AMFER - Removal of Ammonia from Digestate & Wastewater
Nitrogen removal from ammonia containing water / sludge / digestate and the production of (artificial) fertiliser. During the fermentation of manure and other organic substrates the organic nitrogen present is largely transformed into ammonia (NH4) nitrogen. The high nitrogen content constitutes a limiting factor for field application of the digestate (as a result of European nitrate directive). Current digestate treatment is making use of biological pathways to convert NH4–N into nitrogen gas. These techniques require considerable amounts of energy and result in the loss of nitrogen as nutrient. The AMFER® technology can be applied to produce ammoniumsulphate, which can be used as an (artificial) fertiliser.
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Via a batchwise or continuous operation the ammoni...
Via a batchwise or continuous operation the ammonia is liberated and removed. For this purpose the digestate is simultaneously heated and aerated. The process is executed at a temperature of around 60°C and there is no need to add chemicals. The thermal energy required can be obtained form the existing CHP installation.
Process
As a result of the raise of both temperature and pH the ammonia (NH3) is liberated and effectively removed via aeration. The stripping air is transferred from the stripping tank into the washing column. In this column the air stream is brought into contact with an acid washing fluid (H2S04), whereby the NH3 is fixated under formation of ammonium sulphate ((NH4)2S04). The cleaned air is reintroduced in the process for aeration or purged to the outside.
Results
The operational costs (OPEX) of the AMFER® installation are very attractive in comparison to other nitrogen removal technologies. They consist of costs for the maintenance, the electrical energy for the pumps, the aeration and the purchase of the acid.
This is largely compensated however by the revenue...
This is largely compensated however by the revenue from the commercialisation of the ammonium sulphate fertiliser. The fertiliser (NPK = 9-0-0-26(SO3)) can be directly applied in liquid form or can be used as a raw material in fertiliser production 3).