Sus ainable Chemis y and Pha macy 30 (2022) 100836
A ailable online 18 Sep embe 2022
2352-5541/© 2022 The Au ho s. Published by Else ie B.V. This is an open access a icle unde he CC BY-NC-ND license
(h p://c ea i ecommons.o g/licenses/by-nc-nd/4.0/).
En i onmen al assessmen o he alo iza ion o glyce ol o he
p oduc ion o hype he mophilic β-glucosidase unde a
bio e ine y app oach
Helena Feijoo, Ana A ias
*
, Ma ia Te esa Mo ei a
CRETUS, Depa men o Chemical Enginee ing, School o Enginee ing, Uni e sidade de San iago de Compos ela, 15705, San iago de Compos ela,
Spain
ARTICLE INFO
Keywo ds:
Bioe hanol
Y. lipoly ica
Bio echnological p ocess
En i onmen al assessmen
Ci cula economy
Was e side-s eams alo iza ion
ABSTRACT
Bioe hanol p oduc ion echnologies om lignocellulosic biomass a e no ye op imized and do no
compe e economically wi h i s -gene a ion bioe hanol p oduc ion. S a egies ha e been in es-
iga ed o p oduce mo e ac i e, s able and empe a u e- ole an enzymes o be used o biomass
hyd olysis such as he hype he mophilic β-glucosidase p oduced by Ya owia lipoly ica. The use
o his s ain o e s an addi ional compe i i e ad an age, as i can use glyce ol s eam om he
biodiesel p ocess as a ca bon sou ce. In his way, no only is a by-p oduc o bio uel p oduc ion
used, bu he enzyme could be applied in he p oduc ion o lignocellulosic e hanol, inc easing he
alue chain by closing he bioeconomy cycle. To his end, la ge-scale p ocess modelling o
β-glucosidase p oduc ion has been de eloped o collec he in en o y da a needed o li e cycle
assessmen me hodology. The e men a ion s age is he la ges con ibu o o en i onmen al
impac s, wi h elec ici y being he main ho spo iden i ied, con ibu ing mo e han 50% in mos
impac ca ego ies. Residual glyce ol has also been iden i ied as a c i ical inpu , wi h a signi ican
con ibu ion in some ca ego ies. To imp o e he en i onmen al p o ile, a sensi i i y analysis has
been ca ied ou conside ing educ ions in elec ici y and hea consump ion, and o he al e na i e
oil-based esou ces o he p oduc ion o biodiesel. This analysis iden i ied ha la ge en i on-
men al educ ions could be achie ed, which makes he alo iza ion o he glyce ol ob ained as a
side s eam o biodiesel p oduc ion mo e ealis ic.
1. In oduc ion
In he con ex o he ansi ion owa ds he sus ainabili y o ene gy p oduc ion and use, he alo iza ion o was e s eams has been
he main d i e in he sea ch o al e na i es in bio uel p oduc ion (Clause e al., 2021; S egmann e al., 2020a). In an e o o
p omo e ene gy sel -su iciency, bioe hanol anks i s as a subs i u e o ossil pe ol. Howe e , he eeds ock unc ionali y o
i s -gene a ion bioe hanol p oduc ion is es ic ed due o he use o ce eals as eeds ock, which is in di ec con lic wi h hei use o
ood and eed, as well as o e exploi a ion o a able land (Be ndes e al., 2013; Damme e al., 2017; Ha lík e al., 2011; Tudge e al.,
2021). Second-gene a ion bioe hanol p oduc ion ills he gap o he i s gene a ion using non-edible eeds ocks om ag icul u al and
o es y esidues (Adi iya e al., 2016; Jusakul iji e al., 2021; Robak and Balce ek, 2018). Lignocellulosic and s a chy ma e ials can
be po en ial sou ces o e men able suga s used as a ca bon sou ce in he o mula ion o cul u e media o e men a i e p ocess (Dey
* Co esponding au ho .
E-mail add ess: [email p o ec ed] (A. A ias).
Con en s lis s a ailable a ScienceDi ec
Sus ainable Chemis y and Pha macy
jou nal homepage: www.else ie .com/loca e/scp
h ps://doi.o g/10.1016/j.scp.2022.100836
Recei ed 9 Augus 2022; Recei ed in e ised o m 3 Sep embe 2022; Accep ed 11 Sep embe 2022
Sus ainable Chemis y and Pha macy 30 (2022) 100836
2
e al., 2020; Jusakul iji e al., 2021; Rosales-Calde on and A an es, 2019; Saini e al., 2015a). Despi e he di e en s ages in he
p oduc ion o second-gene a ion bioe hanol, he ini ial s ages o eleasing e men able suga s by enzyma ic hyd olysis a e o pa icula
ele ance o he concep ual design o he o e all p ocess and bioe hanol yield (La a-Se ano e al., 2018; MacRelli e al., 2012; Sha ma
e al., 2022; Vasi´
c e al., 2021).
In he case o biodiesel, he p oduc ion p ocess conside ing he anses e i ica ion eac ion is applied in mos indus ies, gene a ing
glyce ol wi h a deg ee o pu i y be ween 50 and 80% (Abdul Raman e al., 2019; Pi e al., 2019). The p esence o a y acid me hyl
e he s, me hanol, soap and ash impu i ies leads o he need o pu i ica ion, mainly based on a dis illa ion p ocess, which i is no a
iable economic op ion (Abdul Raman e al., 2019). To his end, his bioglyce ol is a low pu i y alue o use as a aw ma e ial in
pha maceu icals, cosme ics and ood p oduc s, which educes i s ma ke abili y and applicabili y, hus becoming a ‘was e’ a he han a
‘ esou ce’ (Win and T abold, 2018). In his con ex , he de elopmen o an e icien and economically iable s a egy would be based
on he use o c ude glyce ol in bio-based mic obial p ocess such as enzyme p oduc ion. Enzymes can ac selec i ely and con e high
molecula weigh polyme s p esen in biomass in o hei e men able monome ic suga uni s (Ho n e al., 2012; Hou ani e al., 2021;
Hyeon e al., 2014; Souza e al., 2018).
