Biohydrogen Production from Food Waste: Current Status, Limitations

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Biohydrogen production from Food Waste: Current Status, Limitations, and Future Perspectives Yeo-Myeong Yun, Mo-Kwon Lee, Seong-Won Im, Antonella Marone, Eric Trably, Sang-Ryong Shin, Min-Gyun Kim, Si-Kyung Cho, Dong-Hoon Kim

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Yeo-Myeong Yun, Mo-Kwon Lee, Seong-Won Im, Antonella Marone, Eric Trably, et al.. Biohydrogen production from Food Waste: Current Status, Limitations, and Future Perspectives. Bioresource Technology, Elsevier, 2018, pp.79-87. 10.1016/j.biortech.2017.06.107. hal-02628592

HAL Id: hal-02628592 https://hal.inrae.fr/hal-02628592 Submitted on 26 May 2020

HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Version postprint errors maybediscoveredwhichcould affect content,and the al review oftheresultingproofbe manu The manuscript. the of version early this providing are we acce been has that manuscript unedited an of file PDF a is This Bioresource Technology S-K., Kim, D-H., Biohydrogen production from Food Waste: Curren Please 20June2017 cite this article as: Yun, Y-M., Lee, M-K., June2017 19 Im, S-W., Ma 30April2017 Accepted Date: Revised Date: S0960-8524(17)31011-8 Received Date: BITE18344 To appearin: Reference: DOI: PII: Trably, Sang-RyongShin,Min-Gyu Yeo-Myeong Yun,Mo-KwonLee,Seong-WonIm,AntonellaMarone,Er Future Perspectives Biohydrogen productionfromFoodWaste:CurrentStatus,Limitat Review Accepted Manuscript Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: Bioresource Technology http://dx.doi.org/10.1016/j.biortech.2017.06.107 (2017),doi: 10.1016/j.biortech.2017.06.107 fore it is published in its fin fore itispublishedinits Comment citer cedocument: n Kim,Si-KyungCho,Dong-Hoon http://dx.doi.org/10.1016/j.biortech.2017.06.107

al form. Please note that during the production process during the form. Pleasenotethat al l legaldisclaimers that app pted for publication. As a service to our customers our to service a As publication. for pted rone, A., Trably, E., Shin, S-R., Kim, M-G., Cho, M-G., Kim, S-R., Shin, E., Trably, A., rone, script will undergo copyediting, typesetting, and typesetting, copyediting, undergo will script ions, and t Status, Limitations, and Future Perspectives, Kim ic ly to the journalpertain. Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: Ilsandong-gu, Goyang, Gyeonggi-do, Republic Goyang,Ilsandong-gu,Gyeonggi-do, Korea of d c RepublicKorea of b RepublicDaejeon Koreagu, 305-701, of a Shin Ryong Yeo-MyeongYun Perspectives Future Limita Status, Current Waste: Food from production Biohydrogen H statusof current the first, article, H exhibitinghigher nature, cont carbohydrate high has (FW) waste Food rate. production degr to capability its to owing applicable practically most ABSTRACT fax:860-7562; +82-32-873-7560) * INRA, UR0050 LaboratoireUR0050l’EnvironnementBiotechnologiede deINRA, Department of Civil and Environmental Engineering, KAIST, Department KAIST, of Engineering, CivilEnvironmental and Corresponding author: Dong-HoonKim author: Corresponding dhkim77(E-mail address: ofBiologicalScience,Department Environmental Donggukand ofInhaCivilDepartment University, Engineering, Inharo,100 mn te aiu booia rue fr H for routes biological various the Among b , Min-Gyun Kim,Min-Gyun a , Mo-Kwon Lee Mo-Kwon , 10.1016/j.biortech.2017.06.107 Comment citer cedocument: 2 production potential than that of other organic wastes. In organic wastes. other of that productionpotentialthan b , Si-Kyung ChoSi-Kyung , b 2 , Seong-Won ,Seong-Won Im

production from FW by dark fermentation and the strategies the fermentationand dark byFWfrom production d , Dong-HoonKim , 2 production, dark fermentation is considered the the considered is fermentation dark production, 1 b , Antonella Marone,Antonella d ognc ats n hg H high and wastes organic ade Nam-gu, IncheonNam-gu, 402-751, 373-1 Guseong-dong, Yuseong-373-1 Guseong-dong, b,* University, Dongguk-ro, 32 ent and easily hydrolysable in in hydrolysable easily and ent @inha.ac.kr, Tel:+82-32- , F-11100 , Narbonne,France c , Trably , Eric tions, and tions,

c this review review this , Sang- , 2

od at (W i oe f h ms audn ad problem and abundant most the of one is (FW) waste Food Currently, H Currently, INTRODUCTION Food waste; Dark fermentation;waste; Dark Food 2 is almost exclusively made by physico-chemical methods t methods physico-chemical by made exclusively almost is 10.1016/j.biortech.2017.06.107 Comment citer cedocument: 2

production from FW by dark fermentation is questionable. questionable. is fermentation dark by FW from production 2 il ad at rmvl fiiny r as introduced. also are efficiency removal waste and yield

Hydrogen; Economic assessment; Integrated system Hydrogen;Integrated Economicassessment; 2 2 ,i eoee uigtetetetpoes isduringprocess. recovered treatment ), the ean fuel is generated from polluting and and polluting from generated is fuel ean scussed. Economic assessment revealed assessment Economic scussed. rgy consumptive than physico-chemical physico-chemical thanrgyconsumptive other sources and methods to obtain H obtain to methodsand sources other l wie euig at ses ideal seems waste reducing while als nverting dark fermentation effluent to to effluent fermentation dark nverting emitting significant greenhouse gases greenhousegases emittingsignificant e if clean fuel (also it could be a raw raw coulda beit fuel(also if clean e nt (75-85%). However, as FW has has FW as However, (75-85%). nt hen, the technical and economic economic and technical the hen, de (AIT, 2010; Jang et al., 2015). al., et Jang(AIT,2010; de collection and transportation due due transportation and collection . ilgcl H Biological y. atic organic solid wastes, wastes, solid organic atic hat split fossil fuels. fuels. fossil split hat

production production 2

Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: dark fermentation and the strategies applied for enhanced pe enhanced for applied strategies the and fermentation dark the first, article, review this In applied. practically to as doubts still are there views, of point economical types. reactor various of employment the and parameters, techniques, pretreatment various through maximized been has H high reductionsimultaneously:ofthe environmental burden pr and such waste of treatment the with combined when addition, H its and energy, external require practical most the considered is fermentation dark them, ferme dark and photo-fermentation,biophotolysis, indirect H generate to approaches of range wide a include They ones. H the Since (COD). demand H mol units: three in increaseH to was studies batch of mainpurpose The 1. Table operation2.1 Batch CURRENT 2. STATUS removal waste perspectives efficiencyfuture withalong o current Finally, discussed. is feasibility economic the H low of limitation technical the Then, ic F hs ihr abhdae otn ad biodegradabilit and content carbohydrate higher has FW Since H 2 production performances under batch operation and the stra the and operation batch under performances production 2 production potential and rate are generally achievable. Dark achievable. generally are rate and potential production 2 /mol hexose, mL H mL hexose, /mol 10.1016/j.biortech.2017.06.107 Comment citer cedocument: 2 pouto oeta fcroyrts s uh ihrta l than higher much is carbohydrates of potential production

2 production rate is much faster than other processes. In In processes. other than faster much is rate production 2 yield from FW by dark fermentation is mentioned, and and mentioned, is fermentation dark by FW from yield 2 /g volatile solids (VS), and mL H mL and (VS), solids volatile /g 3 current status of H of status current fot t frhr nrae H increase further to efforts n dark fermentationnFW dark of covered. are ly applicable method since it does not not does it since method applicable ly hte ti poes s ed t be to ready is process this whether ntation (Kim and Kim, 2011). Among 2011). Kim, and (Kim ntation s W i cn ov to problems two solve can it FW, as oductionofcleanenergy. 2 summarized. briefly are rformance yield, which have been expressed expressed beenhave which yield, However, from engineering and and engineering from However, 2 , including direct biophotolysis, biophotolysis, direct including , the optimization of operation operation of optimization the tegies applied are arranged in in arranged are applied tegies y than other organic wastes, wastes, organic other than y fermentation performance performance fermentation 2 production from FW by by FW from production 2 /g chemical oxygen oxygen chemical /g

2 yield and and yield ipids ipids Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: feasible feedstock for H for feedstock feasible but basis, hexose a on waste livestock and sludge, sewage H H for suitable is al., 2013). et H The reason. thermodynamic acetate However, acetate. into degraded are carbohydrates H maximum the Theoretically, not. are are butyrate and acetate as such metabolites liquid Some metabolic several through proceeds degradation carbohydrate al et (Dong view of point scientific a from performance H the proteins, and favorable microbes select to but hydrolysis the increase ro the that seemed It 2015). al., et Jang 2014, al., et Kim 2009; H the increased have concentra content, includingandtotalcarbohydrate COD, VS recomme highly is it but results, and study their of purpose H into FW of content energy the of 10% H mL 133 of 2011 al., (Kimet than 10% an sludge sewage of those while 30-70%, ranges FW of content 2 The expression of H Theexpression of Various pretreatments such as heat-, alkali-, andheat-, acid-tr suchas pretreatments Various production potential of organic solid wastes. Similar H Similar wastes. solid organic of potential production 2 /g COD /g 2 production. The H The production. 2 il o a eoe ai i a iprat atr n th in factor important an is basis hexose a on yield 2 added yield by 5-20 times compared to the control (Im et al., 2012; al., et (Im control the to compared times 5-20 by yield 10.1016/j.biortech.2017.06.107 2 Comment citer cedocument: yield on a hexose basis is not sufficient to determi sufficientyieldbasisto not is hexosea on 2 production, owing to its higher carbohydrate content. The content. carbohydrate higherits to owingproduction, achieved by Jang et al. (2015) corresponds to the conversionthe corresponds to (2015) al. et by Jang achieved b ). Considering that 1 kg COD is equivalent to 1.4m to is equivalent COD kg 1 Considering that ). 2 yield, in general, does not exceed 3 mol H mol 3 exceednot does general,in yield,

