Eko - Anaerobic Plant
The whole world understands that fossil fuels are limited and we will not be able to keep the present level of energy use. One solution is the use of agricultural biomass ( dedicated cultivations, agricultural waste, waste produced by food farming industry) and livestock effluents (swine, bovine, ovine slurry and dung), which, through anaerobic digestion, are turned into biogas, totally used to produce energy. Fossil fuels have been forming for million years, while biomass exploiting time, through anaerobic digestion, is equal to its regeneration time. CO2 emissions to the atmosphere are altogether nonexistent, since the quantity released during the process to produce energy is equivalent to the quantity used by the plant to grow.
We can save 200 gr of CO2 for each Kwh of electricity produced through this process, considering also that decomposing organic waste, without any treatment, release CH4 which has a greenhouse effect 20 times superior to CO2.
The following socio-economic contexts help promoting this technology:
- increase of global demand for green energy.
- demand to reduce CO2 and other greenhouse gases.
- exponential increase of the price of fossil fuels.
- demand for energy indipendency
The positive aspects of the use of agricultural biomass and waste, and livestock slurry through anaerobic digestion are as follows:
- biomass is a renewable energy source (FER)
- reduction of CO2 emissions
- opportunity for farmers to be competitive,to have revenues ( through power selling, Green Certificates,Energy Bill),and energy indipendency
- keeping biodiversity of cultivations, soil fertility and renaturalization of overused soil through anaerobic digestion stable and odourless muds
- reduction of road transport. Eko Technology uses a “short distribution” plant with power lower than 1MWe, plants placed in an area of 100 hectares and using the surrounding agricultural resources
ANAEROBIC DIGESTION OF ORGANIC FRACTION OF MUNICIPAL SOLID WASTE (O.F.M.S.W.)
Anaerobic digestion of M.S.W. and biomass are actual news and a great opportunity to meet the demand for waste disposal and to have eco-friendly and economic advantages from biogas production.
There has been in Europe a continuous increase of annual waste disposal ( from 2001 to 2005, increase of 430.000 ton/year) and of number and size of plants for the last ten years. In Spain, Belgium, Holland, Switzerland and Germany, 5-10% of O.F.M.S.W. potentiality is processed through anaerobic digestion.
In Italy, 1% of O.F.M.S.W. potentiality is processed through anaerobic digestion only, so we can foresee an important development for the next years, since new suppliers for this technology and new companies operating in the waste field entered the italian market.
Recent environment laws support this development and on one hand, they impose separate waste collection of organic fraction of M.S.W. and the gradual removal of organic waste destined to landfill site, on the other hand they promote, also with economic aids, power production from renewable sources.
Anaerobic digestion plants for power production are considered renewable sources and so they benefit of incentive pays.
Raw material is a revenue in anaerobic digestion plant management if it has no value as it is and the owner needs to get rid of it.
EKO TECHNOLOGY TERMOPHILIC ANAEROBIC PLANT
The anaerobic digestion is a biochemical conversion process of complex organic substances into biogas through specialized microorganisms.
The conversion into biogas takes place in absence of oxigen (airtight digestors mean absence of greenhouse gas emissions and smells). Biogas is composed 60-80% of methane and the rest of carbon dioxide.
Biogas is used for endothermal engines to produce power.
The produced heat is used for self-consumption.
The following biomass and organic waste are conveniently used to produce biogas:
- animal dungs ( swine, bovine, ovine)
- coltural residues ( straw, beetroot etc...)
- agricultural and industrial organic waste (buttermilk, plant waste,sludges, wastewater from distilleries, breweries, wine producer)
- waste from slaughtering ( grease, entrails, blood, flotation sludges
- depuration sludges
- organic fractions of municipal solid waste and kitchen waste
- energy cultivation (maize, sorghum, grass)
- human excrements (organic, solid and liquid)
PRODUCTS FROM ANAEROBIC DIGESTION
The main products from anaerobic digestion are three:
- biogas used for energy purposes
- The sludges, obtained after dehydration and separation process at the end of the anaerobic cycle, are used in agriculture, since they have chemical and physical requirements, complying with the present laws . It has fertilizing elements and fixed nitrogen, so the plants can easily assimilate it.
- The sludge, after the process of anaerobic stabilization, is odourless.
- Another advantage of anaerobic digestion is the little quantity of produced sludges: each kilo of dry biomass produces, after the anaerobic digestion, 50 grams of stable and hygienized sludge, while aerobic processes of composting produce more biomass and smell due to the presence of oxigene
- The water produced after the solid-liquid separation, flows to a biological purification system which returns both a purified water ( suitable for the sewers or for the soil , prior further treatment, or to be used as dilution water for the digesters or for irrigation), and a damp sludge with a methanization potencial of 42 Nm3/ton, which is sent again to anaerobic digestion process with the other substrata to provide for the organic waste during delivery alteration and to grant a constant nutrient supply
THE TECHNOLOGICAL CHOICE: “THERMOPHILIA”
Eko Technology builds plants to transform fermenting organic fractions through thermophilic anaerobic digestion where digester temperature reaches 55°C. This kind of anaerobic digester is an off-center plant producing power, granting economy, safety and revenue to run the production process.
This process has the following features:
- wet system with 10%-15% of dry materials and a carbon/nitrogen ratio <20
- thermophilic process (T=55°)
- nonstop process with recirculation
- totally mixed digesters
- substratum permanence of 15-22 days
- control of stability and function parameters is made through an automatic data capture (PLC, process level control)
Eko Technology is aiming to increase the total efficiency of the anaerobic plant, acting on the following points
increase of the degrading efficiency of the plant and increase of methane percentage in biogas through thermal thermophilic process
agricultural use of the solids separated of anaerobic final process, stable and odourless , according to the present laws
reuse of the water, coming from the biological purifier joined to the anaerobic plant, for irrigation or industrial use.
The advantages of the thermophilic anaerobic digestion:
- reduction of carbon dioxide for each kWe produced and increase of the biogas heating power ( 75% standard methane average )
- better anaerobic degradation
- it is possible to reduce the digester size without reducing the biogas production
- elimination of pathogens (salmonella etc...) this way it is not necessary to disinfect the product from anaerobic final cycle.
- Higher level of nitrogen in nitrification form (free form) in the wastewater to purify, which is more quickly used by the aerobic bacterial flora ( elimination of the pre-treatments of the liquids separated of anaerobic final cycle)
- low production of stable and sterilized sludges, therefore odourless.
- The sludge is a very good agricultural fertilizer, with nitrogen quickly absorbed by plants
THE DELIVERY OF THE BEST BIOGAS QUALITY IS THE GUARANTEE FOR THE BEST ENERGY PERFORMANCE
Degrading efficiency of an anaerobic plant depends on several factors, such as the choice of building and caulking materials of the digesters, the kind of process, etc....
Therefore, at the beginning of planning and calculation, we have to consider very carefully the factors determinig the gap among the academic results and the real ones.
From 1973 on, as a consequence of the oil crisis, people showed great interest for anaerobic digestion, but the great expectations were not completely satisfied.
Anaerobic digestion was considered not sure and too complicated to manage the great quantity of materials involved.
Critical attitudes for anaerobic digestion mainly derived from the low technical knowledge and the low practical experience. Nowadays, the anarobic digestion process has improved very much due to new knowledge and successful implementations.
Eko Technology is proposing new technology and plants which are strictly related to the optimization of the degrading process, to obtain a larger and constant methane production; lower is the quantity of the material to digest, more stable is the product.
The maximization of the biogas quality is the result of careful studies and controls on the plants and on the process.