Recycling of organic waste of poultry farms on the basis of cavitation vortex technologies with production of biogas and an algal feed additive.
A poultry farm for 400,000 laying hens produces up to 130 tons of litter a day
One ton of litter can yield 130 m3 of biogas
One m3 of biogas yields 2kWt*h of electric power and 2kWt*h of heat.
Besides energy, litter can be used to produce
- valuable feed additives
- agricultural fertilizers
Recycling of organic waste of poultry farms is a serious problem associated with its chemical composition. Litter is classified under class 3 toxicity; besides, pathogenic microorganisms can develop in it. Poultry breeding waste are still among the main factor of spread of infectious and invasive diseases in the area where the farm is situated.
The population morbidity level in the areas where large poultry farms operate is 1.6 times higher than its average in the Russian Federation.
On most farms, waste recycling systems are obsolete and do not comply with environmental standards. About 30 % of all Russian poultry farms do not have sewage purification systems.
As evidenced by the practice of operation of industrial poultry farms, ignoring the environmental approach to recycling of litter caused a sharp decline in the quality of crops, hazardous contamination of groundwater, surface water and air pool as well as increased morbidity of animals and population of environmental etiology.
At the same time, farmers need high-grade organic fertilizers to maintain and improve soil fertility.
The existing methods to recycle poultry farm waste by natural microbiological digestion are low effective in connection with the long period of recycling and release of a relatively small amount of biogas per unit time. Recycling of this type of waste in a cascade of waste water treatment facilities is very costly.
The development and implementation of highly-efficient technologies providing technological recycling of litter become increasingly important for nature protection, enhancing labor safety for supporting staff, preserving the population health and enhancing the profitability of production.
Current state of research and development in the area of recycling of organic waste of poultry farms
Biotechnological methods are used to recycle the waste of agricultural enterprises in China, India, Denmark, Germany, Austria and Italy.
Today Germany has about 800 farm bioenergy installations, and Austria has more than 100. Germany has more than 4,000 installations producing biogas from municipal wastewater, France has 150 and Switzerland has 134. There are 89 systems for biogas collection and recycling on solid waste landfills in Italy, in Sweden there are 73. Europe has a total of about 6,400 operating biogas energy installations of various types, Germany being the undisputed leader in biogas technologies. European installations produce 10.37 TWt*h of electric power and 36.53 PJ of heat per year.
However, it is difficult to import technologies proposed by these countries to Russia for the following reasons:
The technological installations developed in China and India are hardly suitable for Russia as they are intended for small enterprises and operation in a warm climate
The technological installations developed in Europe are expensive, intended for a warmer climate and are equipped with expensive automatic control devices requiring standard waste to be recycled.
Capital expenditures for the construction of 1 m3 methane tank of a farm biogas installation reach ˆ2,000 in Austria and Switzerland and ˆ400 in Germany and Italy.
This difference in the prices is explained by different approaches to design and construction of facilities. German farmers construct these installations themselves using finished parts, and an Italian installation presents a tank covered with a plastic membrane that does not use control of the reactor. In Austria and Switzerland, the installations are constructed by commercial companies. The solutions of European countries are not cost effective as the payback period of such lines is from 7 to 15 years, despite the fact that the developers get large subsidies from public funds.
The novelty of the proposed solutions and the main advantages of the innovation technology
The novelty and the main advantages of the proposed technology are predetermined by the use of two innovation developments: a gas-vortex bioreactor and a rotary-pulsation cavitator.
A rotary-pulsation cavitator operates on the basis of the principle of rupture of continuous liquid medium followed by the “collapse” of air bubbles. Disintegration and dispersion of biowaste particles occurs in it simultaneously with sterilization of reactive mass. The obtained sterile suspension is a nutrient medium for microorganisms recycling organic waste.
The gas-vortex bioreactor is a device of the new generation having no close world analogs in the principle of stirring.
The device provides effective mixing of the medium, including a viscous one, with low energy expenditures (5-6 times lower than devices with a stirrer) and provides the most optimal conditions for the development of microorganisms.
In the experts’ opinion, it is one of the most promising developments in the area of high technologies in Russia.
The developed technology provides high efficiency, considerably reduces the length of the technological cycle, increases biogas yield per unit time due to the cavitator used to mill litter to nanosized particles that are more easily attacked by enzymes and due to the fact that the gas-vortex bioreactor creates the most optimal conditions for vital activity of microorganisms producing these enzymes.
Biotechnological methods to recycle litter on the basis of innovation developments help reduce number of repositories, eliminate environment pollution and provide the production of high-quality fertilizers, electric power, heat, and feed additives.
Brief description of the technology
Dry litter is supplied through stone and metal catchers to the mill for preliminary grinding and then to rotary-pulsation cavitators where they are mixed with water. At this stage, the litter is milled to nanosized particles and sterilized to eliminate helminths and pathogenic microorganisms. Sterile fluid comes to gas-vortex bioreactors, is inoculated with a consortium of aerobic microorganisms, and aerobic digestion takes place. After aerobic digestion, the fluid is pumped to the second line of gas-vortex bioreactors for methane anaerobic digestion where it is inoculated with a consortium of anaerobic microorganisms. Then biogas from bioreactors is separated, dried and sent to gas-holders.
The released methane is supplied to a cogenerator to produce electric power and hot water.
The released carbon dioxide is supplied to gas-vortex aquareactors for cultivation of chlorella, which is a valuable feed additive in birds’ diet.
Liquid fraction produced as a result of the technological process after anaerobic digestion is a valuable biological fertilizer. It is transferred for packing and/or granulation, drying and packing.
Substances present in the produced organic fertilizers take a form easily digestible by plants making them efficient immediately after adding to soil. Substances of auxin class accelerating the growth and development of plants are synthesized in the bioreactor during the process of thermophilic digestion. When added to soil, liquid organic fertilizers help preserve moisture even in dry weather due to the presence of humus materials.
Litter-removal of stones and metal objects-preliminary grinding on a mill-grinding in RPC-aerobic digestion (hydrolysis) in BR-aerobic digestion in BR-biogas purification and drying –gas separation-gas storage-gas use.
GVR –production of the liquid fraction of fertilizers-packing and/or granulation, drying and packing.
The production line consists of the following modules:
• module for preparation and processing of litter equipped with gas-vortex bioreactors and rotary-pulsation cavitators.
• module for biogas production; module for production of fertilizers;
• module for energy and heat production;
• module for carbon dioxide production;
• module for microalgae cultivation;
• module for automatic control.
The first and two latter modules are developed, while the others are procured in a standard version.
Application of innovation biotechnologies for recycling litter solves the problem of cost effective recycling of poultry farm waste by:
- considerably reducing the recycling period due to multiple acceleration of the process of microbiological degradation of waste
- obtaining additional energy resources
- obtaining additional forage resources
- producing biofertilizers.