2 yields on VS and COD basis are more directly relate directlymore are basis COD and VS on yields 2 il fo hxs i 4 o H mol 4 is hexose from yield 2 Atos a cos te nt f H of unit the choose may Authors . 4 related with H with related eatments have been applied to FW, and to eatmentsappliedbeenhave cannot be the only metabolite due to to due metabolite only the be cannot ., 2009). Under anaerobic condition, condition, anaerobic Under 2009). ., 2 yields could be obtained from FW, FW, from obtained be could yields o H for in epeetd betions presented. dd ht usrt characteristics substrate that nded FW is considered a much more more much a considered is FW pathways, as shown in Table 2. 2. Table in shown as pathways, d livestock waste are lower than than lower are waste livestock d 2 le of pretreatment was not to to not was pretreatment of le rdcin I te previous the In production. 2 production, but others but production, ne whether a feedstock a whether ne 2 /mol hexose (Lalman (Lalman hexose /mol 2 e evaluation of the the of evaluation e /mol hexose, if all all if hexose, /mol 3 H 2 2 yield on the the on yield carbohydrate

, the H the ,

Kim et al., et Kim of almost almost of 2 d with with d yield Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: alkali-treated FW at pH 13FWpH washalf alkali-treated achieveamount at ofthe H on effect improved H a increasingH for important H of activity b produce to known also are LAB 1997). Holzapfel, and (Stiles carbohydra degrading reactions metabolic known all their mil of processes fermentation many in enriched are LAB charac metabolic unique their to Owing 2015). al., et Jang 2014; H while FW untreated in species bact acid lactic that showed clearly sequencing generation fermentation. after FW pretreated and untreated of COD) t in differences no were there 1, Table in shown studies 2011 al., et (Kim condition temperature activity thefact thethat attributed yield,whichto was thermo condition, mesophilic to Compared 2014). al., et (Kim H mol 1.39 to decreased but H The significaperiod short fermentation,thisentire the of 5.0 of values initial the from drop pH for period the Although Kim al.(2011 Accordinget to H batch on ratio) microorganism to (food F/M h efcs f prtn prmtr icuig H substrate pH, including parameters operating of effects The 2 yield gradually increased (Kim et al., 2009). Acid pretreatmen Acid 2009). al., et (Kim increased gradually yield 2 yield ranged 1.6-1.7 mol H mol 1.6-1.7 rangedyield 2 -producers (Noike et al., 2002). The strength of pretreatment of strength The 2002). al., et (Noike -producers 2 10.1016/j.biortech.2017.06.107 rdcin Km t l, 04, n te mut f H of amount the and 2014), al., et (Kim production Comment citer cedocument: 2 production. As the heating temperature increased60 fromheating temperature Asthe production. a 2 ) and Xiao et al. (2013), the optimal initial pH was found optimal was initialthe pH al. (2013), et and Xiao ) ml hexose /mol 2 poues ee oiat n h perae oe Km t a et (Kim one pretreated the in dominant were -producers 2

/mol hexose /mol c ). A high F/M ratio (on a VS basis) ranging 7-10 was was 7-10 ranging basis) VS a (on ratio F/M high A ). added t 0 CDL idctn sbtae inhibition substrate indicating COD/L, g 80 at 5 added 2 ntly affected the H the affected ntly studied. been have FW from production at 5-60 g COD/L (on a carbohydrate basis), carbohydrate a (on COD/L g 5-60 at of indigenous LAB was suppressed at high LABindigenous wasat suppressed of Microbial analysis conducted by next by conducted analysis Microbial d at pHand(Jang 11 al.,12 et 2015). at d k, meats, cereals, and vegetables, and vegetables, and cereals, meats, k, he solubilization (soluble COD/total COD/total (soluble solubilization he ra LB wr te ot abundant most the were (LAB) eria e ae reeat o H to irrelevant are tes -9.0 to 5.0 was less than one-tenth one-tenth than lesswas 5.0 to -9.0 philic condition showed higher H higher showed condition philic ocnrto, eprtr, and temperature, concentration, teristics and antibiotic function, function, antibiotic and teristics acteriocins, which suppress the the suppress which acteriocins, t at pH 4 did not show any show not did 4 pH at t 2 productionperformance. was also found to be to found also was 2 rdcin from production

2 production o C to 90 to C to be 8.0. to o C, C, l., l., 2

Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: 2.2 Continuous operationContinuous 2.2 sludgeactivated adding waste sludgeandseparately.primary 2011 al., et (Kim FW the in those concentration higher much at Ca and Fe of existence the s sewage by performance increased the studies, previous Unlike r nitrogen to carbon balanced more a to led FW to sludge of Sreela-or and al.(2004) Kimrequirement.et source nitrogen H of growth the short be may it nature, hydrolysable easily and content al.,(Panet of2008). 7 F/M ratio H for preferable rate Lof15 H sludge,immobilized andand obtained self-flocculated doc the liquid-typefromobtainedorganics. Wudesignedal. (2006) a et highestthe achievedVHPRfrom LFW 10.7 was H concentration controllinghydraulicandre substrate the amount ofFW, highexpressedorganic asloading often rate to tellperformanceofoperation.continuousthe Toachiev H higha stablemicrobialfor concentrationat consortium 2 H producing for substrate suitable a is FW though Even The maininThe process continuousofa goal organic waste tre yield, volumetricH 2 /L/h from/L/hcontaining sucrose wastewater. Thishugediffere 2 2 production, while the highest yield of 57 mL H mL 57 of yield highest the while production, poues Swg sug i a od addt a a co-substrat a as candidate good a is sludge Sewage -producers. 2 10.1016/j.biortech.2017.06.107 Comment citer cedocument: production rate (VHPR) is often considered the main(VHPR)isproductionimpor oftenconsideredthe rate b

). Zhou et al. (2013) achieved a high H high a achieved (2013) al. et Zhou ). 6 2 /L/d, which was far lowerwhich /L/d, farthan valuewas the and fast Therefore,insteadtreatment. and of tention time (HRT).tention time Asshownin Table 3, of nitrogen which is a vital nutrient for nutrient vital a is which nitrogen of e highinputlarge eVHPR, ofthea (OLR), has (OLR), byattemptedbeen s in the sewage sludge compared to to compared sludge sewage the in s atment isretain anto active et al. (2011) found that the addition addition the foundthat al.(2011) et umented highest H umented highest 2 owing to its high carbohydrate carbohydrate high its to owing reactor containing reactor silicone- to icesn H increasing atio, ludge addition was ascribed to to ascribed was addition ludge 2 /g VS /g nce resulted fromncethe resulted added 2 yield from FW by by FW from yield was attained at an at attained was 2 production t me the meet to e tant indicator tant

production. Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: continuous H continuous technicalinsuchlong-termfouling,difficulties, ope as achieveHoweve successful2014). al.,high to (Leeet VHPR duringItseemed2010). al., broth settling(Kim that time et couldlimitation but settling there be to r due the time,a L 2.73 H retentiontime(SRT) and HRT separately same the at O fromhydraulicbeenretentionhave employe retention, membranebioreactor, and sequencingbatch whosereactor,purp configurations reactor but operation, continuoussuch other involvedinlow solihydrolysisreactionof the rate step range. mesophilictemperature To inhibit activity,LABthe K mesophilicmight be This operation. therelated to vigorous H instudies.regime continuous ShinAccording to al.(2004) et mo batchwasComparedthe thermophilicregime studies, to inoculum,used, suc feedstock other operatingand parameters, butconcludeit is wrong, optimal reasonabletheto that fixedHRT inal.,d (Leeet ofCSTR4 intermittent an 2010 whilewasVHPRhighest substhighest the the observedat lowestsubstrateg concentration observed of46.4 the at 2 It wasdifficult general It draw effec to the conclusionon Awas reactor stirred(CSTR) tankthe fr mostcontinuous yield of 1.8 molyield H of1.8 2 /L/d at/L/d SRT 120 h and HRT h.36 ASRThigh can be attained 2 productionfrom FW. a fixedexample, at HRTFor d, of1.6 2 /molhexose 10.1016/j.biortech.2017.06.107 Comment citer cedocument: added

, while it was limited0.1mol to it was whileH , 7 d. Kim et al. (2008) controlledal. Kim(2008) solidet d. ration. conditions vary depending on the varyconditionson depending d waste degradation. waste d LR, and highestachievedthe LR, of VHPR COD/L inbaffledanaerobican reactor, ise of biogas and lipidiseinofacidifiedbiogasand the t ofHRTt concentration and on substrate rate concentration rate of112 COD/Lg a at b asbaffledanaerobic reactor, activity of the indigenousactivityLAB the in of the membranewere bioreactors ). We). is or right tellcannot which equently used reactor for typethe usedreactor equently re frequently re mesophilicthan used r, maythesefaceconfigurations , a thermophilicoperation showed im et al. (2008) and Kim et al.andal. im(2008) Kimet et h as temperature and pH. h astemperature ose wereseparatesolid ose to byenoughproviding 2 /mol hexose /mol the highestthe wasVHPR

added under under Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: ueos tde hv son ht abhdae ae prefer are carbohydrates that shown have studies Numerous fermentation,usedinexplaine feedstock anddark well were acetogenic(3)H and broth, the limitatio thermodynamic (1) the to attributed is this and H actual the However, fermentation. dark H Low 3.1 LIMITATIONS 3. al.,(Paudel been2017). et attempted withbrownwater,which asdilutingdecreas to acted water fed (2010) alkali-pretreatmentmesophiFW fedpH underafter at 12 H of amount small A bydegradationreactions a there and acids, amino various to hydrolyzed are Proteins H for substrate suitable a not H of source a be Glyc2003).al., et (Layprotein-richonesfat-and of that H Expe2000).al.,et Okamoto 2009; al., et negligible (Dong were an meat) lean and protein-(egg the from those while rice, H fermentation. 2 W osss f o ol croyrts u as ohr nutr other also but carbohydrates only not of consists FW molesmentionedH 4 As Batchof operation’, ‘2.1 production potential of carbohydrate-rich solid waste was waste solidcarbohydrate-rich productionpotential of 2 yield 2 2 ils f 939. m/ V hv be ahee fo cbae c cabbage, from achieved been have VS mL/g 19.3-96.0 of yields production but small amount. Heyndrickx et al. (1991) report al.(1991) Heyndrickxet smallamount. production but 10.1016/j.biortech.2017.06.107 2 Comment citer cedocument: a b gnrtd i sl aio cd erdto, u i w it but degradation, acid amino sole via generated be can Clostridium 2 rdcin bt s n xeln sbtae o slet pr solvent for substrate excellent an is but production, 2 -consuming reaction. These reasons can be applied to all to applied becanreasonsThese reaction.-consuming

