [33]

Chlorella asccharophila Carpet mill 23 1810 42 [34]Scenedesmus sp Carpet mill 12654 1280 162 [34]

Chlorella sp Centrate MuinicipalWastewater 2314 3353 775 [35]

Hindakia sp Centrate MuinicipalWastewater 2750 2830 778 [35]


Scenedesmus sp Centrate MuinicipalWastewater 2475 3009 745 [35]

Auxenochlorella protothecoides Concentrated MuinicipalWastewater 2688 289 777 [36]

Chlamydomonas Mexicana Piggery Wastewater NA 33 plusmn 34a031 plusmn 003

a [37]Scenedesmus obliquus Piggery Wastewater NA 31 plusmn 08

a024 plusmn 003

a [37]lowastNA Not AvailableaExpressed in dwtL

primarily from metabolic interconversions of extra derivedcompounds whereas 50 ormore of phosphorus arises fromsynthetic detergents [27] Nitrogen and phosphorus are thetwo important nutrient compounds to analyze a water sourcefor potential algae growth The principal forms in whichthey arise in wastewater are NH

4(ammonia) NOminus2 (nitrite)

NOminus3 (nitrate) and PO4

3minus (orthophosphate) The nutrientremoval efficiency of some of the microalgal species reportedtill date is given in Table 2

Algal growth and nutrient removal characteristics ofmicroalgae Chlorella vulgaris using artificial wastewater inbatch experiments showed that C vulgaris can completelyremove up to 212mg Lminus1 ammonia-nitrogen concentrationbut showed low phosphorus removal with 77mg Lminus1 initialPO4-P concentration with 78 efficiency [94] A promis-

ing strain A protothecoides UMN280 isolated from a localmunicipal wastewater plant shows high nutrient removalefficiency aswell as its high growth rate and lipid productivityThe results of the six-day batch cultivation showed thatthe maximal removal efficiencies for total nitrogen totalphosphorus chemical oxygen demand (COD) and totalorganic carbon (TOC) were over 59 81 88 and 96

respectively with high growth rate (0490 dminus1) high biomassproductivity (269mg Lminus1 dminus1) and high lipid productivity(78mg Lminus1 dminus1) [36] Studies have demonstrated ability ofEuglena sp originally isolated from the sewage treatmentplants and showing good lipid content of 246 (ww)efficient nutrient uptakewithin a short span of eight days andprofuse biomass productivity (132mg Lminus1 dminus1) [44]

Sturm and Lamer [96] do an assessment on energybalance of microalgal production in open ponds coupledwith nutrient removal from wastewater energy for algalbiodiesel production They studied microalgal yields andnutrient removal rate from four pilot scale reactors (2500gallons each) fed with wastewater effluent from a municipalwastewater treatment plant for six months using a totalof 12 million gallons per day processed by the wastewatertreatment plant Hence it shows that the direct combustionof algal biomass may be a more viable energy source thanbiofuel production especially when the lipid content of drybiomass (10 in this field experiment) is lower than the highvalues reported in lab scale reactors (50 60) Yang et al[97] examined nutrients usages to generate 1 kg of microalgaebiodiesel using nonrecycled freshwater It will require 3726 kg


Table 2 Nutrient removal efficiency of microalgal species

Microalgal species Wastewater type Nitrogen Phosphate COD ReferenceChlorella vulgaris Textile wastewater (444ndash451) (331ndash333) (383ndash623) [38]

Scenedesmus sp LX1Modified effluent of a wastewatertreatment plant of an electric factoryby photo-membrane bioreactor

46 100 NA [39]

Chlorella sorokiniana and aerobicbacteria Potato processing industry gt95 807 848 [40]

Chlorella sorokiniana and aerobicbacteria Pig manure 827 580 623 [40]

Chlamydomonas sp TAI-2 Industrial wastewater 100 33 NA [41]Auxenochlorella protothecoidesUMN280 Concentrated municipal wastewater 59 81 88 [36]

Chlorella Mexicana Piggery wastewater 62 28 NA [37]Scenedesmus obliquus Piggery effluent 23ndash58 48ndash69 NA [42]Chlamydomonas Polypyrenoideum Dairy industry wastewater 74ndash90 70 NA [43]Euglena sp Sewage treatment plant 93 66 NA [44]lowastNA Not Available

of water 033 kg of nitrogen and 071 kg of phosphate andalso shows decrease of water and nutrients usage by 84 and55 using recycling harvest water and reduction in 90 ofwater requirement eliminating the need for all the nutrientsexcept phosphate by using seawastewater as culturemediumIn another study 1L biodiesel was produced consumingnutrient between 023 and 155 kg nitrogen and 29ndash145 gof phosphorus depending on the cultivation conditions formicroalgae [98]