Fu he mo e, he implemen a ion o ci cula economy models in indus y o en in ol es he use o was e s eams o lignocellulosic-
based by-p oduc s, i.e., biomass (Dahmen e al., 2019; De i e al., 2022; Saini e al., 2015b). Bioeconomy is conside ed as an in eg a ed
solu ion o educe he dependence on ossil esou ces, use enewable esou ces, maximize euse and ecycling o aw ma e ials and
ex end he li e span o p oduc s om he design s age (Holden e al., 2022). The shi om linea p oduc ion o ci cula p ocess is an
essen ial s ep on he way o achie ing a bioeconomy manu ac u ing amewo k (S egmann e al., 2020b; Venka esh and Se, 2021).
Resou ce conse a ion is achie ed h ough open o closed end-o -li e (EoL) s a egies, whose al e na i es ange om mechanical,
chemical o biological p ocesses, ene gy eco e y and/o compos ing (Baue e al., 2017; Tan and Lame s, 2021).
I is in his amewo k ha his manusc ip ocuses, as i conside s he use o a by-p oduc o he biodiesel p oduc ion p ocess,
glyce ol, o ob ain he enzyme β-glucosidase, wi h wide applica ions in bio echnological p ocesses due o i s abili y o selec i ely
ca alyze he con e sion o cellobiose p oduced by enzyma ic b eakdown o cellulose in o e men able suga s. This hype he mophilic
enzyme could be used in he ood indus y o hyd olysis, o he elease o a oma ic compounds, o enhance he la o o ood and
be e ages, o he ex ac ion o medicinal compounds by clea age o phenolic glucosides and o he hyd olysis and b eakdown o
lignocellulosic biomass o p oduce bio uels (Ahmed e al., 2017; Singh e al., 2016; S i as a a e al., 2019; S adwick e al., 2017;
Tu ne e al., 2006). The c ude applica ion o his enzyme makes i an essen ial inpu o he de elopmen o bio e ine ies based on
lignocellulosic ma e ials. In his sense, he use o a side s eam o was e om biodiesel p oduc ion o ob ain his enzyme, which could
in ac be eused la e in he same p ocess, could be conside ed as a sus ainable, ci cula and en i onmen al- iendly s a egy. To assess
i s ad an ages, la ge-scale p ocess modelling has been de eloped ha in eg a es he main s eps in he bio echnological p oduc ion o
β-glucosidase. The p ocess simula ion allows he collec ion o in en o y da a necessa y o he applica ion o he Li e Cycle Assessmen
me hodology.
2. P ocess desc ip ion
As a basis o he bio echnological concep ual design o he p ocess, i is necessa y o analyze he biochemical eac ion kine ics
ep esen ing mic obial g ow h and enzyme p oduc ion. The e men a ion s a egy is de eloped acco ding o a ed-ba ch scheme, as i
p o ides highe yields and p oduc i i y compa ed o ba ch ope a ions (Abdella e al., 2020). I should be no ed ha he p oduc ion o
β-glucosidase occu s in acellula ly, as highe enzyme i e s a e achie ed, ep esen ing added alue and compe i i e pe o mance
compa ed o ex acellula enzyme sec e ion (Abdella e al., 2020; Soe ae and Vandamme, 2009). Wi h his in mind, mic obial g ow h
in e men e s has been modelled in Supe P o Designe , wi h biomass being he main p oduc ob ained (CH
1.8
O
0.5
N
0.2
), in which
in acellula β-glucosidase is p oduced:
92.09 C3H8O3+4.59 NH3+66.76 O2→ 33.15 CH1.8O0.5N0.2+72.78 CO2+57.51 H2O
The cul u e medium was o mula ed based on a glyce ol concen a ion o 40 g/L, supplemen ed wi h NH
4
H
2
PO
4
, KH
2
PO
4
and
MgSO
4
⋅7H
2
O and he ope a ional condi ions ha allow he p oduc ion o be a-glucosidase co espond o a empe a u e o 30 ◦C and
pH 4, as hese a e he mos sui able condi ions o he g ow h o Y. lipoly ica (Chen e al., 2018; He n´
andez-Guzm´
an e al., 2016). In
addi ion, as his is an ae obic p ocess, il e ed ai is ed a a a e o 0.5 m h ough di use s placed a he bo om o he main and seed
e men e s. A he end o he e men a ion, he biomass concen a ion ob ained is 19 g/L. This alue is ob ained by conside ing he
kine ic pa ame e s o he speci ic g ow h a e, he Monod cons an , as well as he eac o olume and inle low a e (Blanco e al.,
2021).