sp.: sole amino acid degradation and the Sticklandacidthereacti and degradation soleamino sp.: 2 yield is lower than 50% of the theoretical maximum, theoretical the of 50% than lower is yield 8 2 can be generated from 1 mole of glucose in frommolebe can ofglucose generated 1 erol, the main component of lipids,could mainof component the erol, ,()eitneo non-H of existence (2) n, d lipid-(fat and chicken skin) rich FW rich skin) chicken and lipid-(fat d e substrate concentration substrate FW,e of has re two types of anaerobic amino acid acid amino anaerobic of types two re yLla ta.(03. al.(2013). byd Lalmanet approximately 20 times higher than higher timesapproximately 20 et sc a poen ad lipids. and proteins as such ients rimental results indicated that the indicatedthe that rimentalresults e fr H for red lic operation. Co-digestion licoperation. 2 production in dark dark in production ed that glycerolis edthat 2 2

producers in producers ros and arrots, oduction. oduction. types of of types ould be be ould on. on. Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: stable H stable f 12.5 pH at FW of alkali-pretreatment that reported was it including bacteria spore-forming while ind acid-shock, and alkali-, heat-, as such pretreatments i of supply the to this attributed and operation, continuous H unstable observed (2007) al. et Jo decomposed was it inoculum, of addition and pretreatment non-H indigenous energycorresponds ofto the only 5% ofFW content with Achieving 2008). H a conditionfro andstorage ranges(timeand temperature), con carbohydrate The reaction. Stickland the in consumed assessment, economican conducted we issue, this address fermentati dark whether to as concern a stillis there Economic3.2. feasibility an itfrequentlyproductionsince thisofchemical requires kind burden economic high a imposes method this However, 2010). H the increased which attempted, t of alkali-treatment performance, the recover To 2009). H 2 lhuh H Although rdcin a nt utie wt te eciain f LA of reactivation the with sustained not was production The other problem associated with obtaining lowH problemwith The obtaining other associated 2 production (Kim et al., 2008). Even though FW was pretreated a pretreated was FW though Even 2008). al., et (Kim production 2 ol b drvd rm at mtras i a environmental an via materials waste from derived be would 2 producers, in particular, LAB. When FW was cultivated at cultivated was FW When LAB. particular, in producers, 2 yieldmol H of2 10.1016/j.biortech.2017.06.107 Comment citer cedocument: 2

il fo 04 o . ml H mol 0.8 to 0.4 from yield 2 emnain efrac i te ramn f W unde FW of treatment the in performance fermentation 2 Clostridium /mol hexose ishexoseth but success,considered/mol asa generally 9 sp. were cultivated (Kim et al., 2009). Also, 2009). al., et (Kimcultivated were sp. on of FW is economically feasible or not. Tonot. feasibleor economicallyis FWof on 2 yield from FW is the continued supply of issupplyyieldcontinuedFW fromthe of m 30% to 70% on a CODbasis a 70% mal.,on to (Li 30% et he entire broth in the fermenter has been been hasfermenter inthe broth entirehe a carbohydrate content carbohydrate ofa30%. igenous LAB were selectively killed killed selectively were LAB igenous ndigenous LAB. By applying various applying By LAB. ndigenous assuming a high H high a assuming -shock. -shock. eto F dpns n h de and diet the on depends FW of tent mainly to lactate (Kim et al., 2009). al., et (Kim lactate to mainly or 1 d was an essential step for the the for step essential an was d 1 or (ag t l, 05 Km t al., et Kim 2015; al., et (Jang B 2 ml hexose /mol

cno wrat stable warrant cannot d t pH 11 or 12, stable 12, or 11 pH t 2 35 yield of 2.26 mol 2.26 ofyield ly friendly route, route, friendly ly added o C without any without C

Km t al., et (Kim

is r r Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: ot Lci e a. 20) Te rft a b gie fo t from gained be can profit The 2002). al., et (Luccio cost est costwas labor the and 1998), (Benemann, cost capital wer costs maintenance and expenses Annual chemicals. of use O 1994). Lettinga, suchelectricity,for asmaintenancethose costs wat and Haandel (Van cost construction total se and use land of cost the and (2013), Claassen. and Vrije w cost construction The costs. installation and use, land andinclude profits. Theannualcost cost, capital operating 200size m fermenter wasset to kg/m 200 be assumedto were content carbohydrate year. per T d 360 operating yearswhile 20 lifespanofa and 3), H H USD/kg 10-30 ranging cost previously the H USD/kg 3.2 be m 1,400 × 2.26/12 ×COD/d amount the FW. Considering of treatment the through gained USD 360,000 Meanwhile,respectively. USD/y, 548,568 and USD 1,636,560 swing (PSA). adsorption removingcost, CO of rate a using calculated was i profit the fermentation, removal COD since However, 2012). (NABO, waste USD/ton 2 Table 4 summarizes the costs and benefits for the econ the for benefitsand costs the summarizesTable 4 ae o te siae css bv, h ttl capital total the above, costs estimated the on Based /mol hexose at an OLR of 100 kg COD/m kg anof100 OLR /mol hexose at 2 (= [(1,636,560/20 + 548,568) – 360,000]/(949,200/11.2)). This is lower than lower is This 360,000]/(949,200/11.2)). – 548,568) + [(1,636,560/20 (= 2 from the produced biogas, was calculated that isbiogas, fromcarried waso calculated that produced the 10.1016/j.biortech.2017.06.107 Comment citer cedocument: 3 × 360 d) production per year, per productionH the d) 360 × 3 raig10tn fF e a. treating oftonsFW, 100 day. per

3 /d (obtained from the highest values invalueshighest Tablesfrom (obtainedthe /d and 1 2 10 Hn t l, 2016 al., et (Han er use, and annual expenses like labor, andandlabor, use, like annual er the expenses 3 and 50% on a COD basis,respectively. The COD a on 50% and 10 USD/ton FW. The cost for purification for cost The FW. USD/ton 10 imated to be 50% of the total operating operating total the of 50% be to imated as estimated according to the study of of study the to according estimated as capital, the including assessment, omic s the construction costs of all facilities, facilities, constructionofallthes costs ot n ana oeaig ot are costs operating annual and cost t up was estimated to be 50% of the the of 50% be to estimated was up t e ramn o F, hc i 100 is which FW, of treatment he of 949,200 m 949,200 of he COD concentration of FW and FWand of concentration CODhe 2 production cost is estimated to to is productionestimated cost the of 25% be to estimated e a Hn t l, 2016 al., et Han ; perating costs consisted of of consisted costs perating s limited to 10% in dark dark in 10% to limited s 3 ut through pressure pressure ut through H of profit could be be could profit of 2 (10 ton Carbo. Carbo. ton (10

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Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: related to microbialis veryrelated fuela to promis cells(MFC), microbialfermentationcel dark processes, electrolysis couldAmong m products. biotechnologiesthat utilizethe the morethanandthirdscarbon ofH two the and scaleH Microbial4.1. electrolysis cells STRATEGIES INCREASE4. TO H H H ofprice cost production this However, assessment. economic this (H performance high the from resulted might which 2012), et al., Moreno 2015). fermentationinsystemal., dark two-stage a(Dhar et fewstudieswithdealt H electricityfor investigated(ElMekawy MFCs using generation AMECs. wide applyvarietyandofto wastes wastewate dependingg/L concentrationremaineddilution VS (5-50 the on fermentation Duringreductionused.isof of VS FW,30-60% dark fermentationgenerate dark classical, H single-stage to 2 In MEC applications, however,food-processingInapplications,MEC wastewater IncreasingH the pouto rmF ydr emnaini usinbe productionfrom FWfermentationis by questionable. dark 2 production. Dark fermentation only results fromproduction.fermentation Dark only partialresults 2 (0.5-3.2 USD/kg H USD/kg (0.5-3.2 2 yieldfermentationmain fromremains ofdark the ch one 10.1016/j.biortech.2017.06.107 Comment citer cedocument: 2 production by MECs both as a single-stage process or coupleprocess bothproductionor bysingle-stage as a MECs 2 ) (Bartels et al., 2010), indicating that the economic f economic the indicatingthat 2010), al., (Bartelset )

2 YIELD AND OBTAIN MOREENERGYOBTAIN YIELD AND 2 contents is converted to microbialis contents metabolic to by-converted 11 2015; Lu et al., 2009; Marone et al.,al., 2017; 2009; 2015;Maroneet Luet ing candidate for augmentationing thecandidate of 2 ls (MECs), anls emerging(MECs), technology wt ihefcec Kmre l,21) al.,with 2016). et high efficiency (Kumar rs from the food industry fromfood rs hasbeen the is still higher than the current selling current the than higher still is 2 etabolic byproducts generated bygeneratedbyproducts etabolic yield and OLR) values applied in in applied values OLR) and yield rather than FW were morerather FWoftenthanwere et al., 2015), but, to date,al., but, 2015), only to et rate) isdirectlyhigh stillrate) to oxidation of organic substrates, oforganic oxidation substrates, generally achieved, but but the generally achieved, allenges for large-for allenges

easibility of of easibility d with with d Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: from 336 to 725%. TheH from to 336 ofhighersuppliedwheretimesthanamount t the energy, Regardlessamoprocess.two-stepthe asubstrate, ofthe H generatefor factories spiritstheirpotential to andcoming fromby-products juicwastewaters fruit cheese, Recently,evaluated2015).al.and(2017) al.,et compar Marone onl fermentation inenergyMECsrecoveryandwere dark mol (6 fermentationandH wasMEC57% juicefromrecoverybeetintegrated sugarachieved anusing andS et reached2009).input substrate)(Lu electricalal., 70% and287%, reachedinput, voltage based overallup on the to en overallH untilsincenow, most required, studiesofthecarried out al.,cheese 2017). raw whey et (Marone perliter be vinasseLcould8.1 ±ofproduced raw and 1.4 of H fromfollowedby residues productiongenerated spirit cheese be exploited H interestingforto substrates needwithout intotheaccoun takingMeanwhile,of dilution. COD suitablemostsince wasitthebes providedsubstrate the w darkfermentation Amongcomparison the alone. to tested One of the main current challengesMECsmain foris One scal ofthe current fermentationByanwithsystemtr a forcombining MECs consumed 2 recovery of 96% has corresponding96% obtained.beenThe recovery of elect (corresponding to around9.82mol (correspondingto H 10.1016/j.biortech.2017.06.107 Comment citer cedocument: 2 yield increased13 bothus timesprocessesbyto were up when