8 Conclusion

Presently key bottleneck of biofuel production frommicroal-gae is that the current technologies do not allow an economicand sustainable biofuel production at todayrsquos energy pricesalthough high biomass lipid productivity and nutrientremoval efficiency of wastewater grown microalgae makethem promising as a feedstock for renewable energy Fur-thermore there is need to analyse nutrient consumptionrates of wastewater derived algal biofuels bioprospectingof different wastewater habitats to explore indigenous oilproducing microalgal strains Moreover efforts should bemade by focusing research on development of large-scalecost-effective cultivation systemsThe coupling ofmicroalgaecultivation with wastewater might provide possibility ofphycoremediation CO

2sequestration and low cost nutrient

supply for the algal biomass utilization which will enhancethe economic outlook of microalgae-based biofuel produc-tion systems

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

The authors would like to thank Department of Biotechnol-ogy Kumaun University Nainital for providing necessaryfacilities to carry out this work and also thank Dr AlokShukla Department of Plant Physiology and G B PantUniversity of Agriculture and Technology Pantnagar fortheir suggestions and comments that greatly improved thepaper

References

[1] International Energy Agency Tracking Clean Energy ProgressOCEDIEA Paris France 2013 httpwwwieaorg

[2] US DOE International Energy Outlook Energy InformationAdministration U S Department of Energy Washington DCUSA 2010

[3] BP Statistical Review of World Energy 2011 httpwwwbpcomstatistical review

[4] S A Khan R Rashmi M Z Hussain S Prasad and U CBanerjee ldquoProspects of biodiesel production from microalgaein Indiardquo Renewable and Sustainable Energy Reviews vol 13 no9 pp 2361ndash2372 2009

[5] IndiaBiofuelAnnals 2013 httpgainfasusdagovRecent20GAIN20PublicationsBiofuels20Annual New20DelhiIndia 8-13-2013pdf

[6] International Energy Agency Energy Balances of OECD Coun-tries 2004-2005 IEA Paris France 2007 httpwwwieaorg

[7] Energy InformationAgency ldquoAnnual energy reviewrdquo Tech RepDOEEIA-384 EIA 2005 httpwwweiadoegov

[8] Intergovernmental Panel on Climate Change ldquoIPCC summaryfor policymakersrdquo in Climate Change 2007The Physical ScienceBasis Contribution of Working Group I to the Fourth AssessmentReport of the Intergovernmental Panel on Climate Change pp7ndash22 Cambridge University Press 2007

[9] H Y Hu X Li Y Yu Y H Wu M Sagehashi andA Sakoda ldquoDomestic wastewater reclamation coupled withbiofuelbiomass production based on microalgae a novel


wastewater treatment process in the futurerdquo Journal of Waterand Environment Technology vol 9 pp 199ndash207 2011

[10] J Sheehan T Dunahay J Benemann and P Roessler ldquoAlook back at the US Department of Energyrsquos Aquatic SpeciesProgrammdashBiodiesel from algaerdquo Tech Rep NRELTP-580-24190 Prepared for the U S Department of Energy by theNational Renewable Energy Laboratory Golden Colo USA1998

[11] J K Pittman A P Dean and O Osundeko ldquoThe poten-tial of sustainable algal biofuel production using wastewaterresourcesrdquoBioresource Technology vol 102 no 1 pp 17ndash25 2011

[12] I Rawat R Ranjith Kumar T Mutanda and F Bux ldquoDualrole of microalgae phycoremediation of domestic wastewaterand biomass production for sustainable biofuels productionrdquoApplied Energy vol 88 no 10 pp 3411ndash3424 2011

[13] E Stephens I L Ross JHMussgnug et al ldquoFuture prospects ofmicroalgal biofuel production systemsrdquo Trends in Plant Sciencevol 15 no 10 pp 554ndash564 2010

[14] Y Chisti and J Yan ldquoEnergy from algae current status andfuture trends Algal biofuelsmdasha status reportrdquo Applied Energyvol 88 no 10 pp 3277ndash3279 2011

[15] L Barsanti and P Gualtiery Algae Anatomy Biochemistry andBiotechnology CRC Taylor amp Francis New York NY USA2006

