3.2 The Organic Fraction of Municipal Solid Waste
(OFMSW)
The organic fraction of municipal solid waste (OFMSW) is a sustainable
carbohydrate-rich substrate which can be fed to anaerobic mixed culture during
dark fermentation to produce H 2 . De Gioannis et al. [115] listed more than 80 studies
published on H 2 production from OFMSW. OFMSW increasingly attracts the
interest because it represents up to 70% of the total municipal solid waste produced,
whereas the biodegradable fraction (containing 50–70% water) forms about 53% of
the waste composition [116]. A generic theoretical molecular formula (C 6 H 10 O 4 ) has
been proposed by Themelis and Kim [117] for OFMSW. The H 2 potential of such
waste is quite high compared to that from glucose based on the molecular formulae.
Preparing the OFMSW as a substrate for H 2 production requires initial separation,
sorting, and some pretreatment which means an additional cost.
The potential of the organic fraction of municipal solid wastes (OFMSW) to
produce H 2 was investigated in several studies (Table 8.4). Inconsistency and wide
variation exist in the reported yield and production rate of H 2 from the OFMSW for
the same or similar substrate, reactor design, and operation conditions because of the
heterogeneous nature of the OFMSW and lack of its comprehensive characterization
during these studies (Table 8.4). For example, most studies reported the H 2 yield per
gram VS fed, gram COD fed, or gram substrate fed, but they did not analyze for
soluble or particulate carbohydrate, protein, fat, and fiber contents. Overall, the
general trend of the results reported (Table 8.4) indicates the potential of the
OFMSW for H 2 production through dark fermentation. Generally, the H 2 yield
ranged between 43 and 114 mL H 2 /g VS fed for mesophilic and thermophilic
operations, respectively [105, 119]. Hydrogen yield of 150 mL/g OFMSW and a
yield equivalent to 1.35 mol/mol glucose have also been reported (Table 8.4). At
mesophilic operation and a high F/M ratio (0.4 g OFMSW/g biomass), an
H 2 -specific production rate of 43 mL/g VSS/h and 125 mL/g TVS/h has been
reported [67]. Co-substrates increased the H 2 yield and the rate of production both
in mesophilic and thermophilic conditions (Table 8.4).
3.3 Food Processing Wastewater
Industrial wastes from sugar, dairy, olive mill, cheese whey, potato processing, and
brewery plants are carbohydrate-rich and have good potential to produce H 2
(Table 8.5). For example, noodle, potato, and rice processing food industries produce waste containing around 0.44 Æ 0.02 g carbon / kg of dry matter [160]. However, they may require pretreatment to remove undesirable components and to
supplement any deficit nutrients. Generally, waste that contains lignocellulosic
residues needs intensive pretreatment such as acid, alkaline, or thermal hydrolysis
338
A. Hajizadeh et al.
(OFMSW)
The organic fraction of municipal solid waste (OFMSW) is a sustainable
carbohydrate-rich substrate which can be fed to anaerobic mixed culture during
dark fermentation to produce H 2 . De Gioannis et al. [115] listed more than 80 studies
published on H 2 production from OFMSW. OFMSW increasingly attracts the
interest because it represents up to 70% of the total municipal solid waste produced,
whereas the biodegradable fraction (containing 50–70% water) forms about 53% of
the waste composition [116]. A generic theoretical molecular formula (C 6 H 10 O 4 ) has
been proposed by Themelis and Kim [117] for OFMSW. The H 2 potential of such
waste is quite high compared to that from glucose based on the molecular formulae.
Preparing the OFMSW as a substrate for H 2 production requires initial separation,
sorting, and some pretreatment which means an additional cost.
The potential of the organic fraction of municipal solid wastes (OFMSW) to
produce H 2 was investigated in several studies (Table 8.4). Inconsistency and wide
variation exist in the reported yield and production rate of H 2 from the OFMSW for
the same or similar substrate, reactor design, and operation conditions because of the
heterogeneous nature of the OFMSW and lack of its comprehensive characterization
during these studies (Table 8.4). For example, most studies reported the H 2 yield per
gram VS fed, gram COD fed, or gram substrate fed, but they did not analyze for
soluble or particulate carbohydrate, protein, fat, and fiber contents. Overall, the
general trend of the results reported (Table 8.4) indicates the potential of the
OFMSW for H 2 production through dark fermentation. Generally, the H 2 yield
ranged between 43 and 114 mL H 2 /g VS fed for mesophilic and thermophilic
operations, respectively [105, 119]. Hydrogen yield of 150 mL/g OFMSW and a
yield equivalent to 1.35 mol/mol glucose have also been reported (Table 8.4). At
mesophilic operation and a high F/M ratio (0.4 g OFMSW/g biomass), an
H 2 -specific production rate of 43 mL/g VSS/h and 125 mL/g TVS/h has been
reported [67]. Co-substrates increased the H 2 yield and the rate of production both
in mesophilic and thermophilic conditions (Table 8.4).
3.3 Food Processing Wastewater
Industrial wastes from sugar, dairy, olive mill, cheese whey, potato processing, and
brewery plants are carbohydrate-rich and have good potential to produce H 2
(Table 8.5). For example, noodle, potato, and rice processing food industries produce waste containing around 0.44 Æ 0.02 g carbon / kg of dry matter [160]. However, they may require pretreatment to remove undesirable components and to
supplement any deficit nutrients. Generally, waste that contains lignocellulosic
residues needs intensive pretreatment such as acid, alkaline, or thermal hydrolysis
338
A. Hajizadeh et al.