With the gradual increase in algal waste, its disposal has become a key problem in the field of marine environmental protection. Anaerobic digestion (AD) of algal biomass is one potential method for its treatment in a beneficial manner. However, AD of algae is hindered because of strong resilient cell walls, and hence, pretreatment of algae biomass before AD is an essential process. In this study, green algae (Enteromorpha) were used as the research substrate to explore the damage and impact of NaOH–urea pretreatment on biomass. Scanning electron microscopy and thermogravimetric analysis were used to analyze the damage of the cell wall structure of Enteromorpha via NaOH–urea pretreatment. The response surface method (RSM) was used for the optimization of pretreatment conditions to obtain the best experimental conditions. The experimental independent variables were pretreatment time, pretreatment temperature, and NaOH–urea concentration. RSM results showed that the optimal conditions are pretreatment time of 50 min, NaOH–urea concentration of 5.89%, and pretreatment temperature of −16 °C. AD was carried out under these conditions. The results showed that cumulative gas production for the control group was 231.5 ml whereas the biogas yield for best optimal conditions was 521.5 and 413 ml, respectively. In addition, AD reaction kinetics was evaluated by two mathematical kinetic models. It was found that modified Gompertz model is more suitable for describing the AD behavior.

1.
G.
Mehdi
,
N.
Ali
,
S.
Hussain
,
A. A.
Zaidi
,
A. H.
Shah
, and
M. M.
Azeem
, in
2019 2nd International Conference on Computing, Mathematics and Engineering Technologies
(IEEE, Piscataway, NJ,
2019
), pp.
1
4
.
2.
K.
Mazloomi
and
C.
Gomes
,
Renewable Sustainable Energy Rev.
16
,
3024
(
2012
).
3.
R.
Kothari
,
D.
Buddhi
, and
R. L.
Sawhney
,
Renewable Sustainable Energy Rev.
12
,
553
(
2008
).
4.
A. H. S.
Hassan
,
T.
Mietzel
,
R.
Brunstermann
,
S.
Schmuck
,
J.
Schoth
,
M.
Küppers
, and
R.
Widmann
,
World J. Microbiol. Biotechnol.
34
,
176
(
2018
).
5.
A. A.
Zaidi
,
S. Z.
Khan
,
H.
Almohamadi
,
E. R. I.
Mahmoud
, and
M. N.
Naseer
,
Bull. Chem. React. Eng. Catal.
16
(
2
),
374
(
2021
).
6.
P.
Intanoo
,
P.
Chaimongkol
, and
S.
Chavadej
,
Int. J. Hydrogen Energy
41
,
6107
(
2016
).
7.
J.
Cheng
and
M.
Zhu
,
Bioresour. Technol.
144
,
623
(
2013
).
8.
R.
Angeriz-Campoy
,
C. J.
Álvarez-Gallego
, and
L. I.
Romero-García
,
Bioresour. Technol.
194
,
291
(
2015
).
9.
M. A.
Khan
,
H. H.
Ngo
,
W.
Guo
,
Y.
Liu
,
X.
Zhang
,
J.
Guo
,
S. W.
Chang
,
D. D.
Nguyen
, and
J.
Wang
,
Renewable Energy
129
,
754
(
2018
).
10.
A. H.
Salem
,
R.
Brunstermann
,
T.
Mietzel
, and
R.
Widmann
,
Int. J. Hydrogen Energy
43
,
4856
(
2018
).
11.
L.
Zhao
,
G.-L.
Cao
,
A.-J.
Wang
,
W.-Q.
Guo
,
H.-Y.
Ren
, and
N.-Q.
Ren
,
Bioresour. Technol.
145
,
103
(
2013
).
12.
Y.-T.
Fan
,
Y.
Xing
,
H.-C.
Ma
,
C.-M.
Pan
, and
H.-W.
Hou
,
Int. J. Hydrogen Energy
33
,
6058
(
2008
).
13.
C.-C.
Chen
,
Y.-S.
Chuang
,
C.-Y.
Lin
,
C.-H.
Lay
, and
B.
Sen
,
Int. J. Hydrogen Energy
37
,
15540
(
2012
).
14.
S.
Pattra
,
S.
Sangyoka
,
M.
Boonmee
, and
A.
Reungsang
,
Int. J. Hydrogen Energy
33
,
5256
(
2008
).
15.
G.
Ivanova
,
G.
Rákhely
, and
K. L.
Kovács
,
Int. J. Hydrogen Energy
34
,
3659
(
2009
).
16.
A. A.
Zaidi
,
F.
RuiZhe
,
Y.
Shi
,
S. Z.
Khan
, and
K.
Mushtaq
,
Int. J. Hydrogen Energy
43
,
14202
(
2018
).
17.
I.
Ntaikou
,
E.
Koutros
, and
M.
Kornaros
,
Bioresour. Technol.
100
,
5928
(
2009
).
18.
S.-K.
Han
and
H.-S.
Shin
,
Int. J. Hydrogen Energy
29
,
569
(
2004
).
19.
J.-J.
Lay
,
Y.-J.
Lee
, and
T.
Noike
,
Water Res.
33
,
2579
(
1999
).