[16] R E Lee Phycology Cambridge University Press New YorkNY USA 1980

[17] G Markou I Angelidaki and D Georgakakis ldquoMicroalgalcarbohydrates an overview of the factors influencing carbohy-drates production and of main bioconversion technologies forproduction of biofuelsrdquo Applied Microbiology and Biotechnol-ogy vol 96 pp 631ndash645 2012

[18] Y Chisti ldquoBiodiesel from microalgaerdquo Biotechnology Advancesvol 25 no 3 pp 294ndash306 2007

[19] J Brodie and J Lewis Unravelling the Algae The Past Presentand Future of Algal Systematics vol 75 of Systematics AssociationSpecial Volumes CRC Press London UK 2007

[20] P M Schenk S R Thomas-Hall E Stephens U C MarxJ H Mussgnug and C Posten ldquoSecond generation biofuelshigh efficiency microalgae for biodiesel productionrdquo BioenergyResearch vol 1 pp 20ndash43 2008

[21] J R Benemann J C van Olst M J Massingill et al ldquoThecontrolled eutrophication process using microalgae for CO

2

utilization and agricultural fertilizer recyclingrdquo in GreenhouseGas Control Technologiesmdash6th International Conference pp1433ndash1438 Pergamon Oxford UK 2003

[22] A Demirbas ldquoUse of algae as biofuel sourcesrdquo Energy Conver-sion and Management vol 51 no 12 pp 2738ndash2749 2010

[23] P Alvira E Tomas-Pejo M Ballesteros and M J Negro ldquoPre-treatment technologies for an efficient bioethanol productionprocess based on enzymatic hydrolysis a reviewrdquo BioresourceTechnology vol 101 no 13 pp 4851ndash4861 2010

[24] P J McGinn K E Dickinson S Bhatti J Frigon S R Guiotand S J OrsquoLeary ldquoIntegration of microalgae cultivation withindustrial waste remediation for biofuel and bioenergy produc-tion opportunities and limitationsrdquo Photosynth Research vol109 pp 231ndash247 2011

[25] T G Ellis ldquoChemistry of wastewaterrdquo in Environmental andEcological Chemistry Volume II p 452 Department of CivilConstruction and Environmental Engineering Ames IowaUSA 2011

[26] N F Gray Biology of Wastewater Treatment Oxford UniversityPress Oxford UK 1989

[27] N Abdel-Raouf A A Al-Homaidan and I B M IbraheemldquoMicroalgae and wastewater treatmentrdquo Saudi Journal of Bio-logical Sciences vol 19 pp 257ndash275 2012

[28] Y H Cheung and M H Wong ldquoProperties of animal manuresand sewage sludges and their utilization for algal growthrdquoAgricultural Wastes vol 3 no 2 pp 109ndash122 1981

[29] N F Y Tam and Y S Wong ldquoWastewater nutrient removalby Chlorella pyrenoidosa and Scenedesmus sprdquo EnvironmentalPollution vol 58 no 1 pp 19ndash34 1989

[30] N F Y Tam and Y S Wong ldquoThe comparison of growth andnutrient removal efficiency of Chlorella pyrenoidosa in settledand activated sewagesrdquo Environmental Pollution vol 65 no 2pp 93ndash108 1990

[31] S Sawayama T Minowa Y Dote and S Yokoyama ldquoGrowth ofthe hydrocarbon-rich microalga Botryococcus braunii in secon-darily treated sewagerdquo Applied Microbiology and Biotechnologyvol 38 no 1 pp 135ndash138 1992

[32] D Voltolina B Cordero M Nieves and L P Soto ldquoGrowthof Scenedesmus sp in artificial wastewaterrdquo Bioresource Technol-ogy vol 68 no 3 pp 265ndash268 1999

[33] I Woertz A Feffer T Lundquist and Y Nelson ldquoAlgae grownon dairy and municipal wastewater for simultaneous nutrientremoval and lipid production for biofuel feedstockrdquo Journal ofEnvironmental Engineering vol 135 no 11 pp 1115ndash1122 2009

[34] S Chinnasamy A Bhatnagar R W Hunt and K C DasldquoMicroalgae cultivation in a wastewater dominated by carpetmill effluents for biofuel applicationsrdquo Bioresource Technologyvol 101 no 9 pp 3097ndash3105 2010

[35] W Zhou Y Li M Min B Hu P Chen and R Ruan ldquoLocalbioprospecting for high-lipid producing microalgal strains tobe grown on concentrated municipal wastewater for biofuelproductionrdquo Bioresource Technology vol 102 no 13 pp 6909ndash6919 2011