The subsequen s eps o he p ocess co espond o a cascade s a egy, in which he sepa a ion o he biomass, cell lysis o elease he
in acellula enzyme, as well as a sequence o pu i ica ion s eps ha e been conside ed. Mo eo e , he mos commonly used o ma o
comme cializa ion o β-glucosidase is in solu ion, so a eeze-d ying s age is no necessa y (Fe ei a e al., 2018a). The downs eam
p ocess conside s he use o a mic o il e o concen a e he low s eam ob ained jus a e e men a ion has inished. A e il a ion,
wi h a concen a ion o a ound 90 g/L (Fe ei a e al., 2018a), he second s ep is cell dis up ion o he elease o he in acellula
enzyme using a high-p essu e homogeniza ion uni (HG-101) acco ding o he ollowing mass balance (Chen e al., 2018; Middelbe g,
2000).
Biomass → 0.43 Cell Deb is +0.4P o eins +0.1β−Glucosidase +0.07 Glycogen
A e cell dis up ion, β-glucosidase is mainly in solu ion wi h sal s and cellula deb is. To sepa a e he main p oduc , a disc
H. Feijoo e al.
Sus ainable Chemis y and Pha macy 30 (2022) 100836
3
cen i uge ollowed by a dead-end il a ion is used, as i p o ides an e icien sepa a ion o he emaining biomass and cell deb is
(Fe ei a e al., 2018a; Heinzle e al., 2007; Soe ae and Vandamme, 2009).
Ul a il a ion is he i s s age o he pu i ica ion p ocedu e, wi h he β-glucosidase concen a ed by a ac o o 2 (Hema a hi and
Ragha a ao, 2011). Al hough he ul a il a ion ou pu s eam has signi ican ly educed he concen a ion o sal s, pu i ica ion p o-
ceeds wi h ion exchange (IEX) and dia il a ion s eps. Conside ing IEX, i is based on he sepa a ion o componen s by di e en
e en ion imes on he solid suppo , equi ing he addi ion o he ollowing chemicals: HCl (5% w/w) and NaCl (0.5 M) as washing
agen s and NaCl (0.5 M) and NaOH (20% w/w) o he egene a ion o he ion exchange esin (Al-Asheh and Aidan, 2020). The inpu
s eam o he IEX uni is mainly composed o wa e , glyce ol, KH
2
PO
4
, p o eins, β-glucosidase enzyme, glycogen and o ganic ma e .
To his end, he goal o he IEX uni is o sepa a e he s eam o β-glucosidase, which goes o he dia il a ion s age o emo e esidual
sal s, while he es a e ea ed as was e. The las s age is dia il a ion, o ob ain a highe pu i ied p oduc , as i is e ained in he
memb ane by adding he bu e solu ion, in his case ci ic acid, as a ma ix o s abilize he inal p oduc (Xia e al., 2022; Zhang e al.,
2017).
3. En i onmen al analysis using LCA me hodology
LCA is a me hodology o assessing he en i onmen al p o ile o a p oduc and/o a p ocess by iden i ying and quan i ying all mass,
ene gy and was e s eams associa ed. These da a a e compiled in wha a e called “Li e Cycle In en o y (LCI)" which is displayed
acco ding o he unc ional uni selec ed, ha is, he e e ence uni used o he mass, ene gy and was e balances. This me hodology is
applied acco ding o he de elopmen o ou main s eps, which a e desc ibed below in he amewo k o he manusc ip .
3.1. De ini ion o he goal and scope o he s udy
The objec i e o he wo k is he analysis o he en i onmen al bu dens o he bio echnological alo iza ion o glyce ol as a ca bon
sou ce o he mic obial p oduc ion o β-glucosidase. In e ms o sys em bounda ies, a “c adle- o- ac o y” app oach has been selec ed,
which includes all s ages om eeds ock and ene gy esou ce ex ac ion o he bio e ine y ga e, i.e., he p oduc ion o β-glucosidase as
he main p oduc and was ewa e as side s eams (Fig. 1). On he o he hand, he en i onmen al bu dens o cons uc ion, decom-
missioning and in as uc u e main enance we e excluded om he assessmen , as o he au ho s ha e shown ha he en i onmen al
impac s o hese a e negligible (A ias e al., 2021, 2022; Falano e al., 2014). Finally, ega ding he unc ional uni (FU), wo we e
selec ed o e alua ion. On he one hand, 1 ba ch/ope a ing cycle and, on he o he hand, he p oduc ion o 1 kg o β-glucosidase. The
selec ion o hese wo UFs has been based on ob aining an en i onmen al p o ile ha allows he en i onmen al loads o be assessed
globally, i.e., seeking o e alua e he sus ainabili y o he indus ial acili y and compa e i wi h o he p ocesses, and a a mo e in-
di idual le el, o allow compa ison o he e iciency and ecological al e na i e o he p oduc ion o his enzyme.
3.2. Da a collec ion o he LCI
Li e a u e da a we e used as a basis o pe o m he mass and ene gy balances o he p ocess, and o scale i up o an indus ial
manu ac u ing le el, Supe P o Designe ® has been used o model he bio echnological p ocess. Once he p ocess was modelled and all
mass, ene gy and was e lows we e de ined and calcula ed, he LCI could be quan i ied. The backg ound da a o all LCI inpu s we e
ob ained om he Ecoin en da abase. Fu he mo e, in o de o iden i y he p ocess s eps wi h he highes con ibu ion o en i on-
men al damage, he o e all p ocess has been di ided in o he main equipmen used in he glyce ol eco e y ou e. Wi h his, i has been
possible o pe o m he app op ia e sensi i i y analysis o y o achie e an e en be e en i onmen al p o ile, based on he componen s
o he in en o y da a ha lead o he highes en i onmen al load, o he p ocess.