2 2 /molhexose productioninsystem vinassetwo-stage such awere 12 2 byinfermentation withMECcouplingan dark 2 /mol hexose) with 72% ofCODremoval,/molhexose)with 72% added ing up. In this domain, furtherInthisresearchis ing domain, up. t total hydrogen yieldtotalLH hydrogen± 0.3 of1.6 t unt of energy produced was at leastwas atunt of energy three produced which insucceededH heelectricalefficiency ranged energy y 35% and 34%, respectively andy et 34%, 35% (Dhar ), while the individualwhileof the ), efficiencies biohydrogen ofdark process e, paper, sugar,fruit processingpaper, e, and eatingan molasses wastewaters, t the need of dilution, the most t needdilution, the the of astewaters,fruit juice wastewater whey. Indeed, up to 28 ±L up 5 to whey.ofH Indeed, imilarly,overallthe energy ergy efficiency (relative to the efficiency(relativeto ergy 2 could be produced percouldliter be ofproduced ed six different industrial different sixed ricalenergy efficiency, 2 production, dealt production,

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Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: operational temperature al.,(i.e.(iioperational9°C) 2014), (Wang et temperature prevent CH to strategiesproposed been have etal., al.,etis 2017)applicablewhich 2014; Montpart not Rago a byinhibitors by-products excludinganduseof chemicalMEC, the al.,Whenet (Lalaurette2009). complextreati substrates as maincontaminationbeenthe causehasoftenreported biogas produced wasCH continuousAlthoughconsistent aCODsolubleremoval of winerywith developedtreat systemMECto an wastewaters pilot-scaleH forsignificant system havescale-upal.MECsfrom to onlyattempted Cusick (2011) et notallowitsdo but succestechnology on any prediction provided withinformati bench-scaleusefulthat reactors H for favorable environment H withprocess two-stage the and process CH produce to methanogens furt to is removal COD) as to referred (often pollutant CH 4.2. al.,al.,et(Montpart 2017).et 2014; substrate Rago fed-batchafor al., reductiontime cycleofthe et (Lu al.,(ii 2016), hydraulicretention timeet (Sosa-hernández As shown in Table 5, another approach for both increasing bi increasing both for approach another Tablein 5, shown As 4 pouto production 10.1016/j.biortech.2017.06.107 Comment citer cedocument: 4 , comprising± H 86 biogas,6% ofno , the and 4 2 . The fundamental difference between the conventional the between difference fundamental The . production while the former does not. Co-combustion of H of Co-combustion not. does former the while production 2

production industryfromThe authors food residues. 2 and CH and 4 evolution.low includeuseTheseof the (i) 13 4 co-production is that the latter has a specific a has latter the that isco-production 2009), and (iv)useparticularof a2009), the on about functioningthe about ofMECon ng FW or food-processing ngFWwastewater or now, industrialIndeed,up to at scale. s of process failureintreatingofMEC process ) a low acetate concentrationlow acetate aand ) i) air exposure of the cathode and i)aircathode exposure ofthe e uiie eann ognc cd by acids organic remaining utilize her 62 ± 20% was achieved, mostwas± achieved, 62 of the20% a maximumm a 1 capacityof oenergy recovery and enhancing enhancing and recovery oenergy bench experiments to a to experimentsbench t industrial severalscale,t (Marone et al.,et 2017;(Marone 2 wasCH recovered.

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and and Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: 3. h rao o otiig ih H high obtaining of reason The 93%. H mL205 H thermophilic in yields The efficient. more astageprocess demonstrated that two temperature-phased(2008) efficienprocess the respectively, of removal CODwhile fermentation inw ofsystem two-stage pilot-scale the remoCOD 94%FWinofwith energy the of content (68%)] H mL 41 be to found and system fermentation two-stage the operated also (2008) H onlyin 8% from efficiency conversion bioenergythe combustioncomparedthe ofto CH CH inH water diluting as utilized becan effluent constructionoperationCHandofthe inco treatment and selling energyincrease significantly ene More ASBR. the to compared as UASB the in shorter OLRCHand al. et (Jung (UASB) reactor blanket sludge anaerobic up-flow (ASBR)showed higher bioebatch anaerobicreactor sequencing CH use and collected synthetically was FW carbohydrate-rich Han and Shin (2004) found that the cogeneration of H of cogeneration the foundthat (2004) Shin andHan n diinl datg o a eunil CH sequential a of advantage additional An 4 4 emne wr apid o te ramn o dr fermen dark of treatment the for applied were fermenter less reduce could ‘hythane’) as to referred (often mixture 2 g S n 44m CH mL 464 and VS /g 4 production rate were approximately werethree higher,times productionrate and 2 10.1016/j.biortech.2017.06.107 Comment citer cedocument: g O ad 1 m CH mL 310 and COD /g 4 4

g S rsetvl, hl CD eoa efcec reached efficiency removal COD while respectively, VS, /g alone (Cooney et al., 2007). alone et (Cooney 4 fretrsol ecniee. fermentershould considered. be 2 il oe 20 L H mL 200 over yield 2 2 rdcin n mspii CH mesophilic and production fermentation. Jung et al. (2013) and Kraemer and and Kraemer and (2013) al. et Jungfermentation. 14 4 4 4 emnain ytm s ht h methanogenic the that is system fermentation g O, qiaet o 1 [H 71% to equivalent COD, /g ere 290 mL290 ere H me. However, the additional costs for the for costs additionalHowever,the me. 2 cy was 95% (Han et al., 2005). Chu et al et Chu2005). al., et (Han 95% was cy production to 78%. Antonopoulou et al 78%. et Antonopoulou to production 2 and CHand d, which is not realistic. Two types of of Twotypes realistic. not is which d, val efficiency.valH The rgy gain and pollutant removal can can removal pollutant and gain rgy maximum H maximum 2 21) Hwvr h maximum the However, 2013). , /g VS in above studies was that that was studies above in VS /g nergy recovery performance than nergythan recovery performance for H for 4 2 ain flet DE, where (DFE), effluent tation from FW markedly increased increased markedlyFWfrom /g VS andmL VS 240 /g CH irgn xds emissions oxides nitrogen 2 and CH 2 the HRTthe times was7.5 and CH and 4 rdcin were production 4 production was production was 2 and CHand 2

3) CH + (3%) 4

yields were were yields 4 4 /g VS, VS, /g yield 4

Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: this phenomenon may lower the accuracy of pH control, w control, pH of accuracy the lower may phenomenon this e may zone dead A 2001). al., et (Amanullah fermenter the whet uncertain is it implementation, practical in and up fermenter,inlab-scalesufficientagitationenabl a ca Homogeneity 2010). Chung, and Lee 2009; al., et Jayalakshmi 2012; m 0.15-0.5 sizeranged Fermenter FUTURE 5. PERSPECTIVES externalchemicalbuffer. bu alkali an as sludge returning by 5.0-5.5 at pH the e adjusted Lee 40-50%. approximately by control pH for addition alkaline CH ofrecycling that reported (2005) Bagley 2013;al.,Trchounian al.,Genetic 2015). modificationet such low,stillyieldsapproximately were one butthe wastes, H low the is FW of fermentation d and sludge, fermentation.is dark information availableon sewage sludge, digestion anaerobic on done been Eshtiaghi 2014; al., et (Dai feedstock of type the and rate, sol the on depending varies which values, constant not are visc as such properties rheological of informed well be to agitator an of design theFor 2015). al., et (Moon production eot o plt ad ulsae tde o dr ferment dark on studies full-scale and pilot- on Reports s rvosy etoe, n o te igs osals for obstacles biggest the of one mentioned, previously As 10.1016/j.biortech.2017.06.107 Comment citer cedocument: 3 2 , which was far smaller than the practical size (Cavina sizepractical the than farsmaller which was , il. fw teps ee ae o rdc H produce to made were attempts few A yield.

4 fermented effluent reduced the required amount of of amount required the reduced effluent fermented 15 ing precise pH control. However, ingwhencontrol. precisepH scaling- her the pH would be uniform throughout throughout uniform be would pH the her third of those from carbohydrates (Liu et et (Liufromcarbohydrates those of third osity, storage, and loss moduli. These These moduli. loss and storage, osity, et al., 2016). Numerous works have works Numerous 2016). al., et hich, in turn, causes a decrease in H in decrease a causes turn, in hich, d ocnrto, eprtr, shear temperature, concentration, id and efficient mixing, it is important isit mixing, efficientand xist with insufficient agitation, and and agitation, insufficient with xist as by knocking out genes by to asrelated out knocking to o F ae ut limited. quite are FW of ation the practical application of dark dark of application practical the fr ihu te diin f any of addition the without ffer a. (2010 al. t gse sur, u little but slurry, igested n be guaranteed with with guaranteed be n a successfully )

2 from lipid lipid from to et al., et to 2

Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: fermentation, which was equivalent to 41% of the energythe c 41%of to equivalent whichwas fermentation, Aphoto-fermentingorganism.a H high indigen the using latctate-fe ofcentrifugation throughobtained supernatant lactate to FW fermented (2013) Kim and Kim H highachieve “da of process combined the on out carried been have studies H to processed further be can SCFAs These FW. representi remain, butyrate and acetate including (SCFAs) ferme dark successful After 1). (Fig. processing chemical 2007). vanpromising (KleerebezemLoosdrecht, and waste actual treating in culture pure of use the However, H non o antimicrobials, green feed, animal as directly utilized s selective enable which tails, hydrocarbon longer their Steinbusch2011).al., Theseet higherhaveenergy densities a et (Grootscholten heptanoate and caprylate as such MCFAs fermentation, dark of metabolites soluble possible the Acetat growth. microalgae by biodiesel (MCFAs)and acids moreH get to Thepossibleroute econ lowerthe can footprint and large reactor a requires reaction low the However, FW. from obtained ever yield Although the H the Although The produced SCFAs can be further converted to liquidbiofue SCFAsto converted produced furtherThe be can 2 -producing pathways in the degradation of proteins and lipids ca lipids and proteins of degradation the in pathways -producing 2 yield, but the research on using FW as a feedstock isfeedstock a FWusingas researchon the yield,but 2 yield from FW is limited, DFE can be further utilized f utilized further be can DFE limited, is FW from yield 10.1016/j.biortech.2017.06.107 Comment citer cedocument: 2 byin mentioned‘4.1’wasMECsection in detail.