[36] W Zhou Y Li M Min et al ldquoGrowing wastewater-bornmicroalga Auxenochlorella protothecoidesUMN280 on concen-trated municipal wastewater for simultaneous nutrient removaland energy feedstock productionrdquo Applied Energy vol 98 pp433ndash440 2012

[37] R A Abou-Shanab M K Ji H C Kim K J Paeng and BH Jeon ldquoMicroalgal species growing on piggery wastewateras a valuable candidate for nutrient removal and biodieselproductionrdquo Journal of EnvironmentalManagement vol 115 pp257ndash264 2013

[38] S L Lim W L Chu and S M Phang ldquoUse of Chlorellavulgaris for bioremediation of textilewastewaterrdquo BioresourceTechnology vol 101 pp 7314ndash7322 2010

[39] S Zhen-Feng L Xin H Hong-Ying W Yin-Hu and NTsutomu ldquoCulture of Scenedesmus sp LX1 in the modifiedeffluent of a wastewater treatment plant of an electric factory byphoto-membrane bioreactorrdquo Bioresource Technology vol 102no 17 pp 7627ndash7632 2011

[40] D Hernandez B Riano M Coca and M C Garcıa-GonzalezldquoTreatment of agro-industrial wastewater using microalgae-bacteria consortium combined with anaerobic digestion of theproduced biomassrdquo Bioresource Technology vol 135 pp 598ndash603 2012

[41] L FWu P C Chen A P Huang and CM Lee ldquoThe feasibilityof biodiesel production by microalgae using industrial wastew-aterrdquo Bioresource Technology vol 113 pp 14ndash18 2012


[42] M Ji RAbou-Shanab JHwang et al ldquoRemoval of nitrogen andphosphorus from piggery wastewater effluent using the greenmicroalga Scenedesmus obliquusrdquo Journal of EnvironmentalEngineering vol 139 pp 1198ndash1205 2013

[43] R Kothari R Prasad V Kumar and D P Singh ldquoProductionof biodiesel frommicroalgaeChlamydomonas polypyrenoideumgrown on dairy industry wastewaterrdquo Bioresource Technologyvol 144 pp 499ndash503 2013

[44] D M Mahapatra H N Chanakya and T V RamachandraldquoEuglena sp as a suitable source of lipids for potential useas biofuel and sustainable wastewater treatmentrdquo Journal ofApplied Phycology vol 25 pp 855ndash865 2013

[45] European Nations Innovating for Sustainable Growth A Bioe-conomy for Europe European Nations Brussels Belgium 2012httpwwweceuropaeubioeconomypdf2012 commisionstaff workingpdf

[46] L Fahm The Waste of Nations The Economic Utilisation ofHuman Waste in Agriculture Allenhand Osmun amp Co PuMontclair NJ USA 1980

[47] P Amerasinghe R M Bhardwaj C Scott K Jella and FMarshall ldquoUrban wastewater and agricultural reuse challengesin Indiardquo IWMI Research Report 147 International WaterManagement Institute (IWMI) Colombo Sri Lanka 2013httpageconsearchumnedubitstream11583422H045769pdf

[48] CPCB (Central Pollution Control Board) pp 1ndash9 2011httpunstatsunorgunsdenvironmentenvpdfpap wasess3-b6indiapdf

[49] J de la Noue G Laliberte and D Proulx ldquoAlgae and wastewaterrdquo Journal of Applied Phycology vol 4 pp 247ndash254 1992

[50] F B Green T J Lundquist and W J Oswald ldquoEnergetics ofadvanced integrated wastewater pond systemsrdquo Water Scienceand Technology vol 31 no 12 pp 9ndash20 1995

[51] W J Oswald H B Gotaas C G Golueke and W R KellenldquoAlgae in waste treatmentrdquo Sewage and Industrial Wastes vol29 pp 437ndash455 1957

[52] A Bhatnagar S Chinnasamy M Singh and K C DasldquoRenewable biomass production by mixotrophic algae in thepresence of various carbon sources and wastewatersrdquo AppliedEnergy vol 88 no 10 pp 3425ndash3431 2011

[53] M Prathima Devi G Venkata Subhash and S VenkataMohanldquoHeterotrophic cultivation of mixed microalgae for lipid accu-mulation and wastewater treatment during sequential growthand starvation phases effect of nutrient supplementationrdquoRenewable Energy vol 43 pp 276ndash283 2012