3.3. Li e cycle impac assessmen (LCIA) acco ding o MidPoin hie a chical ReCiPe 2016 me hodology
Fo assessing he en i onmen al loads o he p ocess, acco ding o he da a p o ided in he LCI, ReCiPe 2016 hie a chis MidPoin
calcula ion me hodology V1.03 Wo ld has been used o he cha ac e iza ion ac o s o 18 midpoin impac ca ego ies, which a e lis ed
in Table 1. On he o he hand, he SimaP o so wa e has been used o de elop he compu a ional implemen a ion o he da a compiled
in he LCIs.
Fig. 1. Sys em bounda ies conside ed o assessing he en i onmen al p o ile o β-glucosidase p oduc ion.
H. Feijoo e al.
Sus ainable Chemis y and Pha macy 30 (2022) 100836
4
3.4. In e p e a ion o he en i onmen al p o ile and cha ac e iza ion alues
Once he en i onmen al loads and con ibu ions o he inpu da a we e ob ained, a sensi i i y analysis was ca ied ou , ocusing on
hose ma e ials ha lead o a highe en i onmen al con ibu ion, called ho spo s. Fo his, a ious p ocess al e na i es and op imi-
za ion p ocedu es we e e alua ed, wi h he aim o p o iding an imp o ed en i onmen al p o ile and guidance on wha esea che s and
s akeholde s should ocus on in o de o de elop mo e sus ainable and less en i onmen ally damaging p oduc ion sys ems.
4. Resul s and discussion
The in eg a ion o enzyma ic p ocesses o biomass alo iza ion equi es con i ming whe he enzyme p oduc ion and use is ca ied
ou unde en i onmen al sus ainabili y c i e ia. To his end, modelling he p oduc ion o β-glucosidase using he simula ion ool
Supe P o Designe allows he collec ion o in en o y da a necessa y o he applica ion o he li e cycle assessmen me hodology. A he
same ime, seeking o analyze he p o ile in mo e de ail, mo e in-dep h s udies we e ca ied ou a he s ages leading o he highes
en i onmen al con ibu ion, pu suing o iden i y he easons o such impac loads. Wi h he aim o e alua ing scena ios wi h mo e
con incing sus ainabili y alues, sensi i i y analyses we e pe o med a ound he iden i ied c i ical poin s.
4.1. Li e cycle in en o ies
The in en o y da a o he bio echnological p ocess conside ing as unc ional uni a ba ch is shown in Table 2, while he da a
co esponding o 1 kg o β-glucosidase is shown in Table 3. On he o he hand, he inpu s used om he Ecoin en da abase a e
depic ed on Table 4.
4.2. Modelling esul s
The capaci y o he acili y is 5200 kg o was e glyce ol pe ba ch p ocess. The selec ed capaci y has been de ined acco ding o o he
e e ences on he p oduc ion o his enzyme as well as p ocess a iables such as esidual glyce ol o be p ocessed, amoun o enzyme
p oduced and he capaci ies o he equipmen (Fe ei a e al., 2018b; Klein-Ma cuschame e al., 2012; Tus´
e e al., 2014). The main
modelling equipmen o he acili y is included in Table 4, wi h i s main capaci y alues, oge he wi h he numbe o uni s equi ed.
The p ocess has been di ided in o wo main sec ions, hose equi ed o e men a ion, bo h seed o inoculum p epa a ion and main
e men a ion o he p oduc ion o he enzyme, and he downs eam s age equi ed o pu i ica ion, based on a cascade p ocess wi h
se en main s eps, which we e desc ibed in Sec ion 2.
4.3. En i onmen al esul s
ReCiPe MidPoin calcula ion me hodology was applied o sco e he en i onmen al impac s associa ed wi h β-glucosidase p o-
duc ion p ocess (see Table 5). Table 6 includes he absolu e impac alues ob ained.
In addi ion, in o de o e alua e he o e all p ocess, o iden i y which o he s ages leads o he highes en i onmen al load and
he e o e whe e imp o emen s and op imiza ion a e needed, Fig. 2 is depic ed.
As can be seen, he s age leading o he highes en i onmen al load is he main e men a ion s age, as expec ed, ollowed by
dia il a ion, bu wi h a much less signi ican con ibu ion in compa ison. The eason o he en i onmen al load o he dia il a ion
s age is due o he use o ci ic acid in he il e (Gabe e al., 2020). To iden i y he eason o such a high en i onmen al load in he
main e men a ion s age, Fig. 3 shows he en i onmen al p o ile o his single s age, acco ding o he LCI da a p o ided in Tables 1 and
2
In he en i onmen al p o ile o he main e men e , h ee main ho spo s can be iden i ied: elec ici y, glyce ol and s eam e-
qui emen s. Fo he impac ca ego ies ce ainly, as in he case o MRS and WC, he main con ibu o s a e ammonium dihyd ogen
phospha e and p ocess emissions, espec i ely. The eason o he huge impac con ibu ion o glyce ol comes om he backg ound
ac i i ies o i s p oduc ion. I should be no ed ha , e en i a alo iza ion ou e is p oposed, a ze o-impac alue canno be assumed o
his glyce ol esidue, as se e al s eps a e equi ed o ob ain i , as a side s eam o he bio uel p oduc ion p ocess. As o elec ici y and
s eam loads, he ac ha hey a e ob ained om ossil esou ces, whose impac damages a e well known, leads o such a la ge
con ibu ion. I a educed impac alue is pu sued, he sou ce could be modi ied by op ing o enewable-based ene gies, whose
en i onmen al impac alues a e lowe . These al e na i es o he ene gy sou ce a e an aspec o be s udied in he sensi i i y analysis,
which a e p esen ed in he ollowing sec ions o his manusc ip .
