Biogas production is traditionally carried out by fermenting animal waste such as solid and liquid manure. This animal waste can be mixed with other household waste or food processing waste. Depending on the composition of the processed raw materials, different levels and energy values of biogas yield can be expected http://max64.ru/.
The amount of waste generated depends on the age and type of animals, as well as on the season. The average amount of biogas that can be obtained from 1 m3 of animal waste is estimated at 20-25 m3, although 30-35 m3 is considered to be a cost-effective amount in technical and economic terms. This amount of gas can be obtained by mixing animal waste and household waste with other raw materials that have a high dry organic matter content, namely, food industry waste or plant matter.
Fermentable raw materials can be divided into three categories:
Agricultural: solid manure, slurry, energy crops, biomass residues, etc .;
Industrial: starch, waste from slaughterhouses, dairy and sugar factories, pharmaceutical, cosmetic and paper industries, etc.;
Fermentation material can be divided into main (fermentation of which can occur independently, without adding other types of raw materials) and auxiliary. The main fermentation material is considered to be manure, slurry, young grass, and the auxiliary material is vegetable waste from vegetables and fruits, organic waste, food residues, fats, molasses, organic products that are split naturally - biologically, household waste, etc.
Due to the addition of auxiliary material with a high dry organic matter content, the production of biogas can be significantly increased, especially when using fats, the addition of which leads to an increase in gas production several times. Mixed fermentation, that is, the simultaneous fermentation of various types and types of raw materials, delays the accumulation process and requires the construction of large tanks, but this measure pays off due to the increase in biogas production. Too much loading with organic substances, at the same time, can disrupt the ratio of raw materials and, as a result, lead to a sudden decrease in biogas production and even to the death of bacterial colonies responsible for the fermentation process.
Preparation of fermented raw materials requires the fulfillment of certain conditions. The condition for the use of organic material in the fermentation process is the absence of toxic compounds in it, as well as the appropriate degree of grinding of the material, which can increase the productivity of biogas production by up to 20%. The use of homogeneous raw materials contributes to the efficient course of the fermentation process. Unwanted process components are inhibitors that are difficult to biodegrade, such as disinfectants, detergents, antibiotics and pesticides used in agriculture.
During the harvesting of the main crop, a large amount of by-product biomass is left unused or burned in the fields, thus generating additional emissions of carbon dioxide into the atmosphere. This biomass can be effectively used for biogas production. The biogas potential of residual biomass in Ukraine is 2.13 million tons of fuel equivalent.
Using the example of winter wheat and corn for grain, it is possible to assess the energy potential of agricultural by-products, which can be realized with the help of a biogas plant.
This example shows that when using such by-products of the agro-industrial complex as straw and vinasse, it is possible to obtain, in addition to the main product (alcohol with an energy potential of 23 MW * h / ha * year), almost twice as much energy - 45 MW * h / ha * year from by-products. At the same time, the preparation of biomass, in particular straw, for anaerobic fermentation is an important factor for the possibility of its full and effective use.