[54] L Xin H Hong-Ying and Y Jia ldquoLipid accumulation andnutrient removal properties of a newly isolated freshwatermicroalga Scenedesmus sp LX1 growing in secondary effluentrdquoNew biotechnology vol 27 no 1 pp 59ndash63 2010

[55] H N Chanakya D M Mahapatra S Ravi V S Chauhan andR Abitha ldquoSustainability of large-scale algal biofuel productionin Indiardquo Journal of the Indian Institute of Science vol 92 no 1pp 63ndash98 2012

[56] R J Craggs S Heubeck T J Lundquist and J R BenemannldquoAlgal biofuels from wastewater treatment high rate algalpondsrdquo Water Science and Technology vol 63 no 4 pp 660ndash665 2011

[57] J B K Park R J Craggs and A N Shilton ldquoWastewater treat-ment high rate algal ponds for biofuel productionrdquo BioresourceTechnology vol 102 no 1 pp 35ndash42 2011

[58] R Putt M Singh S Chinnasamy and K C Das ldquoAn effi-cient system for carbonation of high-rate algae pond water toenhance CO

2mass transferrdquo Bioresource Technology vol 102

no 3 pp 3240ndash3245 2011[59] B Viswanath and F Bux ldquoBiodiesel production potential of

wastewater microalgae Chlorella sp Under photoautotrophicand Heterotrophic growth conditionsrdquo British Journal of Engi-neering and Technology vol 1 pp 251ndash264 2012

[60] S A Scott M P Davey J S Dennis et al ldquoBiodiesel from algaechallenges and prospectsrdquo Current Opinion in Biotechnologyvol 21 no 3 pp 277ndash286 2010

[61] RM Knuckey M R Brown R Robert and DM F FramptonldquoProduction of microalgal concentrates by flocculation andtheir assessment as aquaculture feedsrdquo Aquacultural Engineer-ing vol 35 no 3 pp 300ndash313 2006

[62] A Papazi P Makridis and P Divanach ldquoHarvesting Chlorellaminutissima using cell coagulantsrdquo Journal of Applied Phycologyvol 22 no 3 pp 349ndash355 2010

[63] J Morales J de la Noue and G Picard ldquoHarvesting marinemicroalgae species by chitosan flocculationrdquoAquacultural Engi-neering vol 4 no 4 pp 257ndash270 1985

[64] D Vandamme I Foubert B Meesschaert and K MuylaertldquoFlocculation of microalgae using cationic starchrdquo Journal ofApplied Phycology vol 22 no 4 pp 525ndash530 2010

[65] G Shelef A Sukenik and M Green Microalgae Harvestingand Processing A Literature Review Technion Research andDevelopment Foundation Haifa Israel 1984

[66] N Uduman Y Qi M K Danquah G M Forde and AHoadley ldquoDewatering of microalgal cultures a major bottle-neck to algae-based fuelsrdquo Journal of Renewable and SustainableEnergy vol 2 no 1 Article ID 012701 15 pages 2010

[67] S O Gultom and B Hu ldquoReview of microalgae harvesting viaco-pelletization with filamentous fungusrdquo Energies vol 6 pp5921ndash5939 2013

[68] R Harun M Singh G M Forde andM K Danquah ldquoBiopro-cess engineering ofmicroalgae to produce a variety of consumerproductsrdquo Renewable and Sustainable Energy Reviews vol 14no 3 pp 1037ndash1047 2010

[69] K K Sharma S Garg Y Li A Malekizadeh and P M SchenkldquoCritical analysis of current microalgae dewatering techniquesrdquoBiofuels vol 4 pp 397ndash407 2013

[70] J Kim G Yoo H Lee et al ldquoMethods of downstreamprocessing for the production of biodiesel from microalgaerdquoBiotechnology Advances vol 31 no 6 pp 862ndash876 2013

[71] S F Sing A Isdepsky M A Borowitzka and N RMoheimanildquoProduction of biofuels frommicroalgaerdquoMitigation andAdap-tation Strategies for Global Change vol 18 pp 47ndash72 2011

[72] K Bozbas ldquoBiodiesel as an alternative motor fuel productionand policies in the EuropeanUnionrdquoRenewable and SustainableEnergy Reviews vol 12 no 2 pp 542ndash552 2008

[73] S Kaur M Sarkar R B Srivastava H K Gogoi and MC Kalita ldquoFatty acid profiling and molecular characterizationof some freshwater microalgae from India with potential forbiodiesel productionrdquoNewBiotechnology vol 29 no 3 pp 332ndash344 2012