2 yield of 8.35 molH 8.35 yield of 16 2 y E ad ht-emnain Extensive photo-fermentation. and MEC by eparation from the broth. MCFAs can be be MCFAscan broth. the from eparation omic feasibility of the integrated system. integrated the feasibilityof omic rmented residue was converted to H to converted wasresidue rmented croin niios o idrcl by indirectly or inhibitors, corrosion r ntation of FW, short-chain fatty acids acids fatty FW,short-chain of ntation have been biologically elongated to to elongated biologically been have ontent inFW.H highest ontent the wasThis and lower solubilities in water due to lowersolubilitiesin and water ng 40-60% of the energy content of of content energy the of 40-60% ng e, lactate, and propionate, which are are which propionate, and lactate, e, rate of photo-fermentation, which which photo-fermentation, of rate 2 sc a F i nt economically not is FW as such s /mol hexose was attained byattainedphoto- was hexose /mol ls including medium-chain fatty fatty medium-chainincludingls rk- and photo-fermentation” to to photo-fermentation” and rk- l., 2013; Kucek et al., 2016; 2016; al., et Kucek 2013; l., limited (Zong et al., 2009). al., et limited(Zong ous LAB, and then the the then and LAB, ous n increase the H the increase n or valuable fuel and and fuel valuable or

2 yield. 2 by 2

Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: ocnrtos f ctt ad uyae n F wr gene were DFE in butyrate and acetate of concentrations broth the from yield extraction high achieve to order in soluble highlySCFAsSince 2013).are Lovitt, and (Zacharof on depending respectively, $/kg, 2.0-2.5 and $/kg 0.4-0.8 ranges acid industries. pharmaceutical and chemical, processing, food ( microalgaefrom stilltechnicala remains challenge means feasible economically an finding However, biofuels. for approach sustainable promising a be a to seems cultivation fermentation dark of Coupling 2016). al., et (Turon butyrate hi containing effluents on favored is growth microalgae that mic lipid-rich of growth the for tested been has DFE 2014). as such biofuels into chemistry organic with conversion FW.from by-products essvalue maximizeof also is the It al., 2017; et Yan al., 2010). et H bothproduce to attempts indus fermentation and pharmaceuticals, polymers, in applied biocompat and biodegradable is It (PHAs). polyhydroxyalkanoates chemic of candidate possible other The form. dissociated SCFAswhi increases,ofform undissociated of proportion proce fermentation as larger becomes effect inhibitory MoreoYang, and2003). Zhu 2014; al., et (Kim inhibition production On the other hand, the SCFAs in DFE themselves have ow have SCFAsthemselves theDFE inhand, other the On s ecie aoe dr fretto cn e integrated be can fermentation dark above, described As 10.1016/j.biortech.2017.06.107 Comment citer cedocument: 2 and PHAs from carbohydrate substances, but not fromFW( not but substances, carbohydrate from PHAsand

17 Kimal., 2013). et eds with pH decrease. At low pH, the the pH, low At decrease. pH with eds ential to generate energy generate from solid the to ential ch has higher toxicity compared to the to compared toxicityhigher has ch al that can be derived from DFE is is DFE from derived be can that al idee o jt ul (prt e al., et (Spirito fuels jet or biodiesel h pie f ctc cd n butyric and acid acetic of price The Km t l, 06. oee, the However, 2016). al., et (Kim gh acetate concentration rather than than rather concentration acetate gh roalgae, and there was a consensus consensus a was there and roalgae, , their concentration should be high high be should concentration their , producing both gaseous and liquid and gaseous both producing n values; they can be applied in the the in applied be can they values; n rally below 50 g COD/L due to to due COD/L g 50 below rally for harvesting and extracting lipid lipid extracting and harvesting for tries. There have been several several been have There tries. with various technologies to to technologies various with d eeorpi microalgae heterotrophic nd ible, and is currently widely widely currently is and ible, ver, in batch operation, the operation, batch inver, h prt ad grade and purity the

Luongo Luongo Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: coupling with MECs and methane fermentation.methanes couplingandThereare with MECs further incremadebeenhaveLAB.Attemptsindigenous to content, thermodynamiclimitedcarbohydrate limitation H fromfermentation.studiesNumerousachievableFW by dark ha higherComparedother H organic wastes, to solid SUMMARY 6. fromfuelschemicals DFE. and energ the supplement also can upgradin production energy additional after vehicles and households to supplied directly or andderived theCH ofenergy ofDFE, content sol The digestion. anaerobic conventional by DFE of part 1. REFERENCES 2015R1C1A1A02037289). ICTMinistryKorean(MSIP: the ofScience, Government bywassupported NationalThistheFoundation Researchwork ACKNOWLEDGEMENT FW. fuelvaluableformaximiz whichchemicaland can processing, 2

yield and VHPR, but itsyield but feasibilityeconomicstill isVHPR, and Amanullah McFarlane,A.,Emery, C.M., Nienow, A.N., 10.1016/j.biortech.2017.06.107 Comment citer cedocument:

4 can be utilized for heat and electricity generation, andheatfor electricitygeneration, be utilized can 18 2 production potential and rate are generally productionpotentialrate and found to befound questionable, to duetheto s, and unwanted fermentationledunwantedand by s, and Future Planning)and Future (NRF- id part generally accounts for 30-50% for accounts generally part id A.W.,Scale-down model 2001. to ase H ase everal possible routes to utilize to everalroutes DFE possible y requirement in the processing of of processing the in requirement y e the value of by-products from by-products valuethe eof of Korea (NRF) grant funded (NRF)grant Korea by of ve been conducted to maximize conducted to beenve 2 yieldby and energy recovery g (Kim et al., 2016). This This 2016). al., et (Kim g

Hydrogen Energ. 33, 4739-4746.Hydrogen Energ.33, processhydrogenmethanefrfor phased two-stage production and Chu,C.F., Li, Y.Y., Xu,K.Q., Ebie, Y., Inamori, Y., Hydrogen J. Int.scale long-termEneexperience. pilot wastefromfermentationby food productioncoupled dark with Giuliano,C., Cavinato, Bolzonella,Pavan,A., P.D., Hydrogen J. 17239-17245.Int. waste. Energ.40, biohydrogenforfro stirred-tankreactor continuousproduction Castillo-Hernandez, Mar-Alvarez,Moreno-AndradeA., I., in waste Environ.Sci.California. Technol.1120-1128. 51, Jin,Robinson, Breunig,L., H.M., Scown,C.D.,A., 2017.Bio ofIEA/H2/10/TR2-98.Hydrogen, Internationalthe AgencyProgram,Subt Hydrogen Energy 1998. ProcessanalysisBenermann, economics F.R., and of fromalternativeandconventional energy Int. sources. 2010.Olson,Pate, M.B.,J.R.,N.K., Bartels, Anecono forCenter Regional Resource AsiaPacific. the and Asian Institute of Technology,Municipalmanageme 2010. waste 5227-5233. Chem.Eng.47, Res. intw wheya from cheese methane Biohydrogenproduction and G., Antonopoulou, Stamatelatou,K., Venetsaneas, N., inlarge-scalespatialsimulate variationsbioreactors pH

Cooney,Benemann,C.,Maynard,Cannizzaro, 2007 N., M., J., 10.1016/j.biortech.2017.06.107 Comment citer cedocument:

19 Kong, H.N., 2008. Kong,H.N., ApH-andtemperature- , Cecchi, , F., Bio-hydrogen 2012. J.Hydrogen 8371-8384. Energ.35, rg. 37,11549-11555.rg. Kornaros,Lyberatos,M., G., 2008. michydrogensurveyproduction of . Biotechnol. Bioeng. 73, 390-399..Biotechnol. Bioeng. 73, , I., 2015.Start-up andI., operation , of ask B, Annexask B, Photoproduction 10, biophotolysis of water. Report to biophotolysiswater. of energy food from potential m organicrestaurant solid anaerobic digestion process: process: digestionanaerobic A o-stage anaerobic process. Ind. anaerobic Ind. o-stage process. . Two-phaseanaerobic nt report. report. nt AIT/UNEP om food waste.J. Int.food om

fermentation. Int. J.Int.Hydrogen fermentation. 34,812-820. Energ. characteristicsorganicofthefraction municipal soof L.,Zhenhong, Dong, Y., Yongming,Xiaoying, S., K., Yu,Z. electrolysis Bioresource Technol. cell. 223-230. 198, juicebiohydrogenfermbeet integrated anusing process of dark Dhar, Elbeshbishy,B.R., H H.S.,Lee,Hafez, 2015. H., E., digestion.Bioresource Technol.6-10. 174, Dong,B.,Gai, 2014.RheologyDai,X., X., evolution of s fedwinerywastewater. Appl.2053-2063. Microbiol.89, Biotechnol. 2011. B.E., Logan, Performance continuopilot-scaleofa Bryan,Parker, R.D., Cusick, B., Merrill,D.S., M.D., 2651. mixtures.Bioreproduction forhydrogen-methanedigestion of fermentation. Trans.enerhydrogennew fermentation. Koreanand ofthe 2008.S.Y.,Park, Kim, EconomicGim,evalua J.W., B.J., J.Hydrogen 809-819.Int. Energ.30, B.C.R., Ewan, Allen,R.W.K., 2005. Afiguremeritasse of and yieldofsecondarydigested mixtures.stress Water Res Markis,Eshtiaghi, F., N., Mai, Zain,2016.P D., K.H., 73, 213-225. Res.Int. system(BES): The synchronizedrecoveryen of sustainable S.V.,2015.FoodandD.,Pant, as subs agricultural wastes ElMekawy, Bajracharya, Hegab,Srikanth, H. S., A.,S., 10.1016/j.biortech.2017.06.107 Comment citer cedocument:

