(3.2) > ultrasonic (2.9) > ultraviolet (2.9) > control (2.7) [235]. The dry heat was
found the best pretreatment for preparing inoculum for palm oil mill effluent and
corn stover hydrolysate. However, wet heat was found better for dairy processing
wastewater, while inhibiting the methanogens by BESA was the best pretreatment
for biodiesel production waste (glycerol).
For H 2 production from corn stalk waste, acid has been reported as the best
culture pretreatment to prepare H 2 -producing inoculum from cow dung compost
compared to base (alkaline) and infrared radiation [238]. For dairy wastewater dark
fermentation using anaerobic sludge, BESA has been shown efficient for H 2 evolution and substrate removal [220]. However, conflicting conclusions have been
reported regarding which pretreatment is the best compared to acid, heat, and their
combination [203]. Mu et al. [239] reported that compared to thermal, microwave,
thermal-alkaline, and microwave-alkaline pretreatments, alkaline treatment was the
best to prepare H 2 -producing inoculum from anaerobic mixed culture to convert
sugar beet pulp.
5 Bioreactors Types and Configuration for H 2 Production
Almost all types of reactor designs have been used to enhance the H 2 yield and
production rate from industrial waste (Tables 8.1, 8.2, 8.3, 8.4, 8.5, and 8.6). These
types of reactors included batch, anaerobic fluidized bed (AFBR), continuously
stirred tank reactor (CSTR), anaerobic fluidized bed bioreactor (AFBR), expanded
granular sludge bed reactors (EGSBR), leaching bed reactor (LBR), and anaerobic
sequence batch reactor (ASBR). Generally, for commercial application of industrial
waste treatment and H 2 production, the reactor should provide robust, reliable, and
stable performance in terms of H 2 production rate and yield and minimum temporal
fluctuations in operational parameters over the long-term operation [85]. Optimization of reactor design should aim to increase the H 2 production rate through
improving the biomass immobilization by granulation, membranes, or carriers and
increase the H 2 yield by effluent recycling to allow complete substrate degradation.
Although operating at short HRT to match the fast growth rate of the H 2 -producing
acidogenic biomass would achieve the highest H 2 production rate, complex substrates such as food processing wastewater may require a longer HRT, particularly
when they contain proteins and fats.
354
A. Hajizadeh et al.
found the best pretreatment for preparing inoculum for palm oil mill effluent and
corn stover hydrolysate. However, wet heat was found better for dairy processing
wastewater, while inhibiting the methanogens by BESA was the best pretreatment
for biodiesel production waste (glycerol).
For H 2 production from corn stalk waste, acid has been reported as the best
culture pretreatment to prepare H 2 -producing inoculum from cow dung compost
compared to base (alkaline) and infrared radiation [238]. For dairy wastewater dark
fermentation using anaerobic sludge, BESA has been shown efficient for H 2 evolution and substrate removal [220]. However, conflicting conclusions have been
reported regarding which pretreatment is the best compared to acid, heat, and their
combination [203]. Mu et al. [239] reported that compared to thermal, microwave,
thermal-alkaline, and microwave-alkaline pretreatments, alkaline treatment was the
best to prepare H 2 -producing inoculum from anaerobic mixed culture to convert
sugar beet pulp.
5 Bioreactors Types and Configuration for H 2 Production
Almost all types of reactor designs have been used to enhance the H 2 yield and
production rate from industrial waste (Tables 8.1, 8.2, 8.3, 8.4, 8.5, and 8.6). These
types of reactors included batch, anaerobic fluidized bed (AFBR), continuously
stirred tank reactor (CSTR), anaerobic fluidized bed bioreactor (AFBR), expanded
granular sludge bed reactors (EGSBR), leaching bed reactor (LBR), and anaerobic
sequence batch reactor (ASBR). Generally, for commercial application of industrial
waste treatment and H 2 production, the reactor should provide robust, reliable, and
stable performance in terms of H 2 production rate and yield and minimum temporal
fluctuations in operational parameters over the long-term operation [85]. Optimization of reactor design should aim to increase the H 2 production rate through
improving the biomass immobilization by granulation, membranes, or carriers and
increase the H 2 yield by effluent recycling to allow complete substrate degradation.
Although operating at short HRT to match the fast growth rate of the H 2 -producing
acidogenic biomass would achieve the highest H 2 production rate, complex substrates such as food processing wastewater may require a longer HRT, particularly
when they contain proteins and fats.
354
A. Hajizadeh et al.