[74] A R Medina E M Grima A G Gimenez and M J IGonzalez ldquoDownstream processing of algal polyunsaturatedfatty acidsrdquo Biotechnology Advances vol 3 pp 517ndash580 1998

[75] J Folch M Lees and G H S Stanley ldquoA simple method forthe isolation and purification of total lipids from animal tissuesrdquoThe Journal of Biological Chemistry vol 226 pp 497ndash509 1957


[76] E G Bligh and W J Dyer ldquoA rapid method of total lipidextraction and purificationrdquo Canadian Journal of Biochemistryand Physiology vol 37 no 8 pp 911ndash917 1959

[77] C Crampon O Boutin and E Badens ldquoSupercritical carbondioxide extraction of molecules of interest frommicroalgae andseaweedsrdquo Industrial and Engineering Chemistry Research vol50 no 15 pp 8941ndash8953 2011

[78] E Ryckebosch KMuylaert and I Foubert ldquoOptimization of ananalytical procedure for extraction of lipids from microalgaerdquoJournal of the American Oil Chemistsrsquo Society vol 89 pp 189ndash198 2011

[79] A Sathish and R C Sims ldquoBiodiesel from mixed culture algaevia a wet lipid extraction procedurerdquo Bioresource Technologyvol 118 pp 643ndash647 2012

[80] M L Eltgroth R L Watwood and G V Wolfe ldquoProductionand cellular localization of neutral long-chain lipids in thehaptophyte algae Isochrysis galbana and Emiliania huxleyirdquoJournal of Phycology vol 41 no 5 pp 1000ndash1009 2005

[81] W Chen C Zhang L Song M Sommerfeld and Q Hu ldquoAhigh throughputNile redmethod for quantitativemeasurementof neutral lipids in microalgaerdquo Journal of MicrobiologicalMethods vol 77 no 1 pp 41ndash47 2009

[82] T Mutanda D Ramesh S Karthikeyan S Kumari A Anan-draj and F Bux ldquoBioprospecting for hyper-lipid producingmicroalgal strains for sustainable biofuel productionrdquo Biore-source Technology vol 102 no 1 pp 57ndash70 2011

[83] Z Zhao ldquoComment on heterogeneous catalytic deoxygenationof stearic acid for production of biodieselrdquo Industrial andEngineering Chemistry Research vol 45 no 20 p 6874 2006

[84] A Demirbas ldquoBiodiesel fuels from vegetable oils via catalyticand non-catalytic supercritical alcohol transesterifications andother methods a surveyrdquo Energy Conversion and Managementvol 44 no 13 pp 2093ndash2109 2003

[85] C V McNeff L C McNeff B Yan et al ldquoA continuous catalyticsystem for biodiesel productionrdquo Applied Catalysis A Generalvol 343 no 1-2 pp 39ndash48 2008

[86] L Brennan and P Owende ldquoBiofuels from microalgaemdashareview of technologies for production processing and extrac-tions of biofuels and co-productsrdquo Renewable and SustainableEnergy Reviews vol 14 no 2 pp 557ndash577 2010

[87] M J Griffiths and S T L Harrison ldquoLipid productivity asa key characteristic for choosing algal species for biodieselproductionrdquo Journal of Applied Phycology vol 21 no 5 pp 493ndash507 2009

[88] Q Hu M Sommerfeld E Jarvis et al ldquoMicroalgal triacyl-glycerols as feedstocks for biofuel production perspectives andadvancesrdquo Plant Journal vol 54 no 4 pp 621ndash639 2008

[89] L L Beer E S Boyd J W Peters and M C PosewitzldquoEngineering algae for biohydrogen and biofuel productionrdquoCurrent Opinion in Biotechnology vol 20 no 3 pp 264ndash2712009

[90] L Lardon A Helias B Sialve J Steyer and O Bernard ldquoLife-cycle assessment of biodiesel production from microalgaerdquoEnvironmental Science and Technology vol 43 no 17 pp 6475ndash6481 2009

[91] M P Devi and S Venkata Mohan ldquoCO2supplementation

to domestic wastewater enhances microalgae lipid accumula-tion under mixotrophic microenvironment effect of spargingperiod and intervalrdquo Bioresource Technology vol 112 pp 116ndash123 2012