20 Mehanna,Kiely, M., P.D., Liu, G., lidmixed culture bywastes anaerobic redicting the apparent viscosityredicting andapparent the M., Nigam, M., P.S., Singh, Mohan,A., us flowusmicrobial electrolysiscell tion of hydrogenproductionbyof tion trates for bioelectrochemicalfor trates ludge through high-solidludge through anaerobic ssment of the routes to hydrogen. routes ofthe to ssment ydrogenfromsugarproduction . 95,159-164. . gy society. 19, 145-155. 19, society. gy ergy and waste treatment. Food ergy treatment. waste and ,2009.Hydrogen production source source Technol.2642- 98, entation and microbialentationand

analysis of a novel bioprocess combining solid state fermeanalysisbioprocess combiningnovelstate ofasolid Gu,Shi,J.J., Y.W., J.H., Tang,Han,Yan, W.,Y.T., 107-112. 202, fermentativeforfood w frombioprocess hydrogenproduction Liu,2016a. Techno-ecoJ.H., Han,Fang,J., Tang, W., Z.X., Hydrogen J. 569-577.Int. waste. Energ.29, 2004.BiohydrogenShin, by H.S., Han, S.K., production anaerobi 138. Watehydrogenesismethanogenesis.combinationofacidogenic and Kim,Kim, Han,S.H., S.K., H.W., 2005.PiloShin, H.S., Technol.715-718. 136, heptanoateproductionfromand rate propionate ethanol using Grootscholten, T.I.M.,Steinbusch, H. Hamelers, K.J.J., community analysis and limitationcommunityofoperation.continuousand analysis wasteHydrogenby fermentation food 2015. ofpre alkali-shock Kim, S., Jang, D.H., Yun, Y.M.,K M.K.,Lee, Moon, C., Hydrogen J. 37,8330-8337.Int. feedstock. Energ. infermentativepyrosequencing dark H 2012. Kim,Kim,Kim,W.T.,Bact Im, D.H., K.H., M.S., 637-647. Microbiol.Biotechnol.32, by Vos,Ley,Vancanneyt, P.D., J.D., Heyndrickx,M., M., H 2 production from food waste. Int. J.22619-Int.Hydrogenfood productionwaste.from 41, Energ. Clostridium butyricum Clostridium 10.1016/j.biortech.2017.06.107 Comment citer cedocument: LMG 1212t2 andand 1213t1 LMG 1212t2

2 -producing reactor using reactor as a -producing organicwastes 21 Li, Y.F., 2016b. Li,Techno-economicY.F., V.M,Buisman,High2013. C.J.N., 1991. Thefermentation ofglycerol C. pasteurianum C. ang,W.S., Kwak,Kim,S.S., M.S., t-scale two-stage process:a two-stage t-scale erialbycommunityanalyses ntation and dark fermentation forfermentation ntationdark and Bioresource Bioresource Technol.215- 186, nomiccombinedofaevaluation aste. BioresourceTechnol.aste. chain elongation. Bioresource Bioresource chain elongation. treatment: Microbial treatment: c fermentation of food fermentationfood ofc 22625. r Sci. r Technol.131- 52, LMG 3285. Appl.LMG 3285.

by next generationJ.16302-16309.Hydrogen byEnerg. 39, next Int. sequencing. fermentationwas hydrogen ofacid-pretreatment on food of K M.K.,C.,Lee,Yun,Jang, W.M., Moon, S., Kim, D.H., 120-127. 139, Technol. effluentmethane inasoffermenter dilutinghydro water hydrogenfer bymethaneorganic waste andsolidto two-stage Cho,Shin,C.,Kim,S.K.,K.W., Moon, H.S., Jung,S.H., 300-308. Biotechnol.131, microflorainfoohydrogen-producing fromstructure anaerobic J.M.,C.O.,Park,Jeon,D.S., Lee, J.H., 2007.Proc Jo, ininclinedflow waste reactor.an plug J.Int.Hydrogen E Sukumaran,Joseph,K., Jayalakshmi, S., V.,2009. Biohydrogengen 222. converting food waste to hydrogenmethane.food waste to converting andBioresource Kim,2013.Development Kim,novelofa thre D.H., M.S., Technol.8423-8431. 102, Kim,2011. Kim,biologicalD.H., forM.S., Hydrogenases hy Energ.35,1590-1594. fo(ASBR)producingtreating anaerobicreactor batch sequencing Kim,Kim, K.Y.,Kim,D.H., S.H., 2010.Experi Shin, H.S. 8646-8652. 102, Technol. offermentationindependentoperationalfo hydrogenof on pH Jung,Kim, K.W., Kim,Shin, Kim, H.S M.S., D.H., S.H., 10.1016/j.biortech.2017.06.107 Comment citer cedocument:

22 essstabilitymicrobial communityand gen fermentation. genBioresource Kim,2013.Conversion D.H., of eg 4 8485. nerg.34,8854-8858. ., 2011a.initialEffect., of pH ang, W.S., Kim,2014.Effect ang,W.S., M.S., e-stage fermentation e-stage system ence of a pilot-scale hydrogen-pilot-scaleofa ence te: Microbial te: communityanalysis drogen production. Bioresource Bioresource production. drogen Technol.267-274. 127, mentationreusesystem with od waste. Bioresource od dwastecontaining J. kimchi. od waste. Int. J.Int.Hydrogen waste. od eration from eration kitchen

co-digestion of food wasteHydrogeand J. food co-digestionsewageInt. ofsludge. 2004.FeasibilityHan,Shin,S.K., bio H.S., Kim, ofS.H., biogasrec and Lacticacidwaste: food fromvalueMore 2016. Na,J.G., Kim,M.S., M.K.,Lee, Ryu, Chang,H., Y.K., J.H wastefromcontrol. by hydrogenInt. food temperature Kim,Wu,D.H., K.W.,Jeong,J., Shin, Kim, H.S. M.S., fattyforbacteriaphotosynthetic Bioracidsproduction. Hwang,J.H.,Lee, Kim,D.H., Y., Kim,Kang, S., M.S., inoculumEnzyme addition.Microb. Tech. 45,181-187. Shin,Kim, 2009.Hydrogen H.S.,fermentat Kim, D.H., S.H., Technol.8501-8506. 102, wastesynergistically food fermentatiohydrogenenhances Kim,Kim, Kim,H.W.,D.H., S.H., Kim,Shin, H.M.S., Kucek, L.A., Nguyen, Kucek,M., L.A., L.T., Angenent, 2016.Conversion of system two-phasereactor Environ. Sci.with recycle. T Kraemer,J.T., Bagley, 2005.Continuousfermentativ D.M., Curr.production. 207-212.Opin. 18, Biotech. M.C.M., 2007.vanKleerebezem, Loosdrecht Mixedculture R., 213-218. ProcessBiochem. 43, asafood waste function of time of solidsretention 2008.OptimizationHan,Shin,S.K., H.S., Kim, S.H., of Kumar,G., Bakonyi, P., Kobayashi, T.,Xu,K.-Q., Siva microbiome.continuously a fedWaterreactor Res.93,163-171. 10.1016/j.biortech.2017.06.107 Comment citer cedocument:

23 independent of hydraulicretention time. Triolo,J.M., Yun, Y.M.,Kim, D.H., echnol.3819-3825. 39, esource esource Technol.277-282. 148, , 2011c. , Naturalinducement of 2013.Continuous cultivationof gurunathan, P., gurunathan, Kim,Buitrón, S.-H., S., 2011b. S., Sewagesludge additionto continuous hydrogenfermentation continuous hydrogenproductionby anaerobic n performance. Bioresource nBioresource performance. ydrogen10666-10673. Energ.36, e hydrogenproductionusing ea ion of food wasteionwithout food of n Energ. 29, 1607-1616.n Energ.29, overy.Water 208-216.96,Res.

biotechnologybioenergy for L -lactate inton-caproate by -lactate

Lee, D.Y.,Lee, Ebie, Y.,Xu,K.Q.,Li, Y.Y., Inamori, Y. Energ.28,1361-1367. digestedhydrogen on wastesby theirto conversion heat-shock Lay,Ku,C.H., Chang,2003.Influence Fan, J., K.S., J.J., 775-778. fluxfermentationanalyinconsumption balance using dark Moon,Chaganti,Kim,2013.C., J.A., S.R., Lalman,D.H., Hydrogen J. 6201-6210. electrohydrogenesis. Energ.34, Int. inprocessfromHydrogen celluloseproduction two-stage a E., Lalaurette, S.,Mohagheghi, Thammannagowda, ManessA., 879-891. Renaugmentation: fermentativehydrogen. of dark Thecase G.,Nemestóthy, Bélafi-Bakó,K., 2016.EnhancementN., of vegetable kitchen waste. Int. J.Int.Hydrogen vegetableEnerg. 35,13458-13466. waste. kitchen 2010b.S.S., Cheng, Thermophilicbio-energyhy on study process Kuo,P.C.,Li, Z.K.,Lee, S.L., Chen, I.C., Tien, Y. fermentation.J. hydrogen/methaneInt.Hydrogen combinedEne Lee, Y.W.,2010.Bioproduction foChung,fromJ., hydrogen of Hydrogen J. 39,16863-16871.Int. bioreactor. Energ. in waste from hydrogen continuousrate sufood production on InamoriXu,K.Q.,Li,Kobayashi, Y.Y., D.Y., Lee,T., sludge. withrecirculationof digester the Bioresource T fromfoodwasteth in high-solidproduction two-stage the 10.1016/j.biortech.2017.06.107 Comment citer cedocument:

24 M., Huang, M., Y.J.,Chuang, C.P., Wong,S.C., , 2010a. Continuous ,2010a. H , Y., 2014.Effectloading oforganic Y., , echnol.S42-S47. 101, of chemical nature oforganicof chemicalnature ermophilicfermentation process ElucidatingacetogenicH sis. Bioresource Bioresource Technol.sis. 146, combining fermentationcombiningand ew.Sustain.Energy Rev. 57, biofuel production via microbialbiofuelvia production bmergedmembraneanaerobic sludge. Int. J.Hydrogen sludge. Int. , P.-C., , Logan, 2009.B.E., od waste by waste od pilot-scale rg. 35, 11746-11755. 35, rg. drogen fermentationwith drogen 2 and CH