Table 1
ReCiPe MidPoin impac ca ego ies analysed o he en i onmen al assessmen o β-glucosidase p oduc ion.
Ac onym Impac ca ego y Uni Ac onym Impac ca ego y Uni
GW Global Wa ming kg CO
2
eq TET Te es ial Eco oxici y kg 1.4-DCB
SOD S a osphe ic Ozone Deple ion kg CFC
11
eq FET F eshwa e Eco oxici y kg 1.4-DCB
IR Ionizing adia ion kBq Co-60 eq MET Ma ine Eco oxici y kg 1.4-DCB
OF Ozone Fo ma ion kg NO
x
eq HC Human ca cinogenic kg 1.4-DCB
FPF Fine Pa icula e Fo ma ion kg PM
2.5
eq HNC Human non-ca cinogenic kg 1.4-DCB
OZ Ozone Fo ma ion kg NO
x
eq LU Land use m
2
a c op eq
TA Te es ial Acidi ica ion kg SO
2
eq MRS Mine al Resou ces Sca ci y kg Cu eq
FE F eshwa e Eu ophica ion kg P eq FRS Fossil Resou ces Sca ci y kg oil eq
ME Ma ine Eu ophica ion kg N eq WC Wa e Consump ion m
3
H. Feijoo e al.
Sus ainable Chemis y and Pha macy 30 (2022) 100836
5
Table 2
Li e Cycle In en o y o he bio- echnological p oduc ion o β-glucosidase om biodiesel (FU: 1 ba ch).
1
s
s age: Seed Fe men e [V =m
3
] 4
h
s age: Cell dis up ion
Inpu s: Resou ces Inpu s: Elec ici y/hea Inpu s: esou ces Inpu s: elec ici y/hea
Ai 3195.3 Kg S eam 5260.51 MJ Wa e , cooling 4.88 m
3
Elec ici y 0.89 kWh
Wa e , cooling 472.63 m
3
Elec ici y 536.94 kWh 5
h
s age: Cen i uga ion
Inpu s: Ma e ials Ou pu s: Emissions o ai Inpu s: Elec ici y/hea Ou pu s: Was e o ea men
Residual glyce ol 261.72 Kg N
2
2451.19 kg Elec ici y 285.09 kWh Was ewa e 0.93 m
3
Wa e 4.64 m
3
O
2
626.73 kg 6
h
s age: Dead-end il a ion
(NH
4
)H
2
PO
4
40.97 Kg CO
2
122.72 kg Ou pu s: Was e o ea men
MgSO
4
⋅7H
2
O 3.28 Kg Was ewa e 0.59 m
3
KH
2
PO
4
82.57 Kg 7
h
s age: Ul a il a ion
Yeas 4.97 Kg Inpu s: Elec ici y/hea Ou pu s: Was e o ea men
2
nd
s age: Main Fe men e [V =m
3
] Elec ici y 26.52 kWh Was ewa e 7.88 m
3
Inpu s: Resou ces Inpu s: Elec ici y/hea 8
h
s age: Ion exchange
Ai 140982 Kg S eam 83009.70 MJ Inpu s: Ma e ials Ou pu s: Was e o ea men
Wa e , cooling 472.63 m
3
Elec ici y 45370.60 kWh Wa e 9.81 m
3
Was ewa e 8.30 m
3
Inpu s: Ma e ials Ou pu s: Emissions o ai NaCl 194 kg
Residual glyce ol 3632.50 Kg N
2
110553.20 kg HCl 6.9 kg
Wa e 14971.26 m
3
O
2
30851.60 kg NaOH 772.07 kg
(NH
4
)H
2
PO
4
633.51 Kg CO
2
2954.50 kg 9
h
s age: Dia il a ion
MgSO
4
⋅7H
2
O 53.47 Kg Inpu s: Ma e ials Ou pu s: P oduc
KH
2
PO
4
1210.69 Kg Wa e 1.72 m
3
Enzyma ic cock ail 2187.09 kg
Yeas 72.93 Kg Ci ic acid 485.06 kg
3
d
s age: Mic o il a ion Inpu s: Elec ici y/hea Ou pu s: Was e o ea men
Inpu s: Elec ici y/hea Ou pu s: Was e o ea men Elec ici y 31.28 kWh Was ewa e 0.04 m
3
Elec ici y 127.68 kWh Was ewa e 64.98 m
3
H. Feijoo e al.
Sus ainable Chemis y and Pha macy 30 (2022) 100836
6
As men ioned abo e, in he MRS ca ego y, he use o ammonium dihyd ogen phospha e ca ies a signi ican en i onmen al bu den
associa ed o he p oduc ion o mine al e ilize s. The e o e, he e is a consump ion o mine al esou ces ha has a di ec impac on
his ca ego y. As o he con ibu ion o emissions om he on-si e p ocess in he WC ca ego y, i is he esul o he need o wa e o
cooling, aken om na u e, which does no ha e a con ibu ion in o he impac ca ego ies, due o i s na u al o igin, bu does in he WC
Table 3
Li e Cycle In en o y o he bio- echnological p oduc ion o β-glucosidase om biodiesel (FU: 1 kg o enzyma ic cock ail).
