Table 3
Microalgae pretreatment for improved AD in continuous reactors
Microalgae species
Pretreatment conditions
AD conditions
Methane yield
increase
References
Scenedesmus
sp. and Chlorella
sp.
Thermal: 100 °C, 8 h
CSTR
a
: 3.7% TS, 28 days HRT
b
33% (0.270 L
CH
4 /g VS)
Chen and
Oswald (1998)
Scenedesmus
sp., Monorraphidium
sp. and diatoms biomass
Thermal: 75 and 95 °C,
10 h
CSTR: 37 °C, 0.7 g VS/Ld, 20 days
HRT
70% (0.180 L
CH
4 /g VS)
Passos and
Ferrer (2014)
Pediastrum
sp., Micractinium
sp. and
Scenedesmus
sp.
Thermal: 60 °C, 2–6 h
AVR
c
: 20 °C, 1.2 g VS/Ld, 91 days
SRT
d
32% (0.136 L
CH
4 /g VS)
Kinnunen et al.
(2014)
Nannochloropsis salina
Thermal: 100–120 °C, 2 h
CSTR: 38 °C, 2.0 g VS/Ld, 120 days
HRT
108% (0.130 L
CH
4 /g VS)
Schwede et al.
(2013)
Oocystis
biomass
Thermal: 130 °C, 15 min
CSTR: 37 °C, 0.7 g VS/Ld, 20 days
HRT
42% (0.120 L
CH
4 /g VS)
Passos and
Ferrer (2015)
Chlorella vulgaris
Thermal: 120 °C, 40 min
CSTR: 35 °C, 1.5 g COD/Ld, 15 days
HRT
48% (0.126 L
CH4/g COD)
Sanz et al.
(2017)
Scenedesmus
sp., Monorraphidium
sp. and diatoms biomass
Microwave: 70 MJ/kg VS,
26 g TS/L
CSTR: 35 °C, 0.8 g VS/Ld, 20 days
HRT
60% (0.272 L
CH
4 /g VS)
Passos et al.
(2014b)
Chlorella vulgaris
Enzymatic: protease (0.585
UA), 65 g TS/L
CSTR: 35 °C, 1.5 g COD/Ld, 20 days
HRT
260% (0.128 L
CH
4 /g COD)
Mahdy et al.
(2015)
Scenedesmus
sp.
Enzymatic: rumen
microorganisms fermenter
AnMBR
e
: 38 °C, 0.2 g COD/Ld,
31 days HRT, 100 days SRT
0.203 L CH
4 /g
COD
Giménez et al.
(2017)
Notes
a
CSTR stands for complete stirred tank reactor,
b
HRT stands for hydraulic retention time,
c
AVR stands for accumulating volume reactor,
d
SRT stands
for sludge retention time, and
e
AnMBR stands for anaerobic membrane bioreactor
12 Biofuels from Microalgae: Biomethane
253