Global warming and increasing prices of fossil fuels influencing the improvement of renewable energy and biofuel production technologies. Bioethanol production by biomass digestion promises to be one of the most effective methods for producing renewable and sustainable energy. Lignocellulosic raw materials include agricultural wastes, forest products or energy crops and constitute abundant, widely distributed and inexpensive feedstocks for biofuels production. The major compositions of plant cell wall are cellulose, hemicellulose and lignin. High amount of sugars can be produced from cellulose and hemicellulose, using acid as the catalyst, or enzymatic hydrolysis and reformed into bioethanol by a fermentation procedure.
Most physical and chemical pre-treatment using acid, alkali, processes require special instrument and consume a lot of energy and generate inhibitors which will affect enzymatic hydrolysis and fermentation. Many researches displayed that biological pretreatment such as bacteria, fungus (white-, brown-, and soft-rot fungi), deuteromycetes and ascomycetes can enhance the hydrolysis productivity because of generating low inhibitors and limited energy utilization. Furthermore, biological pretreatment compared to other pretreatment process such as organosolvant and ammonium fiber explosion (AFEX) is considered as cheap process and have been less investigated
Animal slurry is widely used as a fertilizer in organic
farms. Dairy cattle typically produce between 42 kg and 64 kg (depending on
body weight) of manure per day, so if they are housed for 50% of the year that
corresponds to 7.6-11.6 tonnes per cow. In many developing nations, animalfaeces have been composted and used to fertilize farm fields. Many factors,
including the type and concentration of substrate, temperature, moisture, pH,
etc., may affect the performance of the anaerobic digestion process in the
bioreactor. The anaerobic digestion of organic waste is also an environmentally
useful technology.described the benefits of this process to reduce
environmental pollution in two main ways: the sealed environment of the process
prevents exit of methane into the atmosphere, while burning of the methane will
release carbon–neutral carbon dioxide (no net effect on atmospheric carbon
dioxide and other greenhouse gases).
On the other hand, the anaerobic process
has some disadvantages such as long retention times and low removal
efficiencies of organic compounds. Consequently, various physical, chemical and
enzymatic pretreatments are required to increase substrate solubility andaccelerate the biodegradation rate of solid organic waste. In the described
manner of treating the liquid manure its temperature is augmented; our findings
show that in the summer time that it is possible to supply the air from outside
the barn to the aerator pump whereas in winter it is recommendable to supply
warmed air from the barn interior. In this way the liquid manure heating is
accelerated and at the same time the barn microclimate, from which the bad
smell is removed, is improved.