1
s
s age: Seed Fe men e [V =m
3
] 4
h
s age: Cell dis up ion
Inpu s: Resou ces Inpu s: Elec ici y/hea Inpu s: esou ces Inpu s: elec ici y/hea
Ai 1.461 Kg S eam 2.41 MJ Wa e , cooling 0.002 m
3
Elec ici y 0.407 Wh
Wa e , cooling 0.216 m
3
Elec ici y 0.25 kWh 5
h
s age: Cen i uga ion
Inpu s: Ma e ials Ou pu s: Emissions o ai Inpu s: Elec ici y/hea Ou pu s: Was e o ea men
Residual glyce ol 0.120 Kg N
2
1.12 kg Elec ici y 0.130 kWh Was ewa e 0.423 L
Wa e 0.002 m
3
O
2
0.29 kg 6
h
s age: Dead-end il a ion
(NH
4
)H
2
PO
4
0.019 Kg CO
2
0.06 kg Ou pu s: Was e o ea men
MgSO
4
⋅7H
2
O 0.002 Kg Was ewa e 0.271 L
KH
2
PO
4
0.038 Kg 7
h
s age: Ul a il a ion
Yeas 0.003 Kg Inpu s: Elec ici y/hea Ou pu s: Was e o ea men
2
nd
s age: Main Fe men e [V =m
3
] Elec ici y 0.012 kWh Was ewa e 0.004 m
3
Inpu s: Resou ces Inpu s: Elec ici y/hea 8
h
s age: Ion exchange
Ai 64.46 Kg S eam 37.95 MJ Inpu s: Ma e ials Ou pu s: Was e o ea men
Wa e , cooling 0.216 m
3
Elec ici y 20.75 kWh Wa e 0.004 m
3
Was ewa e 0.004 m
3
Inpu s: Ma e ials Ou pu s: Emissions o ai NaCl 0.089 kg
Residual glyce ol 1.661 Kg N
2
50.55 kg HCl 0.003 kg
Wa e 6.845 m
3
O
2
14.11 kg NaOH 0.353 kg
(NH
4
)H
2
PO
4
0.289 Kg CO
2
1.351 kg 9
h
s age: Dia il a ion
MgSO
4
⋅7H
2
O 0.024 Kg Inpu s: Ma e ials Ou pu s: P oduc
KH
2
PO
4
0.554 Kg Wa e 0.790 L Enzyma ic cock ail 1 kg
Yeas 0.033 Kg Ci ic acid 0.222 kg
3
d
s age: Mic o il a ion Inpu s: Elec ici y/hea Ou pu s: Was e o ea men
Inpu s: Elec ici y/hea Ou pu s: Was e o ea men Elec ici y 0.014 kWh Was ewa e 1.864 L
Elec ici y 0.058 kWh Was ewa e 0.029 m
3
Table 4
Da abase used o conside ing he backg ound p ocess o he inpu s equi ed o he LCI.
Componen Da abase
Bioglyce ol Soy biodiesel, p oduc ion, a plan /kg/RNA
Cooling wa e Wa e , p ocess and cooling, unspeci ied na u al o igin
Elec ici y Elec ici y, medium ol age {Eu ope wi hou Swi ze land}|ma ke g oup o |Cu -o , U
Was ewa e Was ewa e , a e age {Eu ope wi hou Swi ze land}|ma ke o was ewa e , a e age| Cu -o , U
Ci ic acid Ci ic acid {GLO}| ma ke o | Cu -o , U
Wa e Tap wa e {Eu ope wi hou Swi ze land}| ma ke o | Cu -o , U
NaCl Sodium chlo ide, b ine solu ion {GLO}| ma ke o | Cu -o , U
HCl Hyd ochlo ic acid, wi hou wa e , in 30% solu ion s a e {RER}| ma ke o | Cu -o , U
NaOH Sodium hyd oxide, wi hou wa e , in 50% solu ion s a e {GLO}| ma ke o | Cu -o , U
(NH
4
)H
2
PO
4
Monoammonium phospha e {RER}| ma ke o monoammonium phospha e|Cu -o , U
MgSO
4
⋅7H
2
O Magnesium sul a e {RER}| p oduc ion | Cu -o , U
KH
2
PO
4
Po assium sul a e {RER}| ma ke o po assium sul a e | Cu -o , U
Yeas Yeas pas e, om whey, a e men a ion/CH U
Hea Hea , om s eam, in chemical indus y {RER}| ma ke o hea , om s eam, in chemical indus y | Cu -o , U
S eam S eam, in chemical indus y {RER}| ma ke o s eam, in chemical indus y | Cu -o , U
Rapeseed oil Glyce ine {Eu ope wi hou Swi ze land}| es e i ica ion o ape oil | Cu -o , U
Palm oil Glyce ine {RoW}| es e i ica ion o palm oil | Cu -o , U
Soybean oil Glyce ine {BR}| es e i ica ion o soybean oil | Cu -o , U
Table 5
Main equipmen o he la ge-scale modelling o β-glucosidase p oduc ion, wi h he cha ac e is ic sizes and capaci y alues.
Equipmen Uni s Size Uni s Equipmen Uni s Size Uni s
Ai il e 5 3.75 m
3
/s Tank 1 5.27 m
3
Blending Tank 2 40.39 m
3
Homogenize 1 5.30 m
3
/h
Cen i ugal Comp esso 1 933.75 kW Mic o il e 2 79.65 m
2
Dead-End Fil e 1 70.00 m
2
PBA Column 2 495.38 L
Dia il e 1 39.10 m
2
Seed Fe men e 1 6.24 m
3
Disk-S ack Cen i uge 2 1.99 m
3
/h Ul a il e 1 33.15 m
2
H. Feijoo e al.
Sus ainable Chemis y and Pha macy 30 (2022) 100836
7
ca ego y as i s consump ion leads o a educ ion o he plane ’s wa e esou ces.