Lu, L., Ren,Xing,2009.HydrogenB.E., N., Logan,product L., D., Lu, economics.161-166. process Desalination147, pervaporati productionfermentationby selectiveto coupled 2002.C.P.,Alves, Borges, T.L.M., M.D.,Economic Luccio, 15704–15710.Hydrogen J. 37, Int. waste. Energ. biohydrogenTechnoeconomicfromofevaluationwa production Liu,Hsu,Chang,Chu, C.Y., Li, Y.F., Y.C., C.W.,P.L., 3196-3205.Hydrogen Energ.38, infermentationhydrogenandof anaerobicbiod1,3-propanediol Christiansen,Xu,Z.,Li, Pamas, B., Liu,K., B., R., J.Int.fermentation hydrogenHydrowithwaste. kitchen performancestirintermittent-continuousevaluation of Z.K.,Lee,Kuo,S.C.,Lin, Li,Wang,S.L., J.S., Y.H., 1621. andin by-products In wastewaters bio-refinery aframework. enhancemicrobialbio-hydrogenand productionelectrolysisto Steyer, Latrille,E., J., Alcaraz-Gonzalez, V.,Ber Marone, A., Ayala-Campos, O.R., Trably, Carmona-M E., Bioresource fermentationproducts. Technol.228, 171-175. Photofermentative 2017. hydrogenandproductionof ploy- Luongo, V.,Ghimire, L.,Fabbricino,Frunzo, d’AnA., M., 24,3055-3060. cell. Biosens.Bioelectron. ethanol-H 2 -coproducing fermentation reactor usingmi single-chamberfermentationa -coproducingreactor 10.1016/j.biortech.2017.06.107 Comment citer cedocument:

25 net, N., 2017.Couplingfermentationnet, dark 2013.Optimizing productionofthe Cheng,2008. ProcessS.S., red tank reactor for anaerobicfor reactor tank red Lin, P.J., Wu,2012.S.Y.,Lin, P.J., gen1522-1531. Energ.33, artinez, A.A.,Moscoviz,R., tonio, G., tonio, Pirozzi, F., G., Esposito, β on: effect of membrane effect ofon on: costs -hydroxybutyrate from dark -hydroxybutyrate analysis of ethanol and fructose analysisand of ethanol t. J. Hydrogen J. 1909- Energ.t. 42, fromagro-industrial ioneffluentfrom with an iesel glycerol. Int. J. ieselInt. glycerol. stewater and agriculturalstewater crobialelectrolysis

Oh, Y.K., Kim, Y.J., Kim,Park, Kim, 2006.S.H., Oh, Y.K., Y.J., Econom M.S., Hydroge oforganic J. Int. lactic bybacteria. wastesacid Noike, T., Takabatake,H.,O., Mizuno, Ohba,InhibiM., 2002. National Office, AssemblyBiogasBudget 2012. business assessm Hydrogen J. 168-175. electrolysis. Energ.40, Int. fefromhydrogencheeseproductionof Integration dark whey: Escapa, R., Moreno, Cara,Carracedo,A.,J., Góm B., 595-601. 179, Effect 2015. accuracyofthe hydrogen controlfermeon ofpH Jang,C., S., Moon, Yun, Y.M.,Kim,K M.K., Lee, D.H., 615. microbialchamberdifferent electrolysiscells with c Rago,Guisasola,N., L.,Baeza,J.A., Montpart, 20 A., (OLR) on H on (OLR) 2017.Seo,G.T.,Yoo,Y.S., Kang,Y.J., EffectPaudel,S., J.6968-6975.Hydrogen 33, Int. Energ. waste food from biohydrogenproduction on microorganismratio Ying,Y.,Zhang, H., Sun,El-Mashad,R., H.M.,Pan,J., 25-32. 41, materialsorganicofcharateristicthefraction muni of Miyahara,M., Okamoto, T.,Mizuno,Noike, O., T.,2000.B 98-108. society17, Trans. biohydrogen/biomethane Kore ofproductiontheprocess. 2 and CH 10.1016/j.biortech.2017.06.107 Comment citer cedocument: 4 production anaerobic byfoodwa ofco-digestion two-stage

26 omplex substrates. Wateromplexsubstrates. Res.68,601- cipal solid wastes. wastes. solidWater cipal Sci. Technol. ez, X., 2015. X., ez, Aprocessfor two-stage 14. Hydrogen production in14.Hydrogenproduction single nr.2,16-31 nEnerg.27,1367-1371. ang,W.S., Kwak,Kim,S.S., M.S., 2008. food Effect ofto of volumetric organic loading rate loadingofvolumetricrate organic ic evaluation of two-step ictwo-step evaluation of iologicalhydrogenpotential of ntation. Bioresource Bioresource ntation. Technol. rmentation and biocatalyzedrmentationand tion of hydrogen fermentationhydrogen of tion an hydrogennewanand energy via anaerobic fermentation. fermentation. viaanaerobic ent in Korea. ent

ste and ste Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: 73. 72. 71. 70. 69. 77. 76. 75. 74.

sludge for hydrogenfor mixedStatsludgecultures:productionby anaerobic Sreela-or,Plangklang,C., P., Imai, T.,Reungsang, A., 27,115-122.Biotech. microbiomesin elongation recover to reactor anaerobic Richter,C.M., Spirito, Rabaey,H., Stams,K., A.J. fermentation. Bioresource from alcoholican Technol. G., Parra-saldívar,2016. R., Applicationmicrobialofel S.C.,Popat,Parameswaran, P.,Sosa-hernández, O., Al J. mesophilicInt.Hydrogen thermophilicE acidogenesis. and Shin,Youn,H.S., J.H.,2004.Hydrogen Kim,production fr S.H., Chem. J. cheese assolewheysubstrate. Technol. Biot L.,Baeza,J.A., Guisasola, Rago, 2017.BioelectrocheA., 484-493.Waste Manage. 61, brownwater. Trchounian,K., Abrahamyan, V.,Poladyan, A., Trchounian Bioresource Technol.114, 270-274. inand waste kitchenmunicipal mesophilicwastewater food Tawfik, 2012.ContinuousEl-Qelish, A., M., hydrogenproduction J.Food Microbiol.1-29. Int. 36, Holzapfel, Stiles,W.H.,M.E., Lacticbacteri 1997. acid biomass.grade 216-224.Energy 4, Sci. Environ. andfuelfrom caprylate formation ofacetate: caproate Hamelers,Steinbusch,K.J.J., H.V.M., BuismPlugge, C.M., Hydrogen J. 14227-14237.Int. optimization. Energ. 36, 10.1016/j.biortech.2017.06.107 Comment citer cedocument:

27 M., M., L.T., Angenent, 2014.Chain echnol. 92, 173-179. echnol.92, 200, 342-349. 200, 2011.Co-digestionwasteand food of emán-nava, G.S., emán-nava, Torres,C.I.,Buitrón, and chemical production fromlowchemicaland production ectrolysis cells to treat spentyeast treat ectrolysiscellsto a of foods and their current taxonomy. current and foods their of a resources from waste. Curr.resourcesfrom waste. Opin. micalhydrogenproduction with , , 2015. EscheriachiaA., coli an, C.J.N., 2011. C.J.N., an, Biological anaerobic baffledanaerobic reactor. eg 9 3516. 1355-1363.nerg. 29, om food waste infood waste anaerobic om isticalfactors key fromofco-digestion

4-5. 245-254. wastefromin integrated food productionprocesstwo-stage Wang,Zhao, X., Y.C.,2009. Abenchstudyfermen scale of 103-123. pp. Netherlands, biologicalhydrogenDutchandproduction.methane Biological Wijffels,Bio-methane (Eds.), S Barten & Bio-hydrogen: H. Vrije, T.D.,Claassen, P.A.M., Darkhydrogen ferment 2003. climate.John hot regionsa with Wiley&Inc.,Sons VanHaandel, Lettinga, A.C., G., 1994. Anaerobictr sewage effluentsmicroalgaeforassubstrates growth: Areview. Turon, V., Trably,Steyer,Fouilland, E., E., J.P., 2016. differentHydrogenfermentationat pHs. J. 40 Int. Energ. andina formate batchhydrogen upon growth production culture Yan,Miao,M.,Ruan,Zhao, H., Q., W., CoR.,Song, 2010. 13907-13913.Int.Hydrogenwaste. J. 38, digestionfood Energ. of Ng,Fung,K.M., L.,2013.BiohydrogenDeng,K.Y., Z., Xiao, ge 946. containingsludge.silicone-immobilizedself-flocculated and inhydrogenhigh- bacterialproductionand community structure Wu,S.Y., Hung,C.H.,Chen, Lin, H.W.,C.N., Lee, A.S. J.Hydrogen 19369-19375.Int. Energ.39, microbialfedsingle-bychambercellsmol electrolysis Wang, Y.,Guo, W.,Chang,Xing,2014.Hydrogen product D., J., 10.1016/j.biortech.2017.06.107 Comment citer cedocument:

28 New York. Potentialitiesfermentation of dark asses wastewater at lowat wastewater temperature. asses Process Biochem. 51, 1843-1854. ProcessBiochem. 51, , Chang, 2006.Fermentative, J.S., , 9935-9941. , tative hydrogen and methanehydrogenandtative uplinghydrogenofandthe . Int. J. Hydrogen J. Int. Energ. 34, . tatus and perspectivestatus of eatment: Afor practical guide ations, in: Reith,ations,R.H. J.H. Biotechnol. Bioeng. 93, 934- Bioeng.93, Biotechnol. Hydrogen Foundation., Foundation., Hydrogen rate anaerobic bioreactors rate loneandglycerolco- with ion biocathode using neration fromnerationanaerobic

fermentation. Biomassfermentation. Bioenerg.33,1458-1463. wasteprocessby food fromtwo-step ofadarcassava and Zong, W., Yu,Zhang,R., P., Zhou,Fan, Z., 2009.EffiM., inbutyricfibrous to bioreactor.acidbeda Biotechnol. P Zhu, Y., Yang,S.T., 2003. Adaptationof 710-718. 130, Technol. wasteanaerobicfor food productionandof co-digestionwa Nakhla,2013.OptimizationP., G.,Elbeshbishy, Zhou, E., of fattyacids. Waste Biomass Valor.557-581. 4, Zacharof,M.P., Lovitt,R.W. Complex 2013, effluentstrea 4508-4512. algae. 101, (PHA) productionpolyhydroxyalkanoates anaerobic digesthrough 10.1016/j.biortech.2017.06.107 Comment citer cedocument:

Clostridium tyrobutyricum Clostridium 29 rog. 19,365-372.rog. k fermentationk photo- and cient hydrogen cient gasproduction msofvolatilepotential asa source tewater biosolids. Bioresource tewater biologicalhydrogen tion from tion Taihublue for enhancedfor tolerance

fatty acids, PHAs = Polyhydroxyalkanoates) PHAsPolyhydroxyalkanoates) acids, fatty= e Microbial = MEC acids, fatty Short-chain (SCFAs= fo of fermentation dark of system Integrated 1 Fig. 10.1016/j.biortech.2017.06.107 Comment citer cedocument:

30 od waste with effluent conversion process process conversion effluent with waste od lectrolysis cells, MCFAs = Medium-chain Medium-chain MCFAs= cells, lectrolysis

-0gV/ 35 g5-50 VS/L 30 g Carbo. 30 g Carbo. 30 g Carbo. 30 g Carbo. 30 30 g Carbo. 30 g Carbo. 30 30 gcarbo.30 Substrate COD/L COD/L COD/L COD/L COD/L COD/L COD/L COD/L Carbo. Carbo. 5-80 g5-80 N.A. N.A. a a 37 37 35-60 ep H Temp. 35 35 35 37 35 35 35 2 production performance from food waste by dark fermentation dark by waste food from performance production o o o o o o o o o o 2.11mol H C mol 1.71 H C mL 77.0-79.1 H C mol 1.92 H C C mol 1.74 H C C 1.05 mol 1.05 H C mL 102.63 H C C C mol 2.26 H C o C 1.79 mol 1.79 H C 10.1016/j.biortech.2017.06.107 Comment citer cedocument: 2 1.71 mol 1.71 H yedpraddsbtae Strategyenhanceto performance yield peradded substrate 153.5 mL 153.5 H 162 mL162 H 133 mL/g133 COD

2 2 2 2 2 2 2 2 /mol hexose /mol mlhxs Temperaturechange (35-60 hexose /mol hexose /mol hexose /mol Acid-treatment (pH1.0-4.0) hexose /mol hexose /mol /mol hexose hexose /mol /mol hexose hexose /mol 2 /g VS /g 2 2 /gVS /gVS 2 /g VS /g 31 Co-digestion(FWSWS + Heat-(90 ratios40:1,30:1,(10:1,20:1, and50:1) andalkali-treatmentfor1 (pH13 d) n.) Co-digestion at variousCo-digestion at substrate Alkali-treatment6h) (pH9-13, Heat-treatment(90 Substrateconcentration change (FW:SWS (FW:SWS InitialchangepH (5.0-9.0) Initialchange6,8)pH (5, o (5-80COD/L)g Carbo. C for 20 m),20 acid-(pHfor C d),for1 1 concentration odgsin Co-digestion a =1:-04 :0, 10:0-10:4, = 0:10), b = 0:100-100:0), = o C for 20 m) Im et al. (2012)et Im al. m)for20 C b ) at differentat) C/N (The H (The

C) C) Reference 2 yield Sreela-oret al. Xiao etXiao al. Jang etJang al. Kimet al. Kimet al. Kimet al. Kimet al. Kimet al. Kimet al. Kimet al. (2011 (2011 (2011 (2004) (2014) (2013) (2015) (2014) (2009) (2011) b c a ) ) ) ) ) Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: No relationNo H H Table2 Typicalfermin degradation reactionsglucose dark a N.A.=Not available; 2 2 consumption production N.A. a 37 o b C C SWS=Sewage sludge; 10.1016/j.biortech.2017.06.107 Comment citer cedocument: H Glucose2CO+ Glucose2H + Glucose Glucose Glucose Glucose GlucoseH + Glucose2H + 2 + CO+ 1.84 mol 1.84 H 76 mL76 H 165 mL165 H 2 → → → →

Reactions → 2Ethanol + 2CO 2Ethanol+ 2CO+ Butanol 2Lactate 2CO+ Butyrate

2 2 Formate O 2 2 /mol hexose hexose /mol 2

O /g COD /g 2 2 → c /g VS /g + 2H + → PSPrimary = sludge; → 2Propionate + 2H 2Propionate+ Acetone + 3CO Acetone+ 2Acetate + 2CO 2Acetate+ 2

32 → 2Succinate2H + 2 2 + H + 2 2 + 2H + 2 Co-digestion(FWPS + O nain entation d 2 WAS = Waste activated sludge 2

+ 4H 2 2 O + 4H 2 2 2

O c +WAS

d ) ) Zhou etZhou al. (2013) Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI: VHPR value indicated hereindicatedvalue VHPRwasobtainedoptimal under co H Continuous 3 Table

Membrane bioreactor i-CSTR Reactor ASBR ASBR CSTR CSTR ABR type d g g f f

19.0-57.0 29.0 15.4 COD/L/d COD/L/d COD/L/d COD/L/d gVS/L/d 125.4 g 125.4 VS/L/d 19, 28 19, OLR 70.2 1.2 g 1.2 20 g g g - -

47.0 27.0 g - a HRT

10.1016/j.biortech.2017.06.107 24-8 h 24-8 Comment citer cedocument: 10.5 h 10.5 2 42-24 14.0, 35 d 1.6 18.7, rdcin efrac fo fo wse y ak fermentati dark by waste food from performance production 36 h 36 55 d4 5 d5 h b

Temp.

55 35 35 55 35 35, 35, o o o o o o o C C C C C C C C

H peradded 111.1mL substrate H H mL 38.1 61.7 mL 61.7 mL 12.9 11.2mL H /gCOD 0.9 mol 0.9 mol 1.8 hexose 2 /gCOD gVS 2 2 2 mol H H /g VS /g VS

H yield 2 2 2 / / /

(38 g(38 VS/L/d) 10.7 L 10.7 0.1 L 0.1 H L 0.4 H 2.1 L 2.1 L 2.7 L 1.0 L 0.4 SRT h)100 SRT (HRT 24 h,24 (HRT (6 g(6 VS/L, COD/L/d) COD/L/d) COD/L/d) condition) (125.4 g (125.4 (optimal VHPR 55oC) (28 g(28 g(29

H H H H H 2 2 2 2 2 2 ndition.) ndition.) 2 /L/d /L/d /L/d /L/d /L/d /L/d /L/d /L/d c

(19, 28g (19, COD/L/d) HRT (70.2, 89.4,(70.2,g125.4 Strategyenhanceto Temp.comparison VSconcentration (19-57g VS/L/d) C/N C/N ratio changeg10 (3- h),SRT change OLR change OLR change OLR 4736,g (29, performance OLR OLR OLR (160-24h) COD/L/d) COD/L/d)

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TableH for Economicassessment 4 continuouslystirred reactor;tank d a OLR = Organic rate; = loading OLR ABR = Anaerobic baffled reactor; reactor; baffled Anaerobic = ABR Operation costOperation Annual capital 19% of capital cost 310,946 Benemann et al., 1998 Benemann et 310,946 19% ofcapital cost Annualcapital CSTR Construction Maintenance 6% of capital cost 98,194 Benemann et al., 1998 Benemann et 98,194 6% ofcapital cost Maintenance Capital costCapital Additional Additional Materials Chemicals 48,000 Oh et al., 2006 Oh et 48,000 Chemicals Materials f

COD/L/d gVS/L/d 17.7-106 C arbo. Purification (PSA/Fermenter ratio: 1.09) 388,040 Gim et al., Gimet 388,040 ratio:1.09)Purification (PSA/Fermenter 10.1016/j.biortech.2017.06.107 Food waste grinding, Heat exchanger 258,000 Han et al., 2016 Han et 258,000 grinding,exchanger waste Food Heat Storage tank (25% of fermenter cost) 89,000 Han et al., 2016 Han et 89,000 Storage ofcost) fermenter(25% tank 48-4 h 48-4 Comment citer cedocument: b (50% of construction(50% cost) HRT = Hydraulicretentiontime;=HRT Item Item

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Tablefermentation ofPerformancesystemtwo-stage c 5 Productioncost Waste treatment H 65 mL65 H substrate substrate 2 yield per added tes ao ot(0 fttloeaigcs) 148 Lucci 91,428 cost(20% of total Labor operating cost) Others Profit VS VS cost cost 1 2 st /g /g sae 2 stage Bioenergy (% ofFW(% recovery recovery input) 6 operatingcost)/Annual H 10.1016/j.biortech.2017.06.107 Comment citer cedocument: Annual cost (CapitalAnnual+cost/20y cost 10% cost10% of treatment (100 USD/tonwaste) (100 546 mL546 CH (per added (per CH substrate)

VS VS 4 yield 6,0 360,000 nd 4 stage stage /g /g 35 2 production production Bioenergy (% ofFW(% recovery input) 2 N.A. 82 onverting food waste to H waste food to onverting

3.2 USD/kgH 3.2 eoa removal COD (%) (%) 360,000 NABO, 2012 NABO, 360,000 a

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a N.A. = Not availableNot = N.A. 161 mL161 H mL205 H mL290 H mL310 H 41 mL41 H COD COD VS VS VS VS VS VS 2 2 2 2 2 /g /g /g /g /g /g /g 19 28 11 3 9 10.1016/j.biortech.2017.06.107 Comment citer cedocument: 310 mL310 CH mL250 CH mL464 CH mL240 CH mL210 CH

COD COD COD VS VS VS VS 4 4 4 4 4 /g /g /g /g /g /g 36 70 89 Jung et al., 2013al., Jung et 94 al., Chu2008 et 89 68 al., 2005 Han et 93 70 95 86 52 70 (on a VS(on basis) basis) 3 73% Antonopoulou et Antonopoulou HanShin, and

al., 2008 al.,

2004 Version postprint Kim, D.-H. (Auteurde correspondance) (2018).Biohydrogen production fromFood Waste:Current Yun, Y.-M., Lee,M.-K., Im,S.-W.,Marone, A.,Trably, E.,Shin,S.-R., Kim,M.-G., Cho,S.-K., Status, Limitations, andFuture Perspectives. Bioresource Technology (248),79-87. , DOI:

Integrated system fermentationIntegrated vaconverting effluent to Strategiesincrease H to Technicalfermentatiolimitationof economicaldark and fermentationstatus of dark appliCurrent with strategies fermentationfoodwaste Criticaldark (F ofon reviews 10.1016/j.biortech.2017.06.107 Comment citer cedocument: 2 yield andmore energy gain

37 W) W) ed for enhancementfor ed rious fuels rious chemicals and n performance of FW nperformanceofFW