[92] S Venkata Mohan and M P Devi ldquoFatty acid rich effluentfrom acidogenic biohydrogen reactor as substrate for lipidaccumulation in heterotrophic microalgae with simultaneoustreatmentrdquo Bioresource Technology vol 123 pp 627ndash635 2012

[93] P J He BMao CM Shen LM ShaoD J Lee and J S ChangldquoCultivation of Chlorella vulgaris on wastewater containinghigh levels of ammonia for biodiesel productionrdquo BioresourceTechnology vol 129 pp 177ndash181 2013

[94] S Aslan and I K Kapdan ldquoBatch kinetics of nitrogen and phos-phorus removal from synthetic wastewater by algaerdquo EcologicalEngineering vol 28 no 1 pp 64ndash70 2006

[95] J Garcıa B F Green T Lundquist R Mujeriego MHernandez-Marine and W J Oswald ldquoLong term diurnalvariations in contaminant removal in high rate ponds treatingurban wastewaterrdquo Bioresource Technology vol 97 no 14 pp1709ndash1715 2006

[96] B S M Sturm and S L Lamer ldquoAn energy evaluation ofcoupling nutrient removal from wastewater with algal biomassproductionrdquoApplied Energy vol 88 no 10 pp 3499ndash3506 2011

[97] J Yang M Xu Q Hu M Sommerfeld and Y Chen ldquoLife-cycle analysis on biodiesel production from microalgae waterfootprint and nutrients balancerdquo Bioresource Technology vol102 pp 159ndash165 2011

[98] C Rosch J Skarka and N Wegerer ldquoMaterials flow modelingof nutrient recycling in biodiesel production from microalgaerdquoBioresource Technology vol 107 pp 191ndash199 2012

TribologyAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

FuelsJournal of


Journal ofPetroleum Engineering


Industrial EngineeringJournal of


Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

CombustionJournal of


Journal of


Renewable Energy

Submit your manuscripts athttpwwwhindawicom


StructuresJournal of


RotatingMachinery


EnergyJournal of


Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Nuclear InstallationsScience and Technology of


Solar EnergyJournal of


Wind EnergyJournal of


Nuclear EnergyInternational Journal of


High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


harnessed for biofuels including biodiesel bioethanol bio-hydrogen and combustible gases Microalgal biofuel systemsare capable of producing clean and sustainably produced fuelsfor the future while eradicating the food versus fuel and forestversus fuel concerns associated with first generation biofuelsand lignocellulosic processes based on wood feedstocks [13]Although there had been enough debate on algal biofuelsstill they are not commercialized as their economic viabilityis questionable Despite being so advantageous the technoe-conomics of present microalgal biofuel production systems isnot effective to compete with petroleum-based conventionalfuels as it is accompanied with high cost production Themajor expenditure of a current algae biofuel technologydepends on algae cultivation system harvesting and lipidextraction methods But certainly their outlook is promisingand both the developed nations and the emerging economiesare interested in algal fuels [14]

2 Microalgae Advantages asa Source of Biofuel

Microalgae are prokaryotic or eukaryotic photosyntheticmicroorganisms some of which can also form a chain orcolony ranging from a few micrometers to a few hundredmicrometers and are generally ubiquitous in nature Algae area broad category that has no proper taxonomic classification[15] They are primitive plants (thallophytes) that is lackingroots stems and leaves have no sterile covering of cellsaround the cells and have chlorophyll as their primaryphotosynthetic pigment [16] Algae can be divided into twomain categories that is macroalgae which are multicellularand size up to several meters and microalgae are small sizeorganisms ranging from sizes 02 120583m to 100 120583m or evenhigher [17] Microalgae have high rate of areal biomassproductivity compared to traditional agricultural crops likecorn and soya bean and oil content in microalgae can exceed80 dry weight of biomass [18] Generally algae are dividedinto five main groups

(i) blue-green algae (Cyanophyceae)(ii) green algae (Chlorophyceae)(iii) diatoms (Bacillariophyceae)(iv) red algae (Rhodophyceae)(v) brown algae (Phaeophyceae)

Although Cyanobacteria (blue-green algae) are classified tothe domain of bacteria being photosynthetic prokaryotesthey are often considered as ldquoalgaerdquo [19] There are manypromising attributes of microalgae which make them desir-able for biofuel production The main source of carbon forthe growth of microalgae is atmospheric carbon dioxide [20]Severalmicroalgae species can growwell onnonpotablewater(brackish wastewater and seawater) their is a possibilitythat biofuel production can be coupled with one of thesesystems in future This coupling does not compete for arableland which can be used for agricultural purpose and also foreliminating the use of freshwater resources The productionof biofuels from algae can be coupled with flue gas CO