4.4. Sensi i i y analysis
The sensi i i y analysis was pe o med acco ding o he main ho spo s o he p ocess, ha is, he main e men a ion is he s age wi h
he highes g oss en i onmen al load. The eason behind hese esul s is based on he ene gy equi emen s, bo h elec ici y and s eam,
oge he wi h he bio-based glyce ol. Acco dingly, di e en modi ica ions we e conside ed: ype o oil-based eeds ock o biodiesel
Table 6
Absolu e en i onmen al impac alues o β-glucosidase p oduc ion. Func ional uni : 1 kg o β-glucosidase cock ail.
Ac onym Impac ca ego y Uni Ac onym Impac ca ego y Uni
GW 19.37 kg CO
2
eq TET 29.41 kg 1.4-DCB
SOD 4.70⋅10
−5
kg CFC
11
eq FET 0.35 kg 1,4-DCB
IR 4.77 kBq Co-60 eq MET 0.48 kg 1,4-DCB
OF 0.03 kg NO
x
eq HC 0.59 kg 1,4-DCB
FPF 0.03 kg PM
2.5
eq HNC 21.24 kg 1,4-DCB
OZ 0.03 kg NO
x
eq LU 8.38 m
2
a c op eq
TA 0.09 kg SO
2
eq MRS 0.03 kg Cu eq
FE 0.01 kg P eq FRS 5.06 kg oil eq
ME 0.02 kg N eq WC 7.48 m
3
Fig. 2. En i onmen al p o ile o β-glucosidase enzyme p oduc ion.
Fig. 3. En i onmen al p o ile o he main e men e .
H. Feijoo e al.
Sus ainable Chemis y and Pha macy 30 (2022) 100836
8
p oduc ion (Fig. 4), educ ion o elec ici y and ype o ene gy sou ce (Fig. 5) and, o s eam, biomass alo iza ion, a educ ion o s eam
equi emen s and a change in he hea sou ce (Fig. 6).
The al e na i e esou ces e alua ed o glyce ol p oduc ion we e soybean oil and palm oil. Bo h a e common eeds ocks used o
p oduce bio uel, o example, in he case o soybean oil, acco ding o he Na ional Pe oleum Agency, in B azil almos 75% o all
biodiesel is p oduced using soybean oil as a enewable sou ce (Anas ´
acio e al., 2014).
In he case o Eu ope, he mos used and a ailable ege able oil o biodiesel p oduc ion is apeseed oil, accoun ing o 6.5⋅10
6
MT,
ollowed by palm oil, 1.54⋅10
6
, and soybean oil, 7.20⋅10
5
MT, acco ding o EU Bio uels Annual 2019 Repo (Flach e al., 2019).
The e o e, hese oilseed eeds ocks ha e been selec ed o he en i onmen al sensi i i y analysis. In addi ion, esidual glyce ol has also
been conside ed as a ze o-impac s eam, as i is conside ed a was e om biodiesel p oduc ion, and he ac ha i is eco e ed h ough
a bio echnological p ocess o he p oduc ion o a high added alue compound, a oiding i s managemen as was e, i s associa ed
impac s and he e o e educing i s impac on he en i onmen .
The en i onmen al esul s and hei subsequen compa ison be ween he p oposed scena ios a e shown in Fig. 4. As can be seen, he
use o palm oil as a eeds ock seems o be he bes om he en i onmen al poin o iew, as i p oduces he leas en i onmen al damage
in all he impac ca ego ies e alua ed in compa ison wi h he o he esou ces. In con as , in he case o soybean oil, i is in almos all
impac ca ego ies he scena io ha leads o he highes en i onmen al bu dens, wi h he excep ion o ou ca ego ies: SOD, TA, ME and
HNC, whe e he use o apeseed oil has he highes con ibu ion on he en i onmen . On he o he hand, as expec , he ac o
conside ing bio-glyce ol as esidual s eam wi h an assigned ze o impac , leads o he bes en i onmen al al e na i e pe o mance,
wi h signi ican educed impac s in compa ison wi h he base case scena io. To his end, o his i s al e na i e sensi i i y assessmen ,
palm oil could be selec ed as he p e e ed eeds ock o glyce ol p oduc ion and, when possible, assigna ion o ze o impac o he
esidual glyce ol is conside ed as he op imum and mo e desi able scena io om he en i onmen al poin o iew.
When assessing he elec ici y equi emen s, a 25% educ ion in ene gy has been conside ed, based on he p emise ha as he
modelling is based on labo a o y da a, i is no op imized da a on a la ge scale, so he ange o imp o emen is qui e wide, especially in
e ms o ene gy consump ion. Some imp o emen has been achie ed wi h his op imized scena io in mainly all impac ca ego ies, as
could be seen in Fig. 5, bu he esul s we e no as p onounced as hose ob ained by he second op imized op ion. This second
sensi i i y assessmen has been ca ied ou by modi ying he elec ici y sou ce da abase. In he baseline scena io, he Eu opean
elec ici y mix has been used, which includes he a e age mix o elec ici y sou ces used in Eu opean coun ies, which ha e a la ge
sha e o ossil ene gy esou ces. In con as , in he case o No way, mos o he elec ici y p oduced comes om hyd opowe , a
enewable ene gy ha leads o a signi ican educ ion o he impac , as could be seen in Fig. 5. In ac , in impac ca ego ies such as IR
and FE, he en i onmen al load is educed by almos 80%, and o FET, MET and HC he impac is educed by 60%. Howe e , as would
be p edic ed, being a hyd oelec ic powe plan , in he WC ca ego y, he use o his echnology leads o a highe en i onmen al load
due o wa e use, bu he di e ence be ween he o he wo scena ios is no signi ican , as i is less han 10%.