20.
M.
Neureiter
,
H.
Danner
,
C.
Thomasser
,
B.
Saidi
, and
R.
Braun
, “
Dilute-acid hydrolysis of sugarcane bagasse at varying conditions
,”
Appl. Biochem. Biotechnol.
98
,
49
58
(
2002
).
21.
Y.
Shi
,
K.
Huang
,
R.
Feng
,
R.
Wang
,
G.
Liu
,
A. A.
Zaidi
, and
K.
Zhang
,
IOP Conf. Ser.: Earth Environ. Sci.
450
,
12025
(
2020
).
22.
C. Y.
Wang
and
H. Q.
Xie
, “
Study on nutrients uptake kinetics of typical enteromorpha algae from lianyungang
,”
Adv. Mater. Res.
111
,
610
613
(
2013
).
23.
A. A.
Zaidi
,
R.
Feng
,
A.
Malik
,
S. Z.
Khan
,
Y.
Shi
,
A. J.
Bhutta
, and
A. H.
Shah
,
Processes
7
,
24
(
2019
).
24.
H.-P.
Fink
,
P.
Weigel
, and
A.
Bohn
,
J. Macromol. Sci., Part B
38
,
603
(
1999
).
25.
T.
Liebert
,
Cellular Solvents: For Analysis, Shaping and Chemical Modifications
(
American Chemical Society
,
2010
), pp.
1
3
.
26.
J.
Eckelt
and
B. A.
Wolf
,
Macromol. Chem. Phys.
206
,
227
(
2005
).
27.
H.
Zhang
,
J.
Wu
,
J.
Zhang
, and
J.
He
,
Macromolecules
38
,
8272
(
2005
).
28.
R. P.
Swatloski
,
S. K.
Spear
,
J. D.
Holbrey
, and
R. D.
Rogers
,
J. Am. Chem. Soc.
124
,
4974
(
2002
).
29.
A.
Isogai
and
R. H.
Atalla
,
Cellulose
5
,
309
(
1998
).
30.
Y.
Dai
,
M.
Si
,
Y.
Chen
,
N.
Zhang
,
M.
Zhou
,
Q.
Liao
,
D.
Shi
, and
Y.
Liu
,
Bioresour. Technol.
198
,
725
(
2015
).
31.
X.
Qin
,
A.
Lu
,
J.
Cai
, and
L.
Zhang
,
Carbohydr. Polym.
92
,
1315
(
2013
).
32.
G.
Casella
 et al,
Applied Regression Analysis: A Research Tool
, 2nd ed. (
Springer-Verlag New York, Inc
.,
1998
).
33.
S.
Kotz
and
N. L.
Johnson
, “
Information theory and an extension of the maximum likelihood rinciple
,” in
Breakthroughs in Statistics
(
Springer
,
New York, NY
,
1992
), pp.
270
310
.
34.
A. A.
Zaidi
,
S. Z.
Khan
, and
Y.
Shi
,
Mater. Today Proc.
39
,
1025
(
2021
).
35.
M.
Waligórska
,
Chem. Process Eng.
33
,
585
(
2012
).
36.
A.
Xia
,
A.
Jacob
,
M. R.
Tabassum
,
C.
Herrmann
, and
J. D.
Murphy
,
Bioresour. Technol.
205
,
118
(
2016
).
37.
D.
Karadag
and
J. A.
Puhakka
,
Int. J. Hydrogen Energy
35
,
10954
(
2010
).
38.
A. A.
Zaidi
,
F.
RuiZhe
,
A.
Malik
,
S. Z.
Khan
,
A. J.
Bhutta
,
Y.
Shi
, and
K.
Mushtaq
,
Int. J. Hydrogen Energy
44
,
14661
(
2019
).
39.
APHA
,
Standard Methods for the Examination of Water and Wastewater
(
American Public Health Association
,
1995
).
40.
I.
Syaichurrozi
,
Budiyono
, and
S.
Sumardiono
,
Bioresour. Technol.
149
,
390
(
2013
).
41.
B.
Deepanraj
,
V.
Sivasubramanian
, and
S.
Jayaraj
,
Int. J. Hydrogen Energy
42
,
26522
(
2017
).
42.
C. S.
Wong
and
W. K.
Li
,
J. Time Ser. Anal.
19
,
113
(
1998
).
43.
Q.
Yan
,
A.
Wang
,
C.
Yu
,
N.
Ren
,
Y.
Zhang
, and
G.
Zhang
,
Int. J. Hydrogen Energy
36
,
405
(
2011
).
44.
J.-I.
Park
,
J.
Lee
,
S. J.
Sim
, and
J.-H.
Lee
,
Biotechnol. Bioprocess Eng.
14
,
307
(
2009
).
45.
Y.
Shi
,
K.
Huang
,
X.
Pan
,
G.
Liu
,
Y.
Cai
,
A. A.
Zaidi
, and
K.
Zhang
,
Bioresour. Technol.
329
,
124932
(
2021
).
46.
R.
Feng
,
A. A.
Zaidi
,
K.
Zhang
, and
Y.
Shi
,
Period. Polytech. Chem. Eng.
63
,
65
(
2018
).
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