2

mitigation wastewater treatment and production of high-value chemicals [21 22] Many species of microalgae producesignificant quantities of lipids which can be converted tobiodiesel through process of transesterification Microal-gal biodiesel has characteristics related to petroleum-baseddiesel including density viscosity flash point cold flow andcalorific valueMicroalgae can be harvested batch-wise nearlyall year round providing a reliable and constant supply ofoil [20] Microalgae does not require the use of chemicalunlike terrestrial plants requiring herbicides or pesticideswhich affect the environment adversely and increase thecost of production Lignin is generally absent in microalgaeand other large biopolymers (found in woody biomass) thatmay hinder with biomass processing and conversion [23]Apart from this the residual algal biomass mainly composedof proteins and carbohydrates can be processed to variousbiofuels including methane and alcohol fuels and it can alsoproduce other nonfuel coproducts which can be recoveredand formulated into products with high market value suchas nutriceuticals therapeutics and animal feeds [24]

3 Microalgal Farming Using Wastewater forBiofuel Production

Due to global expansion of human population and advancedliving standards of people a high level of water pollu-tion is generated worldwide Wastewater is basically endproduct generated by domestic municipal agricultural andindustrial sources [25] The composition of wastewater isa reflection of the life styles and technologies practiced inthe producing society [26] Wastewater generally containsorganic mass like proteins carbohydrates lipids volatileacids and inorganic content containing sodium calciumpotassium magnesium chlorine sulphur phosphate bicar-bonate ammonium salts and heavy metals [27] Excess ofthese nutrient loads in surrounding water bodies causeseutrophication or algal blooms often due to anthropogenicwaste production

More than 300 million tonnes of biodegradable house-hold and household-like wastes industrial wastes and otherwastes are generated every year in the European Unionand stay mostly unexploited [45] Human beings generateapproximatelysim3 billion tonnes of domesticwastewater everyyear [46] In India annually due to migration of people intocities the figures are expected to reach about 600 millionby 2030 making and simultaneously increasing pressure onurban return flow (wastewater) which is usually about 70ndash80 of the water supply [47] The recent reports of CentralPollution Control Board [48] NewDelhi India revealed thatthe wastewater generation in the nation is around 40 billionlitres per day largely from urban areas and ironically only 20ndash30 of the generated wastewater is subjected to treatmentIn majority of the developing nations the main sources ofwastewater generation are domestic municipal agriculturaland industrial activities which are foremost released intoenvironment without having sufficient treatment steps Manyspecies of microalgae are able to efficiently grow in waste-water environment through their capability to use abundant



2and produce




2requirement that


3R998400OHCatalyst


+ +

CH2ndashOOCndashR1

CHndashOOCndashR2

CH2ndashOOCndashR3


CH2ndashOHCHndashOH

CH2ndashOH
























and C20




2sparging







4


4


4








Lipid content( DW)


Reference
















a024 plusmn 003














46 100 NA [39]






8 Conclusion






Acknowledgments


References
























2
























































































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of



















2and produce




2requirement that


3R998400OHCatalyst


+ +

CH2ndashOOCndashR1

CHndashOOCndashR2

CH2ndashOOCndashR3


CH2ndashOHCHndashOH

CH2ndashOH
























and C20




2sparging







4


4


4








Lipid content( DW)


Reference
















a024 plusmn 003














46 100 NA [39]






8 Conclusion






Acknowledgments


References
























2
























































































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of































and C20




2sparging







4


4


4








Lipid content( DW)


Reference
















a024 plusmn 003














46 100 NA [39]






8 Conclusion






Acknowledgments


References
























2
























































































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of





















and C20




2sparging







4


4


4








Lipid content( DW)


Reference
















a024 plusmn 003














46 100 NA [39]






8 Conclusion






Acknowledgments


References
























2
























































































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of





















Lipid content( DW)


Reference
















a024 plusmn 003














46 100 NA [39]






8 Conclusion






Acknowledgments


References
























2
























































































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of





















46 100 NA [39]






8 Conclusion






Acknowledgments


References
























2
























































































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of































2
























































































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of



















































































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of














































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of





















FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of

















Documents

Review Article Coupling of Algal Biofuel Production …downloads.hindawi.com/journals/tswj/2014/210504.pdfphotosynthetic pigment [ ]. Algae can be divided into two main categories,