Photocatalysis / Nitrogen Eater System

Picture: Draw of the prototype including the three photocatalytic reactors.

DESCRIPTION OF THE PROCESS

We propose an innovation based on a whole new concept, as a result of a research financed by the Regione Lombardia within the project Invito Permanente 2007 – 2009 named "Photovoltaic treatment for the processing of the nitrogenous compounds inside liquid manure".

The technical pro position of the innovation is based on the processing of the nitrogenous compounds inside the liquid manure into gaseous nitrogen, through photocatalysis process.

The system can operate both on zootechnical liquid manure as such, and on the digestate liquid manure after a treatment of mechanical separation, in particular it works on the liquid separated fractions that it drags and it contains almost all the nitrogen produced at origin.
The system we suggest, totally innovative, is based on the reduction of the nitrogen content in husbandry's manure through photocatalythic oxidation of the ammonium hydrogen, mainly at ammonia nitrogen, on semiconductor metallic oxids especially adusted.
In particular, the separated liquid part of the husbandry's manure is first made thermostable and aerated, then put in contact with thin films of photo-active phase, enlightened by special lamps. The disposition of the system includes the
adoption of three reactors made mainly in stainless steel and in pyrex-glass designed for the photocatalytic treatment.
The liquid matter coming from the separation station is then stored in the first tank which is equipped with submerged lamps at low consumption where it is subjected to photo-oxidation of the ammonia mainly in molecular nitrogen.
The second reactor is designed for the percolation of the liquid part on a slipway that is covered of photo-active phase radiated with an external lamp. This film is active even under radiation by lamps simulating the light of the sun. The liquid that is specially treated, in which we find the conversion of the nitrogenous compounds up to 60% in 6 hours of radiance with a selectivity of the molecular nitrogen up to 80%, is then collected and conveyed to the final storage for the distribution planned according to the laws.

The stripped nitrogen fraction of the first reactor in gaseous phase is then conveyed to the nitrogen in a photocatalytic cell that operates in gas-solid phase. This simple system does not require management by specialized technicians and allows the farm sto stay within the limits according the rules of the Direttive Nitrati with investment and management costs which amount to a third compared with the current costs.

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