glass marbles, and plastic mesh when suspended in digester slurry reportedly led to
an increase in the gas yield by 10–20%.
Prasad (Prasad 1985) studied the effects of adding bagasse, Gulmohar leaves,
wheat straw, groundnut shells, and leguminous plant leaves as additives to cattle
dung on the biogas yield, gas composition, and extent of biodegradation. These
additives were separately mixed with cattle dung in the ratio of 1 part (oven dry) to
10 parts of fresh dung containing 19.2% of TS on weight basis. Anaerobic fermentation was carried out under batch process in bottles in laboratory at ambient
temperature between 30 and 32
C for 9 weeks. The volume of biogas generated
in 24 h was measured every day and gas composition analyzed periodically. It has
been concluded that addition of additives is advantageous for obtaining a high gas
yield.
6.2
Materials and Methods
6.2.1 Materials
Cassava was purchased from local supermarket in Salalah, Sultanate of Oman.
Wheat bran was kindly provided by Salalah Mills Company SAOG, Raysut, Sultanate of Oman. Sewage sludge was kindly supplied by Salalah Sanitary Drainage
Services Company SAOC, Raysut, Sultanate of Oman. Samples were used without
further treatment.
6.2.2 Methods
6.2.2.1 Preparation of Cassava Wastewater
Fresh cassava was peeled and 3 kg of peeled cassava root was weighed. The roots
were washed and cut into pieces. The cut roots were crushed with water in blender,
and the final mixture was filtered. The filtrate was used as cassava wastewater for
further analysis without any further dilution (Liu et al.).
6.2.2.2 Analytical Procedures
The total carbohydrate, lipid, and protein contents in the samples were estimated by
anthrone (Hedge et al. 1962), Soxhlet extraction (Saim et al. 1997), and microKjeldahl (Pellet and Young 1980) methods.
6.2.2.3 Stoichiometric Analysis
The procedure for stoichiometric analysis of biogas production is as follows:
1. The contents of carbohydrates, lipids, and proteins were estimated in cassava
wastewater, wheat bran, and sewage sludge.
2. The percentages of carbon, hydrogen, oxygen, nitrogen, and sulfur present in
carbohydrates, lipids, and proteins are known from the literature.
6 Stoichiometric Analysis of Biogas Production from Industrial Residues
147
an increase in the gas yield by 10–20%.
Prasad (Prasad 1985) studied the effects of adding bagasse, Gulmohar leaves,
wheat straw, groundnut shells, and leguminous plant leaves as additives to cattle
dung on the biogas yield, gas composition, and extent of biodegradation. These
additives were separately mixed with cattle dung in the ratio of 1 part (oven dry) to
10 parts of fresh dung containing 19.2% of TS on weight basis. Anaerobic fermentation was carried out under batch process in bottles in laboratory at ambient
temperature between 30 and 32
C for 9 weeks. The volume of biogas generated
in 24 h was measured every day and gas composition analyzed periodically. It has
been concluded that addition of additives is advantageous for obtaining a high gas
yield.
6.2
Materials and Methods
6.2.1 Materials
Cassava was purchased from local supermarket in Salalah, Sultanate of Oman.
Wheat bran was kindly provided by Salalah Mills Company SAOG, Raysut, Sultanate of Oman. Sewage sludge was kindly supplied by Salalah Sanitary Drainage
Services Company SAOC, Raysut, Sultanate of Oman. Samples were used without
further treatment.
6.2.2 Methods
6.2.2.1 Preparation of Cassava Wastewater
Fresh cassava was peeled and 3 kg of peeled cassava root was weighed. The roots
were washed and cut into pieces. The cut roots were crushed with water in blender,
and the final mixture was filtered. The filtrate was used as cassava wastewater for
further analysis without any further dilution (Liu et al.).
6.2.2.2 Analytical Procedures
The total carbohydrate, lipid, and protein contents in the samples were estimated by
anthrone (Hedge et al. 1962), Soxhlet extraction (Saim et al. 1997), and microKjeldahl (Pellet and Young 1980) methods.
6.2.2.3 Stoichiometric Analysis
The procedure for stoichiometric analysis of biogas production is as follows:
1. The contents of carbohydrates, lipids, and proteins were estimated in cassava
wastewater, wheat bran, and sewage sludge.
2. The percentages of carbon, hydrogen, oxygen, nitrogen, and sulfur present in
carbohydrates, lipids, and proteins are known from the literature.
6 Stoichiometric Analysis of Biogas Production from Industrial Residues
147