214
Water for Energy and Fuel Production
Nandy et al. [71] treated high-strength distillery spent wash in the fixed-film,
fixed-bed, two-stage anaerobic reactors using cheaper and abundantly available pebbles as media. The experiments were carried out in the laboratory as well as in the
pilot-scale operation. The results showed that the overall chemical oxygen demand
(COD) removal was about 80% with a specific biogas yield of 0.3 m 3 CH 4 /kg COD.
For a two-stage system, while the packed bed reactor can be easily fed with the spent
wash, the detention period for each reactor has to be increased to obtain the COD
removal close to 80%. In both reactors, the biogas yield decreased for HRT beyond
2.43 days. Feeding to the reactors can only be stopped for a maximum of three days,
and the reactors become sour and need to be reenergized for a pH level <6.0. Most
efficient operation was obtained at a temperature of 35°C–40°C and a pH of 7.0.
Greater depth of reactor gave poorer performance and no clogging of the reactor was
observed for 18 months.
8.4.4 SWine WASTe
Chen et al. [55] examined various engineering options of conversion of swine waste
to biomethanol. They applied target costing method in the development of marketable and environment-friendly product such as biomethanol from swine waste.
Biomethanol is produced from methane, which is generated by anaerobic digestion
of swine waste.
8.4.5 ByProduCTS oF BiodieSel ProduCTion
The process of biodiesel production is predominantly carried out by catalyzed
transesterification. Besides the desired methyl esters, the process produces several
byproducts such as crude glycerol, oil-pressed cakes, and washing water. Crude
glycerol or g-phase is a heavier, separate liquid phase, composed mainly of glycerol.
Numerous types of oil cakes such as canola, rapeseed, coconut, cottonseed, groundnut oil, mustard oil, olive oil, palm kernel, sesame oil, soybean, and sunflower are
also created in this process. Although their composition widely varies depending
on the parameters and substrates used for biodiesel production, all these byproducts
provide valuable feedstock for biogas production. The study by Kolesarova et al. [59]
leads to the following conclusions:
1. Crude glycerol from biodiesel production is a valuable substrate for
anaerobic degradation and the production of biogas using g-phase as a
single substrate.
2. G-phase also has a great potential as a co-substrate by anaerobic treatment
of different types of organic wastes such as organic fraction of MSW,
mixture of olive mill wastewater, slaughterhouse wastewater, corn maize,
maize silage, and swine manure.
3. Olive cakes and olive meals along with rapeseed and sunflower oil cakes
can be used for anaerobic digestion to produce biogas and methane. High
stability of the anaerobic digestion of sunflower oil cake under mesophilic
conditions was obtained. With the increased amount of oil gained from
Water for Energy and Fuel Production
Nandy et al. [71] treated high-strength distillery spent wash in the fixed-film,
fixed-bed, two-stage anaerobic reactors using cheaper and abundantly available pebbles as media. The experiments were carried out in the laboratory as well as in the
pilot-scale operation. The results showed that the overall chemical oxygen demand
(COD) removal was about 80% with a specific biogas yield of 0.3 m 3 CH 4 /kg COD.
For a two-stage system, while the packed bed reactor can be easily fed with the spent
wash, the detention period for each reactor has to be increased to obtain the COD
removal close to 80%. In both reactors, the biogas yield decreased for HRT beyond
2.43 days. Feeding to the reactors can only be stopped for a maximum of three days,
and the reactors become sour and need to be reenergized for a pH level <6.0. Most
efficient operation was obtained at a temperature of 35°C–40°C and a pH of 7.0.
Greater depth of reactor gave poorer performance and no clogging of the reactor was
observed for 18 months.
8.4.4 SWine WASTe
Chen et al. [55] examined various engineering options of conversion of swine waste
to biomethanol. They applied target costing method in the development of marketable and environment-friendly product such as biomethanol from swine waste.
Biomethanol is produced from methane, which is generated by anaerobic digestion
of swine waste.
8.4.5 ByProduCTS oF BiodieSel ProduCTion
The process of biodiesel production is predominantly carried out by catalyzed
transesterification. Besides the desired methyl esters, the process produces several
byproducts such as crude glycerol, oil-pressed cakes, and washing water. Crude
glycerol or g-phase is a heavier, separate liquid phase, composed mainly of glycerol.
Numerous types of oil cakes such as canola, rapeseed, coconut, cottonseed, groundnut oil, mustard oil, olive oil, palm kernel, sesame oil, soybean, and sunflower are
also created in this process. Although their composition widely varies depending
on the parameters and substrates used for biodiesel production, all these byproducts
provide valuable feedstock for biogas production. The study by Kolesarova et al. [59]
leads to the following conclusions:
1. Crude glycerol from biodiesel production is a valuable substrate for
anaerobic degradation and the production of biogas using g-phase as a
single substrate.
2. G-phase also has a great potential as a co-substrate by anaerobic treatment
of different types of organic wastes such as organic fraction of MSW,
mixture of olive mill wastewater, slaughterhouse wastewater, corn maize,
maize silage, and swine manure.
3. Olive cakes and olive meals along with rapeseed and sunflower oil cakes
can be used for anaerobic digestion to produce biogas and methane. High
stability of the anaerobic digestion of sunflower oil cake under mesophilic
conditions was obtained. With the increased amount of oil gained from