The las sensi i i y analysis conce ns he consump ion o s eam as he main hea ing sou ce. The i s op imized scena io is ene gy
eco e y using he biomass p oduced in he e men a ion s age. This could be conside ed as a sus ainable and ci cula economy
p ocedu e, as a “was e” s eam om he p ocess is used as a “sou ce” o s eam p oduc ion. This equi es anae obic diges ion coupled
wi h a cogene a ion uni . The esul s ob ained by his alo iza ion do no lead o a signi ican educ ion o en i onmen al damage,
because he amoun o biomass p oduced wi hin he e men a ion is no oo high, so i does no allow o p oduce an abundan amoun
o he mal ene gy. Since he esul s ob ained we e no su icien ly sa is ac o y, he op ion o p oposing a 25% educ ion in s eam
consump ion was conside ed. This al e na i e has been ca ied ou based on he same p ecep men ioned in he sensi i i y analysis o
he elec ical equi emen s: he ac ha he la ge-scale modelling is ca ied ou on he basis o labo a o y-le el da a, he ange o
imp o emen is ex ensi e. Fu he mo e, by pe o ming a ype o analysis, gi en he a ie y o empe a u es handled h oughou he
p ocess, i would be possible o use he p ocess lows hemsel es as hea ans e agen s, hus educing he consump ion o esou ces
and u ili ies. This al e na i e sensi i i y scena io has esul ed in signi ican educ ions in impac , as can be seen in Fig. 6, wi h GW, FRS
and TET being he ca ego ies whe e he g ea es dec ease in en i onmen al load has been obse ed. Bu , looking o an e en mo e
op imized scena io, he use o an al e na i e esou ce o s eam p oduc ion has been conside ed, namely a enewable bio-based
esou ce, in his case municipal was e eco e ed by incine a ion. The impac educ ion is obse able in almos all impac ca e-
go ies, wi h he GW, FRS and TET impac ca ego ies achie ing a huge imp o emen . To his end, i was hough ha he e alua ed
sensi i i y analysis scena ios o educing he in-p ocess en i onmen al s eam load led o educ ion in mos o he ca ego ies, he
al e na i e o using hea om lignocellulosic was e seems o be he mos a ac i e, as he impac alues could be educed by 20%–30%
in some o he impac ca ego ies unde s udy.
5. Key poin s o imp o e pe o mance
Acco ding o he main ho spo s iden i ied on he p e ious sensi i i y assessmen , he main key poin s o imp o emen could be
ca ego ized as:
5.1. Sou ce o bio-glyce ol p oduc ion
(Schmid , 2010) has de eloped an en i onmen al assessmen o e he impac s on he soybean and apeseed oil cul i a ion. Taking
in o accoun a consis en modelling co e ing bo h oil mill and ag icul u al s ages, soybean oil p oduc ion leads o a highe con ibu ion
in mos he impac ca ego ies, wi h he excep ion o s a osphe ic ozone deple ion (SOD), e es ial acidi ica ion (TA), ma ine
eu ophica ion (ME) and land use (LU). These esul s a e in line wi h he one ob ained o his manusc ip , as in hose impac ca ego ies
men ioned he use o apeseed oil en ails a highe en i onmen al load in compa ison wi h soybean oil.
H. Feijoo e al.
Sus ainable Chemis y and Pha macy 30 (2022) 100836
9
On he o he hand, he a ionale behind he lowe en i onmen al impac o palm oil is based on he ac ha i is by a he mos
e icien and p oduc i e ege able oil due o i s as g ow h and low soil occupa ion. I s high c op yield makes i in one o he mos
sus ainable lignocellulosic eeds ock (Beye e al., 2020; Oos e ee , 2020).
5.2. Ene gy sou ce: mo ing om ossil o enewable esou ces
Looking o educe he deple ion o ossil esou ces and he en i onmen al bu dens esul ing om he use o non- enewable ene gy,
he use o enewable esou ces could be conside ed as an e icien and sus ainable al e na i e (ˇ
Se eˇ
so ´
a e al., 2020). Se e al s udies
ha e ocused on analysing he en i onmen al bu dens associa ed wi h he di e en ene gy sou ces, one o hem is he ETC epo
(Bouman, 2020). The a oided impac s o he di e en bioene gy al e na i es ha e been e alua ed, concluding ha an o e all 1.8⋅10
3
M o CO
2
eq could be a oided, wi h he use o hyd o he mal, onsho e wind and sola pho o ol aic ene gies con ibu ing he mos on
he educ ion o en i onmen al loads. Bu , on he o he hand, highe en i onmen al loads could be ob ained in oxici y impac s and
land occupa ion, gi en he need o ag icul u al ac i i ies, e ilize s, g oss in as uc u es, and specialized ma e ials o he con-
s uc ion o he necessa y equipmen (Bouman, 2020). Simila ends we e concluded by (He wich e al., 2015) in e ms o land
occupa ion, ha no signi ican en i onmen al bu den is ob ained, when assessing hyd opowe and pho o ol aics, ce ain highe
impac is obse ed.
Fig. 4. Sensi i i y analysis I: al e na i e sou ce o glyce ol. RO: Rapeseed Oil, SO: Soybean Oil, PO: Palm Oil and Residue: esidual glyce ol as a ze o-impac inpu .
Fig. 5. Sensi i i y analysis II: elec ici y educ ion and change on elec ici y mix o No way one.
H. Feijoo e al.
