Within manure management strategies, treatment facilities aiming at reducing the nitrogen content of effluent to be spread on fields do not have to become a source of pollution themselves through transferring the problem from soil and water to the atmosphere. In this context, an interesting solution for the treatment of slurry that meets both requirements is the nitrification-denitrification (DN-N) process. The biological reactions that occur in a DN-N plant remove nitrogen as N2, an inert gas in the atmosphere, thus reducing further fermentation and the consequent emission of nitrogen from the following storage and land spreading operations. Nitrification is positively affected by temperature. According to Monod kinetic, a nitrogen removal rate at 30 °C is three times greater than the amount that can be processed at 20 °C. This has been verified through an experimental test using a DN-N pilot plant operating with swine liquid manure. The nitrogen removal rate increased from 1.5 gN-NH4/d to more than 8 g N-NH4/d. At a farm-scale, to warm the nitrification reactor, the heat generated by the CHP unit of a biogas plant can be used. Keeping a high and constant temperature in the nitrification reactor allows a steady nitrification-dentirification process during the entire year, and the possibility, when needed, to increase the load without increasing the volume of tank reactors.
Use of heat from anaerobic digestion to improve the nitrification-denitrification process. first results from a pilot plant
RUMOR, CLELIA;GUERCINI, STEFANO;
2012
Abstract
Within manure management strategies, treatment facilities aiming at reducing the nitrogen content of effluent to be spread on fields do not have to become a source of pollution themselves through transferring the problem from soil and water to the atmosphere. In this context, an interesting solution for the treatment of slurry that meets both requirements is the nitrification-denitrification (DN-N) process. The biological reactions that occur in a DN-N plant remove nitrogen as N2, an inert gas in the atmosphere, thus reducing further fermentation and the consequent emission of nitrogen from the following storage and land spreading operations. Nitrification is positively affected by temperature. According to Monod kinetic, a nitrogen removal rate at 30 °C is three times greater than the amount that can be processed at 20 °C. This has been verified through an experimental test using a DN-N pilot plant operating with swine liquid manure. The nitrogen removal rate increased from 1.5 gN-NH4/d to more than 8 g N-NH4/d. At a farm-scale, to warm the nitrification reactor, the heat generated by the CHP unit of a biogas plant can be used. Keeping a high and constant temperature in the nitrification reactor allows a steady nitrification-dentirification process during the entire year, and the possibility, when needed, to increase the load without increasing the volume of tank reactors.
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